path: root/erts/emulator/sys/unix/sys.c

/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 1996-2017. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * %CopyrightEnd%
 */

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

#ifdef ISC32
#define _POSIX_SOURCE
#define _XOPEN_SOURCE
#endif

#include <sys/times.h>		/* ! */
#include <time.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/uio.h>
#include <termios.h>
#include <ctype.h>
#include <sys/utsname.h>
#include <sys/select.h>

#ifdef ISC32
#include <sys/bsdtypes.h>
#endif

#include <termios.h>
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif

#define ERTS_WANT_BREAK_HANDLING
#define ERTS_WANT_GOT_SIGUSR1
#define WANT_NONBLOCKING    /* must define this to pull in defs from sys.h */
#include "sys.h"
#include "erl_thr_progress.h"

#if defined(__APPLE__) && defined(__MACH__) && !defined(__DARWIN__)
#define __DARWIN__ 1
#endif

#ifdef USE_THREADS
#include "erl_threads.h"
#endif

#include "erl_mseg.h"

extern char **environ;
erts_smp_rwmtx_t environ_rwmtx;

#define MAX_VSIZE 16		/* Max number of entries allowed in an I/O
				 * vector sock_sendv().
				 */
/*
 * Don't need global.h, but bif_table.h (included by bif.h),
 * won't compile otherwise
 */
#include "global.h"
#include "bif.h"

#include "erl_check_io.h"
#include "erl_cpu_topology.h"

extern int  driver_interrupt(int, int);
extern void do_break(void);

extern void erl_sys_args(int*, char**);

/* The following two defs should probably be moved somewhere else */

extern void erts_sys_init_float(void);


#ifdef DEBUG
static int debug_log = 0;
#endif

#ifdef ERTS_SMP
erts_smp_atomic32_t erts_got_sigusr1;
#define ERTS_SET_GOT_SIGUSR1 \
  erts_smp_atomic32_set_mb(&erts_got_sigusr1, 1)
#define ERTS_UNSET_GOT_SIGUSR1 \
  erts_smp_atomic32_set_mb(&erts_got_sigusr1, 0)
static erts_smp_atomic32_t have_prepared_crash_dump;
#define ERTS_PREPARED_CRASH_DUMP \
  ((int) erts_smp_atomic32_xchg_nob(&have_prepared_crash_dump, 1))
#else
volatile int erts_got_sigusr1;
#define ERTS_SET_GOT_SIGUSR1 (erts_got_sigusr1 = 1)
#define ERTS_UNSET_GOT_SIGUSR1 (erts_got_sigusr1 = 0)
static volatile int have_prepared_crash_dump;
#define ERTS_PREPARED_CRASH_DUMP \
  (have_prepared_crash_dump++)
#endif

erts_smp_atomic_t sys_misc_mem_sz;

#if defined(ERTS_SMP)
static void smp_sig_notify(char c);
static int sig_notify_fds[2] = {-1, -1};

#ifdef ERTS_SYS_SUSPEND_SIGNAL
static int sig_suspend_fds[2] = {-1, -1};
#endif

#endif

jmp_buf erts_sys_sigsegv_jmp;

static int crashdump_companion_cube_fd = -1;

/********************* General functions ****************************/

/* This is used by both the drivers and general I/O, must be set early */
static int max_files = -1;

/* 
 * a few variables used by the break handler 
 */
#ifdef ERTS_SMP
erts_smp_atomic32_t erts_break_requested;
#define ERTS_SET_BREAK_REQUESTED \
  erts_smp_atomic32_set_nob(&erts_break_requested, (erts_aint32_t) 1)
#define ERTS_UNSET_BREAK_REQUESTED \
  erts_smp_atomic32_set_nob(&erts_break_requested, (erts_aint32_t) 0)
#else
volatile int erts_break_requested = 0;
#define ERTS_SET_BREAK_REQUESTED (erts_break_requested = 1)
#define ERTS_UNSET_BREAK_REQUESTED (erts_break_requested = 0)
#endif

#ifndef ERTS_SMP
volatile Uint erts_signal_sigterm = 0;
#define ERTS_SET_SIGNAL_SIGTERM (erts_signal_sigterm = 1)
#define ERTS_CLEAR_SIGNAL_SIGTERM (erts_signal_sigterm = 0)
#endif

/* set early so the break handler has access to initial mode */
static struct termios initial_tty_mode;
static int replace_intr = 0;
/* assume yes initially, ttsl_init will clear it */
int using_oldshell = 1;

#ifdef ERTS_ENABLE_KERNEL_POLL

int erts_use_kernel_poll = 0;

struct {
    int (*select)(ErlDrvPort, ErlDrvEvent, int, int);
    int (*event)(ErlDrvPort, ErlDrvEvent, ErlDrvEventData);
    void (*check_io_as_interrupt)(void);
    void (*check_io_interrupt)(int);
    void (*check_io_interrupt_tmd)(int, ErtsMonotonicTime);
    void (*check_io)(int);
    Uint (*size)(void);
    Eterm (*info)(void *);
    int (*check_io_debug)(ErtsCheckIoDebugInfo *);
} io_func = {0};


int
driver_select(ErlDrvPort port, ErlDrvEvent event, int mode, int on)
{
    return (*io_func.select)(port, event, mode, on);
}

int
driver_event(ErlDrvPort port, ErlDrvEvent event, ErlDrvEventData event_data)
{
    return (*io_func.event)(port, event, event_data);
}

Eterm erts_check_io_info(void *p)
{
    return (*io_func.info)(p);
}

int
erts_check_io_debug(ErtsCheckIoDebugInfo *ip)
{
    return (*io_func.check_io_debug)(ip);
}


static void
init_check_io(void)
{
    if (erts_use_kernel_poll) {
	io_func.select			= driver_select_kp;
	io_func.event			= driver_event_kp;
#ifdef ERTS_POLL_NEED_ASYNC_INTERRUPT_SUPPORT
	io_func.check_io_as_interrupt	= erts_check_io_async_sig_interrupt_kp;
#endif
	io_func.check_io_interrupt	= erts_check_io_interrupt_kp;
	io_func.check_io_interrupt_tmd	= erts_check_io_interrupt_timed_kp;
	io_func.check_io		= erts_check_io_kp;
	io_func.size			= erts_check_io_size_kp;
	io_func.info			= erts_check_io_info_kp;
	io_func.check_io_debug		= erts_check_io_debug_kp;
	erts_init_check_io_kp();
	max_files = erts_check_io_max_files_kp();
    }
    else {
	io_func.select			= driver_select_nkp;
	io_func.event			= driver_event_nkp;
#ifdef ERTS_POLL_NEED_ASYNC_INTERRUPT_SUPPORT
	io_func.check_io_as_interrupt	= erts_check_io_async_sig_interrupt_nkp;
#endif
	io_func.check_io_interrupt	= erts_check_io_interrupt_nkp;
	io_func.check_io_interrupt_tmd	= erts_check_io_interrupt_timed_nkp;
	io_func.check_io		= erts_check_io_nkp;
	io_func.size			= erts_check_io_size_nkp;
	io_func.info			= erts_check_io_info_nkp;
	io_func.check_io_debug		= erts_check_io_debug_nkp;
	erts_init_check_io_nkp();
	max_files = erts_check_io_max_files_nkp();
    }
}

#ifdef ERTS_POLL_NEED_ASYNC_INTERRUPT_SUPPORT
#define ERTS_CHK_IO_AS_INTR()	(*io_func.check_io_as_interrupt)()
#else
#define ERTS_CHK_IO_AS_INTR()	(*io_func.check_io_interrupt)(1)
#endif
#define ERTS_CHK_IO_INTR	(*io_func.check_io_interrupt)
#define ERTS_CHK_IO_INTR_TMD	(*io_func.check_io_interrupt_tmd)
#define ERTS_CHK_IO		(*io_func.check_io)
#define ERTS_CHK_IO_SZ		(*io_func.size)

#else /* !ERTS_ENABLE_KERNEL_POLL */

static void
init_check_io(void)
{
    erts_init_check_io();
    max_files = erts_check_io_max_files();
}

#ifdef ERTS_POLL_NEED_ASYNC_INTERRUPT_SUPPORT
#define ERTS_CHK_IO_AS_INTR()	erts_check_io_async_sig_interrupt()
#else
#define ERTS_CHK_IO_AS_INTR()	erts_check_io_interrupt(1)
#endif
#define ERTS_CHK_IO_INTR	erts_check_io_interrupt
#define ERTS_CHK_IO_INTR_TMD	erts_check_io_interrupt_timed
#define ERTS_CHK_IO		erts_check_io
#define ERTS_CHK_IO_SZ		erts_check_io_size

#endif

void
erts_sys_schedule_interrupt(int set)
{
    ERTS_CHK_IO_INTR(set);
}

#ifdef ERTS_SMP
void
erts_sys_schedule_interrupt_timed(int set, ErtsMonotonicTime timeout_time)
{
    ERTS_CHK_IO_INTR_TMD(set, timeout_time);
}
#endif

Uint
erts_sys_misc_mem_sz(void)
{
    Uint res = ERTS_CHK_IO_SZ();
    res += erts_smp_atomic_read_mb(&sys_misc_mem_sz);
    return res;
}

/*
 * reset the terminal to the original settings on exit
 */
void sys_tty_reset(int exit_code)
{
  if (using_oldshell && !replace_intr) {
    SET_BLOCKING(0);
  }
  else if (isatty(0)) {
    tcsetattr(0,TCSANOW,&initial_tty_mode);
  }
}

#ifdef __tile__
/* Direct malloc to spread memory around the caches of multiple tiles. */
#include <malloc.h>
#if defined(MALLOC_USE_HASH)
MALLOC_USE_HASH(1);
#endif
#endif

#ifdef USE_THREADS

#ifdef ERTS_THR_HAVE_SIG_FUNCS

/*
 * Child thread inherits parents signal mask at creation. In order to
 * guarantee that the main thread will receive all SIGINT, and
 * SIGUSR1 signals sent to the process, we block these signals in the
 * parent thread when creating a new thread.
 */

static sigset_t thr_create_sigmask;

#endif /* #ifdef ERTS_THR_HAVE_SIG_FUNCS */

typedef struct {
#ifdef ERTS_THR_HAVE_SIG_FUNCS
    sigset_t saved_sigmask;
#endif
    int sched_bind_data;
} erts_thr_create_data_t;

/*
 * thr_create_prepare() is called in parent thread before thread creation.
 * Returned value is passed as argument to thr_create_cleanup().
 */
static void *
thr_create_prepare(void)
{
    erts_thr_create_data_t *tcdp;

    tcdp = erts_alloc(ERTS_ALC_T_TMP, sizeof(erts_thr_create_data_t));

#ifdef ERTS_THR_HAVE_SIG_FUNCS
    erts_thr_sigmask(SIG_BLOCK, &thr_create_sigmask, &tcdp->saved_sigmask);
#endif
    tcdp->sched_bind_data = erts_sched_bind_atthrcreate_prepare();

    return (void *) tcdp;
}


/* thr_create_cleanup() is called in parent thread after thread creation. */
static void
thr_create_cleanup(void *vtcdp)
{
    erts_thr_create_data_t *tcdp = (erts_thr_create_data_t *) vtcdp;

    erts_sched_bind_atthrcreate_parent(tcdp->sched_bind_data);

#ifdef ERTS_THR_HAVE_SIG_FUNCS
    /* Restore signalmask... */
    erts_thr_sigmask(SIG_SETMASK, &tcdp->saved_sigmask, NULL);
#endif

    erts_free(ERTS_ALC_T_TMP, tcdp);
}

static void
thr_create_prepare_child(void *vtcdp)
{
    erts_thr_create_data_t *tcdp = (erts_thr_create_data_t *) vtcdp;

#ifdef ERTS_ENABLE_LOCK_COUNT
    erts_lcnt_thread_setup();
#endif

#ifndef NO_FPE_SIGNALS
    /*
     * We do not want fp exeptions in other threads than the
     * scheduler threads. We enable fpe explicitly in the scheduler
     * threads after this.
     */
    erts_thread_disable_fpe();
#endif

    erts_sched_bind_atthrcreate_child(tcdp->sched_bind_data);
}

#endif /* #ifdef USE_THREADS */

void
erts_sys_pre_init(void)
{
#ifdef USE_THREADS
    erts_thr_init_data_t eid = ERTS_THR_INIT_DATA_DEF_INITER;
#endif

    erts_printf_add_cr_to_stdout = 1;
    erts_printf_add_cr_to_stderr = 1;

#ifdef USE_THREADS

    eid.thread_create_child_func = thr_create_prepare_child;
    /* Before creation in parent */
    eid.thread_create_prepare_func = thr_create_prepare;
    /* After creation in parent */
    eid.thread_create_parent_func = thr_create_cleanup,

#ifdef ERTS_THR_HAVE_SIG_FUNCS
    sigemptyset(&thr_create_sigmask);
    sigaddset(&thr_create_sigmask, SIGINT);   /* block interrupt */
    sigaddset(&thr_create_sigmask, SIGTERM);  /* block terminate signal */
    sigaddset(&thr_create_sigmask, SIGUSR1);  /* block user defined signal */
#endif

    erts_thr_init(&eid);

#ifdef ERTS_ENABLE_LOCK_CHECK
    erts_lc_init();
#endif

#ifdef ERTS_ENABLE_LOCK_COUNT
    erts_lcnt_init();
#endif

#endif /* USE_THREADS */

    erts_init_sys_time_sup();

#ifdef USE_THREADS

#ifdef ERTS_SMP
    erts_smp_atomic32_init_nob(&erts_break_requested, 0);
    erts_smp_atomic32_init_nob(&erts_got_sigusr1, 0);
    erts_smp_atomic32_init_nob(&have_prepared_crash_dump, 0);
#else
    erts_break_requested = 0;
    erts_got_sigusr1 = 0;
    have_prepared_crash_dump = 0;
#endif

#endif /* USE_THREADS */

    erts_smp_atomic_init_nob(&sys_misc_mem_sz, 0);

    {
      /*
       * Unfortunately we depend on fd 0,1,2 in the old shell code.
       * So if for some reason we do not have those open when we start
       * we have to open them here. Not doing this can cause the emulator
       * to deadlock when reaping the fd_driver ports :(
       */
      int fd;
      /* Make sure fd 0 is open */
      if ((fd = open("/dev/null", O_RDONLY)) != 0)
	close(fd);
      /* Make sure fds 1 and 2 are open */
      while (fd < 3) {
	fd = open("/dev/null", O_WRONLY);
      }
      close(fd);
    }

    /* We need a file descriptor to close in the crashdump creation.
     * We close this one to be sure we can get a fd for our real file ...
     * so, we create one here ... a stone to carry all the way home.
     */

    crashdump_companion_cube_fd = open("/dev/null", O_RDONLY);

    /* don't lose it, there will be cake */
}

void
erl_sys_init(void)
{

#ifdef USE_SETLINEBUF
    setlinebuf(stdout);
#else
    setvbuf(stdout, (char *)NULL, _IOLBF, BUFSIZ);
#endif

    erts_sys_init_float();

    /* we save this so the break handler can set and reset it properly */
    /* also so that we can reset on exit (break handler or not) */
    if (isatty(0)) {
	tcgetattr(0,&initial_tty_mode);
    }
    tzset(); /* Required at least for NetBSD with localtime_r() */
}

/* signal handling */

SIGFUNC sys_signal(int sig, SIGFUNC func)
{
    struct sigaction act, oact;

    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    act.sa_handler = func;
    sigaction(sig, &act, &oact);
    return(oact.sa_handler);
}

#ifdef USE_THREADS
#undef  sigprocmask
#define sigprocmask erts_thr_sigmask
#endif

void sys_sigblock(int sig)
{
    sigset_t mask;

    sigemptyset(&mask);
    sigaddset(&mask, sig);
    sigprocmask(SIG_BLOCK, &mask, (sigset_t *)NULL);
}

void sys_sigrelease(int sig)
{
    sigset_t mask;

    sigemptyset(&mask);
    sigaddset(&mask, sig);
    sigprocmask(SIG_UNBLOCK, &mask, (sigset_t *)NULL);
}

void erts_sys_sigsegv_handler(int signo) {
    if (signo == SIGSEGV) {
        longjmp(erts_sys_sigsegv_jmp, 1);
    }
}

/*
 * Function returns 1 if we can read from all values in between
 * start and stop.
 */
int
erts_sys_is_area_readable(char *start, char *stop) {
    int fds[2];
    if (!pipe(fds)) {
        /* We let write try to figure out if the pointers are readable */
        int res = write(fds[1], start, (char*)stop - (char*)start);
        if (res == -1) {
            close(fds[0]);
            close(fds[1]);
            return 0;
        }
        close(fds[0]);
        close(fds[1]);
        return 1;
    }
    return 0;

}

static ERTS_INLINE int
prepare_crash_dump(int secs)
{
#define NUFBUF (3)
    int i;
    char env[21]; /* enough to hold any 64-bit integer */
    size_t envsz;
    DeclareTmpHeapNoproc(heap,NUFBUF);
    Port *heart_port;
    Eterm *hp = heap;
    Eterm list = NIL;
    int has_heart = 0;

    UseTmpHeapNoproc(NUFBUF);

    if (ERTS_PREPARED_CRASH_DUMP)
	return 0; /* We have already been called */

    heart_port = erts_get_heart_port();

    /* Positive secs means an alarm must be set
     * 0 or negative means no alarm
     *
     * Set alarm before we try to write to a port
     * we don't want to hang on a port write with
     * no alarm.
     *
     */

    if (secs >= 0) {
	alarm((unsigned int)secs);
    }

    /* close all viable sockets via emergency close callbacks.
     * Specifically we want to close epmd sockets.
     */

    erts_emergency_close_ports();

    if (heart_port) {
	has_heart = 1;
	list = CONS(hp, make_small(8), list); hp += 2;
	/* send to heart port, CMD = 8, i.e. prepare crash dump =o */
	erts_port_output(NULL, ERTS_PORT_SIG_FLG_FORCE_IMM_CALL, heart_port,
			 heart_port->common.id, list, NULL);
    }

    /* Make sure we have a fd for our crashdump file. */
    close(crashdump_companion_cube_fd);

    envsz = sizeof(env);
    i = erts_sys_getenv__("ERL_CRASH_DUMP_NICE", env, &envsz);
    if (i >= 0) {
	int nice_val;
	nice_val = i != 0 ? 0 : atoi(env);
	if (nice_val > 39) {
	    nice_val = 39;
	}
	erts_silence_warn_unused_result(nice(nice_val));
    }

    UnUseTmpHeapNoproc(NUFBUF);
#undef NUFBUF
    return has_heart;
}

int erts_sys_prepare_crash_dump(int secs)
{
    return prepare_crash_dump(secs);
}

static ERTS_INLINE void
break_requested(void)
{
  /*
   * just set a flag - checked for and handled by
   * scheduler threads erts_check_io() (not signal handler).
   */
#ifdef DEBUG			
  fprintf(stderr,"break!\n");
#endif
  if (ERTS_BREAK_REQUESTED)
      erts_exit(ERTS_INTR_EXIT, "");

  ERTS_SET_BREAK_REQUESTED;
  ERTS_CHK_IO_AS_INTR(); /* Make sure we don't sleep in poll */
}

/* set up signal handlers for break and quit */
#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
static RETSIGTYPE request_break(void)
#else
static RETSIGTYPE request_break(int signum)
#endif
{
#ifdef ERTS_SMP
    smp_sig_notify('I');
#else
    break_requested();
#endif
}

static void stop_requested(void) {
    Process* p = NULL;
    Eterm msg, *hp;
    ErtsProcLocks locks = 0;
    ErlOffHeap *ohp;
    Eterm id = erts_whereis_name_to_id(NULL, am_init);

    if ((p = (erts_pid2proc_opt(NULL, 0, id, 0, ERTS_P2P_FLG_INC_REFC))) != NULL) {
        ErtsMessage *msgp = erts_alloc_message_heap(p, &locks, 3, &hp, &ohp);

        /* init ! {stop,stop} */
        msg = TUPLE2(hp, am_stop, am_stop);
        erts_queue_message(p, locks, msgp, msg, am_system);

        if (locks)
            erts_smp_proc_unlock(p, locks);
        erts_proc_dec_refc(p);
    }
}

#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
static RETSIGTYPE request_stop(void)
#else
static RETSIGTYPE request_stop(int signum)
#endif
{
#ifdef ERTS_SMP
    smp_sig_notify('S');
#else
    ERTS_SET_SIGNAL_SIGTERM;
    ERTS_CHK_IO_AS_INTR();
#endif
}

static ERTS_INLINE void
sigusr1_exit(void)
{
    char env[21]; /* enough to hold any 64-bit integer */
    size_t envsz;
    int i, secs = -1;

    /* We do this at interrupt level, since the main reason for
     * wanting to generate a crash dump in this way is that the emulator
     * is hung somewhere, so it won't be able to poll any flag we set here.
     */
    ERTS_SET_GOT_SIGUSR1;

    envsz = sizeof(env);
    if ((i = erts_sys_getenv_raw("ERL_CRASH_DUMP_SECONDS", env, &envsz)) >= 0) {
	secs = i != 0 ? 0 : atoi(env);
    }

    prepare_crash_dump(secs);
    erts_exit(ERTS_DUMP_EXIT, "Received SIGUSR1\n");
}

#ifdef ETHR_UNUSABLE_SIGUSRX
#warning "Unusable SIGUSR1 & SIGUSR2. Disabling use of these signals"

#else

#ifdef ERTS_SYS_SUSPEND_SIGNAL
void
sys_thr_suspend(erts_tid_t tid) {
    erts_thr_kill(tid, ERTS_SYS_SUSPEND_SIGNAL);
}

void
sys_thr_resume(erts_tid_t tid) {
    int i = 0, res;
    do {
        res = write(sig_suspend_fds[1],&i,sizeof(i));
    } while (res < 0 && errno == EAGAIN);
}
#endif

#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
static RETSIGTYPE user_signal1(void)
#else
static RETSIGTYPE user_signal1(int signum)
#endif
{
#ifdef ERTS_SMP
   smp_sig_notify('1');
#else
   sigusr1_exit();
#endif
}

#ifdef ERTS_SYS_SUSPEND_SIGNAL
#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
static RETSIGTYPE suspend_signal(void)
#else
static RETSIGTYPE suspend_signal(int signum)
#endif
{
    int res, buf[1], tmp_errno = errno;
    do {
        res = read(sig_suspend_fds[0], buf, sizeof(int));
    } while (res < 0 && errno == EINTR);

    /* restore previous errno in case read changed it */
    errno = tmp_errno;
}
#endif /* #ifdef ERTS_SYS_SUSPEND_SIGNAL */

#endif /* #ifndef ETHR_UNUSABLE_SIGUSRX */

static void
quit_requested(void)
{
    erts_exit(ERTS_INTR_EXIT, "");
}

#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
static RETSIGTYPE do_quit(void)
#else
static RETSIGTYPE do_quit(int signum)
#endif
{
#ifdef ERTS_SMP
    smp_sig_notify('Q');
#else
    quit_requested();
#endif
}

/* Disable break */
void erts_set_ignore_break(void) {
    sys_signal(SIGINT,  SIG_IGN);
    sys_signal(SIGTERM, SIG_IGN);
    sys_signal(SIGQUIT, SIG_IGN);
    sys_signal(SIGTSTP, SIG_IGN);
}

/* Don't use ctrl-c for break handler but let it be 
   used by the shell instead (see user_drv.erl) */
void erts_replace_intr(void) {
  struct termios mode;

  if (isatty(0)) {
    tcgetattr(0, &mode);
    
    /* here's an example of how to replace ctrl-c with ctrl-u */
    /* mode.c_cc[VKILL] = 0;
       mode.c_cc[VINTR] = CKILL; */
    
    mode.c_cc[VINTR] = 0;	/* disable ctrl-c */
    tcsetattr(0, TCSANOW, &mode);
    replace_intr = 1;
  }
}

void init_break_handler(void)
{
   sys_signal(SIGINT, request_break);
   sys_signal(SIGTERM, request_stop);
#ifndef ETHR_UNUSABLE_SIGUSRX
   sys_signal(SIGUSR1, user_signal1);
#endif /* #ifndef ETHR_UNUSABLE_SIGUSRX */
   sys_signal(SIGQUIT, do_quit);
}

void sys_init_suspend_handler(void)
{
#ifdef ERTS_SYS_SUSPEND_SIGNAL
   sys_signal(ERTS_SYS_SUSPEND_SIGNAL, suspend_signal);
#endif
}

int sys_max_files(void)
{
   return(max_files);
}

/************************** OS info *******************************/

/* Used by erlang:info/1. */
/* (This code was formerly in drv.XXX/XXX_os_drv.c) */

char os_type[] = "unix";

static int
get_number(char **str_ptr)
{
    char* s = *str_ptr;		/* Pointer to beginning of string. */
    char* dot;			/* Pointer to dot in string or NULL. */

    if (!isdigit((int) *s))
	return 0;
    if ((dot = strchr(s, '.')) == NULL) {
	*str_ptr = s+strlen(s);
	return atoi(s);
    } else {
	*dot = '\0';
	*str_ptr = dot+1;
	return atoi(s);
    }
}

void
os_flavor(char* namebuf, 	/* Where to return the name. */
	  unsigned size) 	/* Size of name buffer. */
{
    struct utsname uts;		/* Information about the system. */
    char* s;

    (void) uname(&uts);
    for (s = uts.sysname; *s; s++) {
	if (isupper((int) *s)) {
	    *s = tolower((int) *s);
	}
    }
    strcpy(namebuf, uts.sysname);
}

void
os_version(pMajor, pMinor, pBuild)
int* pMajor;			/* Pointer to major version. */
int* pMinor;			/* Pointer to minor version. */
int* pBuild;			/* Pointer to build number. */
{
    struct utsname uts;		/* Information about the system. */
    char* release;		/* Pointer to the release string:
				 * X.Y or X.Y.Z.
				 */

    (void) uname(&uts);
    release = uts.release;
    *pMajor = get_number(&release);
    *pMinor = get_number(&release);
    *pBuild = get_number(&release);
}

void init_getenv_state(GETENV_STATE *state)
{
   erts_smp_rwmtx_rlock(&environ_rwmtx);
   *state = NULL;
}

char *getenv_string(GETENV_STATE *state0)
{
   char **state = (char **) *state0;
   char *cp;

   ERTS_SMP_LC_ASSERT(erts_smp_lc_rwmtx_is_rlocked(&environ_rwmtx));

   if (state == NULL)
      state = environ;

   cp = *state++;
   *state0 = (GETENV_STATE) state;

   return cp;
}

void fini_getenv_state(GETENV_STATE *state)
{
   *state = NULL;
   erts_smp_rwmtx_runlock(&environ_rwmtx);
}

void erts_do_break_handling(void)
{
    struct termios temp_mode;
    int saved = 0;
    
    /*
     * Most functions that do_break() calls are intentionally not thread safe;
     * therefore, make sure that all threads but this one are blocked before
     * proceeding!
     */
    erts_smp_thr_progress_block();

    /* during break we revert to initial settings */
    /* this is done differently for oldshell */
    if (using_oldshell && !replace_intr) {
      SET_BLOCKING(1);
    }
    else if (isatty(0)) {
      tcgetattr(0,&temp_mode);
      tcsetattr(0,TCSANOW,&initial_tty_mode);
      saved = 1;
    }
    
    /* call the break handling function, reset the flag */
    do_break();

    ERTS_UNSET_BREAK_REQUESTED;

    fflush(stdout);
    
    /* after break we go back to saved settings */
    if (using_oldshell && !replace_intr) {
      SET_NONBLOCKING(1);
    }
    else if (saved) {
      tcsetattr(0,TCSANOW,&temp_mode);
    }

    erts_smp_thr_progress_unblock();
}

#ifdef ERTS_SIGNAL_SIGTERM
void erts_handle_signal_sigterm(void) {
    ERTS_CLEAR_SIGNAL_SIGTERM;
    stop_requested();
}
#endif

/* Fills in the systems representation of the jam/beam process identifier.
** The Pid is put in STRING representation in the supplied buffer,
** no interpretatione of this should be done by the rest of the
** emulator. The buffer should be at least 21 bytes long.
*/
void sys_get_pid(char *buffer, size_t buffer_size){
    pid_t p = getpid();
    /* Assume the pid is scalar and can rest in an unsigned long... */
    erts_snprintf(buffer, buffer_size, "%lu",(unsigned long) p);
}

int
erts_sys_putenv_raw(char *key, char *value) {
    return erts_sys_putenv(key, value);
}
int
erts_sys_putenv(char *key, char *value)
{
    int res;
    char *env;
    Uint need = strlen(key) + strlen(value) + 2;

#ifdef HAVE_COPYING_PUTENV
    env = erts_alloc(ERTS_ALC_T_TMP, need);
#else
    env = erts_alloc(ERTS_ALC_T_PUTENV_STR, need);
    erts_smp_atomic_add_nob(&sys_misc_mem_sz, need);
#endif
    strcpy(env,key);
    strcat(env,"=");
    strcat(env,value);
    erts_smp_rwmtx_rwlock(&environ_rwmtx);
    res = putenv(env);
    erts_smp_rwmtx_rwunlock(&environ_rwmtx);
#ifdef HAVE_COPYING_PUTENV
    erts_free(ERTS_ALC_T_TMP, env);
#endif
    return res;
}

int
erts_sys_getenv__(char *key, char *value, size_t *size)
{
    int res;
    char *orig_value = getenv(key);
    if (!orig_value)
	res = -1;
    else {
	size_t len = sys_strlen(orig_value);
	if (len >= *size) {
	    *size = len + 1;
	    res = 1;
	}
	else {
	    *size = len;
	    sys_memcpy((void *) value, (void *) orig_value, len+1);
	    res = 0;
	}
    }
    return res;
}

int
erts_sys_getenv_raw(char *key, char *value, size_t *size) {
    return erts_sys_getenv(key, value, size);
}

/*
 * erts_sys_getenv
 * returns:
 *  -1, if environment key is not set with a value
 *   0, if environment key is set and value fits into buffer size
 *   1, if environment key is set but does not fit into buffer size
 *      size is set with the needed buffer size value
 */

int
erts_sys_getenv(char *key, char *value, size_t *size)
{
    int res;
    erts_smp_rwmtx_rlock(&environ_rwmtx);
    res = erts_sys_getenv__(key, value, size);
    erts_smp_rwmtx_runlock(&environ_rwmtx);
    return res;
}

int
erts_sys_unsetenv(char *key)
{
    int res;
    erts_smp_rwmtx_rwlock(&environ_rwmtx);
    res = unsetenv(key);
    erts_smp_rwmtx_rwunlock(&environ_rwmtx);
    return res;
}

void
sys_init_io(void)
{
}

#if (0) /* unused? */
static int write_fill(fd, buf, len)
int fd, len;
char *buf;
{
    int i, done = 0;
    
    do {
	if ((i = write(fd, buf+done, len-done)) < 0) {
	    if (errno != EINTR)
		return (i);
	    i = 0;
	}
	done += i;
    } while (done < len);
    return (len);
}
#endif

extern const char pre_loaded_code[];
extern Preload pre_loaded[];

void erts_sys_alloc_init(void)
{
}

#if ERTS_HAVE_ERTS_SYS_ALIGNED_ALLOC
void *erts_sys_aligned_alloc(UWord alignment, UWord size)
{
#ifdef HAVE_POSIX_MEMALIGN
    void *ptr = NULL;
    int error;
    ASSERT(alignment && (alignment & (alignment-1)) == 0); /* power of 2 */
    error = posix_memalign(&ptr, (size_t) alignment, (size_t) size);
#if HAVE_ERTS_MSEG
    if (error || !ptr) {
	erts_mseg_clear_cache();
	error = posix_memalign(&ptr, (size_t) alignment, (size_t) size);
    }
#endif
    if (error) {
	errno = error;
	return NULL;
    }
    if (!ptr)
	errno = ENOMEM;
    ASSERT(!ptr || (((UWord) ptr) & (alignment - 1)) == 0);
    return ptr;
#else
#  error "Missing erts_sys_aligned_alloc() implementation"
#endif
}

void erts_sys_aligned_free(UWord alignment, void *ptr)
{
    ASSERT(alignment && (alignment & (alignment-1)) == 0); /* power of 2 */
    free(ptr);
}

void *erts_sys_aligned_realloc(UWord alignment, void *ptr, UWord size, UWord old_size)
{
    void *new_ptr = erts_sys_aligned_alloc(alignment, size);
    if (new_ptr) {
	UWord copy_size = old_size < size ? old_size : size;
	sys_memcpy(new_ptr, ptr, (size_t) copy_size);
	erts_sys_aligned_free(alignment, ptr);
    }
    return new_ptr;
}

#endif

void *erts_sys_alloc(ErtsAlcType_t t, void *x, Uint sz)
{
    void *res = malloc((size_t) sz);
#if HAVE_ERTS_MSEG
    if (!res) {
	erts_mseg_clear_cache();
	return malloc((size_t) sz);
    }
#endif
    return res;
}

void *erts_sys_realloc(ErtsAlcType_t t, void *x, void *p, Uint sz)
{
    void *res = realloc(p, (size_t) sz);
#if HAVE_ERTS_MSEG
    if (!res) {
	erts_mseg_clear_cache();
	return realloc(p, (size_t) sz);
    }
#endif
    return res;
}

void erts_sys_free(ErtsAlcType_t t, void *x, void *p)
{
    free(p);
}

/* Return a pointer to a vector of names of preloaded modules */

Preload*
sys_preloaded(void)
{
    return pre_loaded;
}

/* Return a pointer to preloaded code for module "module" */
unsigned char*
sys_preload_begin(Preload* p)
{
    return p->code;
}

/* Clean up if allocated */
void sys_preload_end(Preload* p)
{
    /* Nothing */
}

/* Read a key from console, used by break.c
   Here we assume that all schedulers are stopped so that erl_poll
   does not interfere with the select below.
*/
int sys_get_key(fd)
int fd;
{
    int c, ret;
    unsigned char rbuf[64];
    fd_set fds;

    fflush(stdout);		/* Flush query ??? */

    FD_ZERO(&fds);
    FD_SET(fd,&fds);

    ret = select(fd+1, &fds, NULL, NULL, NULL);

    if (ret == 1) {
        do {
            c = read(fd,rbuf,64);
        } while (c < 0 && errno == EAGAIN);
        if (c <= 0)
            return c;
    }

    return rbuf[0]; 
}


extern int erts_initialized;
void
erl_assert_error(const char* expr, const char* func, const char* file, int line)
{   
    fflush(stdout);
    fprintf(stderr, "%s:%d:%s() Assertion failed: %s\n",
            file, line, func, expr);
    fflush(stderr);
#if !defined(ERTS_SMP) && 0
    /* Writing a crashdump from a failed assertion when smp support
     * is enabled almost a guaranteed deadlocking, don't even bother.
     *
     * It could maybe be useful (but I'm not convinced) to write the
     * crashdump if smp support is disabled...
     */
    if (erts_initialized)
	erl_crash_dump(file, line, "Assertion failed: %s\n", expr);
#endif
    abort();
}

#ifdef DEBUG

void
erl_debug(char* fmt, ...)
{
    char sbuf[1024];		/* Temporary buffer. */
    va_list va;
    
    if (debug_log) {
	va_start(va, fmt);
	vsprintf(sbuf, fmt, va);
	va_end(va);
	fprintf(stderr, "%s", sbuf);
    }
}

#endif /* DEBUG */

/*
 * Called from schedule() when it runs out of runnable processes,
 * or when Erlang code has performed INPUT_REDUCTIONS reduction
 * steps. runnable == 0 iff there are no runnable Erlang processes.
 */
void
erl_sys_schedule(int runnable)
{
    ERTS_CHK_IO(!runnable);
    ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
}


#ifdef ERTS_SMP

static erts_smp_tid_t sig_dispatcher_tid;

static void
smp_sig_notify(char c)
{
    int res;
    do {
	/* write() is async-signal safe (according to posix) */
	res = write(sig_notify_fds[1], &c, 1);
    } while (res < 0 && errno == EINTR);
    if (res != 1) {
	char msg[] =
	    "smp_sig_notify(): Failed to notify signal-dispatcher thread "
	    "about received signal";
	erts_silence_warn_unused_result(write(2, msg, sizeof(msg)));
	abort();
    }
}

static void *
signal_dispatcher_thread_func(void *unused)
{
#ifdef ERTS_ENABLE_LOCK_CHECK
    erts_lc_set_thread_name("signal_dispatcher");
#endif
    while (1) {
	char buf[32];
	int res, i;
	/* Block on read() waiting for a signal notification to arrive... */
	res = read(sig_notify_fds[0], (void *) &buf[0], 32);
	if (res < 0) {
	    if (errno == EINTR)
		continue;
	    erts_exit(ERTS_ABORT_EXIT,
		     "signal-dispatcher thread got unexpected error: %s (%d)\n",
		     erl_errno_id(errno),
		     errno);
	}
	for (i = 0; i < res; i++) {
	    /*
	     * NOTE 1: The signal dispatcher thread should not do work
	     *         that takes a substantial amount of time (except
	     *         perhaps in test and debug builds). It needs to
	     *         be responsive, i.e, it should only dispatch work
	     *         to other threads.
	     *
	     * NOTE 2: The signal dispatcher thread is not a blockable
	     *         thread (i.e., not a thread managed by the
	     *         erl_thr_progress module). This is intentional.
	     *         We want to be able to interrupt writing of a crash
	     *         dump by hitting C-c twice. Since it isn't a
	     *         blockable thread it is important that it doesn't
	     *         change the state of any data that a blocking thread
	     *         expects to have exclusive access to (unless the
	     *         signal dispatcher itself explicitly is blocking all
	     *         blockable threads).
	     */
	    switch (buf[i]) {
	    case 0: /* Emulator initialized */
                break;
	    case 'S': /* SIGTERM */
		stop_requested();
		break;
	    case 'I': /* SIGINT */
		break_requested();
		break;
	    case 'Q': /* SIGQUIT */
		quit_requested();
		break;
	    case '1': /* SIGUSR1 */
		sigusr1_exit();
		break;
	    default:
		erts_exit(ERTS_ABORT_EXIT,
			 "signal-dispatcher thread received unknown "
			 "signal notification: '%c'\n",
			 buf[i]);
	    }
	}
	ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
    }
    return NULL;
}

static void
init_smp_sig_notify(void)
{
    erts_smp_thr_opts_t thr_opts = ERTS_SMP_THR_OPTS_DEFAULT_INITER;
    thr_opts.detached = 1;
    thr_opts.name = "sys_sig_dispatcher";

    if (pipe(sig_notify_fds) < 0) {
	erts_exit(ERTS_ABORT_EXIT,
		 "Failed to create signal-dispatcher pipe: %s (%d)\n",
		 erl_errno_id(errno),
		 errno);
    }

    /* Start signal handler thread */
    erts_smp_thr_create(&sig_dispatcher_tid,
			signal_dispatcher_thread_func,
			NULL,
			&thr_opts);
}

static void
init_smp_sig_suspend(void) {
#ifdef ERTS_SYS_SUSPEND_SIGNAL
  if (pipe(sig_suspend_fds) < 0) {
    erts_exit(ERTS_ABORT_EXIT,
	     "Failed to create sig_suspend pipe: %s (%d)\n",
	     erl_errno_id(errno),
	     errno);
  }
#endif
}

#ifdef __DARWIN__

int erts_darwin_main_thread_pipe[2];
int erts_darwin_main_thread_result_pipe[2];

static void initialize_darwin_main_thread_pipes(void) 
{
    if (pipe(erts_darwin_main_thread_pipe) < 0 || 
	pipe(erts_darwin_main_thread_result_pipe) < 0) {
	erts_exit(ERTS_ERROR_EXIT,"Fatal error initializing Darwin main thread stealing");
    }
}

#endif
void
erts_sys_main_thread(void)
{
    erts_thread_disable_fpe();
#ifdef __DARWIN__
    initialize_darwin_main_thread_pipes();
#endif
    /* Become signal receiver thread... */
#ifdef ERTS_ENABLE_LOCK_CHECK
    erts_lc_set_thread_name("signal_receiver");
#endif

    smp_sig_notify(0); /* Notify initialized */

    /* Wait for a signal to arrive... */

#ifdef __DARWIN__
    while (1) {
	/*
	 * The wx driver needs to be able to steal the main thread for Cocoa to
	 * work properly.
	 */
	fd_set readfds;
	int res;

	FD_ZERO(&readfds);
	FD_SET(erts_darwin_main_thread_pipe[0], &readfds);
	res = select(erts_darwin_main_thread_pipe[0] + 1, &readfds, NULL, NULL, NULL);
	if (res > 0 && FD_ISSET(erts_darwin_main_thread_pipe[0],&readfds)) {
	    void* (*func)(void*);
	    void* arg;
	    void *resp;
            res = read(erts_darwin_main_thread_pipe[0],&func,sizeof(void* (*)(void*)));
            if (res != sizeof(void* (*)(void*)))
                break;
            res = read(erts_darwin_main_thread_pipe[0],&arg,sizeof(void*));
            if (res != sizeof(void*))
                break;
	    resp = (*func)(arg);
	    write(erts_darwin_main_thread_result_pipe[1],&resp,sizeof(void *));
	}

        if (res == -1 && errno != EINTR)
            break;
    }
    /* Something broke with the main thread pipe, so we ignore it for now.
       Most probably erts has closed this pipe and is about to exit. */
#endif /* #ifdef __DARWIN__ */

    while (1) {
#ifdef DEBUG
	int res =
#else
	(void)
#endif
	    select(0, NULL, NULL, NULL, NULL);
	ASSERT(res < 0);
	ASSERT(errno == EINTR);
    }
}

#endif /* ERTS_SMP */

#ifdef ERTS_ENABLE_KERNEL_POLL /* get_value() is currently only used when
				  kernel-poll is enabled */

/* Get arg marks argument as handled by
   putting NULL in argv */
static char *
get_value(char* rest, char** argv, int* ip)
{
    char *param = argv[*ip]+1;
    argv[*ip] = NULL;
    if (*rest == '\0') {
	char *next = argv[*ip + 1];
	if (next[0] == '-'
	    && next[1] == '-'
	    &&  next[2] == '\0') {
	    erts_fprintf(stderr, "bad \"%s\" value: \n", param);
	    erts_usage();
	}
	(*ip)++;
	argv[*ip] = NULL;
	return next;
    }
    return rest;
}

#endif /* ERTS_ENABLE_KERNEL_POLL */

void
erl_sys_args(int* argc, char** argv)
{
    int i, j;

    erts_smp_rwmtx_init(&environ_rwmtx, "environ");

    i = 1;

    ASSERT(argc && argv);

    while (i < *argc) {
	if(argv[i][0] == '-') {
	    switch (argv[i][1]) {
#ifdef ERTS_ENABLE_KERNEL_POLL
	    case 'K': {
		char *arg = get_value(argv[i] + 2, argv, &i);
		if (strcmp("true", arg) == 0) {
		    erts_use_kernel_poll = 1;
		}
		else if (strcmp("false", arg) == 0) {
		    erts_use_kernel_poll = 0;
		}
		else {
		    erts_fprintf(stderr, "bad \"K\" value: %s\n", arg);
		    erts_usage();
		}
		break;
	    }
#endif
	    case '-':
		goto done_parsing;
	    default:
		break;
	    }
	}
	i++;
    }

 done_parsing:

#ifdef ERTS_ENABLE_KERNEL_POLL
    if (erts_use_kernel_poll) {
	char no_kp[10];
	size_t no_kp_sz = sizeof(no_kp);
	int res = erts_sys_getenv_raw("ERL_NO_KERNEL_POLL", no_kp, &no_kp_sz);
	if (res > 0
	    || (res == 0
		&& sys_strcmp("false", no_kp) != 0
		&& sys_strcmp("FALSE", no_kp) != 0)) {
	    erts_use_kernel_poll = 0;
	}
    }
#endif

    init_check_io();

#ifdef ERTS_SMP
    init_smp_sig_notify();
    init_smp_sig_suspend();
#endif

    /* Handled arguments have been marked with NULL. Slide arguments
       not handled towards the beginning of argv. */
    for (i = 0, j = 0; i < *argc; i++) {
	if (argv[i])
	    argv[j++] = argv[i];
    }
    *argc = j;

}