aboutsummaryrefslogblamecommitdiffstats
path: root/erts/emulator/beam/io.c
blob: 8c1126aa6ec1de11a423f38be01c215c449b2260 (plain) (tree)
1
2
3
4
5
6
7
8
9
10
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734

                   
  
                                                        
  




                                                                      
  



                                                                         
  
















                                                                       
                    























                                                                                                 














                                                                             








                                                                    




                               

                  

                                       
























                                                                       










































































                                                                                
                                                                                               
























































































                                                                














                                    



                            










                                                                














































































































                                                                            

                                                     
                                                                     


                         
                                                             
















































































































































































































































                                                                              
                                       














































































































































































































































































































































































































































































                                                                                         
                                                                                


























































































                                                                          















































                                                                        






                                                       
                                                                                       












                                                  
                                                                    










                                                                
                                            
                                            





































































































































































































































































                                                                                     

                                                     




                                             
                                                   













































































































































                                                                             

                                                         




                                             
                                                           









































































































                                                                              
                                
































































































































































































                                                                               
                           




                                                           
                             


























































































































































































































                                                                                       

                                                               


                                                     
                                                                        


























































































































































                                                                                     
                                                                    




























































































































































































































































































































































































                                                                               


                                                         


                                                                   
      




                                                       


                                                         


                                                                   
      





































































































































































                                                                             


                                                              





                                                      
      



                                                       


                                                              





                                                     
      





































                                                                                                      

                                                             




                                                             
                                                           






























                                                                         

                                                              


                                                    
                                                            





























































































































































                                                                                 
                                                                    

































                                                                           
                                                                    











































































                                                                                
                                                                     










































                                                                             
          


                                          
                                                     

 
          


                                          
                                                        

 
          


                                          
                                                        

















































































































                                                                       
                             

                            
                                                    
                              
                             








                                                 
                             

                               
                                                       
                             
                             










                                                 
                             

                               
                                                       
                              
                             








                                                  

























                                                                        


































                                                                                      
                    








                                                                         
          




                                  
          

                                  
                                            
                
                                                               
                            



                
          

                                  
                                            
                

                                                               
































































































































































































































































































































































































                                                                               
                                




                                                          
                                            
















                                                                  
                            





























                                                         
                                                                  
     
                                  






                                       
                         




                               



                                                












                                                                




                                                            
 

                
 








                                                                
 


                                                                     
 




                                                  
























































                                                                                                      
 

                































                                                         


















































                                                                                             

                                                                         
              














                                                     




















































                                                                                             














                                                                  
                              
                                                         
                                    




                                            
                                


                                                            
                              

                                                     
                                




















































































































































































































































































































                                                                                                







                                                                 































































































































































































































































                                                                                       
/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 1996-2011. All Rights Reserved.
 *
 * The contents of this file are subject to the Erlang Public License,
 * Version 1.1, (the "License"); you may not use this file except in
 * compliance with the License. You should have received a copy of the
 * Erlang Public License along with this software. If not, it can be
 * retrieved online at http://www.erlang.org/.
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * %CopyrightEnd%
 */

/* 
 * I/O routines for manipulating ports.
 */

#define ERL_IO_C__

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "sys.h"

/* must be included BEFORE global.h (since it includes erl_driver.h) */
#include "erl_sys_driver.h"
#include "erl_nif.h"

#include "erl_vm.h"
#include "global.h"
#include "erl_process.h"
#include "dist.h"
#include "big.h"
#include "erl_binary.h"
#include "erl_bits.h"
#include "erl_version.h"
#include "error.h"

extern ErlDrvEntry fd_driver_entry;
extern ErlDrvEntry vanilla_driver_entry;
extern ErlDrvEntry spawn_driver_entry;
extern ErlDrvEntry *driver_tab[]; /* table of static drivers, only used during initialization */

erts_driver_t *driver_list; /* List of all drivers, static and dynamic. */
erts_smp_mtx_t erts_driver_list_lock; /* Mutex for driver list */
static erts_smp_tsd_key_t driver_list_lock_status_key; /*stop recursive locks when calling 
							 driver init */
static erts_smp_tsd_key_t driver_list_last_error_key;  /* Save last DDLL error on a 
							  per thread basis (for BC interfaces) */

Port*      erts_port; /* The port table */
erts_smp_atomic_t erts_bytes_out;	/* No bytes sent out of the system */
erts_smp_atomic_t erts_bytes_in;	/* No bytes gotten into the system */

Uint erts_max_ports;
Uint erts_port_tab_index_mask;

const ErlDrvTermData driver_term_nil = (ErlDrvTermData)NIL;

erts_driver_t vanilla_driver;
erts_driver_t spawn_driver;
erts_driver_t fd_driver;

static int init_driver(erts_driver_t *, ErlDrvEntry *, DE_Handle *);
static void terminate_port(Port *p);
static void pdl_init(void);
#ifdef ERTS_SMP
static void driver_monitor_lock_pdl(Port *p);
static void driver_monitor_unlock_pdl(Port *p);
#define DRV_MONITOR_LOCK_PDL(Port) driver_monitor_lock_pdl(Port)
#define DRV_MONITOR_UNLOCK_PDL(Port) driver_monitor_unlock_pdl(Port)
#else
#define DRV_MONITOR_LOCK_PDL(Port) /* nothing */
#define DRV_MONITOR_UNLOCK_PDL(Port) /* nothing */
#endif

static ERTS_INLINE ErlIOQueue*
drvport2ioq(ErlDrvPort drvport)
{
    int ix = (int) drvport;
    Uint32 status;

    if (ix < 0 || erts_max_ports <= ix)
	return NULL;

    if (erts_get_scheduler_data()) {
	ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(&erts_port[ix]));
	ERTS_LC_ASSERT(!erts_port[ix].port_data_lock
		       || erts_lc_mtx_is_locked(
			   &erts_port[ix].port_data_lock->mtx));

	status = erts_port[ix].status;
    }
    else {
	erts_smp_port_state_lock(&erts_port[ix]);
	status = erts_port[ix].status;
	erts_smp_port_state_unlock(&erts_port[ix]);

	ERTS_LC_ASSERT((status & ERTS_PORT_SFLGS_INVALID_DRIVER_LOOKUP)
		       || erts_port[ix].port_data_lock);
	ERTS_LC_ASSERT(!erts_port[ix].port_data_lock
		       || erts_lc_mtx_is_locked(
			   &erts_port[ix].port_data_lock->mtx));

    }

    return ((status & ERTS_PORT_SFLGS_INVALID_DRIVER_LOOKUP)
	    ? NULL
	    : &erts_port[ix].ioq);
}

static ERTS_INLINE int
is_port_ioq_empty(Port *pp)
{
    int res;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(pp));
    if (!pp->port_data_lock)
	res = (pp->ioq.size == 0);
    else {
	ErlDrvPDL pdl = pp->port_data_lock;
	erts_mtx_lock(&pdl->mtx);
	res = (pp->ioq.size == 0);
	erts_mtx_unlock(&pdl->mtx);
    }
    return res;
}

int
erts_is_port_ioq_empty(Port *pp)
{
    return is_port_ioq_empty(pp);
}

Uint
erts_port_ioq_size(Port *pp)
{
    int res;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(pp));
    if (!pp->port_data_lock)
	res = pp->ioq.size;
    else {
	ErlDrvPDL pdl = pp->port_data_lock;
	erts_mtx_lock(&pdl->mtx);
	res = pp->ioq.size;
	erts_mtx_unlock(&pdl->mtx);
    }
    return (Uint) res;
}

/*
 * Line buffered I/O.
 */
typedef struct line_buf_context {
    LineBuf **b;
    char *buf;
    int left;
    int retlen;
} LineBufContext;

#define LINEBUF_EMPTY 0
#define LINEBUF_EOL 1
#define LINEBUF_NOEOL 2
#define LINEBUF_ERROR -1

#define LINEBUF_STATE(LBC) ((*(LBC).b)->data[0])

#define LINEBUF_DATA(LBC) (((*(LBC).b)->data) + 1)
#define LINEBUF_DATALEN(LBC) ((LBC).retlen)

#define LINEBUF_INITIAL 100


/* The 'number' field in a port now has two parts: the lowest bits
   contain the index in the port table, and the higher bits are a counter
   which is incremented each time we look for a free port and start from
   the beginning of the table. erts_max_ports is the number of file descriptors,
   rounded up to a power of 2.
   To get the index from a port, use the macro 'internal_port_index';
   'port_number' returns the whole number field.
*/

static erts_smp_spinlock_t get_free_port_lck;
static Uint last_port_num;
static Uint port_num_mask;
erts_smp_atomic32_t erts_ports_snapshot; /* Identifies the _next_ snapshot (not the ongoing) */


static ERTS_INLINE void
kill_port(Port *pp)
{
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(pp));
    erts_port_task_free_port(pp);
    ASSERT(pp->status & ERTS_PORT_SFLGS_DEAD);
}

#ifdef ERTS_SMP

#ifdef ERTS_ENABLE_LOCK_CHECK
int
erts_lc_is_port_locked(Port *prt)
{
    if (!prt)
	return 0;
    return erts_smp_lc_mtx_is_locked(prt->lock);
}
#endif

#endif /* #ifdef ERTS_SMP */

static int
get_free_port(void)
{
    Uint num;
    Uint tries = erts_max_ports;
    Port* port;    

    erts_smp_spin_lock(&get_free_port_lck);
    num = last_port_num + 1;
    for (;; ++num) {	
	port = &erts_port[num & erts_port_tab_index_mask];

	erts_smp_port_state_lock(port);
	if (port->status & ERTS_PORT_SFLG_FREE) {
	    last_port_num = num;
	    erts_smp_spin_unlock(&get_free_port_lck);
	    break;
	}
	erts_smp_port_state_unlock(port);

	if (--tries == 0) {
	    erts_smp_spin_unlock(&get_free_port_lck);
	    return -1;
	}
    }
    port->status = ERTS_PORT_SFLG_INITIALIZING;
#ifdef ERTS_SMP
    ERTS_SMP_LC_ASSERT(erts_smp_atomic_read(&port->refc) == 0);
    erts_smp_atomic_set(&port->refc, 2); /* Port alive + lock */
#endif	
    erts_smp_port_state_unlock(port);
    return num & port_num_mask;
}

/*
 * erts_test_next_port() is only used for testing.
 */
Sint
erts_test_next_port(int set, Uint next)
{
    Uint i, num;
    Sint res = -1;

    erts_smp_spin_lock(&get_free_port_lck);
    if (set) {
	last_port_num = (next - 1) & port_num_mask;
    }
    num = last_port_num + 1;

    for (i=0; i < erts_max_ports && res<0; ++i, ++num) {	
	
	Port* port = &erts_port[num & erts_port_tab_index_mask];

	erts_smp_port_state_lock(port);

	if (port->status & ERTS_PORT_SFLG_FREE) {	   
	    last_port_num = num - 1;
	    res = num & port_num_mask;
	}
	erts_smp_port_state_unlock(port);
    }
    erts_smp_spin_unlock(&get_free_port_lck);
    return res;
}


static void port_cleanup(Port *prt);

#ifdef ERTS_SMP

static void
sched_port_cleanup(void *vprt)
{
    Port *prt = (Port *) vprt;
    erts_smp_mtx_lock(prt->lock);
    port_cleanup(prt);
}

#endif

void
erts_port_cleanup(Port *prt)
{
#ifdef ERTS_SMP
    if (erts_smp_mtx_trylock(prt->lock) == EBUSY)
	erts_schedule_misc_op(sched_port_cleanup, (void *) prt);
    else
#endif
	port_cleanup(prt);
}

void
port_cleanup(Port *prt)
{
#ifdef ERTS_SMP
    Uint32 port_specific;
    erts_smp_mtx_t *mtx;
#endif
    erts_driver_t *driver;

    erts_smp_port_state_lock(prt);

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    driver = prt->drv_ptr;
    prt->drv_ptr = NULL;
    ASSERT(driver);

#ifdef ERTS_SMP

    ASSERT(prt->status & ERTS_PORT_SFLG_FREE_SCHEDULED);
    ERTS_SMP_LC_ASSERT(erts_smp_atomic_read(&prt->refc) == 0);

    port_specific = (prt->status & ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK);

    mtx = prt->lock;
    ASSERT(mtx);

    prt->lock = NULL;

    ASSERT(prt->status & ERTS_PORT_SFLG_PORT_DEBUG);
    ASSERT(!(prt->status & ERTS_PORT_SFLG_FREE));
    prt->status = ERTS_PORT_SFLG_FREE;

    erts_smp_port_state_unlock(prt);    
    erts_smp_mtx_unlock(mtx);

    if (port_specific) {
	erts_smp_mtx_destroy(mtx);
	erts_free(ERTS_ALC_T_PORT_LOCK, mtx);
    }
#endif

    if (driver->handle)
	erts_ddll_dereference_driver(driver->handle);
}


/*
** Initialize v_start to point to the small fixed vector.
** Once (reallocated) we never reset the pointer to the small vector
** This is a possible optimisation.
*/
static void initq(Port* prt)
{
    ErlIOQueue* q = &prt->ioq;

    ERTS_LC_ASSERT(!prt->port_data_lock);

    q->size = 0;
    q->v_head = q->v_tail = q->v_start = q->v_small;
    q->v_end = q->v_small + SMALL_IO_QUEUE;
    q->b_head = q->b_tail = q->b_start = q->b_small;
    q->b_end = q->b_small + SMALL_IO_QUEUE;
}

static void stopq(Port* prt)
{
    ErlIOQueue* q;
    ErlDrvBinary** binp;

    if (prt->port_data_lock)
	driver_pdl_lock(prt->port_data_lock);

    q = &prt->ioq;
    binp = q->b_head;

    if (q->v_start != q->v_small)
	erts_free(ERTS_ALC_T_IOQ, (void *) q->v_start);

    while(binp < q->b_tail) {
	if (*binp != NULL)
	    driver_free_binary(*binp);
	binp++;
    }
    if (q->b_start != q->b_small)
	erts_free(ERTS_ALC_T_IOQ, (void *) q->b_start);
    q->v_start = q->v_end = q->v_head = q->v_tail = NULL;
    q->b_start = q->b_end = q->b_head = q->b_tail = NULL;
    q->size = 0;

    if (prt->port_data_lock) {
	driver_pdl_unlock(prt->port_data_lock);
	driver_pdl_dec_refc(prt->port_data_lock);
	prt->port_data_lock = NULL;
    }
}



static void
setup_port(Port* prt, Eterm pid, erts_driver_t *driver, 
	   ErlDrvData drv_data, char *name, Uint32 xstatus)
{
    ErtsRunQueue *runq = erts_get_runq_current(NULL);
    char *new_name, *old_name;
#ifdef DEBUG
    /* Make sure the debug flags survives until port is freed */
    xstatus |= ERTS_PORT_SFLG_PORT_DEBUG;
#endif
    ASSERT(runq);
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    
    new_name = (char*) erts_alloc(ERTS_ALC_T_PORT_NAME, sys_strlen(name)+1);
    sys_strcpy(new_name, name);
    erts_smp_runq_lock(runq);
    erts_smp_port_state_lock(prt);    
    prt->status = ERTS_PORT_SFLG_CONNECTED | xstatus;
    prt->snapshot = erts_smp_atomic32_read(&erts_ports_snapshot);    
    old_name = prt->name;
    prt->name = new_name;
#ifdef ERTS_SMP
    erts_smp_atomic_set(&prt->run_queue, (erts_aint_t) runq);
#endif
    ASSERT(!prt->drv_ptr);
    prt->drv_ptr = driver;
    erts_smp_port_state_unlock(prt);
    erts_smp_runq_unlock(runq);
#ifdef ERTS_SMP
    ASSERT(!prt->xports);
#endif
    if (old_name) {
	erts_free(ERTS_ALC_T_PORT_NAME, (void *) old_name);
    }

    prt->control_flags = 0;
    prt->connected = pid;
    prt->drv_data = (long) drv_data;
    prt->bytes_in = 0;
    prt->bytes_out = 0;
    prt->dist_entry = NULL;
    prt->reg = NULL;
#ifdef ERTS_SMP
    prt->ptimer = NULL;
#else
    sys_memset(&prt->tm, 0, sizeof(ErlTimer));
#endif
    erts_port_task_handle_init(&prt->timeout_task);
    prt->suspended  = NULL;
    sys_strcpy(prt->name, name);
    prt->nlinks = NULL;
    prt->monitors = NULL;
    prt->linebuf = NULL;
    prt->bp = NULL;
    prt->data = am_undefined;
    /* Set default tracing */
    erts_get_default_tracing(&(prt->trace_flags), &(prt->tracer_proc));

    prt->psd = NULL;

    initq(prt);
}

void
erts_wake_process_later(Port *prt, Process *process)
{
    ErtsProcList** p;
    ErtsProcList* new_p;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if (prt->status & ERTS_PORT_SFLGS_DEAD)
	return;

    for (p = &(prt->suspended); *p != NULL; p = &((*p)->next))
	/* Empty loop body */;

    new_p = erts_proclist_create(process);
    new_p->next = NULL;
    *p = new_p;
}

/*
   Opens a driver.
   Returns the non-negative port number, if successful.
   If there is an error, -1 or -2 or -3 is returned. -2 means that
   there is valid error information in *error_number_ptr.
   Returning -3 means that an error in the given options was detected
   (*error_number_ptr must contain either BADARG or SYSTEM_LIMIT).
   The driver start function must obey the same conventions.
*/
int
erts_open_driver(erts_driver_t* driver,	/* Pointer to driver. */
		 Eterm pid,		/* Current process. */
		 char* name,		/* Driver name. */
		 SysDriverOpts* opts,	/* Options. */
		 int *error_number_ptr)	/* errno in case -2 is returned */
{
    int port_num;
    int port_ix;
    ErlDrvData drv_data = 0;
    Uint32 xstatus = 0;
    Port *port;
    int fpe_was_unmasked;

    if (error_number_ptr)
	*error_number_ptr = 0;

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    if ((port_num = get_free_port()) < 0) {
	if (error_number_ptr) {
	    *error_number_ptr = SYSTEM_LIMIT;
	}
	return -3;
    }

    port_ix = port_num & erts_port_tab_index_mask;
    port = &erts_port[port_ix];
    port->id = make_internal_port(port_num);

    erts_smp_mtx_lock(&erts_driver_list_lock);
    if (!driver) {
	for (driver = driver_list; driver; driver = driver->next) {
	    if (sys_strcmp(driver->name, name) == 0)
		break;
	}
	if (!driver) { 
	    erts_smp_mtx_unlock(&erts_driver_list_lock);
	    if (error_number_ptr)
		*error_number_ptr = BADARG;
	    return -3;
	}
    }
    if (driver == &spawn_driver) {
	char *p;
	erts_driver_t *d;

	/*
	 * Dig out the name of the driver or port program.
	 */

	if (!(opts->spawn_type & ERTS_SPAWN_EXECUTABLE)) {
	    /* No spawn driver default */
	    driver = NULL;
	}


	if (opts->spawn_type != ERTS_SPAWN_EXECUTABLE) {
	    p = name;
	    while(*p != '\0' && *p != ' ')
		p++;
	    if (*p == '\0')
		p = NULL;
	    else
		*p = '\0';

	    /*
	     * Search for a driver having this name.  Defaults to spawn_driver
	     * if not found.
	     */
	    
	    for (d = driver_list; d; d = d->next) {
		if (strcmp(d->name, name) == 0 && 
		    erts_ddll_driver_ok(d->handle)) {
		    driver = d;
		    break;
		}
	    }
	    if (p != NULL)
		*p = ' ';
	}
    }

    if (driver == NULL || (driver != &spawn_driver && opts->exit_status)) {
	erts_smp_mtx_unlock(&erts_driver_list_lock);
	if (error_number_ptr) {
	    *error_number_ptr = BADARG;
	}
	/* Need to mark the port as free again */
	erts_smp_port_state_lock(port);
	port->status = ERTS_PORT_SFLG_FREE;
#ifdef ERTS_SMP
	ERTS_SMP_LC_ASSERT(erts_smp_atomic_read(&port->refc) == 2);
	erts_smp_atomic_set(&port->refc, 0); 
#endif	
	erts_smp_port_state_unlock(port);
	return -3;
    }

    /*
     * We'll set up the port before calling the start function,
     * to allow message sending and setting timers in the start function.
     */

#ifdef ERTS_SMP
    ASSERT(!port->lock);
    port->lock = driver->lock;
    if (!port->lock) {
	port->lock = erts_alloc(ERTS_ALC_T_PORT_LOCK,
					      sizeof(erts_smp_mtx_t));
	erts_smp_mtx_init_x(port->lock,
			    "port_lock",
			    port->id);
	xstatus |= ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK;
    }
#endif

    if (driver->handle != NULL) {
	erts_ddll_increment_port_count(driver->handle);
	erts_ddll_reference_driver(driver->handle);
    }
    erts_smp_mtx_unlock(&erts_driver_list_lock);

#ifdef ERTS_SMP
    erts_smp_mtx_lock(port->lock);
#endif

    setup_port(port, pid, driver, drv_data, name, xstatus);
    
    if (IS_TRACED_FL(port, F_TRACE_PORTS)) {
	trace_port_open(port,
		pid,		
		am_atom_put(port->name, strlen(port->name)));
    }
    
    if (driver->start) {
	if (IS_TRACED_FL(port, F_TRACE_SCHED_PORTS)) {
	    trace_sched_ports_where(port, am_in, am_start);
	}
	port->caller = pid;
	fpe_was_unmasked = erts_block_fpe();
	drv_data = (*driver->start)((ErlDrvPort)(port_ix),
				    name, opts);
	erts_unblock_fpe(fpe_was_unmasked);
	port->caller = NIL;
	erts_unblock_fpe(fpe_was_unmasked);
	if (IS_TRACED_FL(port, F_TRACE_SCHED_PORTS)) {
	    trace_sched_ports_where(port, am_out, am_start);
	}
	if (error_number_ptr && ((long) drv_data) == (long) -2)
	    *error_number_ptr = errno;
#ifdef ERTS_SMP
	if (port->xports)
	    erts_smp_xports_unlock(port);
	ASSERT(!port->xports);
#endif
    }

    if (((long)drv_data) == -1 || 
	((long)drv_data) == -2 || 
	((long)drv_data) == -3) {
	int res = (int) ((long) drv_data);

	if (res == -3 && error_number_ptr) {
	    *error_number_ptr = BADARG;
	}

	/*
	 * Must clean up the port.
	 */
#ifdef ERTS_SMP
	erts_cancel_smp_ptimer(port->ptimer);
#else
	erts_cancel_timer(&(port->tm));
#endif
	stopq(port);
	kill_port(port);
	if (port->linebuf != NULL) {
	    erts_free(ERTS_ALC_T_LINEBUF,
		      (void *) port->linebuf);
	    port->linebuf = NULL;
	}
	if (driver->handle != NULL) {
	    erts_smp_mtx_lock(&erts_driver_list_lock);
	    erts_ddll_decrement_port_count(driver->handle);
	    erts_smp_mtx_unlock(&erts_driver_list_lock);
	}
	erts_port_release(port);
	return res;
    }
    port->drv_data = (long) drv_data;
    return port_ix;
}

#ifdef ERTS_SMP

struct ErtsXPortsList_ {
    ErtsXPortsList *next;
    Port *port;
};

ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(xports_list, ErtsXPortsList, 50, ERTS_ALC_T_XPORTS_LIST)

#endif

/*
 * Driver function to create new instances of a driver
 * Historical reason: to be used with inet_drv for creating
 * accept sockets inorder to avoid a global table.
 */
ErlDrvPort
driver_create_port(ErlDrvPort creator_port_ix, /* Creating port */
		   ErlDrvTermData pid,    /* Owner/Caller */
		   char* name,            /* Driver name */
		   ErlDrvData drv_data)   /* Driver data */
{
    Port *creator_port;
    Port* port;
    erts_driver_t *driver;
    Process *rp;
    int port_num;
    Eterm port_id;
    Uint32 xstatus = 0;

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    creator_port = erts_drvport2port(creator_port_ix);
    if (!creator_port)
	return (ErlDrvTermData) -1;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(creator_port));

    driver = creator_port->drv_ptr;
    erts_smp_mtx_lock(&erts_driver_list_lock);
    if (!erts_ddll_driver_ok(driver->handle)) {
	erts_smp_mtx_unlock(&erts_driver_list_lock);
	return (ErlDrvTermData) -1;
    }

    rp = erts_pid2proc(NULL, 0, pid, ERTS_PROC_LOCK_LINK);
    if (!rp) {
	erts_smp_mtx_unlock(&erts_driver_list_lock);
	return (ErlDrvTermData) -1;   /* pid does not exist */
    }
    if ((port_num = get_free_port()) < 0) {
	errno = ENFILE;
	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
	erts_smp_mtx_unlock(&erts_driver_list_lock);
	return (ErlDrvTermData) -1;
    }

    port_id = make_internal_port(port_num);
    port = &erts_port[port_num & erts_port_tab_index_mask];

#ifdef ERTS_SMP
    ASSERT(!port->lock);
    port->lock = driver->lock;
    if (!port->lock) {
	ErtsXPortsList *xplp = xports_list_alloc();
	xplp->port = port;
	xplp->next = creator_port->xports;
	creator_port->xports = xplp;
	port->lock = erts_alloc(ERTS_ALC_T_PORT_LOCK,
					      sizeof(erts_smp_mtx_t));
	erts_smp_mtx_init_locked_x(port->lock, "port_lock", port_id);
	xstatus |= ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK;
    }

#endif

    if (driver->handle != NULL) {
	erts_ddll_increment_port_count(driver->handle);
	erts_ddll_reference_referenced_driver(driver->handle);
    }
    erts_smp_mtx_unlock(&erts_driver_list_lock);

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(port));

    setup_port(port, pid, driver, drv_data, name, xstatus);
    port->id = port_id;

    erts_add_link(&(port->nlinks), LINK_PID, pid);
    erts_add_link(&(rp->nlinks), LINK_PID, port_id);
    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
    return port_num & erts_port_tab_index_mask;
}

#ifdef ERTS_SMP
void
erts_smp_xports_unlock(Port *prt)
{
    ErtsXPortsList *xplp;

    ASSERT(prt);
    xplp = prt->xports;
    ASSERT(xplp);
    while (xplp) {
	ErtsXPortsList *free_xplp;
	if (xplp->port->xports)
	    erts_smp_xports_unlock(xplp->port);
	erts_port_release(xplp->port);
	free_xplp = xplp;
	xplp = xplp->next;
	xports_list_free(free_xplp);
    }
    prt->xports = NULL;
}
#endif

/* Fills a possibly deep list of chars and binaries into vec
** Small characters are first stored in the buffer buf of length ln
** binaries found are copied and linked into msoh
** Return  vector length on succsess,
**        -1 on overflow
**        -2 on type error
*/

#define SET_VEC(iov, bv, bin, ptr, len, vlen) do {	\
   (iov)->iov_base = (ptr);				\
   (iov)->iov_len = (len);				\
   *(bv)++ = (bin);					\
   (iov)++;						\
   (vlen)++;						\
} while(0)

static int
io_list_to_vec(Eterm obj,	/* io-list */
	       SysIOVec* iov,	/* io vector */
	       ErlDrvBinary** binv, /* binary reference vector */
	       ErlDrvBinary* cbin, /* binary to store characters */
	       int bin_limit)	/* small binaries limit */
{
    DECLARE_ESTACK(s);
    Eterm* objp;
    char *buf  = cbin->orig_bytes;
    int len    = cbin->orig_size;
    int csize  = 0;
    int vlen   = 0;
    char* cptr = buf;

    goto L_jump_start;  /* avoid push */

    while (!ESTACK_ISEMPTY(s)) {
	obj = ESTACK_POP(s);
    L_jump_start:
	if (is_list(obj)) {
	L_iter_list:
	    objp = list_val(obj);
	    obj = CAR(objp);
	    if (is_byte(obj)) {
		if (len == 0)
		    goto L_overflow;
		*buf++ = unsigned_val(obj);
		csize++;
		len--;
	    } else if (is_binary(obj)) {
		ESTACK_PUSH(s, CDR(objp));
		goto handle_binary;
	    } else if (is_list(obj)) {
		ESTACK_PUSH(s, CDR(objp));
		goto L_iter_list;    /* on head */
	    } else if (!is_nil(obj)) {
		goto L_type_error;
	    }	    
	    obj = CDR(objp);
	    if (is_list(obj))
		goto L_iter_list; /* on tail */
	    else if (is_binary(obj)) {
		goto handle_binary;
	    } else if (!is_nil(obj)) {
		goto L_type_error;
	    }
	} else if (is_binary(obj)) {
	    Eterm real_bin;
	    Uint offset;
	    Eterm* bptr;
	    int size;
	    int bitoffs;
	    int bitsize;

	handle_binary:
	    size = binary_size(obj);
	    ERTS_GET_REAL_BIN(obj, real_bin, offset, bitoffs, bitsize);
	    ASSERT(bitsize == 0);
	    bptr = binary_val(real_bin);
	    if (*bptr == HEADER_PROC_BIN) {
		ProcBin* pb = (ProcBin *) bptr;
		if (bitoffs != 0) {
		    if (len < size) {
			goto L_overflow;
		    }
		    erts_copy_bits(pb->bytes+offset, bitoffs, 1,
				   (byte *) buf, 0, 1, size*8);
		    csize += size;
		    buf += size;
		    len -= size;
		} else if (bin_limit && size < bin_limit) {
		    if (len < size) {
			goto L_overflow;
		    }
		    sys_memcpy(buf, pb->bytes+offset, size);
		    csize += size;
		    buf += size;
		    len -= size;
		} else {
		    if (csize != 0) {
			SET_VEC(iov, binv, cbin, cptr, csize, vlen);
			cptr = buf;
			csize = 0;
		    }
		    if (pb->flags) {
			erts_emasculate_writable_binary(pb);
		    }
		    SET_VEC(iov, binv, Binary2ErlDrvBinary(pb->val),
			    pb->bytes+offset, size, vlen);
		}
	    } else {
		ErlHeapBin* hb = (ErlHeapBin *) bptr;
		if (len < size) {
		    goto L_overflow;
		}
		copy_binary_to_buffer(buf, 0,
				      ((byte *) hb->data)+offset, bitoffs,
				      8*size);
		csize += size;
		buf += size;
		len -= size;
	    }
	} else if (!is_nil(obj)) {
	    goto L_type_error;
	}
    }

    if (csize != 0) {
	SET_VEC(iov, binv, cbin, cptr, csize, vlen);
    }

    DESTROY_ESTACK(s);
    return vlen;

 L_type_error:
    DESTROY_ESTACK(s);
    return -2;

 L_overflow:
    DESTROY_ESTACK(s);
    return -1;
}

#define IO_LIST_VEC_COUNT(obj)						\
do {									\
    int _size = binary_size(obj);					\
    Eterm _real;							\
    Uint _offset;							\
    int _bitoffs;							\
    int _bitsize;							\
    ERTS_GET_REAL_BIN(obj, _real, _offset, _bitoffs, _bitsize);		\
    ASSERT(_bitsize == 0);						\
    if (thing_subtag(*binary_val(_real)) == REFC_BINARY_SUBTAG &&	\
	_bitoffs == 0) {						\
	b_size += _size;						\
	in_clist = 0;							\
	v_size++;							\
        if (_size >= bin_limit) {					\
            p_in_clist = 0;						\
            p_v_size++;							\
        } else {							\
            p_c_size += _size;						\
            if (!p_in_clist) {						\
                p_in_clist = 1;						\
                p_v_size++;						\
            }								\
        }								\
    } else {								\
	c_size += _size;						\
	if (!in_clist) {						\
	    in_clist = 1;						\
	    v_size++;							\
	}								\
	p_c_size += _size;						\
	if (!p_in_clist) {						\
	    p_in_clist = 1;						\
	    p_v_size++;							\
	}								\
    }									\
} while (0)


/* 
** Size of a io list in bytes
** return -1 if error
** returns:            - Total size of io list
**           vsize     - SysIOVec size needed for a writev
**           csize     - Number of bytes not in binary (in the common binary)
**           pvsize    - SysIOVec size needed if packing small binaries
**           pcsize    - Number of bytes in the common binary if packing
*/

static int 
io_list_vec_len(Eterm obj, int* vsize, int* csize, 
		int bin_limit, /* small binaries limit */
		int * pvsize, int * pcsize)
{
    DECLARE_ESTACK(s);
    Eterm* objp;
    int v_size = 0;
    int c_size = 0;
    int b_size = 0;
    int in_clist = 0;
    int p_v_size = 0;
    int p_c_size = 0;
    int p_in_clist = 0;

    goto L_jump_start;  /* avoid a push */

    while (!ESTACK_ISEMPTY(s)) {
	obj = ESTACK_POP(s);
    L_jump_start:
	if (is_list(obj)) {
	L_iter_list:
	    objp = list_val(obj);
	    obj = CAR(objp);

	    if (is_byte(obj)) {
		c_size++;
		if (!in_clist) {
		    in_clist = 1;
		    v_size++;
		}
		p_c_size++;
		if (!p_in_clist) {
		    p_in_clist = 1;
		    p_v_size++;
		}
	    }
	    else if (is_binary(obj)) {
		IO_LIST_VEC_COUNT(obj);
	    }
	    else if (is_list(obj)) {
		ESTACK_PUSH(s, CDR(objp));
		goto L_iter_list;   /* on head */
	    }
	    else if (!is_nil(obj)) {
		goto L_type_error;
	    }

	    obj = CDR(objp);
	    if (is_list(obj))
		goto L_iter_list;   /* on tail */
	    else if (is_binary(obj)) {  /* binary tail is OK */
		IO_LIST_VEC_COUNT(obj);
	    }
	    else if (!is_nil(obj)) {
		goto L_type_error;
	    }
	}
	else if (is_binary(obj)) {
	    IO_LIST_VEC_COUNT(obj);
	}
	else if (!is_nil(obj)) {
	    goto L_type_error;
	}
    }

    DESTROY_ESTACK(s);
    if (vsize != NULL)
	*vsize = v_size;
    if (csize != NULL)
	*csize = c_size;
    if (pvsize != NULL)
	*pvsize = p_v_size;
    if (pcsize != NULL)
	*pcsize = p_c_size;
    return c_size + b_size;

 L_type_error:
    DESTROY_ESTACK(s);
    return -1;
}

#define ERL_SMALL_IO_BIN_LIMIT (4*ERL_ONHEAP_BIN_LIMIT)
#define SMALL_WRITE_VEC  16


/* write data to a port */
int erts_write_to_port(Eterm caller_id, Port *p, Eterm list)
{
    char *buf;
    erts_driver_t *drv = p->drv_ptr;
    int size;
    int fpe_was_unmasked;
    
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(p));
    ERTS_SMP_CHK_NO_PROC_LOCKS;

    p->caller = caller_id;
    if (drv->outputv != NULL) {
	int vsize;
	int csize;
	int pvsize;
	int pcsize;
	int blimit;
	SysIOVec iv[SMALL_WRITE_VEC];
	ErlDrvBinary* bv[SMALL_WRITE_VEC];
	SysIOVec* ivp;
	ErlDrvBinary**  bvp;
	ErlDrvBinary* cbin;
	ErlIOVec ev;

	if ((size = io_list_vec_len(list, &vsize, &csize, 
				    ERL_SMALL_IO_BIN_LIMIT,
				    &pvsize, &pcsize)) < 0) {
	    goto bad_value;
	}
	/* To pack or not to pack (small binaries) ...? */
	vsize++;
	if (vsize <= SMALL_WRITE_VEC) {
	    /* Do NOT pack */
	    blimit = 0;
	} else {
	    /* Do pack */
	    vsize = pvsize + 1;
	    csize = pcsize;
	    blimit = ERL_SMALL_IO_BIN_LIMIT;
	}
	/* Use vsize and csize from now on */
	if (vsize <= SMALL_WRITE_VEC) {
	    ivp = iv;
	    bvp = bv;
	} else {
	    ivp = (SysIOVec *) erts_alloc(ERTS_ALC_T_TMP,
					  vsize * sizeof(SysIOVec));
	    bvp = (ErlDrvBinary**) erts_alloc(ERTS_ALC_T_TMP,
					      vsize * sizeof(ErlDrvBinary*));
	}
	cbin = driver_alloc_binary(csize);
	if (!cbin)
	    erts_alloc_enomem(ERTS_ALC_T_DRV_BINARY, ERTS_SIZEOF_Binary(csize));

	/* Element 0 is for driver usage to add header block */
	ivp[0].iov_base = NULL;
	ivp[0].iov_len = 0;
	bvp[0] = NULL;
	ev.vsize = io_list_to_vec(list, ivp+1, bvp+1, cbin, blimit);
	ev.vsize++;
#if 0
	/* This assertion may say something useful, but it can
	   be falsified during the emulator test suites. */
	ASSERT((ev.vsize >= 0) && (ev.vsize == vsize));
#endif
	ev.size = size;  /* total size */
	ev.iov = ivp;
	ev.binv = bvp;
	fpe_was_unmasked = erts_block_fpe();
	(*drv->outputv)((ErlDrvData)p->drv_data, &ev);
	erts_unblock_fpe(fpe_was_unmasked);
	if (ivp != iv) {
	    erts_free(ERTS_ALC_T_TMP, (void *) ivp);
	}
	if (bvp != bv) {
	    erts_free(ERTS_ALC_T_TMP, (void *) bvp);
	}
	driver_free_binary(cbin);
    } else {
	int r;
	
	/* Try with an 8KB buffer first (will often be enough I guess). */
	size = 8*1024;
	/* See below why the extra byte is added. */
	buf = erts_alloc(ERTS_ALC_T_TMP, size+1);
	r = io_list_to_buf(list, buf, size);

	if (r >= 0) {
	    size -= r;
	    fpe_was_unmasked = erts_block_fpe();
	    (*drv->output)((ErlDrvData)p->drv_data, buf, size);
	    erts_unblock_fpe(fpe_was_unmasked);
	    erts_free(ERTS_ALC_T_TMP, buf);
	}
	else if (r == -2) {
	    erts_free(ERTS_ALC_T_TMP, buf);
	    goto bad_value;
	}
	else {
	    ASSERT(r == -1); /* Overflow */
	    erts_free(ERTS_ALC_T_TMP, buf);
	    if ((size = io_list_len(list)) < 0) {
		goto bad_value;
	    }

	    /*
	     * I know drivers that pad space with '\0' this is clearly
	     * incorrect but I don't feel like fixing them now, insted
	     * add ONE extra byte.
	     */
	    buf = erts_alloc(ERTS_ALC_T_TMP, size+1); 
	    r = io_list_to_buf(list, buf, size);
	    fpe_was_unmasked = erts_block_fpe();
	    (*drv->output)((ErlDrvData)p->drv_data, buf, size);
	    erts_unblock_fpe(fpe_was_unmasked);
	    erts_free(ERTS_ALC_T_TMP, buf);
	}
    }
    p->bytes_out += size;
    erts_smp_atomic_add(&erts_bytes_out, size);

#ifdef ERTS_SMP
    if (p->xports)
	erts_smp_xports_unlock(p);
    ASSERT(!p->xports);
#endif
    p->caller = NIL;
    return 0;

 bad_value: 
    p->caller = NIL;
    {
	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
	erts_dsprintf(dsbufp, "Bad value on output port '%s'\n", p->name);
	erts_send_error_to_logger_nogl(dsbufp);
	return 1;
    }
}

/* initialize the port array */
void init_io(void)
{
    int i;
    ErlDrvEntry** dp;
    char maxports[21]; /* enough for any 64-bit integer */
    size_t maxportssize = sizeof(maxports);
    Uint ports_bits = ERTS_PORTS_BITS;
    Sint port_extra_shift;

#ifdef ERTS_SMP
    init_xports_list_alloc();
#endif

    pdl_init();

    if (erts_sys_getenv("ERL_MAX_PORTS", maxports, &maxportssize) == 0) 
	erts_max_ports = atoi(maxports);
    else
	erts_max_ports = sys_max_files();

    if (erts_max_ports > ERTS_MAX_PORTS)
	erts_max_ports = ERTS_MAX_PORTS;
    if (erts_max_ports < 1024)
	erts_max_ports = 1024;

    if (erts_use_r9_pids_ports) {
	ports_bits = ERTS_R9_PORTS_BITS;
	if (erts_max_ports > ERTS_MAX_R9_PORTS)
	    erts_max_ports = ERTS_MAX_R9_PORTS;
    }

    port_extra_shift = erts_fit_in_bits(erts_max_ports - 1);
    port_num_mask = (1 << ports_bits) - 1;

    erts_port_tab_index_mask = ~(~((Uint) 0) << port_extra_shift);
    erts_max_ports = 1 << port_extra_shift;

    erts_smp_mtx_init(&erts_driver_list_lock,"driver_list");
    driver_list = NULL;
    erts_smp_tsd_key_create(&driver_list_lock_status_key);
    erts_smp_tsd_key_create(&driver_list_last_error_key);

    if (erts_max_ports * sizeof(Port) <= erts_max_ports) {
	/* More memory needed than the whole address space. */
	erts_alloc_enomem(ERTS_ALC_T_PORT_TABLE, ~((Uint) 0));
    }

    erts_port = (Port *) erts_alloc(ERTS_ALC_T_PORT_TABLE,
				    erts_max_ports * sizeof(Port));

    erts_smp_atomic_init(&erts_bytes_out, 0);
    erts_smp_atomic_init(&erts_bytes_in, 0);

    for (i = 0; i < erts_max_ports; i++) {
	erts_port_task_init_sched(&erts_port[i].sched);
#ifdef ERTS_SMP
	erts_smp_atomic_init(&erts_port[i].refc, 0);
	erts_port[i].lock = NULL;
	erts_port[i].xports = NULL;
	erts_smp_spinlock_init_x(&erts_port[i].state_lck, "port_state", make_small(i));
#endif
	erts_port[i].tracer_proc = NIL;
	erts_port[i].trace_flags = 0;

	erts_port[i].drv_ptr = NULL;
	erts_port[i].status = ERTS_PORT_SFLG_FREE;
	erts_port[i].name = NULL;
	erts_port[i].nlinks = NULL;
	erts_port[i].monitors = NULL;
	erts_port[i].linebuf = NULL;
	erts_port[i].port_data_lock = NULL;
    }

    erts_smp_atomic32_init(&erts_ports_snapshot, (erts_aint32_t) 0);
    last_port_num = 0;
    erts_smp_spinlock_init(&get_free_port_lck, "get_free_port");

    sys_init_io();

    erts_smp_tsd_set(driver_list_lock_status_key, (void *) 1);
    erts_smp_mtx_lock(&erts_driver_list_lock);

    init_driver(&fd_driver, &fd_driver_entry, NULL);
    init_driver(&vanilla_driver, &vanilla_driver_entry, NULL);
    init_driver(&spawn_driver, &spawn_driver_entry, NULL);
    for (dp = driver_tab; *dp != NULL; dp++)
	erts_add_driver_entry(*dp, NULL, 1);

    erts_smp_tsd_set(driver_list_lock_status_key, NULL);
    erts_smp_mtx_unlock(&erts_driver_list_lock);
}

/*
 * Buffering of data when using line oriented I/O on ports
 */

/* 
 * Buffer states 
 */
#define LINEBUF_MAIN 0
#define LINEBUF_FULL 1
#define LINEBUF_CR_INSIDE 2
#define LINEBUF_CR_AFTER 3

/*
 * Creates a LineBuf to be added to the port structure,
 * Returns: Pointer to a newly allocated and initialized LineBuf.
 * Parameters:
 * bufsiz - The (maximum) size of the line buffer.
 */
LineBuf *allocate_linebuf(bufsiz)
int bufsiz;
{
    int ovsiz = (bufsiz < LINEBUF_INITIAL) ? bufsiz : LINEBUF_INITIAL;
    LineBuf *lb = (LineBuf *) erts_alloc(ERTS_ALC_T_LINEBUF,
					 sizeof(LineBuf)+ovsiz);
    lb->ovsiz = ovsiz;
    lb->bufsiz = bufsiz;
    lb->ovlen = 0;
    lb->data[0] = LINEBUF_MAIN; /* state */
    return lb;
}

/*
 * Initializes a LineBufContext to be used in calls to read_linebuf
 * or flush_linebuf.
 * Returns: 0 if ok, <0 on error.
 * Parameters:
 * lc - Pointer to an allocated LineBufContext.
 * lb - Pointer to a LineBuf structure (probably from the Port structure).
 * buf - A buffer containing the data to be read and split to lines.
 * len - The number of bytes in buf.
 */
static int init_linebuf_context(LineBufContext *lc, LineBuf **lb, char *buf, int len)
{
    if(lc == NULL || lb == NULL)
	return -1;
    lc->b = lb;
    lc->buf = buf;
    lc->left = len;
    return 0;
}

static void resize_linebuf(LineBuf **b)
{
    int newsiz = (((*b)->ovsiz * 2) > (*b)->bufsiz) ? (*b)->bufsiz : 
	(*b)->ovsiz * 2;
    *b = (LineBuf *) erts_realloc(ERTS_ALC_T_LINEBUF,
				  (void *) *b,
				  sizeof(LineBuf)+newsiz);
    (*b)->ovsiz = newsiz;
}

/*
 * Delivers all data in the buffer regardless of newlines (always
 * an LINEBUF_NOEOL. Has to be called until it return LINEBUF_EMPTY.
 * Return values and barameters as read_linebuf (see below).
 */
static int flush_linebuf(LineBufContext *bp)
{
    bp->retlen = (*bp->b)->ovlen;
    switch(LINEBUF_STATE(*bp)){
    case LINEBUF_CR_INSIDE:
	if((*bp->b)->ovlen >= (*bp->b)->ovsiz)
	    resize_linebuf(bp->b);
	LINEBUF_DATA(*bp)[((*bp->b)->ovlen)++] = '\r';
	++bp->retlen; /* fall through instead of switching state... */
    case LINEBUF_MAIN:
    case LINEBUF_FULL:
	(*bp->b)->ovlen = 0;
	LINEBUF_STATE(*bp) = LINEBUF_MAIN;
	if(!bp->retlen)
	    return LINEBUF_EMPTY;
	return LINEBUF_NOEOL;
    case LINEBUF_CR_AFTER:
	LINEBUF_STATE(*bp) = LINEBUF_CR_INSIDE;
	(*bp->b)->ovlen = 0;
	if(!bp->retlen)
	    return LINEBUF_EMPTY;
	return LINEBUF_NOEOL;
    default:
	return LINEBUF_ERROR;
    }    
}

/*
 * Reads input from a buffer and "chops" it up in lines.
 * Has to be called repeatedly until it returns LINEBUF_EMPTY
 * to get all lines in buffer.
 * Handles both <LF> and <CR><LF> style newlines.
 * On Unix, this is slightly incorrect, as <CR><LF> is NOT to be regarded
 * as a newline together, but i treat newlines equally in all systems
 * to avoid putting this in sys.c or clutter it with #ifdef's.
 * Returns: LINEBUF_EMPTY if there is no more data that can be
 *   determined as a line (only part of a line left), LINEBUF_EOL if a whole
 *   line could be delivered and LINEBUF_NOEOL if the buffer size has been
 *   exceeded. The data and the data length can be accesed through the 
 *   LINEBUF_DATA and the LINEBUF_DATALEN macros applied to the LineBufContext.
 * Parameters: 
 * bp - A LineBufContext that is initialized with 
 *   the init_linebuf_context call. The context has to be retained during
 *   all calls that returns other than LINEBUF_EMPTY. When LINEBUF_EMPTY
 *   is returned the context can be discarded and a new can be created when new
 *   data arrives (the state is saved in the Port structure).
 */
static int read_linebuf(LineBufContext *bp)
{
    for(;;){
	if(bp->left == 0)
	    return LINEBUF_EMPTY;
	if(*bp->buf == '\n'){
	    LINEBUF_STATE(*bp) = LINEBUF_MAIN;
	    ++(bp->buf);
	    --(bp->left);
	    bp->retlen = (*bp->b)->ovlen;
	    (*bp->b)->ovlen = 0;
	    return LINEBUF_EOL;
	}
	switch(LINEBUF_STATE(*bp)){
	case LINEBUF_MAIN:
	    if((*bp->b)->ovlen == (*bp->b)->bufsiz)
		LINEBUF_STATE(*bp) = LINEBUF_FULL;
	    else if(*bp->buf == '\r'){
		++(bp->buf);
		--(bp->left);
		LINEBUF_STATE(*bp) = LINEBUF_CR_INSIDE;
	    } else {
		if((*bp->b)->ovlen >= (*bp->b)->ovsiz)
		    resize_linebuf(bp->b);
		LINEBUF_DATA(*bp)[((*bp->b)->ovlen)++] = *((bp->buf)++);
		--(bp->left);
	    }
	    continue;
	case LINEBUF_FULL:
	    if(*bp->buf == '\r'){
		++(bp->buf);
		--(bp->left);
		LINEBUF_STATE(*bp) = LINEBUF_CR_AFTER;
	    } else {
		bp->retlen = (*bp->b)->ovlen;
		(*bp->b)->ovlen = 0;
		LINEBUF_STATE(*bp) = LINEBUF_MAIN;
		return LINEBUF_NOEOL;
	    }
	    continue;
	case LINEBUF_CR_INSIDE:
	    if((*bp->b)->ovlen >= (*bp->b)->ovsiz)
		resize_linebuf(bp->b);
	    LINEBUF_DATA(*bp)[((*bp->b)->ovlen)++] = '\r';
	    LINEBUF_STATE(*bp) = LINEBUF_MAIN;
	    continue;
	case LINEBUF_CR_AFTER:
	    bp->retlen = (*bp->b)->ovlen;
	    (*bp->b)->ovlen = 0;
	    LINEBUF_STATE(*bp) = LINEBUF_CR_INSIDE;
	    return LINEBUF_NOEOL;
	default:
	    return LINEBUF_ERROR;
	}
    }
}

static void
deliver_result(Eterm sender, Eterm pid, Eterm res)
{
    Process *rp;
    ErtsProcLocks rp_locks = 0;

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    ASSERT(is_internal_port(sender)
	   && is_internal_pid(pid)
	   && internal_pid_index(pid) < erts_max_processes);

    rp = erts_pid2proc_opt(NULL, 0, pid, 0, ERTS_P2P_FLG_SMP_INC_REFC);

    if (rp) {
	Eterm tuple;
	ErlHeapFragment *bp;
	ErlOffHeap *ohp;
	Eterm* hp;
	Uint sz_res;
	    sz_res = size_object(res);
	    hp = erts_alloc_message_heap(sz_res + 3, &bp, &ohp, rp, &rp_locks);
	    res = copy_struct(res, sz_res, &hp, ohp);
	    tuple = TUPLE2(hp, sender, res);
	erts_queue_message(rp, &rp_locks, bp, tuple, NIL);
	erts_smp_proc_unlock(rp, rp_locks);
	erts_smp_proc_dec_refc(rp);
    }
}


/* 
 * Deliver a "read" message.
 * hbuf -- byte that are always formated as a list
 * hlen -- number of byte in header
 * buf  -- data 
 * len  -- length of data
 */

static void deliver_read_message(Port* prt, Eterm to,
				 char *hbuf, int hlen,
				 char *buf, int len, int eol)
{
    int need;
    Eterm listp;
    Eterm tuple;
    Process* rp;
    Eterm* hp;
    ErlHeapFragment *bp;
    ErlOffHeap *ohp;
    ErtsProcLocks rp_locks = 0;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));    
    ERTS_SMP_CHK_NO_PROC_LOCKS;

    need = 3 + 3 + 2*hlen;
    if (prt->status & ERTS_PORT_SFLG_LINEBUF_IO) {
	need += 3;
    }
    if (prt->status & ERTS_PORT_SFLG_BINARY_IO && buf != NULL) {
	need += PROC_BIN_SIZE;
    } else {
	need += 2*len;
    }

    rp = erts_pid2proc_opt(NULL, 0, to, 0, ERTS_P2P_FLG_SMP_INC_REFC);
    if (!rp)
	return;

    hp = erts_alloc_message_heap(need, &bp, &ohp, rp, &rp_locks);

    listp = NIL;
    if ((prt->status & ERTS_PORT_SFLG_BINARY_IO) == 0) {
	listp = buf_to_intlist(&hp, buf, len, listp);
    } else if (buf != NULL) {
	ProcBin* pb;
	Binary* bptr;

	bptr = erts_bin_nrml_alloc(len);
	bptr->flags = 0;
	bptr->orig_size = len;
	erts_refc_init(&bptr->refc, 1);
	sys_memcpy(bptr->orig_bytes, buf, len);

	pb = (ProcBin *) hp;
	pb->thing_word = HEADER_PROC_BIN;
	pb->size = len;
	pb->next = ohp->first;
	ohp->first = (struct erl_off_heap_header*)pb;
	pb->val = bptr;
	pb->bytes = (byte*) bptr->orig_bytes;
	pb->flags = 0;
	hp += PROC_BIN_SIZE;

	OH_OVERHEAD(ohp, pb->size / sizeof(Eterm));
	listp = make_binary(pb);
    }

    /* Prepend the header */
    if (hlen > 0) {
	listp = buf_to_intlist(&hp, hbuf, hlen, listp);
    }

    if (prt->status & ERTS_PORT_SFLG_LINEBUF_IO){
	listp = TUPLE2(hp, (eol) ? am_eol : am_noeol, listp); 
	hp += 3;
    }
    tuple = TUPLE2(hp, am_data, listp);
    hp += 3;

    tuple = TUPLE2(hp, prt->id, tuple);
    hp += 3;

    erts_queue_message(rp, &rp_locks, bp, tuple, am_undefined);
    erts_smp_proc_unlock(rp, rp_locks);
    erts_smp_proc_dec_refc(rp);
}

/* 
 * Deliver all lines in a line buffer, repeats calls to
 * deliver_read_message, and takes the same parameters.
 */
static void deliver_linebuf_message(Port* prt, Eterm to, 
				    char* hbuf, int hlen,
				    char *buf, int len)
{
    LineBufContext lc;
    int ret;
    if(init_linebuf_context(&lc,&(prt->linebuf), buf, len) < 0)
	return;
    while((ret = read_linebuf(&lc)) > LINEBUF_EMPTY)
	deliver_read_message(prt, to, hbuf, hlen, LINEBUF_DATA(lc), 
			     LINEBUF_DATALEN(lc), (ret == LINEBUF_EOL));
}

/*
 * Deliver any nonterminated lines in the line buffer before the
 * port gets closed.
 * Has to be called before terminate_port.
 * Parameters:
 * prt -  Pointer to a Port structure for this port.
 */
static void flush_linebuf_messages(Port *prt)
{
    LineBufContext lc;
    int ret;

    ERTS_SMP_LC_ASSERT(!prt || erts_lc_is_port_locked(prt));
    if(prt == NULL || !(prt->status & ERTS_PORT_SFLG_LINEBUF_IO))
	return;

    if(init_linebuf_context(&lc,&(prt->linebuf), NULL, 0) < 0)
	return;
    while((ret = flush_linebuf(&lc)) > LINEBUF_EMPTY)
	deliver_read_message(prt,
			     prt->connected,
			     NULL,
			     0,
			     LINEBUF_DATA(lc), 
			     LINEBUF_DATALEN(lc),
			     (ret == LINEBUF_EOL));
}    

static void
deliver_vec_message(Port* prt,			/* Port */
		    Eterm to,			/* Receiving pid */
		    char* hbuf,			/* "Header" buffer... */
		    int hlen,			/* ... and its length */
		    ErlDrvBinary** binv,	/* Vector of binaries */
		    SysIOVec* iov,		/* I/O vector */
		    int vsize,			/* Size of binv & iov */
		    int csize)			/* Size of characters in 
						   iov (not hlen) */
{
    int need;
    Eterm listp;
    Eterm tuple;
    Process* rp;
    Eterm* hp;
    ErlHeapFragment *bp;
    ErlOffHeap *ohp;
    ErtsProcLocks rp_locks = 0;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    ERTS_SMP_CHK_NO_PROC_LOCKS;

    /*
     * Check arguments for validity.
     */

    rp = erts_pid2proc_opt(NULL, 0, to, 0, ERTS_P2P_FLG_SMP_INC_REFC);
    if (!rp)
	return;

    /*
     * Calculate the exact number of heap words needed.
     */

    need = 3 + 3;		/* Heap space for two tuples */
    if (prt->status & ERTS_PORT_SFLG_BINARY_IO) {
	need += (2+PROC_BIN_SIZE)*vsize - 2 + hlen*2;
    } else {
	need += (hlen+csize)*2;
    }

    hp = erts_alloc_message_heap(need, &bp, &ohp, rp, &rp_locks);

    listp = NIL;
    iov += vsize;

    if ((prt->status & ERTS_PORT_SFLG_BINARY_IO) == 0) {
	Eterm* thp = hp;
	while (vsize--) {
	    iov--;
	    listp = buf_to_intlist(&thp, iov->iov_base, iov->iov_len, listp);
	}
	hp = thp;
    } else {
	binv += vsize;
	while (vsize--) {
	    ErlDrvBinary* b;
	    ProcBin* pb = (ProcBin*) hp;
	    byte* base;

	    iov--;
	    binv--;
	    if ((b = *binv) == NULL) {
		b = driver_alloc_binary(iov->iov_len);
		sys_memcpy(b->orig_bytes, iov->iov_base, iov->iov_len);
		base = (byte*) b->orig_bytes;
	    } else {
		/* Must increment reference count, caller calls free */
		driver_binary_inc_refc(b);
		base = iov->iov_base;
	    }
	    pb->thing_word = HEADER_PROC_BIN;
	    pb->size = iov->iov_len;
	    pb->next = ohp->first;
	    ohp->first = (struct erl_off_heap_header*)pb;
	    pb->val = ErlDrvBinary2Binary(b);
	    pb->bytes = base;
	    pb->flags = 0;
	    hp += PROC_BIN_SIZE;
	    
	    OH_OVERHEAD(ohp, iov->iov_len / sizeof(Eterm));

	    if (listp == NIL) {  /* compatible with deliver_bin_message */
		listp = make_binary(pb);
	    } else {
		listp = CONS(hp, make_binary(pb), listp);
		hp += 2;
	    }
	}
    }

    if (hlen > 0) {		/* Prepend the header */
	Eterm* thp = hp;
	listp = buf_to_intlist(&thp, hbuf, hlen, listp);
	hp = thp;
    }

    tuple = TUPLE2(hp, am_data, listp);
    hp += 3;
    tuple = TUPLE2(hp, prt->id, tuple);
    hp += 3;

    erts_queue_message(rp, &rp_locks, bp, tuple, am_undefined);
    erts_smp_proc_unlock(rp, rp_locks);
    erts_smp_proc_dec_refc(rp);
}


static void deliver_bin_message(Port*  prt,         /* port */
				Eterm to,           /* receiving pid */
				char* hbuf,         /* "header" buffer */
				int hlen,           /* and it's length */
				ErlDrvBinary* bin,  /* binary data */
				int offs,           /* offset into binary */
				int len)            /* length of binary */
{
    SysIOVec vec;

    vec.iov_base = bin->orig_bytes+offs;
    vec.iov_len = len;
    deliver_vec_message(prt, to, hbuf, hlen, &bin, &vec, 1, len);
}

/* flush the port I/O queue and terminate if empty */
/* 
 * Note. 
 *
 * The test for (p->status & ERTS_PORT_SFLGS_DEAD) == 0 is important since the
 * driver's  flush function might call driver_async, which when using no
 * threads and being short circuited will notice that the io queue is empty
 * (after calling the driver's async_ready) and recursively call 
 * terminate_port. So when we get back here, the port is already terminated.
 */
static void flush_port(Port *p)
{
    int fpe_was_unmasked;

    ERTS_SMP_CHK_NO_PROC_LOCKS;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(p));

    if (p->drv_ptr->flush != NULL) {
        if (IS_TRACED_FL(p, F_TRACE_SCHED_PORTS)) {
	    trace_sched_ports_where(p, am_in, am_flush);
	}
	fpe_was_unmasked = erts_block_fpe();
	(*p->drv_ptr->flush)((ErlDrvData)p->drv_data);
	erts_unblock_fpe(fpe_was_unmasked);
        if (IS_TRACED_FL(p, F_TRACE_SCHED_PORTS)) {
	    trace_sched_ports_where(p, am_out, am_flush);
	}
#ifdef ERTS_SMP
	if (p->xports)
	    erts_smp_xports_unlock(p);
	ASSERT(!p->xports);
#endif
    }
    if ((p->status & ERTS_PORT_SFLGS_DEAD) == 0 && is_port_ioq_empty(p)) {
	terminate_port(p);
    }
}

/* stop and delete a port that is ERTS_PORT_SFLG_CLOSING */
static void
terminate_port(Port *prt)
{
    Eterm send_closed_port_id;
    Eterm connected_id = NIL /* Initialize to silence compiler */;
    erts_driver_t *drv;

    ERTS_SMP_CHK_NO_PROC_LOCKS;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    ASSERT(!prt->nlinks);
    ASSERT(!prt->monitors);

    if (prt->status & ERTS_PORT_SFLG_SEND_CLOSED) {
	erts_port_status_band_set(prt, ~ERTS_PORT_SFLG_SEND_CLOSED);
	send_closed_port_id = prt->id;
	connected_id = prt->connected;
    }
    else {
	send_closed_port_id = NIL;
    }

#ifdef ERTS_SMP
    erts_cancel_smp_ptimer(prt->ptimer);
#else
    erts_cancel_timer(&prt->tm);
#endif

    drv = prt->drv_ptr;
    if ((drv != NULL) && (drv->stop != NULL)) {
	int fpe_was_unmasked = erts_block_fpe();
	(*drv->stop)((ErlDrvData)prt->drv_data);
	erts_unblock_fpe(fpe_was_unmasked);
#ifdef ERTS_SMP
	if (prt->xports)
	    erts_smp_xports_unlock(prt);
	ASSERT(!prt->xports);
#endif
    }
    if(drv->handle != NULL) {
	erts_smp_mtx_lock(&erts_driver_list_lock);
	erts_ddll_decrement_port_count(drv->handle); 
	erts_smp_mtx_unlock(&erts_driver_list_lock);
    }
    stopq(prt);        /* clear queue memory */
    if(prt->linebuf != NULL){
	erts_free(ERTS_ALC_T_LINEBUF, (void *) prt->linebuf);
	prt->linebuf = NULL;
    }
    if (prt->bp != NULL) {
	free_message_buffer(prt->bp);
	prt->bp = NULL;
	prt->data = am_undefined;
    }

    if (prt->psd)
	erts_free(ERTS_ALC_T_PRTSD, prt->psd);

    kill_port(prt);

    /*
     * We don't want to send the closed message until after the
     * port has been removed from the port table (in kill_port()).
     */
    if (is_internal_port(send_closed_port_id))
	deliver_result(send_closed_port_id, connected_id, am_closed);

    ASSERT(prt->dist_entry == NULL);
}

void
erts_terminate_port(Port *pp)
{
    terminate_port(pp);
}

static void sweep_one_monitor(ErtsMonitor *mon, void *vpsc)
{
    ErtsMonitor *rmon;
    Process *rp;

    ASSERT(mon->type == MON_ORIGIN);
    ASSERT(is_internal_pid(mon->pid));
    rp = erts_pid2proc(NULL, 0, mon->pid, ERTS_PROC_LOCK_LINK);
    if (!rp) {
	goto done;
    }
    rmon = erts_remove_monitor(&(rp->monitors),mon->ref);
    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
    if (rmon == NULL) {
	goto done;
    }
    erts_destroy_monitor(rmon);
 done:
    erts_destroy_monitor(mon);
}



typedef struct {
    Eterm port;
    Eterm reason;
} SweepContext;

static void sweep_one_link(ErtsLink *lnk, void *vpsc)
{
    SweepContext *psc = vpsc;
    DistEntry *dep;
    Process *rp;
    

    ASSERT(lnk->type == LINK_PID);
    
    if (is_external_pid(lnk->pid)) {
	dep = external_pid_dist_entry(lnk->pid);
	if(dep != erts_this_dist_entry) {
	    ErtsDistLinkData dld;
	    ErtsDSigData dsd;
	    int code;
	    code = erts_dsig_prepare(&dsd, dep, NULL, ERTS_DSP_NO_LOCK, 0);
	    switch (code) {
	    case ERTS_DSIG_PREP_NOT_ALIVE:
	    case ERTS_DSIG_PREP_NOT_CONNECTED:
		break;
	    case ERTS_DSIG_PREP_CONNECTED:
		erts_remove_dist_link(&dld, psc->port, lnk->pid, dep);
		erts_destroy_dist_link(&dld);
		code = erts_dsig_send_exit(&dsd, psc->port, lnk->pid,
					   psc->reason);
		ASSERT(code == ERTS_DSIG_SEND_OK);
		break;
	    default:
		ASSERT(! "Invalid dsig prepare result");
		break;
	    }
	}
    } else {
	ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK|ERTS_PROC_LOCKS_XSIG_SEND;
	ASSERT(is_internal_pid(lnk->pid));
	rp = erts_pid2proc(NULL, 0, lnk->pid, rp_locks);
	if (rp) {
	    ErtsLink *rlnk = erts_remove_link(&(rp->nlinks), psc->port);

	    if (rlnk) {
		int xres = erts_send_exit_signal(NULL,
						 psc->port,
						 rp,
						 &rp_locks, 
						 psc->reason,
						 NIL,
						 NULL,
						 0);
		if (xres >= 0 && IS_TRACED_FL(rp, F_TRACE_PROCS)) {
		    /* We didn't exit the process and it is traced */
		    if (IS_TRACED_FL(rp, F_TRACE_PROCS)) {
			trace_proc(NULL, rp, am_getting_unlinked,
				   psc->port);
		    }
		}
		erts_destroy_link(rlnk);
	    }

	    erts_smp_proc_unlock(rp, rp_locks);
	}
    }
    erts_destroy_link(lnk);
}

/* 'from' is sending 'this_port' an exit signal, (this_port must be internal).
 * If reason is normal we don't do anything, *unless* from is our connected
 * process in which case we close the port. Any other reason kills the port.
 * If 'from' is ourself we always die.
 * When a driver has data in ioq then driver will be set to closing
 * and become inaccessible to the processes. One exception exists and
 * that is to kill a port till reason kill. Then the port is stopped.
 * 
 */
void
erts_do_exit_port(Port *p, Eterm from, Eterm reason)
{
   ErtsLink *lnk;
   Eterm rreason;

   ERTS_SMP_CHK_NO_PROC_LOCKS;
   ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(p));

   rreason = (reason == am_kill) ? am_killed : reason;

   if ((p->status & (ERTS_PORT_SFLGS_DEAD
		     | ERTS_PORT_SFLG_EXITING
		     | ERTS_PORT_SFLG_IMMORTAL))
       || ((reason == am_normal) &&
	   ((from != p->connected) && (from != p->id)))) {
      return;
   }

   if (IS_TRACED_FL(p, F_TRACE_PORTS)) {
   	trace_port(p, am_closed, reason);
   }

   erts_trace_check_exiting(p->id);

   /*
    * Setting the port to not busy here, frees the list of pending
    * processes and makes them runnable.
    */
   set_busy_port((ErlDrvPort)internal_port_index(p->id), 0);

   if (p->reg != NULL)
       (void) erts_unregister_name(NULL, 0, p, p->reg->name);

   erts_port_status_bor_set(p, ERTS_PORT_SFLG_EXITING);

   {
       SweepContext sc = {p->id, rreason};
       lnk = p->nlinks;
       p->nlinks = NULL;
       erts_sweep_links(lnk, &sweep_one_link, &sc);
   }
   DRV_MONITOR_LOCK_PDL(p);
   {
       ErtsMonitor *moni = p->monitors;
       p->monitors = NULL;
       erts_sweep_monitors(moni, &sweep_one_monitor, NULL);
   } 
   DRV_MONITOR_UNLOCK_PDL(p);

   if ((p->status & ERTS_PORT_SFLG_DISTRIBUTION) && p->dist_entry) {
       erts_do_net_exits(p->dist_entry, rreason);
       erts_deref_dist_entry(p->dist_entry); 
       p->dist_entry = NULL; 
       erts_port_status_band_set(p, ~ERTS_PORT_SFLG_DISTRIBUTION);
   }
       
   if ((reason != am_kill) && !is_port_ioq_empty(p)) {
       erts_port_status_bandor_set(p,
				   ~ERTS_PORT_SFLG_EXITING, /* must turn it off */
				   ERTS_PORT_SFLG_CLOSING);
      flush_port(p);
   }
   else {
       terminate_port(p);
   }
}

/* About the states ERTS_PORT_SFLG_EXITING and ERTS_PORT_SFLG_CLOSING used above.
**
** ERTS_PORT_SFLG_EXITING is a recursion protection for erts_do_exit_port().
** It is unclear  whether this state is necessary or not, it might be possible
** to merge it with ERTS_PORT_SFLG_CLOSING. ERTS_PORT_SFLG_EXITING only persists
** over a section of sequential (but highly recursive) code.
**
** ERTS_PORT_SFLG_CLOSING is a state where the port is in Limbo, waiting to
** pass on. All links are removed, and the port receives in/out-put events so
** as soon as the port queue gets empty terminate_port() is called.
*/



/* Command should be of the form
**   {PID, close}
**   {PID, {command, io-list}}
**   {PID, {connect, New_PID}}
**
**
*/
void erts_port_command(Process *proc,
		       Eterm caller_id,
		       Port *port,
		       Eterm command)
{
    Eterm *tp;
    Eterm pid;

    if (!port)
	return;

    erts_smp_proc_unlock(proc, ERTS_PROC_LOCK_MAIN);
    ERTS_SMP_CHK_NO_PROC_LOCKS;
    ASSERT(!INVALID_PORT(port, port->id));

    if (is_tuple_arity(command, 2)) {
	tp = tuple_val(command);
	if ((pid = port->connected) == tp[1]) {
	    /* PID must be connected */
	    if (tp[2] == am_close) {
		erts_port_status_bor_set(port, ERTS_PORT_SFLG_SEND_CLOSED);
		erts_do_exit_port(port, pid, am_normal);
		goto done;
	    } else if (is_tuple_arity(tp[2], 2)) {
		tp = tuple_val(tp[2]);
		if (tp[1] == am_command) {
		    if (erts_write_to_port(caller_id, port, tp[2]) == 0)
			goto done;
		} else if ((tp[1] == am_connect) && is_internal_pid(tp[2])) {
		    port->connected = tp[2];
		    deliver_result(port->id, pid, am_connected);
		    goto done;
		}
	    }
	}
    }

    {
	ErtsProcLocks rp_locks = ERTS_PROC_LOCKS_XSIG_SEND;
	Process* rp = erts_pid2proc_opt(NULL, 0,
					port->connected, rp_locks,
					ERTS_P2P_FLG_SMP_INC_REFC);
	if (rp) {
	    (void) erts_send_exit_signal(NULL,
					 port->id,
					 rp,
					 &rp_locks, 
					 am_badsig,
					 NIL,
					 NULL,
					 0);
	    erts_smp_proc_unlock(rp, rp_locks);
	    erts_smp_proc_dec_refc(rp);
	}

    }
 done:
    erts_smp_proc_lock(proc, ERTS_PROC_LOCK_MAIN);
}

/*
 * Control a port synchronously. 
 * Returns either a list or a binary.
 */
Eterm
erts_port_control(Process* p, Port* prt, Uint command, Eterm iolist)
{
    byte* to_port = NULL;	/* Buffer to write to port. */
				/* Initialization is for shutting up
				   warning about use before set. */
    int to_len = 0;		/* Length of buffer. */
    int must_free = 0;		/* True if the buffer should be freed. */
    char port_result[ERL_ONHEAP_BIN_LIMIT];  /* Default buffer for result from port. */
    char* port_resp;		/* Pointer to result buffer. */
    int n;
    int (*control)(ErlDrvData, unsigned, char*, int, char**, int);
    int fpe_was_unmasked;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if ((control = prt->drv_ptr->control) == NULL) {
	return THE_NON_VALUE;
    }

    /*
     * Convert the iolist to a buffer, pointed to by to_port,
     * and with its length in to_len.
     */
    if (is_binary(iolist) && binary_bitoffset(iolist) == 0) {
	Uint bitoffs;
	Uint bitsize;
	ERTS_GET_BINARY_BYTES(iolist, to_port, bitoffs, bitsize);
	to_len = binary_size(iolist);
    } else {
	int r;

	/* Try with an 8KB buffer first (will often be enough I guess). */
	to_len = 8*1024;
	to_port = erts_alloc(ERTS_ALC_T_TMP, to_len);
	must_free = 1;

	/*
	 * In versions before R10B, we used to reserve random
	 * amounts of extra memory. From R10B, we allocate the
	 * exact amount.
	 */
	r = io_list_to_buf(iolist, (char*) to_port, to_len);
	if (r >= 0) {
	    to_len -= r;
	} else if (r == -2) {	/* Type error */
	    erts_free(ERTS_ALC_T_TMP, (void *) to_port);
	    return THE_NON_VALUE;
	} else {
	    ASSERT(r == -1);	/* Overflow */
	    erts_free(ERTS_ALC_T_TMP, (void *) to_port);
	    if ((to_len = io_list_len(iolist)) < 0) { /* Type error */
		return THE_NON_VALUE;
	    }
	    must_free = 1;
	    to_port = erts_alloc(ERTS_ALC_T_TMP, to_len);
	    r = io_list_to_buf(iolist, (char*) to_port, to_len);
	    ASSERT(r == 0);
	}
    }

    prt->caller = p->id;	/* Internal pid */

    erts_smp_proc_unlock(p, ERTS_PROC_LOCK_MAIN);
    ERTS_SMP_CHK_NO_PROC_LOCKS;

    /*
     * Call the port's control routine.
     */

    port_resp = port_result;
    fpe_was_unmasked = erts_block_fpe();
    n = control((ErlDrvData)prt->drv_data, command, (char*)to_port, to_len,
		&port_resp, sizeof(port_result));
    erts_unblock_fpe(fpe_was_unmasked);
    if (must_free) {
	erts_free(ERTS_ALC_T_TMP, (void *) to_port);
    }
    prt->caller = NIL;
#ifdef ERTS_SMP
    if (prt->xports)
	erts_smp_xports_unlock(prt);
    ASSERT(!prt->xports);
#endif

    erts_smp_proc_lock(p, ERTS_PROC_LOCK_MAIN);
    /*
     * Handle the result.
     */

    if (n < 0) {
	return THE_NON_VALUE;
    }

    if ((prt->control_flags & PORT_CONTROL_FLAG_BINARY) == 0) {	/* List result */
	Eterm ret;	
	Eterm* hp = HAlloc(p, 2*n);
	ret = buf_to_intlist(&hp, port_resp, n, NIL);
	if (port_resp != port_result) {
	    driver_free(port_resp);
	}
	return ret;
    } 
    else if (port_resp == NULL) {
	return NIL;
    } 
    else {                   /* Binary result */
	ErlDrvBinary *dbin;
	ErlHeapBin *hbin;
	if (port_resp != port_result) {
	    dbin = (ErlDrvBinary *) port_resp;
	    if (dbin->orig_size > ERL_ONHEAP_BIN_LIMIT) {
		ProcBin* pb = (ProcBin *) HAlloc(p, PROC_BIN_SIZE);
		pb->thing_word = HEADER_PROC_BIN;
		pb->size = dbin->orig_size;
		pb->next = MSO(p).first;
		MSO(p).first = (struct erl_off_heap_header*)pb;
		pb->val = ErlDrvBinary2Binary(dbin);
		pb->bytes = (byte*) dbin->orig_bytes;
		pb->flags = 0;
		OH_OVERHEAD(&(MSO(p)), dbin->orig_size / sizeof(Eterm));
		return make_binary(pb);
	    }
	    port_resp = dbin->orig_bytes;
	    n = dbin->orig_size;
	} else {
	    dbin = NULL;
	}
	hbin = (ErlHeapBin*) HAlloc(p, heap_bin_size(n));
	ASSERT(n <= ERL_ONHEAP_BIN_LIMIT);
	hbin->thing_word = header_heap_bin(n);
	hbin->size = n;
	sys_memcpy(hbin->data, port_resp, n);
	if (dbin != NULL) {
	    driver_free_binary(dbin);
	}
	return make_binary(hbin);
    }
}

typedef struct {
    int to;
    void *arg;
} prt_one_lnk_data;

static void prt_one_monitor(ErtsMonitor *mon, void *vprtd)
{
    prt_one_lnk_data *prtd = (prt_one_lnk_data *) vprtd;
    erts_print(prtd->to, prtd->arg, "(%T,%T)", mon->pid,mon->ref);
}

static void prt_one_lnk(ErtsLink *lnk, void *vprtd)
{
    prt_one_lnk_data *prtd = (prt_one_lnk_data *) vprtd;
    erts_print(prtd->to, prtd->arg, "%T", lnk->pid);
}

void
print_port_info(int to, void *arg, int i)
{
    Port* p = &erts_port[i];

    if (p->status & ERTS_PORT_SFLGS_DEAD)
	return;

    erts_print(to, arg, "=port:%T\n", p->id);
    erts_print(to, arg, "Slot: %d\n", i);
    if (p->status & ERTS_PORT_SFLG_CONNECTED) {
	erts_print(to, arg, "Connected: %T", p->connected);
	erts_print(to, arg, "\n");
    }

    if (p->nlinks != NULL) {
	prt_one_lnk_data prtd;
	prtd.to = to;
	prtd.arg = arg;
	erts_print(to, arg, "Links: ");
	erts_doforall_links(p->nlinks, &prt_one_lnk, &prtd);
	erts_print(to, arg, "\n");
    }
    if (p->monitors != NULL) {
	prt_one_lnk_data prtd;
	prtd.to = to;
	prtd.arg = arg;
	erts_print(to, arg, "Monitors: ");
	erts_doforall_monitors(p->monitors, &prt_one_monitor, &prtd);
	erts_print(to, arg, "\n");
    }

    if (p->reg != NULL)
	erts_print(to, arg, "Registered as: %T\n", p->reg->name);

    if (p->drv_ptr == &fd_driver) {
	erts_print(to, arg, "Port is UNIX fd not opened by emulator: %s\n", p->name);
    } else if (p->drv_ptr == &vanilla_driver) {
	erts_print(to, arg, "Port is a file: %s\n",p->name);
    } else if (p->drv_ptr == &spawn_driver) {
	erts_print(to, arg, "Port controls external process: %s\n",p->name);
    } else {
	erts_print(to, arg, "Port controls linked-in driver: %s\n",p->name);
    }
}

void
set_busy_port(ErlDrvPort port_num, int on)
{
    ERTS_SMP_CHK_NO_PROC_LOCKS;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(&erts_port[port_num]));

    if (on) {
        erts_port_status_bor_set(&erts_port[port_num],
				 ERTS_PORT_SFLG_PORT_BUSY);
    } else {
        ErtsProcList* plp = erts_port[port_num].suspended;
        erts_port_status_band_set(&erts_port[port_num],
				  ~ERTS_PORT_SFLG_PORT_BUSY);
        erts_port[port_num].suspended = NULL;

	if (erts_port[port_num].dist_entry) {
	    /*
	     * Processes suspended on distribution ports are
	     * normally queued on the dist entry.
	     */
	    erts_dist_port_not_busy(&erts_port[port_num]);
	}

	/*
	 * Resume, in a round-robin fashion, all processes waiting on the port.
	 * 
	 * This version submitted by Tony Rogvall. The earlier version used
	 * to resume the processes in order, which caused starvation of all but
	 * the first process.
	 */

        if (plp) {
            /* First proc should be resumed last */
	    if (plp->next) {
		erts_resume_processes(plp->next);
		plp->next = NULL;
	    }
	    erts_resume_processes(plp);
        }
    }
}

void set_port_control_flags(ErlDrvPort port_num, int flags)
{

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(&erts_port[port_num]));

    erts_port[port_num].control_flags = flags;
}

int get_port_flags(ErlDrvPort ix) { 
    Port* prt = erts_drvport2port(ix);

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if (prt == NULL)
	return 0;

    return (prt->status & ERTS_PORT_SFLG_BINARY_IO ? PORT_FLAG_BINARY : 0) 
	| (prt->status & ERTS_PORT_SFLG_LINEBUF_IO ? PORT_FLAG_LINE : 0);
}


void erts_raw_port_command(Port* p, byte* buf, Uint len)
{
    int fpe_was_unmasked;

    ERTS_SMP_CHK_NO_PROC_LOCKS;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(p));

    if (len > (Uint) INT_MAX)
	erl_exit(ERTS_ABORT_EXIT,
		 "Absurdly large data buffer (%beu bytes) passed to"
		 "output callback of %s driver.\n",
		 len,
		 p->drv_ptr->name ? p->drv_ptr->name : "unknown");

    p->caller = NIL;
    fpe_was_unmasked = erts_block_fpe();
    (*p->drv_ptr->output)((ErlDrvData)p->drv_data, (char*) buf, (int) len);
    erts_unblock_fpe(fpe_was_unmasked);
}

int async_ready(Port *p, void* data)
{
    int need_free = 1;

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    if (p) {
	ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(p));
	ASSERT(!(p->status & ERTS_PORT_SFLGS_DEAD));
	if (p->drv_ptr->ready_async != NULL) {
	    (*p->drv_ptr->ready_async)((ErlDrvData)p->drv_data, data);
	    need_free = 0;
#ifdef ERTS_SMP
	    if (p->xports)
		erts_smp_xports_unlock(p);
	    ASSERT(!p->xports);
#endif
	}
	if ((p->status & ERTS_PORT_SFLG_CLOSING) && is_port_ioq_empty(p)) {
	    terminate_port(p);
	}
    }
    return need_free;
}

static void
report_missing_drv_callback(Port *p, char *drv_type, char *callback)
{
    ErtsPortNames *pnp = erts_get_port_names(p->id);
    char *unknown = "<unknown>";
    char *drv_name = pnp->driver_name ? pnp->driver_name : unknown;
    char *prt_name = pnp->name ? pnp->name : unknown;
    erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();    
    erts_dsprintf(dsbufp, "%T: %s driver '%s' ", p->id, drv_type, drv_name);
    if (sys_strcmp(drv_name, prt_name) != 0)
	erts_dsprintf(dsbufp, "(%s) ", prt_name);
    erts_dsprintf(dsbufp, "does not implement the %s callback!\n", callback);
    erts_free_port_names(pnp);
    erts_send_error_to_logger_nogl(dsbufp);
}

void
erts_stale_drv_select(Eterm port,
		      ErlDrvEvent hndl,
		      int mode,
		      int deselect)
{
    char *type;
    ErlDrvPort drv_port = internal_port_index(port);
    ErtsPortNames *pnp = erts_get_port_names(port);
    erts_dsprintf_buf_t *dsbufp;

    switch (mode) {
    case ERL_DRV_READ | ERL_DRV_WRITE:
	type = "Input/Output";
	goto deselect;
    case ERL_DRV_WRITE:
	type = "Output";
	goto deselect;
    case ERL_DRV_READ:
	type = "Input";
    deselect:
	if (deselect) {
	    driver_select(drv_port, hndl,
			  mode | ERL_DRV_USE_NO_CALLBACK,
			  0);
	}
	break;
    default:
	type = "Event";
	if (deselect)
	    driver_event(drv_port, hndl, NULL);
	break;
    }

    dsbufp = erts_create_logger_dsbuf();
    erts_dsprintf(dsbufp,
		  "%T: %s: %s driver gone away without deselecting!\n",
		  port,
		  pnp->name ? pnp->name : "<unknown>",
		  type);
    erts_free_port_names(pnp);
    erts_send_error_to_logger_nogl(dsbufp);
}

ErtsPortNames *
erts_get_port_names(Eterm id)
{
    ErtsPortNames *pnp;
    ASSERT(is_nil(id) || is_internal_port(id));
    
    if (is_not_internal_port(id)) {
	pnp = erts_alloc(ERTS_ALC_T_PORT_NAMES, sizeof(ErtsPortNames));
	pnp->name = NULL;
	pnp->driver_name = NULL;
    }
    else {
	Port* prt = &erts_port[internal_port_index(id)];
	int do_realloc = 1;
	int len = -1;
	size_t pnp_len = sizeof(ErtsPortNames);
#ifndef DEBUG
	pnp_len += 100; /* In most cases 100 characters will be enough... */
#endif
	pnp = erts_alloc(ERTS_ALC_T_PORT_NAMES, pnp_len);
	do {
	    int nlen;
	    char *name, *driver_name;
	    if (len > 0) {
		erts_free(ERTS_ALC_T_PORT_NAMES, pnp);
		pnp_len = sizeof(ErtsPortNames) + len;
		pnp = erts_alloc(ERTS_ALC_T_PORT_NAMES, pnp_len);
	    }
	    erts_smp_port_state_lock(prt);
	    if (id != prt->id) {
		len = nlen = 0;
		name = driver_name = NULL;
	    }
	    else {
		name = prt->name;
		len = nlen = name ? sys_strlen(name) + 1 : 0;
		driver_name = (prt->drv_ptr ? prt->drv_ptr->name : NULL);
		len += driver_name ? sys_strlen(driver_name) + 1 : 0;
	    }
	    if (len <= pnp_len - sizeof(ErtsPortNames)) {
		if (!name)
		    pnp->name = NULL;
		else {
		    pnp->name = ((char *) pnp) + sizeof(ErtsPortNames);
		    sys_strcpy(pnp->name, name);
		}
		if (!driver_name)
		    pnp->driver_name = NULL;
		else {
		    pnp->driver_name = (((char *) pnp)
					+ sizeof(ErtsPortNames)
					+ nlen);
		    sys_strcpy(pnp->driver_name, driver_name);
		}
		do_realloc = 0;
	    }
	    erts_smp_port_state_unlock(prt);
	} while (do_realloc);
    }
    return pnp;
}

void
erts_free_port_names(ErtsPortNames *pnp)
{
    erts_free(ERTS_ALC_T_PORT_NAMES, pnp);
}

static void schedule_port_timeout(Port *p)
{
    /*
     * Scheduling of port timeouts can be done without port locking, but
     * since the task handle is stored in the port structure and the ptimer
     * structure is protected by the port lock we require the port to be
     * locked for now...
     *
     * TODO: Implement scheduling of port timeouts without locking
     *       the port.
     * /Rickard
     */
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(p));
    (void) erts_port_task_schedule(p->id,
				   &p->timeout_task,
				   ERTS_PORT_TASK_TIMEOUT,
				   (ErlDrvEvent) -1,
				   NULL);
}

ErlDrvTermData driver_mk_term_nil(void)
{
    return driver_term_nil;
}

void driver_report_exit(int ix, int status)
{
   Port* prt = erts_drvport2port(ix);
   Eterm* hp;
   Eterm tuple;
   Process *rp;
   Eterm pid;
   ErlHeapFragment *bp = NULL;
   ErlOffHeap *ohp;
   ErtsProcLocks rp_locks = 0;

   ERTS_SMP_CHK_NO_PROC_LOCKS;
   ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

   pid = prt->connected;
   ASSERT(is_internal_pid(pid));
   rp = erts_pid2proc_opt(NULL, 0, pid, 0, ERTS_P2P_FLG_SMP_INC_REFC);
   if (!rp)
       return;

   hp = erts_alloc_message_heap(3+3, &bp, &ohp, rp, &rp_locks);

   tuple = TUPLE2(hp, am_exit_status, make_small(status));
   hp += 3;
   tuple = TUPLE2(hp, prt->id, tuple);

   erts_queue_message(rp, &rp_locks, bp, tuple, am_undefined);

   erts_smp_proc_unlock(rp, rp_locks);
   erts_smp_proc_dec_refc(rp);
}


static ERTS_INLINE int
deliver_term_check_port(ErlDrvPort drvport)
{
    int res;
    int ix = (int) drvport;
    if (ix < 0 || erts_max_ports <= ix)
	res = -1; /* invalid */
    else {
	Port* prt = &erts_port[ix];
	erts_smp_port_state_lock(prt);
	if (!(prt->status & ERTS_PORT_SFLGS_INVALID_LOOKUP))
	    res = 1; /* ok */
	else if (prt->status & ERTS_PORT_SFLG_CLOSING)
	    res = 0; /* closing */
	else
	    res = -1; /* invalid (dead) */
	erts_smp_port_state_unlock(prt);
    }
    return res;
}

#define ERTS_B2T_STATES_DEF_STATES_SZ 5
#define ERTS_B2T_STATES_DEF_STATES_INC 100

struct b2t_states__ {
    int len;
    int ix;
    int used;
    ErtsBinary2TermState *state;
    ErtsBinary2TermState def_states[ERTS_B2T_STATES_DEF_STATES_SZ];
#ifdef DEBUG
    byte **org_ext;
    byte *def_org_ext[ERTS_B2T_STATES_DEF_STATES_SZ];
#endif
};

static ERTS_INLINE void
init_b2t_states(struct b2t_states__ *b2tsp)
{
    b2tsp->len = ERTS_B2T_STATES_DEF_STATES_SZ;
    b2tsp->ix = 0;
    b2tsp->used = 0;
    b2tsp->state = &b2tsp->def_states[0];
#ifdef DEBUG
    b2tsp->org_ext = &b2tsp->def_org_ext[0];
#endif
}

static ERTS_INLINE void
grow_b2t_states(struct b2t_states__ *b2tsp)
{
    if (b2tsp->state != &b2tsp->def_states[0]) {
	b2tsp->len += ERTS_B2T_STATES_DEF_STATES_INC;
	b2tsp->state = erts_realloc(ERTS_ALC_T_TMP,
				    b2tsp->state,
				    sizeof(ErtsBinary2TermState)*b2tsp->len);
#ifdef DEBUG
	b2tsp->org_ext = erts_realloc(ERTS_ALC_T_TMP,
				      b2tsp->org_ext,
				      sizeof(char *)*b2tsp->len);
#endif
    }
    else {
	ErtsBinary2TermState *new_states;
	new_states = erts_alloc(ERTS_ALC_T_TMP,
				(sizeof(ErtsBinary2TermState)
				 *ERTS_B2T_STATES_DEF_STATES_INC));
	sys_memcpy((void *) new_states,
		   (void *) b2tsp->state,
		   sizeof(ErtsBinary2TermState)*ERTS_B2T_STATES_DEF_STATES_SZ);
	b2tsp->state = new_states;
	b2tsp->len = ERTS_B2T_STATES_DEF_STATES_INC;
#ifdef DEBUG
	{
	    byte **new_org_ext = erts_alloc(ERTS_ALC_T_TMP,
					    (sizeof(char *)
					     *ERTS_B2T_STATES_DEF_STATES_INC));
	    sys_memcpy((void *) new_org_ext,
		       (void *) b2tsp->org_ext,
		       sizeof(char *)*ERTS_B2T_STATES_DEF_STATES_SZ);
	    b2tsp->org_ext = new_org_ext;
	}
#endif
    }
}

static ERTS_INLINE void
cleanup_b2t_states(struct b2t_states__ *b2tsp)
{
    if (b2tsp->state != &b2tsp->def_states[0]) {
	erts_free(ERTS_ALC_T_TMP, b2tsp->state);
#ifdef DEBUG
	erts_free(ERTS_ALC_T_TMP, b2tsp->org_ext);
#endif
    }
}


/*
 * Generate an Erlang term from data in an array (representing a simple stack
 * machine to build terms).
 * Returns:
 * 	-1 on error in input data
 *       0 if the message was not delivered (bad to pid or closed port)
 *       1 if the message was delivered successfully
 */

static int
driver_deliver_term(ErlDrvPort port,
		    Eterm to,
		    ErlDrvTermData* data,
		    int len)
{
#define ERTS_DDT_FAIL do { res = -1; goto done; } while (0)
    Uint need = 0;
    int depth = 0;
    int res;
    Eterm *hp = NULL, *hp_start = NULL, *hp_end = NULL;
    ErlDrvTermData* ptr;
    ErlDrvTermData* ptr_end;
    DECLARE_ESTACK(stack); 
    Eterm mess = NIL;		/* keeps compiler happy */
    Process* rp = NULL;
    ErlHeapFragment *bp = NULL;
    ErlOffHeap *ohp;
    ErtsProcLocks rp_locks = 0;
    struct b2t_states__ b2t;

    init_b2t_states(&b2t);

    /*
     * We used to check port and process here. In the SMP enabled emulator,
     * however, we don't want to that until we have verified the term.
     */

    /*
     * Check ErlDrvTermData for consistency and calculate needed heap size
     * and stack depth.
     */
    ptr = data;
    ptr_end = ptr + len;

    while (ptr < ptr_end) {
	ErlDrvTermData tag = *ptr++;

#define ERTS_DDT_CHK_ENOUGH_ARGS(NEED) \
	if (ptr+((NEED)-1) >= ptr_end) ERTS_DDT_FAIL;

	switch(tag) {
	case ERL_DRV_NIL: /* no arguments */
	    depth++;
	    break;
	case ERL_DRV_ATOM: /* atom argument */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
	    if (is_not_atom(ptr[0])) ERTS_DDT_FAIL;
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_INT:  /* signed int argument */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
#if HALFWORD_HEAP
	    erts_bld_sint64(NULL, &need, (Sint64)ptr[0]);
#else
	    /* check for bignum */
	    if (!IS_SSMALL((Sint)ptr[0]))
		need += BIG_UINT_HEAP_SIZE;  /* use small_to_big */
#endif
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_UINT:  /* unsigned int argument */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
#if HALFWORD_HEAP
	    erts_bld_uint64(NULL, &need, (Uint64)ptr[0]);
#else
	    /* check for bignum */
	    if (!IS_USMALL(0, (Uint)ptr[0]))
		need += BIG_UINT_HEAP_SIZE;  /* use small_to_big */
#endif
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_INT64:  /* pointer to signed 64-bit int argument  */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
	    erts_bld_sint64(NULL, &need, *((Sint64 *) ptr[0]));
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_UINT64:  /* pointer to unsigned 64-bit int argument */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
	    erts_bld_uint64(NULL, &need, *((Uint64 *) ptr[0]));
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_PORT:  /* port argument */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
	    if (is_not_internal_port(ptr[0])) ERTS_DDT_FAIL;
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_BINARY: { /* ErlDrvBinary*, size, offs */
	    ErlDrvBinary* b;
	    Uint size;
	    Uint offset;
	    ERTS_DDT_CHK_ENOUGH_ARGS(3);
	    b = (ErlDrvBinary*) ptr[0];
	    size = ptr[1];
	    offset = ptr[2];
	    if (!b || size + offset > b->orig_size)
		ERTS_DDT_FAIL; /* No binary or outside the binary */
	    need += (size <= ERL_ONHEAP_BIN_LIMIT
			 ? heap_bin_size(size)
			 : PROC_BIN_SIZE);
	    ptr += 3;
	    depth++;
	    break;
	}
	case ERL_DRV_BUF2BINARY: { /* char*, size */
	    byte *bufp;
	    Uint size;
	    ERTS_DDT_CHK_ENOUGH_ARGS(2);
	    bufp = (byte *) ptr[0];
	    size = (Uint) ptr[1];
	    if (!bufp && size > 0) ERTS_DDT_FAIL; 
	    need += (size <= ERL_ONHEAP_BIN_LIMIT
		     ? heap_bin_size(size)
		     : PROC_BIN_SIZE);
	    ptr += 2;
	    depth++;
	    break;
	}
	case ERL_DRV_STRING: /* char*, length */
	    ERTS_DDT_CHK_ENOUGH_ARGS(2);
	    if ((char *) ptr[0] == NULL || (int) ptr[1] < 0) ERTS_DDT_FAIL;
	    need += ptr[1] * 2;
	    ptr += 2;
	    depth++;
	    break;
	case ERL_DRV_STRING_CONS: /* char*, length */
	    ERTS_DDT_CHK_ENOUGH_ARGS(2);
	    if ((char *) ptr[0] == NULL || (int) ptr[1] < 0) ERTS_DDT_FAIL;
	    need += ptr[1] * 2;
	    if (depth < 1) ERTS_DDT_FAIL;
	    ptr += 2;
	    break;
	case ERL_DRV_LIST: /* int */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
	    if ((int) ptr[0] <= 0) ERTS_DDT_FAIL;
	    need += (ptr[0]-1)*2;  /* list cells */
	    depth -= ptr[0];
	    if (depth < 0) ERTS_DDT_FAIL;
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_TUPLE: { /* int */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
	    if ((int) ptr[0] < 0) ERTS_DDT_FAIL;
	    need += ptr[0]+1;   /* vector positions + arityval */
	    depth -= ptr[0];
	    if (depth < 0) ERTS_DDT_FAIL;
	    ptr++;
	    depth++;
	    break;
	}
	case ERL_DRV_PID: /* pid argument */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
	    if (is_not_internal_pid(ptr[0])) ERTS_DDT_FAIL;
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_FLOAT: /* double * */
	    ERTS_DDT_CHK_ENOUGH_ARGS(1);
	    need += FLOAT_SIZE_OBJECT;
	    ptr++;
	    depth++;
	    break;
	case ERL_DRV_EXT2TERM: { /* char *ext, int size */
	    byte* ext;
	    Sint size;
	    Sint hsz;

	    ERTS_DDT_CHK_ENOUGH_ARGS(2);
	    ext = (byte *) ptr[0];
	    size = (Sint) ptr[1];
	    if (!ext || size <= 0)
		ERTS_DDT_FAIL;
	    if (b2t.len <= b2t.ix)
		grow_b2t_states(&b2t);
#ifdef DEBUG
	    b2t.org_ext[b2t.ix] = ext;
#endif
	    hsz = erts_binary2term_prepare(&b2t.state[b2t.ix++], ext, size);
	    if (hsz < 0)
		ERTS_DDT_FAIL; /* Invalid data */
	    need += hsz;
	    ptr += 2;
	    depth++;
	    break;
	}
	default:
	    ERTS_DDT_FAIL;
	}
#undef ERTS_DDT_CHK_ENOUGH_ARGS
    }

    if ((depth != 1) || (ptr != ptr_end))
	ERTS_DDT_FAIL;

    b2t.used = b2t.ix;
    b2t.ix = 0;

    /*
     * The term is OK. Go ahead and validate the port and process.
     */
    res = deliver_term_check_port(port);
    if (res <= 0)
	goto done;

    rp = erts_pid2proc_opt(NULL, 0, to, rp_locks, ERTS_P2P_FLG_SMP_INC_REFC);
    if (!rp) {
	res = 0;
	goto done;
    }

    hp_start = hp = erts_alloc_message_heap(need, &bp, &ohp, rp, &rp_locks);
    hp_end = hp + need;

    /*
     * Interpret the instructions and build the term.
     */
    ptr = data;
    while (ptr < ptr_end) {
	ErlDrvTermData tag = *ptr++;

	switch(tag) {
	case ERL_DRV_NIL: /* no arguments */
	    mess = NIL;
	    break;

	case ERL_DRV_ATOM: /* atom argument */
	    mess = ptr[0];
	    ptr++;
	    break;

	case ERL_DRV_INT:  /* signed int argument */
#if HALFWORD_HEAP
	    mess = erts_bld_sint64(&hp, NULL, (Sint64)ptr[0]);
#else
	    if (IS_SSMALL((Sint)ptr[0]))
		mess = make_small((Sint)ptr[0]);
	    else {
		mess = small_to_big((Sint)ptr[0], hp);
		hp += BIG_UINT_HEAP_SIZE;
	    }
#endif
	    ptr++;
	    break;

	case ERL_DRV_UINT:  /* unsigned int argument */
#if HALFWORD_HEAP
	    mess = erts_bld_uint64(&hp, NULL, (Uint64)ptr[0]);
#else
	    if (IS_USMALL(0, (Uint)ptr[0]))
		mess = make_small((Uint)ptr[0]);
	    else {
		mess = uint_to_big((Uint)ptr[0], hp);
		hp += BIG_UINT_HEAP_SIZE;
	    }
#endif
	    ptr++;
	    break;

	case ERL_DRV_INT64: /* pointer to unsigned 64-bit int argument */
	    mess = erts_bld_sint64(&hp, NULL, *((Sint64 *) ptr[0]));
	    ptr++;
	    break;

	case ERL_DRV_UINT64: /* pointer to unsigned 64-bit int argument */
	    mess = erts_bld_uint64(&hp, NULL, *((Uint64 *) ptr[0]));
	    ptr++;
	    break;

	case ERL_DRV_PORT:  /* port argument */
	    mess = ptr[0];
	    ptr++;
	    break;

	case ERL_DRV_BINARY: { /* ErlDrvBinary*, size, offs */
	    ErlDrvBinary* b = (ErlDrvBinary*) ptr[0];
	    Uint size = ptr[1];
	    Uint offset = ptr[2];

	    if (size <= ERL_ONHEAP_BIN_LIMIT) {
		ErlHeapBin* hbp = (ErlHeapBin *) hp;
		hp += heap_bin_size(size);
		hbp->thing_word = header_heap_bin(size);
		hbp->size = size;
		if (size > 0) {
		    sys_memcpy((void *) hbp->data, (void *) (((byte*) b->orig_bytes) + offset), size);
		}
		mess = make_binary(hbp);
	    }
	    else {
		ProcBin* pb = (ProcBin *) hp;
		driver_binary_inc_refc(b);  /* caller will free binary */
		pb->thing_word = HEADER_PROC_BIN;
		pb->size = size;
		pb->next = ohp->first;
		ohp->first = (struct erl_off_heap_header*)pb;
		pb->val = ErlDrvBinary2Binary(b);
		pb->bytes = ((byte*) b->orig_bytes) + offset;
		pb->flags = 0;
		mess =  make_binary(pb);
		hp += PROC_BIN_SIZE;
		OH_OVERHEAD(ohp, pb->size / sizeof(Eterm));
	    }
	    ptr += 3;
	    break;
	}

	case ERL_DRV_BUF2BINARY: { /* char*, size */
	    byte *bufp = (byte *) ptr[0];
	    Uint size = (Uint) ptr[1];
	    if (size <= ERL_ONHEAP_BIN_LIMIT) {
		ErlHeapBin* hbp = (ErlHeapBin *) hp;
		hp += heap_bin_size(size);
		hbp->thing_word = header_heap_bin(size);
		hbp->size = size;
		if (size > 0) {
		    ASSERT(bufp);
		    sys_memcpy((void *) hbp->data, (void *) bufp, size);
		}
		mess = make_binary(hbp);
	    }
	    else {
		ProcBin* pbp;
		Binary* bp = erts_bin_nrml_alloc(size);
		ASSERT(bufp);
		bp->flags = 0;
		bp->orig_size = (long) size;
		erts_refc_init(&bp->refc, 1);
		sys_memcpy((void *) bp->orig_bytes, (void *) bufp, size);
		pbp = (ProcBin *) hp;
		hp += PROC_BIN_SIZE;
		pbp->thing_word = HEADER_PROC_BIN;
		pbp->size = size;
		pbp->next = ohp->first;
		ohp->first = (struct erl_off_heap_header*)pbp;
		pbp->val = bp;
		pbp->bytes = (byte*) bp->orig_bytes;
		pbp->flags = 0;
		OH_OVERHEAD(ohp, pbp->size / sizeof(Eterm));
		mess = make_binary(pbp);
	    }
	    ptr += 2;
	    break;
	}

	case ERL_DRV_STRING: /* char*, length */
	    mess = buf_to_intlist(&hp, (char*)ptr[0], ptr[1], NIL);
	    ptr += 2;
	    break;

	case ERL_DRV_STRING_CONS:  /* char*, length */
	    mess = ESTACK_POP(stack);
	    mess = buf_to_intlist(&hp, (char*)ptr[0], ptr[1], mess);
	    ptr += 2;
	    break;

	case ERL_DRV_LIST: { /* unsigned */
	    Uint i = (int) ptr[0]; /* i > 0 */

	    mess = ESTACK_POP(stack);
	    i--;
	    while(i > 0) {
		Eterm hd = ESTACK_POP(stack);

		mess = CONS(hp, hd, mess);
		hp += 2;
		i--;
	    }
	    ptr++;
	    break;
	}

	case ERL_DRV_TUPLE: { /* int */
	    int size = (int)ptr[0];
	    Eterm* tp = hp;

	    *tp = make_arityval(size);
	    mess = make_tuple(tp);

	    tp += size;   /* point at last element */
	    hp = tp+1;    /* advance "heap" pointer */

	    while(size--) {
		*tp-- = ESTACK_POP(stack);
	    }
	    ptr++;
	    break;
	}

	case ERL_DRV_PID: /* pid argument */
	    mess = ptr[0];
	    ptr++;
	    break;

	case ERL_DRV_FLOAT: { /* double * */
	    FloatDef f;

	    mess = make_float(hp);
	    f.fd = *((double *) ptr[0]);
	    PUT_DOUBLE(f, hp);
	    hp += FLOAT_SIZE_OBJECT;
	    ptr++;
	    break;
	}

	case ERL_DRV_EXT2TERM: /* char *ext, int size */
	    ASSERT(b2t.org_ext[b2t.ix] == (byte *) ptr[0]);
	    mess = erts_binary2term_create(&b2t.state[b2t.ix++], &hp, ohp);
	    if (mess == THE_NON_VALUE)
		ERTS_DDT_FAIL;
	    ptr += 2;
	    break;

	}
	ESTACK_PUSH(stack, mess);
    }

    res = 1;

 done:

    if (res > 0) {
	mess = ESTACK_POP(stack);  /* get resulting value */
	if (bp)
	    bp = erts_resize_message_buffer(bp, hp - hp_start, &mess, 1);
	else {
	    ASSERT(hp);
	    HRelease(rp, hp_end, hp);	    
	}
	/* send message */
	erts_queue_message(rp, &rp_locks, bp, mess, am_undefined);
    }
    else {
	if (b2t.ix > b2t.used)
	    b2t.used = b2t.ix;
	for (b2t.ix = 0; b2t.ix < b2t.used; b2t.ix++)
	    erts_binary2term_abort(&b2t.state[b2t.ix]);
	if (bp)
	    free_message_buffer(bp);
	else if (hp) {
	    HRelease(rp, hp_end, hp);
	}
    }
#ifdef ERTS_SMP
    if (rp) {
	if (rp_locks)
	    erts_smp_proc_unlock(rp, rp_locks);
	erts_smp_proc_dec_refc(rp);
    }
#endif
    cleanup_b2t_states(&b2t);
    DESTROY_ESTACK(stack);
    return res;
#undef ERTS_DDT_FAIL
}


int 
driver_output_term(ErlDrvPort ix, ErlDrvTermData* data, int len)
{
    Port* prt = erts_drvport2port(ix);

    ERTS_SMP_CHK_NO_PROC_LOCKS;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if (prt == NULL)
	return -1;
    return driver_deliver_term(ix, prt->connected, data, len);
}


int
driver_send_term(ErlDrvPort ix, ErlDrvTermData to, ErlDrvTermData* data, int len)
{
    return driver_deliver_term(ix, to, data, len);
}


/*
 * Output a binary with hlen bytes from hbuf as list header
 * and data is len length of bin starting from offset offs.
 */

int driver_output_binary(ErlDrvPort ix, char* hbuf, int hlen,
			 ErlDrvBinary* bin, int offs, int len)
{
    Port* prt = erts_drvport2port(ix);

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    if (prt == NULL)
	return -1;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    if (prt->status & ERTS_PORT_SFLG_CLOSING)
	return 0;

    prt->bytes_in += (hlen + len);
    erts_smp_atomic_add(&erts_bytes_in, (erts_aint_t) (hlen + len));
    if (prt->status & ERTS_PORT_SFLG_DISTRIBUTION) {
	return erts_net_message(prt,
				prt->dist_entry,
				(byte*) hbuf, hlen,
				(byte*) (bin->orig_bytes+offs), len);
    }
    else
	deliver_bin_message(prt, prt->connected, 
			    hbuf, hlen, bin, offs, len);
    return 0;
}

/* driver_output2:
** Delivers hlen bytes from hbuf to the port owner as a list;
** after that, the port settings apply, buf is sent as binary or list.
**
** Example: if hlen = 3 then the port owner will receive the data
** [H1,H2,H3 | T]
*/
int driver_output2(ErlDrvPort ix, char* hbuf, int hlen, char* buf, int len)
{
    Port* prt = erts_drvport2port(ix);

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    if (prt == NULL)
	return -1;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if (prt->status & ERTS_PORT_SFLG_CLOSING)
	return 0;
    
    prt->bytes_in += (hlen + len);
    erts_smp_atomic_add(&erts_bytes_in, (erts_aint_t) (hlen + len));
    if (prt->status & ERTS_PORT_SFLG_DISTRIBUTION) {
	if (len == 0)
	    return erts_net_message(prt,
				    prt->dist_entry,
				    NULL, 0,
				    (byte*) hbuf, hlen);
	else
	    return erts_net_message(prt,
				    prt->dist_entry,
				    (byte*) hbuf, hlen,
				    (byte*) buf, len);
    }
    else if(prt->status & ERTS_PORT_SFLG_LINEBUF_IO)
	deliver_linebuf_message(prt, prt->connected, hbuf, hlen, buf, len);
    else
	deliver_read_message(prt, prt->connected, hbuf, hlen, buf, len, 0);
    return 0;
}

/* Interface functions available to driver writers */

int driver_output(ErlDrvPort ix, char* buf, int len)
{
    ERTS_SMP_CHK_NO_PROC_LOCKS;
    return driver_output2(ix, NULL, 0, buf, len);
}

int driver_outputv(ErlDrvPort ix, char* hbuf, int hlen, ErlIOVec* vec, int skip)
{
    int n;
    int len;
    int size;
    SysIOVec* iov;
    ErlDrvBinary** binv;
    Port* prt;

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    size = vec->size - skip;   /* Size of remaining bytes in vector */
    ASSERT(size >= 0);
    if (size <= 0)
	return driver_output2(ix, hbuf, hlen, NULL, 0);
    ASSERT(hlen >= 0);       /* debug only */
    if (hlen < 0)
	hlen = 0;

    prt = erts_drvport2port(ix);
    if (prt == NULL)
	return -1;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if (prt->status & ERTS_PORT_SFLG_CLOSING)
	return 0;

    /* size > 0 ! */
    iov = vec->iov;
    binv = vec->binv;
    n = vec->vsize;
    /* we use do here to strip iov_len=0 from beginning */
    do {
	len = iov->iov_len;
	if (len <= skip) {
	    skip -= len;
	    iov++;
	    binv++;
	    n--;
	} else {
	    iov->iov_base += skip;
	    iov->iov_len -= skip;
	    skip = 0;
	}
    } while (skip > 0);

    /* XXX handle distribution !!! */
    prt->bytes_in += (hlen + size);
    erts_smp_atomic_add(&erts_bytes_in, (erts_aint_t) (hlen + size));
    deliver_vec_message(prt, prt->connected, hbuf, hlen, binv, iov, n, size);
    return 0;
}

/* Copy bytes from a vector into a buffer
** input is a vector a buffer and a max length
** return bytes copied
*/
int driver_vec_to_buf(vec, buf, len)
ErlIOVec* vec; 
char* buf;
int len;
{
    SysIOVec* iov = vec->iov;
    int n = vec->vsize;
    int orig_len = len;

    while(n--) {
	int ilen = iov->iov_len;
	if (ilen < len) {
	    sys_memcpy(buf, iov->iov_base, ilen);
	    len -= ilen;
	    buf += ilen;
	    iov++;
	}
	else {
	    sys_memcpy(buf, iov->iov_base, len);
	    return orig_len;
	}
    }
    return (orig_len - len);
}


/*
 * - driver_alloc_binary() is thread safe (efile driver depend on it).
 * - driver_realloc_binary(), and driver_free_binary() are *not* thread safe.
 */

/*
 * reference count on driver binaries...
 */

ErlDrvSInt
driver_binary_get_refc(ErlDrvBinary *dbp)
{
    Binary* bp = ErlDrvBinary2Binary(dbp);
    return (ErlDrvSInt) erts_refc_read(&bp->refc, 1);
}

ErlDrvSInt
driver_binary_inc_refc(ErlDrvBinary *dbp)
{
    Binary* bp = ErlDrvBinary2Binary(dbp);
    return (ErlDrvSInt) erts_refc_inctest(&bp->refc, 2);
}

ErlDrvSInt
driver_binary_dec_refc(ErlDrvBinary *dbp)
{
    Binary* bp = ErlDrvBinary2Binary(dbp);
    return (ErlDrvSInt) erts_refc_dectest(&bp->refc, 1);
}


/*
** Allocation/Deallocation of binary objects 
*/

ErlDrvBinary*
driver_alloc_binary(int size)
{
    Binary* bin;

    if (size < 0)
	return NULL;

    bin = erts_bin_drv_alloc_fnf((Uint) size);
    if (!bin)
	return NULL; /* The driver write must take action */
    bin->flags = BIN_FLAG_DRV;
    erts_refc_init(&bin->refc, 1);
    bin->orig_size = (long) size;
    return Binary2ErlDrvBinary(bin);
}

/* Reallocate space hold by binary */

ErlDrvBinary* driver_realloc_binary(ErlDrvBinary* bin, int size)
{
    Binary* oldbin;
    Binary* newbin;

    if (!bin || size < 0) {
	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
	erts_dsprintf(dsbufp,
		      "Bad use of driver_realloc_binary(%p, %d): "
		      "called with ",
		      bin, size);
	if (!bin) {
	    erts_dsprintf(dsbufp, "NULL pointer as first argument");
	    if (size < 0)
		erts_dsprintf(dsbufp, ", and ");
	}
	if (size < 0) {
	    erts_dsprintf(dsbufp, "negative size as second argument");
	    size = 0;
	}
	erts_send_warning_to_logger_nogl(dsbufp);
	if (!bin)
	    return driver_alloc_binary(size);
    }

    oldbin = ErlDrvBinary2Binary(bin);
    newbin = (Binary *) erts_bin_realloc_fnf(oldbin, size);
    if (!newbin)
	return NULL;

    newbin->orig_size = size;
    return Binary2ErlDrvBinary(newbin);
}


void driver_free_binary(dbin)
ErlDrvBinary* dbin;
{
    Binary *bin;
    if (!dbin) {
	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
	erts_dsprintf(dsbufp,
		      "Bad use of driver_free_binary(%p): called with "
		      "NULL pointer as argument", dbin);
	erts_send_warning_to_logger_nogl(dsbufp);
	return;
    }

    bin = ErlDrvBinary2Binary(dbin);
    if (erts_refc_dectest(&bin->refc, 0) == 0)
	erts_bin_free(bin);
}


/* 
 * Allocation/deallocation of memory for drivers 
 */

void *driver_alloc(size_t size)
{
    return erts_alloc_fnf(ERTS_ALC_T_DRV, (Uint) size);
}

void *driver_realloc(void *ptr, size_t size)
{
    return erts_realloc_fnf(ERTS_ALC_T_DRV, ptr, (Uint) size);
}

void driver_free(void *ptr)
{
    erts_free(ERTS_ALC_T_DRV, ptr);
}

/*
 * Port Data Lock
 */

static void
pdl_init(void)
{
}

static ERTS_INLINE void
pdl_init_refc(ErlDrvPDL pdl)
{
    erts_atomic_init(&pdl->refc, 1);
}

static ERTS_INLINE ErlDrvSInt
pdl_read_refc(ErlDrvPDL pdl)
{
    erts_aint_t refc = erts_atomic_read(&pdl->refc);
    ERTS_LC_ASSERT(refc >= 0);
    return (ErlDrvSInt) refc;
}

static ERTS_INLINE void
pdl_inc_refc(ErlDrvPDL pdl)
{
    erts_atomic_inc(&pdl->refc);
    ERTS_LC_ASSERT(driver_pdl_get_refc(pdl) > 1);
}

static ERTS_INLINE ErlDrvSInt
pdl_inctest_refc(ErlDrvPDL pdl)
{
    erts_aint_t refc = erts_atomic_inctest(&pdl->refc);
    ERTS_LC_ASSERT(refc > 1);
    return (ErlDrvSInt) refc;
}

#if 0 /* unused */
static ERTS_INLINE void
pdl_dec_refc(ErlDrvPDL pdl)
{
    erts_atomic_dec(&pdl->refc);
    ERTS_LC_ASSERT(driver_pdl_get_refc(pdl) > 0);
}
#endif

static ERTS_INLINE ErlDrvSInt
pdl_dectest_refc(ErlDrvPDL pdl)
{
    erts_aint_t refc = erts_atomic_dectest(&pdl->refc);
    ERTS_LC_ASSERT(refc >= 0);
    return (ErlDrvSInt) refc;
}

static ERTS_INLINE void pdl_destroy(ErlDrvPDL pdl)
{
    ERTS_LC_ASSERT(driver_pdl_get_refc(pdl) == 0);
    erts_mtx_destroy(&pdl->mtx);
    erts_free(ERTS_ALC_T_PORT_DATA_LOCK, pdl);
}

#ifdef ERTS_SMP

static void driver_monitor_lock_pdl(Port *p) {
    if (p->port_data_lock) {
	driver_pdl_lock(p->port_data_lock);
    }
    /* Now we either have the port lock or the port_data_lock */
    ERTS_LC_ASSERT(!p->port_data_lock
		   || erts_lc_mtx_is_locked(&(p->port_data_lock->mtx)));
    ERTS_SMP_LC_ASSERT(p->port_data_lock
		       || erts_lc_is_port_locked(p));
}

static void driver_monitor_unlock_pdl(Port *p) {
    /* We should either have the port lock or the port_data_lock */
    ERTS_LC_ASSERT(!p->port_data_lock
		   || erts_lc_mtx_is_locked(&(p->port_data_lock->mtx)));
    ERTS_SMP_LC_ASSERT(p->port_data_lock
		       || erts_lc_is_port_locked(p));
    if (p->port_data_lock) {
	driver_pdl_unlock(p->port_data_lock);
    }
}

#endif

/*
 * exported driver_pdl_* functions ...
 */

ErlDrvPDL
driver_pdl_create(ErlDrvPort dp)
{
    ErlDrvPDL pdl;
    Port *pp = erts_drvport2port(dp);
    if (!pp || pp->port_data_lock)
	return NULL;
    pdl = erts_alloc(ERTS_ALC_T_PORT_DATA_LOCK,
		     sizeof(struct erl_drv_port_data_lock));
    erts_mtx_init(&pdl->mtx, "port_data_lock");
    pdl_init_refc(pdl);
    pp->port_data_lock = pdl;
#ifdef HARDDEBUG
    erts_fprintf(stderr, "driver_pdl_create(%T) -> 0x%08X\r\n",pp->id,(unsigned) pdl);
#endif
    return pdl;
}

void
driver_pdl_lock(ErlDrvPDL pdl)
{
#ifdef HARDDEBUG
    erts_fprintf(stderr, "driver_pdl_lock(0x%08X)\r\n",(unsigned) pdl);
#endif
    pdl_inc_refc(pdl);
    erts_mtx_lock(&pdl->mtx);
}

void
driver_pdl_unlock(ErlDrvPDL pdl)
{
    ErlDrvSInt refc;
#ifdef HARDDEBUG
    erts_fprintf(stderr, "driver_pdl_unlock(0x%08X)\r\n",(unsigned) pdl);
#endif
    erts_mtx_unlock(&pdl->mtx);
    refc = pdl_dectest_refc(pdl);
    if (!refc)
	pdl_destroy(pdl);
}

ErlDrvSInt
driver_pdl_get_refc(ErlDrvPDL pdl)
{
    return pdl_read_refc(pdl);
}

ErlDrvSInt
driver_pdl_inc_refc(ErlDrvPDL pdl)
{
    ErlDrvSInt refc = pdl_inctest_refc(pdl);
#ifdef HARDDEBUG
    erts_fprintf(stderr, "driver_pdl_inc_refc(%p) -> %bed\r\n",
		 pdl, refc);
#endif
    return refc;
}

ErlDrvSInt
driver_pdl_dec_refc(ErlDrvPDL pdl)
{
    ErlDrvSInt refc = pdl_dectest_refc(pdl);
#ifdef HARDDEBUG
    erts_fprintf(stderr, "driver_pdl_dec_refc(%p) -> %bpd\r\n",
		 pdl, refc);
#endif
    if (!refc)
	pdl_destroy(pdl);
    return refc;
}

/* expand queue to hold n elements in tail or head */
static int expandq(ErlIOQueue* q, int n, int tail)
/* tail: 0 if make room in head, make room in tail otherwise */
{
    int h_sz;  /* room before header */
    int t_sz;  /* room after tail */
    int q_sz;  /* occupied */
    int nvsz;
    SysIOVec* niov;
    ErlDrvBinary** nbinv;

    h_sz = q->v_head - q->v_start;
    t_sz = q->v_end -  q->v_tail;
    q_sz = q->v_tail - q->v_head;

    if (tail && (n <= t_sz)) /* do we need to expand tail? */
	return 0;
    else if (!tail && (n <= h_sz))  /* do we need to expand head? */
	return 0;
    else if (n > (h_sz + t_sz)) { /* need to allocate */
	/* we may get little extra but it ok */
	nvsz = (q->v_end - q->v_start) + n; 

	niov = erts_alloc_fnf(ERTS_ALC_T_IOQ, nvsz * sizeof(SysIOVec));
	if (!niov)
	    return -1;
	nbinv = erts_alloc_fnf(ERTS_ALC_T_IOQ, nvsz * sizeof(ErlDrvBinary**));
	if (!nbinv) {
	    erts_free(ERTS_ALC_T_IOQ, (void *) niov);
	    return -1;
	}
	if (tail) {
	    sys_memcpy(niov, q->v_head, q_sz*sizeof(SysIOVec));
	    if (q->v_start != q->v_small)
		erts_free(ERTS_ALC_T_IOQ, (void *) q->v_start);
	    q->v_start = niov;
	    q->v_end = niov + nvsz;
	    q->v_head = q->v_start;
	    q->v_tail = q->v_head + q_sz;

	    sys_memcpy(nbinv, q->b_head, q_sz*sizeof(ErlDrvBinary*));
	    if (q->b_start != q->b_small)
		erts_free(ERTS_ALC_T_IOQ, (void *) q->b_start);
	    q->b_start = nbinv;
	    q->b_end = nbinv + nvsz;
	    q->b_head = q->b_start;
	    q->b_tail = q->b_head + q_sz;	
	}
	else {
	    sys_memcpy(niov+nvsz-q_sz, q->v_head, q_sz*sizeof(SysIOVec));
	    if (q->v_start != q->v_small)
		erts_free(ERTS_ALC_T_IOQ, (void *) q->v_start);
	    q->v_start = niov;
	    q->v_end = niov + nvsz;
	    q->v_tail = q->v_end;
	    q->v_head = q->v_tail - q_sz;
	    
	    sys_memcpy(nbinv+nvsz-q_sz, q->b_head, q_sz*sizeof(ErlDrvBinary*));
	    if (q->b_start != q->b_small)
		erts_free(ERTS_ALC_T_IOQ, (void *) q->b_start);
	    q->b_start = nbinv;
	    q->b_end = nbinv + nvsz;
	    q->b_tail = q->b_end;
	    q->b_head = q->b_tail - q_sz;
	}
    }
    else if (tail) {  /* move to beginning to make room in tail */
	sys_memmove(q->v_start, q->v_head, q_sz*sizeof(SysIOVec));
	q->v_head = q->v_start;
	q->v_tail = q->v_head + q_sz;
	sys_memmove(q->b_start, q->b_head, q_sz*sizeof(ErlDrvBinary*));
	q->b_head = q->b_start;
	q->b_tail = q->b_head + q_sz;
    }
    else {   /* move to end to make room */
	sys_memmove(q->v_end-q_sz, q->v_head, q_sz*sizeof(SysIOVec));
	q->v_tail = q->v_end;
	q->v_head = q->v_tail-q_sz;
	sys_memmove(q->b_end-q_sz, q->b_head, q_sz*sizeof(ErlDrvBinary*));
	q->b_tail = q->b_end;
	q->b_head = q->b_tail-q_sz;
    }

    return 0;
}



/* Put elements from vec at q tail */
int driver_enqv(ErlDrvPort ix, ErlIOVec* vec, int skip)
{
    int n;
    int len;
    int size;
    SysIOVec* iov;
    ErlDrvBinary** binv;
    ErlDrvBinary*  b;
    ErlIOQueue* q = drvport2ioq(ix);

    if (q == NULL)
	return -1;

    size = vec->size - skip;
    ASSERT(size >= 0);       /* debug only */
    if (size <= 0)
	return 0;

    iov = vec->iov;
    binv = vec->binv;
    n = vec->vsize;

    /* we use do here to strip iov_len=0 from beginning */
    do {
	len = iov->iov_len;
	if (len <= skip) {
	    skip -= len;
	    iov++;
	    binv++;
	    n--;
	}
	else {
	    iov->iov_base += skip;
	    iov->iov_len -= skip;
	    skip = 0;
	}
    } while(skip > 0);

    if (q->v_tail + n >= q->v_end)
	expandq(q, n, 1);

    /* Queue and reference all binaries (remove zero length items) */
    while(n--) {
	if ((len = iov->iov_len) > 0) {
	    if ((b = *binv) == NULL) { /* speical case create binary ! */
		b = driver_alloc_binary(len);
		sys_memcpy(b->orig_bytes, iov->iov_base, len);
		*q->b_tail++ = b;
		q->v_tail->iov_len = len;
		q->v_tail->iov_base = b->orig_bytes;
		q->v_tail++;
	    }
	    else {
		driver_binary_inc_refc(b);
		*q->b_tail++ = b;
		*q->v_tail++ = *iov;
	    }
	}
	iov++;
	binv++;
    }
    q->size += size;      /* update total size in queue */
    return 0;
}

/* Put elements from vec at q head */
int driver_pushqv(ErlDrvPort ix, ErlIOVec* vec, int skip)
{
    int n;
    int len;
    int size;
    SysIOVec* iov;
    ErlDrvBinary** binv;
    ErlDrvBinary* b;
    ErlIOQueue* q = drvport2ioq(ix);

    if (q == NULL)
	return -1;

    if ((size = vec->size - skip) <= 0)
	return 0;
    iov = vec->iov;
    binv = vec->binv;
    n = vec->vsize;

    /* we use do here to strip iov_len=0 from beginning */
    do {
	len = iov->iov_len;
	if (len <= skip) {
	    skip -= len;
	    iov++;
	    binv++;
	    n--;
	}
	else {
	    iov->iov_base += skip;
	    iov->iov_len -= skip;
	    skip = 0;
	}
    } while(skip > 0);

    if (q->v_head - n < q->v_start)
	expandq(q, n, 0);

    /* Queue and reference all binaries (remove zero length items) */
    iov += (n-1);  /* move to end */
    binv += (n-1); /* move to end */
    while(n--) {
	if ((len = iov->iov_len) > 0) {
	    if ((b = *binv) == NULL) { /* speical case create binary ! */
		b = driver_alloc_binary(len);
		sys_memcpy(b->orig_bytes, iov->iov_base, len);
		*--q->b_head = b;
		q->v_head--;
		q->v_head->iov_len = len;
		q->v_head->iov_base = b->orig_bytes;
	    }
	    else {
		driver_binary_inc_refc(b);
		*--q->b_head = b;
		*--q->v_head = *iov;
	    }
	}
	iov--;
	binv--;
    }
    q->size += size;      /* update total size in queue */
    return 0;
}


/*
** Remove size bytes from queue head
** Return number of bytes that remain in queue
*/
int driver_deq(ErlDrvPort ix, int size)
{
    ErlIOQueue* q = drvport2ioq(ix);
    int len;
    int sz;

    if ((q == NULL) || (sz = (q->size - size)) < 0)
	return -1;
    q->size = sz;
    while (size > 0) {
	ASSERT(q->v_head != q->v_tail);

	len = q->v_head->iov_len;
	if (len <= size) {
	    size -= len;
	    driver_free_binary(*q->b_head);
	    *q->b_head++ = NULL;
	    q->v_head++;
	}
	else {
	    q->v_head->iov_base += size;
	    q->v_head->iov_len -= size;
	    size = 0;
	}
    }

    /* restart pointers (optimised for enq) */
    if (q->v_head == q->v_tail) {
	q->v_head = q->v_tail = q->v_start;
	q->b_head = q->b_tail = q->b_start;
    }
    return sz;
}


int driver_peekqv(ErlDrvPort ix, ErlIOVec *ev) {
    ErlIOQueue *q = drvport2ioq(ix);
    ASSERT(ev);

    if (! q) {
	return -1;
    } else {
	if ((ev->vsize = q->v_tail - q->v_head) == 0) {
	    ev->size = 0;
	    ev->iov = NULL;
	    ev->binv = NULL;
	} else {
	    ev->size = q->size;
	    ev->iov = q->v_head;
	    ev->binv = q->b_head;
	}
	return q->size;
    }
}

SysIOVec* driver_peekq(ErlDrvPort ix, int* vlenp)  /* length of io-vector */
{
    ErlIOQueue* q = drvport2ioq(ix);

    if (q == NULL) {
	*vlenp = -1;
	return NULL;
    }
    if ((*vlenp = (q->v_tail - q->v_head)) == 0)
	return NULL;
    return q->v_head;
}


int driver_sizeq(ErlDrvPort ix)
{
    ErlIOQueue* q = drvport2ioq(ix);

    if (q == NULL)
	return -1;
    return q->size;
}


/* Utils */

/* Enqueue a binary */
int driver_enq_bin(ErlDrvPort ix, ErlDrvBinary* bin, int offs, int len)
{
    SysIOVec      iov;
    ErlIOVec      ev;

    ASSERT(len >= 0);
    if (len == 0)
	return 0;
    iov.iov_base = bin->orig_bytes + offs;
    iov.iov_len  = len;
    ev.vsize = 1;
    ev.size = len;
    ev.iov = &iov;
    ev.binv = &bin;
    return driver_enqv(ix, &ev, 0);
}

int driver_enq(ErlDrvPort ix, char* buffer, int len)
{
    int code;
    ErlDrvBinary* bin;

    ASSERT(len >= 0);
    if (len == 0)
	return 0;
    if ((bin = driver_alloc_binary(len)) == NULL)
	return -1;
    sys_memcpy(bin->orig_bytes, buffer, len);
    code = driver_enq_bin(ix, bin, 0, len);
    driver_free_binary(bin);  /* dereference */
    return code;
}

int driver_pushq_bin(ErlDrvPort ix, ErlDrvBinary* bin, int offs, int len)
{
    SysIOVec      iov;
    ErlIOVec      ev;

    ASSERT(len >= 0);
    if (len == 0)
	return 0;
    iov.iov_base = bin->orig_bytes + offs;
    iov.iov_len  = len;
    ev.vsize = 1;
    ev.size = len;
    ev.iov = &iov;
    ev.binv = &bin;
    return driver_pushqv(ix, &ev, 0);
}

int driver_pushq(ErlDrvPort ix, char* buffer, int len)
{
    int code;
    ErlDrvBinary* bin;

    ASSERT(len >= 0);
    if (len == 0)
	return 0;

    if ((bin = driver_alloc_binary(len)) == NULL)
	return -1;
    sys_memcpy(bin->orig_bytes, buffer, len);
    code = driver_pushq_bin(ix, bin, 0, len);
    driver_free_binary(bin);  /* dereference */
    return code;
}

static ERTS_INLINE void
drv_cancel_timer(Port *prt)
{
#ifdef ERTS_SMP
    erts_cancel_smp_ptimer(prt->ptimer);
#else
    erts_cancel_timer(&prt->tm);
#endif
    if (erts_port_task_is_scheduled(&prt->timeout_task))
	erts_port_task_abort(prt->id, &prt->timeout_task);
}

int driver_set_timer(ErlDrvPort ix, UWord t)
{
    Port* prt = erts_drvport2port(ix);

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    if (prt == NULL)
	return -1;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    if (prt->drv_ptr->timeout == NULL)
	return -1;
    drv_cancel_timer(prt);
#ifdef ERTS_SMP
    erts_create_smp_ptimer(&prt->ptimer,
			   prt->id,
			   (ErlTimeoutProc) schedule_port_timeout,
			   t);
#else
    erts_set_timer(&prt->tm,
		  (ErlTimeoutProc) schedule_port_timeout,
		  NULL,
		  prt,
		  t);
#endif
    return 0;
}

int driver_cancel_timer(ErlDrvPort ix)
{
    Port* prt = erts_drvport2port(ix);
    if (prt == NULL)
	return -1;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    drv_cancel_timer(prt);
    return 0;
}


int
driver_read_timer(ErlDrvPort ix, unsigned long* t)
{
    Port* prt = erts_drvport2port(ix);

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    if (prt == NULL)
	return -1;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
#ifdef ERTS_SMP
    *t = prt->ptimer ? erts_time_left(&prt->ptimer->timer.tm) : 0;
#else
    *t = erts_time_left(&prt->tm);
#endif
    return 0;
}

int 
driver_get_now(ErlDrvNowData *now_data)
{
    Uint mega,secs,micro;
    ERTS_SMP_CHK_NO_PROC_LOCKS;

    if (now_data == NULL) {
	return -1;
    }
    get_now(&mega,&secs,&micro);
    now_data->megasecs = (unsigned long) mega;
    now_data->secs = (unsigned long) secs;
    now_data->microsecs = (unsigned long) micro;
    return 0;
}

static void ref_to_driver_monitor(Eterm ref, ErlDrvMonitor *mon)
{
    RefThing *refp;
    ASSERT(is_internal_ref(ref));
    ASSERT(sizeof(RefThing) <= sizeof(ErlDrvMonitor));
    refp = ref_thing_ptr(ref);
    memset(mon,0,sizeof(ErlDrvMonitor));
    memcpy(mon,refp,sizeof(RefThing));
}


static int do_driver_monitor_process(Port *prt,
				     Eterm *buf,
				     ErlDrvTermData process,
				     ErlDrvMonitor *monitor)
{
    Process *rp;
    Eterm ref;

    if (prt->drv_ptr->process_exit == NULL) {
	return -1;
    }
    rp = erts_pid2proc_opt(NULL, 0,
			   (Eterm) process, ERTS_PROC_LOCK_LINK,
			   ERTS_P2P_FLG_ALLOW_OTHER_X);
    if (!rp) {
	return 1;
    }

    ref = erts_make_ref_in_buffer(buf);
    erts_add_monitor(&(prt->monitors), MON_ORIGIN, ref, rp->id, NIL);
    erts_add_monitor(&(rp->monitors), MON_TARGET, ref, prt->id, NIL);

    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
    ref_to_driver_monitor(ref,monitor);
    return 0;
}

/*
 * This can be called from a non scheduler thread iff a port_data_lock exists
 */
int driver_monitor_process(ErlDrvPort port,
			   ErlDrvTermData process,
			   ErlDrvMonitor *monitor)
{
    Port *prt;
    int ret;
    Uint32 status;
    ErtsSchedulerData *sched = erts_get_scheduler_data();
    int ix = (int) port;
    if (ix < 0 || erts_max_ports <= ix) {
	return -1;
    }
    prt = &erts_port[ix];

    DRV_MONITOR_LOCK_PDL(prt);

    if (sched) {
	status = erts_port[ix].status;
    } else {
	erts_smp_port_state_lock(prt);
	status = erts_port[ix].status;
	erts_smp_port_state_unlock(prt);
    }

    if (status & ERTS_PORT_SFLGS_INVALID_DRIVER_LOOKUP) {
	DRV_MONITOR_UNLOCK_PDL(prt);
	return -1;
    }

    /* Now (in SMP) we should have either the port lock (if we have a scheduler) or the port data lock
       (if we're a driver thread) */
    ERTS_SMP_LC_ASSERT((sched != NULL || prt->port_data_lock));

#if !HEAP_ON_C_STACK
    if (!sched) {
	/* Need a separate allocation for the ref :( */
	Eterm *buf = erts_alloc(ERTS_ALC_T_TEMP_TERM,
				sizeof(Eterm)*REF_THING_SIZE);
	ret = do_driver_monitor_process(prt,buf,process,monitor);
	erts_free(ERTS_ALC_T_TEMP_TERM,buf);
    } else
#endif
    {
	DeclareTmpHeapNoproc(buf,REF_THING_SIZE);
	UseTmpHeapNoproc(REF_THING_SIZE);
	ret = do_driver_monitor_process(prt,buf,process,monitor);
	UnUseTmpHeapNoproc(REF_THING_SIZE);
    }
    DRV_MONITOR_UNLOCK_PDL(prt);
    return ret;
}

static int do_driver_demonitor_process(Port *prt, Eterm *buf,
				       const ErlDrvMonitor *monitor)
{
    Process *rp;
    Eterm ref;
    ErtsMonitor *mon;
    Eterm to;

    memcpy(buf,monitor,sizeof(Eterm)*REF_THING_SIZE);
    ref = make_internal_ref(buf);
    mon = erts_lookup_monitor(prt->monitors, ref);
    if (mon == NULL) {
	return 1;
    }
    ASSERT(mon->type == MON_ORIGIN);
    to = mon->pid;
    ASSERT(is_internal_pid(to));
    rp = erts_pid2proc_opt(NULL,
			   0,
			   to,
			   ERTS_PROC_LOCK_LINK,
			   ERTS_P2P_FLG_ALLOW_OTHER_X);
    mon = erts_remove_monitor(&(prt->monitors), ref);
    if (mon) {
	erts_destroy_monitor(mon);
    }
    if (rp) {
	ErtsMonitor *rmon;
	rmon = erts_remove_monitor(&(rp->monitors), ref);
	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
	if (rmon != NULL) {
	    erts_destroy_monitor(rmon);
	}
    } 
    return 0;
}

int driver_demonitor_process(ErlDrvPort port,
			     const ErlDrvMonitor *monitor)
{
    Port *prt;
    int ret;
    Uint32 status;
    ErtsSchedulerData *sched = erts_get_scheduler_data();
    int ix = (int) port;
    if (ix < 0 || erts_max_ports <= ix) {
	return -1;
    }
    prt = &erts_port[ix];

    DRV_MONITOR_LOCK_PDL(prt);

    if (sched) {
	status = erts_port[ix].status;
    } else {
	erts_smp_port_state_lock(prt);
	status = erts_port[ix].status;
	erts_smp_port_state_unlock(prt);
    }

    if (status & ERTS_PORT_SFLGS_INVALID_DRIVER_LOOKUP) {
	DRV_MONITOR_UNLOCK_PDL(prt);
	return -1;
    }

    /* Now we should have either the port lock (if we have a scheduler) or the port data lock
       (if we're a driver thread) */
    ERTS_SMP_LC_ASSERT((sched != NULL || prt->port_data_lock));
#if !HEAP_ON_C_STACK
    if (!sched) {
	/* Need a separate allocation for the ref :( */
	Eterm *buf = erts_alloc(ERTS_ALC_T_TEMP_TERM,
				sizeof(Eterm)*REF_THING_SIZE);
	ret = do_driver_demonitor_process(prt,buf,monitor);
	erts_free(ERTS_ALC_T_TEMP_TERM,buf);
    } else
#endif
    {
	DeclareTmpHeapNoproc(buf,REF_THING_SIZE);
	UseTmpHeapNoproc(REF_THING_SIZE);
	ret = do_driver_demonitor_process(prt,buf,monitor);
	UnUseTmpHeapNoproc(REF_THING_SIZE);
    }
    DRV_MONITOR_UNLOCK_PDL(prt);
    return ret;
}

static ErlDrvTermData do_driver_get_monitored_process(Port *prt, Eterm *buf,
					    const ErlDrvMonitor *monitor)
{
    Eterm ref;
    ErtsMonitor *mon;
    Eterm to;

    memcpy(buf,monitor,sizeof(Eterm)*REF_THING_SIZE);
    ref = make_internal_ref(buf);
    mon = erts_lookup_monitor(prt->monitors, ref);
    if (mon == NULL) {
	return driver_term_nil;
    }
    ASSERT(mon->type == MON_ORIGIN);
    to = mon->pid;
    ASSERT(is_internal_pid(to));
    return (ErlDrvTermData) to;
}


ErlDrvTermData driver_get_monitored_process(ErlDrvPort port,
					    const ErlDrvMonitor *monitor)
{
    Port *prt;
    ErlDrvTermData ret;
    Uint32 status;
    ErtsSchedulerData *sched = erts_get_scheduler_data();
    int ix = (int) port;
    if (ix < 0 || erts_max_ports <= ix) {
	return driver_term_nil;
    }
    prt = &erts_port[ix];

    DRV_MONITOR_LOCK_PDL(prt);

    if (sched) {
	status = erts_port[ix].status;
    } else {
	erts_smp_port_state_lock(prt);
	status = erts_port[ix].status;
	erts_smp_port_state_unlock(prt);
    }

    if (status & ERTS_PORT_SFLGS_INVALID_DRIVER_LOOKUP) {
	DRV_MONITOR_UNLOCK_PDL(prt);
	return driver_term_nil;
    }

    /* Now we should have either the port lock (if we have a scheduler) or the port data lock
       (if we're a driver thread) */
    ERTS_SMP_LC_ASSERT((sched != NULL || prt->port_data_lock));

#if !HEAP_ON_C_STACK
    if (!sched) {
	/* Need a separate allocation for the ref :( */
	Eterm *buf = erts_alloc(ERTS_ALC_T_TEMP_TERM,
				sizeof(Eterm)*REF_THING_SIZE);
	ret = do_driver_get_monitored_process(prt,buf,monitor);
	erts_free(ERTS_ALC_T_TEMP_TERM,buf);
    } else
#endif
    {
	DeclareTmpHeapNoproc(buf,REF_THING_SIZE);
	UseTmpHeapNoproc(REF_THING_SIZE);
	ret = do_driver_get_monitored_process(prt,buf,monitor);
	UnUseTmpHeapNoproc(REF_THING_SIZE);
    }
    DRV_MONITOR_UNLOCK_PDL(prt);
    return ret;
}


int driver_compare_monitors(const ErlDrvMonitor *monitor1,
			    const ErlDrvMonitor *monitor2)
{
    return memcmp(monitor1,monitor2,sizeof(ErlDrvMonitor));
}

void erts_fire_port_monitor(Port *prt, Eterm ref)
{
    ErtsMonitor *rmon;
    void (*callback)(ErlDrvData drv_data, ErlDrvMonitor *monitor);
    ErlDrvMonitor drv_monitor;
    int fpe_was_unmasked;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    ASSERT(prt->drv_ptr != NULL);    
    DRV_MONITOR_LOCK_PDL(prt);
    if (erts_lookup_monitor(prt->monitors,ref) == NULL) {
	DRV_MONITOR_UNLOCK_PDL(prt);
	return;
    }
    callback = prt->drv_ptr->process_exit;
    ASSERT(callback != NULL);
    ref_to_driver_monitor(ref,&drv_monitor);
    DRV_MONITOR_UNLOCK_PDL(prt);
    fpe_was_unmasked = erts_block_fpe();
    (*callback)((ErlDrvData) (prt->drv_data), &drv_monitor);
    erts_unblock_fpe(fpe_was_unmasked);
    DRV_MONITOR_LOCK_PDL(prt);
    /* remove monitor *after* callback */
    rmon = erts_remove_monitor(&(prt->monitors),ref);
    DRV_MONITOR_UNLOCK_PDL(prt);
    if (rmon) {
	erts_destroy_monitor(rmon);
    }
}


static int
driver_failure_term(ErlDrvPort ix, Eterm term, int eof)
{
    Port* prt = erts_drvport2port(ix);

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    if (prt == NULL)
	return -1;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    if (eof)
	flush_linebuf_messages(prt);
    if (prt->status & ERTS_PORT_SFLG_CLOSING) {
	terminate_port(prt);
    } else if (eof && (prt->status & ERTS_PORT_SFLG_SOFT_EOF)) {
	deliver_result(prt->id, prt->connected, am_eof);
    } else {
	/* XXX UGLY WORK AROUND, Let do_exit_port terminate the port */
	if (prt->port_data_lock)
	    driver_pdl_lock(prt->port_data_lock);
	prt->ioq.size = 0;
	if (prt->port_data_lock)
	    driver_pdl_unlock(prt->port_data_lock);
	erts_do_exit_port(prt, prt->id, eof ? am_normal : term);
    }
    return 0;
}



/*
** Do a (soft) exit. unlink the connected process before doing
** driver posix error or (normal)
*/
int driver_exit(ErlDrvPort ix, int err)
{
    Port* prt = erts_drvport2port(ix);
    Process* rp;
    ErtsLink *lnk, *rlnk = NULL;

    ERTS_SMP_CHK_NO_PROC_LOCKS;
  
    if (prt == NULL)
        return -1;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    rp = erts_pid2proc(NULL, 0, prt->connected, ERTS_PROC_LOCK_LINK);
    if (rp) {
	rlnk = erts_remove_link(&(rp->nlinks),prt->id);
    }

    lnk = erts_remove_link(&(prt->nlinks),prt->connected);

#ifdef ERTS_SMP
    if (rp)
	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
#endif

    if (rlnk != NULL) {
	erts_destroy_link(rlnk);
    }

    if (lnk != NULL) {
	erts_destroy_link(lnk);
    }

    if (err == 0)
        return driver_failure_term(ix, am_normal, 0);
    else {
        char* err_str = erl_errno_id(err);
        Eterm am_err = am_atom_put(err_str, sys_strlen(err_str));
        return driver_failure_term(ix, am_err, 0);
    }
}


int driver_failure(ErlDrvPort ix, int code)
{
    return driver_failure_term(ix, make_small(code), code == 0);
}

int driver_failure_atom(ErlDrvPort ix, char* string)
{
    Eterm am = am_atom_put(string, strlen(string));
    return driver_failure_term(ix, am, 0);
}

int driver_failure_posix(ErlDrvPort ix, int err)
{
    return driver_failure_atom(ix, erl_errno_id(err));
}

int driver_failure_eof(ErlDrvPort ix)
{
    return driver_failure_term(ix, NIL, 1);
}



ErlDrvTermData driver_mk_atom(char* string)
{
    Eterm am = am_atom_put(string, sys_strlen(string));
    ERTS_SMP_CHK_NO_PROC_LOCKS;
    return (ErlDrvTermData) am;
}

ErlDrvTermData driver_mk_port(ErlDrvPort ix)
{
    Port* prt = erts_drvport2port(ix);
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    return (ErlDrvTermData) prt->id;
}

ErlDrvTermData driver_connected(ErlDrvPort ix)
{
    Port* prt = erts_drvport2port(ix);
    ERTS_SMP_CHK_NO_PROC_LOCKS;
    if (prt == NULL)
	return NIL;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    return prt->connected;
}

ErlDrvTermData driver_caller(ErlDrvPort ix)
{
    Port* prt = erts_drvport2port(ix);
    ERTS_SMP_CHK_NO_PROC_LOCKS;
    if (prt == NULL)
	return NIL;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    return prt->caller;
}

int driver_lock_driver(ErlDrvPort ix)
{
    Port* prt = erts_drvport2port(ix);
    DE_Handle* dh;

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    erts_smp_mtx_lock(&erts_driver_list_lock);

    if (prt == NULL) return -1;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
    if ((dh = (DE_Handle*)prt->drv_ptr->handle ) == NULL) {
	erts_smp_mtx_unlock(&erts_driver_list_lock);
	return -1;
    }
    erts_ddll_lock_driver(dh, prt->drv_ptr->name);
    erts_smp_mtx_unlock(&erts_driver_list_lock);
    return 0;
}


static int maybe_lock_driver_list(void) 
{
    void *rec_lock;
    rec_lock = erts_smp_tsd_get(driver_list_lock_status_key);
    if (rec_lock == 0) {
	erts_smp_mtx_lock(&erts_driver_list_lock);
	return 1;
    }
    return 0;
}
static void maybe_unlock_driver_list(int doit)
{
    if (doit) {
	erts_smp_mtx_unlock(&erts_driver_list_lock);
    }
}
/* 
   These old interfaces are certainly not MT friendly. Hopefully they are only used internally,
   but you never know, so they are kept for BC. As The sys ddll code has no notion
   of locking, I use the driver list lock to mutex this from the code in erl_bif_ddll.c.
   To allow dynamic code loading in the init functions of a driver, recursive locking is 
   handled as in add_driver_entry etc.
   A TSD variable holds the last error for a thread, so that code like
   ...
   x = driver_dl_open(...);
   if (x == NULL)
      y = driver_dl_error();
   ...
   works as long as execution happens in one driver callback even in an SMP emulator. 
   Writing code using these interfaces spanning several driver callbacks between loading/lookup 
   and error handling may give undesired results...
*/
void *driver_dl_open(char * path)
{
    void *ptr;
    int res;
    int *last_error_p = erts_smp_tsd_get(driver_list_last_error_key);
    int locked = maybe_lock_driver_list();
    if ((res = erts_sys_ddll_open(path, &ptr)) == 0) {
	maybe_unlock_driver_list(locked);
	return ptr;
    } else {
	if (!last_error_p) {
	    last_error_p = erts_alloc(ERTS_ALC_T_DDLL_ERRCODES, sizeof(int));
	    erts_smp_tsd_set(driver_list_last_error_key,last_error_p);
	}
	*last_error_p = res;
	maybe_unlock_driver_list(locked);
	return NULL;
    }
}

void *driver_dl_sym(void * handle, char *func_name)
{
    void *ptr;
    int res;
    int *last_error_p = erts_smp_tsd_get(driver_list_lock_status_key);
    int locked = maybe_lock_driver_list();
    if ((res = erts_sys_ddll_sym(handle, func_name, &ptr)) == 0) {
	maybe_unlock_driver_list(locked);
	return ptr;
    } else {
	if (!last_error_p) {
	    last_error_p = erts_alloc(ERTS_ALC_T_DDLL_ERRCODES, sizeof(int));
	    erts_smp_tsd_set(driver_list_lock_status_key,last_error_p);
	}
	*last_error_p = res;
	maybe_unlock_driver_list(locked);
	return NULL;
    }
}
    
int driver_dl_close(void *handle)
{
    int res;
    int locked = maybe_lock_driver_list();
    res = erts_sys_ddll_close(handle);
    maybe_unlock_driver_list(locked);
    return res;
}

char *driver_dl_error(void) 
{
    char *res;
    int *last_error_p = erts_smp_tsd_get(driver_list_lock_status_key);
    int locked = maybe_lock_driver_list();
    res = erts_ddll_error((last_error_p != NULL) ? (*last_error_p) : ERL_DE_ERROR_UNSPECIFIED); 
    maybe_unlock_driver_list(locked);
    return res;
}


#define ERL_DRV_SYS_INFO_SIZE(LAST_FIELD) \
  (((size_t) &((ErlDrvSysInfo *) 0)->LAST_FIELD) \
   + sizeof(((ErlDrvSysInfo *) 0)->LAST_FIELD))

void
driver_system_info(ErlDrvSysInfo *sip, size_t si_size)
{
    /*
     * When adding fields in the ErlDrvSysInfo struct
     * remember to increment ERL_DRV_EXTENDED_MINOR_VERSION
     */

    /*
     * 'smp_support' is the last field in the first version
     * of ErlDrvSysInfo (introduced in driver version 1.0).
     */
    if (!sip || si_size < ERL_DRV_SYS_INFO_SIZE(smp_support)) 
	erl_exit(1,
		 "driver_system_info(%p, %ld) called with invalid arguments\n",
		 sip, si_size);

    /*
     * 'smp_support' is the last field in the first version
     * of ErlDrvSysInfo (introduced in driver version 1.0).
     */
    if (si_size >= ERL_DRV_SYS_INFO_SIZE(smp_support)) {
	sip->driver_major_version = ERL_DRV_EXTENDED_MAJOR_VERSION;
	sip->driver_minor_version = ERL_DRV_EXTENDED_MINOR_VERSION;
	sip->erts_version = ERLANG_VERSION;
	sip->otp_release = ERLANG_OTP_RELEASE;
	sip->thread_support = 
#ifdef USE_THREADS
	    1
#else
	    0
#endif
	    ;
	sip->smp_support = 
#ifdef ERTS_SMP
	    1
#else
	    0
#endif
	    ;

    }

    /*
     * 'scheduler_threads' is the last field in the second version
     * of ErlDrvSysInfo (introduced in driver version 1.1).
     */
    if (si_size >= ERL_DRV_SYS_INFO_SIZE(scheduler_threads)) {
	sip->async_threads = erts_async_max_threads;
	sip->scheduler_threads = erts_no_schedulers;
    }
    /*
     * 'nif_minor_version' is the last field in the third version
     * (driver version 1.5, NIF version 1.0) 
     */
    if (si_size >= ERL_DRV_SYS_INFO_SIZE(nif_minor_version)) {
	sip->nif_major_version = ERL_NIF_MAJOR_VERSION;
	sip->nif_minor_version = ERL_NIF_MINOR_VERSION;
    }
}


static ERTS_INLINE Port *
get_current_port(void)
{
    ErtsSchedulerData *esdp = erts_get_scheduler_data();
    ASSERT(esdp);
    ASSERT(esdp->current_port);
    return esdp->current_port;
}

/*
 * Default callbacks used if not supplied by driver.
 */

static void
no_output_callback(ErlDrvData drv_data, char *buf, int len)
{

}

static void
no_event_callback(ErlDrvData drv_data, ErlDrvEvent event, ErlDrvEventData event_data)
{
    Port *prt = get_current_port();
    report_missing_drv_callback(prt, "Event", "event()");
    driver_event((ErlDrvPort) internal_port_index(prt->id), event, NULL);
}

static void
no_ready_input_callback(ErlDrvData drv_data, ErlDrvEvent event)
{
    Port *prt = get_current_port();
    report_missing_drv_callback(prt, "Input", "ready_input()");
    driver_select((ErlDrvPort) internal_port_index(prt->id), event, 
		  (ERL_DRV_READ | ERL_DRV_USE_NO_CALLBACK), 0);
}

static void
no_ready_output_callback(ErlDrvData drv_data, ErlDrvEvent event)
{
    Port *prt = get_current_port();
    report_missing_drv_callback(prt, "Output", "ready_output()");
    driver_select((ErlDrvPort) internal_port_index(prt->id), event,
		  (ERL_DRV_WRITE | ERL_DRV_USE_NO_CALLBACK), 0);
}

static void
no_timeout_callback(ErlDrvData drv_data)
{

}

static void
no_stop_select_callback(ErlDrvEvent event, void* private)
{
    erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();    
    erts_dsprintf(dsbufp, "Driver does not implement stop_select callback "
			  "(event=%ld, private=%p)!\n", (long)event, private);
    erts_send_error_to_logger_nogl(dsbufp);
}


static int
init_driver(erts_driver_t *drv, ErlDrvEntry *de, DE_Handle *handle)
{
    drv->name = de->driver_name;
    if (de->extended_marker == ERL_DRV_EXTENDED_MARKER) {
	drv->version.major = de->major_version;
	drv->version.minor = de->minor_version;
	drv->flags = de->driver_flags;
    }
    else {
	drv->version.major = 0;
	drv->version.minor = 0;
	drv->flags = 0;
    }
    drv->handle = handle;
#ifdef ERTS_SMP
    if (drv->flags & ERL_DRV_FLAG_USE_PORT_LOCKING)
	drv->lock = NULL;
    else {
	drv->lock = erts_alloc(ERTS_ALC_T_DRIVER_LOCK,
			       sizeof(erts_smp_mtx_t));
	erts_smp_mtx_init_x(drv->lock,
			    "driver_lock",
#if defined(ERTS_ENABLE_LOCK_CHECK) || defined(ERTS_ENABLE_LOCK_COUNT)
			    am_atom_put(drv->name, sys_strlen(drv->name))
#else
			    NIL
#endif
	    );
    }
#endif
    drv->entry = de;

    drv->start = de->start;
    drv->stop = de->stop;
    drv->finish = de->finish;
    drv->flush = de->flush;
    drv->output = de->output ? de->output : no_output_callback;
    drv->outputv = de->outputv;
    drv->control = de->control;
    drv->call = de->call;
    drv->event = de->event ? de->event : no_event_callback;
    drv->ready_input = de->ready_input ? de->ready_input : no_ready_input_callback;
    drv->ready_output = de->ready_output ? de->ready_output : no_ready_output_callback;
    drv->timeout = de->timeout ? de->timeout : no_timeout_callback;
    drv->ready_async = de->ready_async;
    if (de->extended_marker == ERL_DRV_EXTENDED_MARKER)
	drv->process_exit = de->process_exit;
    else
	drv->process_exit = NULL;
    if (de->minor_version >= 3/*R13A*/ && de->stop_select)
	drv->stop_select = de->stop_select;
    else
	drv->stop_select = no_stop_select_callback;

    if (!de->init)
	return 0;
    else {
	int res;
	int fpe_was_unmasked = erts_block_fpe();
	res = (*de->init)();
	erts_unblock_fpe(fpe_was_unmasked);
	return res;
    }
}

void
erts_destroy_driver(erts_driver_t *drv)
{
#ifdef ERTS_SMP
    if (drv->lock) {
	erts_smp_mtx_destroy(drv->lock);
	erts_free(ERTS_ALC_T_DRIVER_LOCK, drv->lock);
    }
#endif    
    erts_free(ERTS_ALC_T_DRIVER, drv);
}

/* 
 * Functions for maintaining a list of driver_entry struct
 * Exposed in the driver interface, and therefore possibly locking directly.
 */

void add_driver_entry(ErlDrvEntry *drv){
    void *rec_lock;
    rec_lock = erts_smp_tsd_get(driver_list_lock_status_key);
    /* 
     * Ignore result of erts_add_driver_entry, the init is not
     * allowed to fail when drivers are added by drivers.
     */
    erts_add_driver_entry(drv, NULL, rec_lock != NULL); 
}

int erts_add_driver_entry(ErlDrvEntry *de, DE_Handle *handle, int driver_list_locked)
{
    erts_driver_t *dp = erts_alloc(ERTS_ALC_T_DRIVER, sizeof(erts_driver_t));
    int res;

    if (!driver_list_locked) {
	erts_smp_mtx_lock(&erts_driver_list_lock);
    }

    dp->next = driver_list;
    dp->prev = NULL;
    if (driver_list != NULL) {
	driver_list->prev = dp;
    }
    driver_list = dp;

    if (!driver_list_locked) {
	erts_smp_tsd_set(driver_list_lock_status_key, (void *) 1);
    }

    res = init_driver(dp, de, handle);

    if (res != 0) {
	/* 
	 * Remove it all again...
	 */
	driver_list = dp->next;
	if (driver_list != NULL) {
	    driver_list->prev = NULL;
	}
	erts_destroy_driver(dp);
    }
	
    if (!driver_list_locked) {
	erts_smp_tsd_set(driver_list_lock_status_key, NULL);
	erts_smp_mtx_unlock(&erts_driver_list_lock);
    }
    return res;
}

/* Not allowed for dynamic drivers */
int remove_driver_entry(ErlDrvEntry *drv)
{
    erts_driver_t *dp;
    void *rec_lock;
    
    rec_lock = erts_smp_tsd_get(driver_list_lock_status_key);
    if (rec_lock == NULL) {
	erts_smp_mtx_lock(&erts_driver_list_lock);
    }
    dp = driver_list;
    while (dp && dp->entry != drv)
	dp = dp->next;
    if (dp) {
	if (dp->handle) {
	    if (rec_lock == NULL) {
		erts_smp_mtx_unlock(&erts_driver_list_lock);
	    }
	    return -1;
	}
	if (dp->prev == NULL) {
	    driver_list = dp->next;
	} else {
	    dp->prev->next = dp->next;
	}
	if (dp->next != NULL) {
	    dp->next->prev = dp->prev;
	}
	erts_destroy_driver(dp);
	if (rec_lock == NULL) {
	    erts_smp_mtx_unlock(&erts_driver_list_lock);
	}
	return 1;
    }
    if (rec_lock == NULL) {
	erts_smp_mtx_unlock(&erts_driver_list_lock);
    }
    return 0;
}

/* very useful function that can be used in entries that are not used
 * so that not every driver writer must supply a personal version
 */
int null_func(void)
{
    return 0;
}

int
erl_drv_putenv(char *key, char *value)
{
    return erts_write_env(key, value);
}

int
erl_drv_getenv(char *key, char *value, size_t *value_size)
{
    return erts_sys_getenv(key, value, value_size);
}