path: root/lib/erl_interface/include/ei.h

/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 1998-2016. 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%
 */
#ifndef EI_H
#define EI_H

#define EI_HAVE_TIMEOUT 1	/* Flag to user code that we have them */
#define USE_EI_UNDOCUMENTED     /* Want declarations for undocumented */

/************************************************************************/
/*          This file defines the complete interface to ei              */
/************************************************************************/

/* -------------------------------------------------------------------- */
/*                   Include types needed below                         */
/* -------------------------------------------------------------------- */

#if defined(__WIN32__)
#include <winsock2.h>
#include <windows.h>
#include <winbase.h>
#endif

#include <stdio.h>		/* Need type FILE */
#include <errno.h>		/* Need EHOSTUNREACH, ENOMEM, ... */

#if !(defined(__WIN32__) || defined(_WIN32)) && !defined(VXWORKS) || (defined(VXWORKS) && defined(HAVE_SENS))
# include <netdb.h>
#endif


/* -------------------------------------------------------------------- */
/*                      Defines part of API                             */
/* -------------------------------------------------------------------- */

/*
 * Some error codes might be missing, so here's a backstop definitions
 * of the ones we use with `erl_errno': 
 */

#ifndef EMSGSIZE		/* Message too long */
#define EMSGSIZE        EIO
#endif

#ifndef ETIMEDOUT		/* Connection timed out */
#define ETIMEDOUT       EIO
#endif

#ifndef EHOSTUNREACH		/* No route to host */
#define EHOSTUNREACH    EIO
#endif

/* FIXME just a few are documented, does it mean they can't be returned? */

#define ERL_ERROR -1           /* Error of some kind */
#define ERL_NO_DAEMON -2       /* No contact with EPMD */
#define ERL_NO_PORT -3         /* No port received from EPMD */   
#define ERL_CONNECT_FAIL -4    /* Connect to Erlang Node failed */
#define ERL_TIMEOUT -5         /* A timeout has expired */
#define ERL_NO_REMOTE -6       /* Cannot execute rsh */

#define ERL_TICK 0    
#define ERL_MSG 1    

#define ERL_NO_TIMEOUT -1

/* these are the control message types */
#define ERL_LINK           1
#define ERL_SEND           2
#define ERL_EXIT           3
#define ERL_UNLINK         4
#define ERL_NODE_LINK      5
#define ERL_REG_SEND       6
#define ERL_GROUP_LEADER   7
#define ERL_EXIT2          8
#define ERL_PASS_THROUGH  'p'

/* new ones for tracing, from Kenneth */
#define ERL_SEND_TT        12
#define ERL_EXIT_TT        13
#define ERL_REG_SEND_TT    16
#define ERL_EXIT2_TT       18
#define ERL_MONITOR_P      19
#define ERL_DEMONITOR_P    20
#define ERL_MONITOR_P_EXIT 21


/* -------------------------------------------------------------------- */
/*           Defines used for ei_get_type_internal() output             */
/* -------------------------------------------------------------------- */
/* 
 * these are the term type indicators used in
 * the external (distribution) format
 */

/* FIXME we don't want to export these..... */

#define ERL_SMALL_INTEGER_EXT 'a'
#define ERL_INTEGER_EXT       'b'
#define ERL_FLOAT_EXT         'c'
#define NEW_FLOAT_EXT         'F'
#define ERL_ATOM_EXT          'd'
#define ERL_SMALL_ATOM_EXT    's'
#define ERL_ATOM_UTF8_EXT     'v'
#define ERL_SMALL_ATOM_UTF8_EXT 'w'
#define ERL_REFERENCE_EXT     'e'
#define ERL_NEW_REFERENCE_EXT 'r'
#define ERL_PORT_EXT          'f'
#define ERL_PID_EXT           'g'
#define ERL_SMALL_TUPLE_EXT   'h'
#define ERL_LARGE_TUPLE_EXT   'i'
#define ERL_NIL_EXT           'j'
#define ERL_STRING_EXT        'k'
#define ERL_LIST_EXT          'l'
#define ERL_BINARY_EXT        'm'
#define ERL_SMALL_BIG_EXT     'n'
#define ERL_LARGE_BIG_EXT     'o'
#define ERL_NEW_FUN_EXT	      'p'
#define ERL_MAP_EXT           't'
#define ERL_FUN_EXT	      'u'
 
#define ERL_NEW_CACHE         'N' /* c nodes don't know these two */
#define ERL_CACHED_ATOM       'C'


/* -------------------------------------------------------------------- */
/*                     Define the erl_errno macro                       */
/* -------------------------------------------------------------------- */

#ifdef __cplusplus
extern "C" {
#endif

/*
 * GCC's attributes are too useful to not use. Other compilers
 * just lose opportunities to optimize and warn.
 */
#if !defined(__GNUC__) || __GNUC__ < 2
# define __attribute__(foo) /* nothing */
#endif

/*
 * Define the 'erl_errno' facility. Unfortunately this lives on in
 * the 'ei' interface as well.... :-(
 */

#if defined(_REENTRANT) || defined(VXWORKS) || defined(__WIN32__)

/* 'erl_errno' as a function return value */
volatile int* __erl_errno_place(void) __attribute__ ((__const__));

#define erl_errno (*__erl_errno_place ())

#else /* !_REENTRANT && !VXWORKS && !__WIN32__ */

extern volatile int __erl_errno;

#define erl_errno __erl_errno

#endif /* !_REENTRANT && !VXWORKS && !__WIN32__ */


/* -------------------------------------------------------------------- */
/*                      Type definitions                                */
/* -------------------------------------------------------------------- */

/*
 * To avoid confusion about the MAXHOSTNAMELEN when compiling the
 * library and when using the library we set a value that we use
 */

#define EI_MAXHOSTNAMELEN 64
#define EI_MAXALIVELEN 63
#define EI_MAX_COOKIE_SIZE 512
#define MAXATOMLEN (255 + 1)
#define MAXATOMLEN_UTF8 (255*4 + 1)
#define MAXNODELEN EI_MAXALIVELEN+1+EI_MAXHOSTNAMELEN

typedef enum { 
    ERLANG_ASCII = 1,
    ERLANG_LATIN1 = 2,
    ERLANG_UTF8 = 4
}erlang_char_encoding;

/* a pid */
typedef struct {
  char node[MAXATOMLEN_UTF8];
  unsigned int num;
  unsigned int serial;
  unsigned int creation;
} erlang_pid;

/* a port */
typedef struct {
  char node[MAXATOMLEN_UTF8];
  unsigned int id;
  unsigned int creation;
} erlang_port;

/* a ref */
typedef struct {
  char node[MAXATOMLEN_UTF8];
  int len;
  unsigned int n[3];
  unsigned int creation;
} erlang_ref;

/* a trace token */
typedef struct {
  long serial;
  long prev;
  erlang_pid from;
  long label;
  long flags;
} erlang_trace;

/* a message */
typedef struct {
  long msgtype;
  erlang_pid from;
  erlang_pid to;
  char toname[MAXATOMLEN_UTF8];
  char cookie[MAXATOMLEN_UTF8];
  erlang_trace token;
} erlang_msg;

/* a fun */
typedef struct {
    long arity;
    char module[MAXATOMLEN_UTF8];
    erlang_char_encoding module_org_enc;
    char md5[16];
    long index;
    long old_index;
    long uniq;
    long n_free_vars;
    erlang_pid pid;
    long free_var_len;
    char* free_vars;
} erlang_fun;

/* a big */
typedef struct {
    unsigned int arity;
    int is_neg;
    void *digits;
} erlang_big;

typedef struct {
    char ei_type;
    int arity;
    int size;
    union {
	long i_val;
	double d_val;
	char atom_name[MAXATOMLEN_UTF8];
	erlang_pid pid;
	erlang_port port;
	erlang_ref ref;
    } value;
} ei_term;

/* XXX */

typedef struct {
  char ipadr[4];             /* stored in network byte order */
  char nodename[MAXNODELEN+1];
} ErlConnect;

typedef struct ei_cnode_s {
    char thishostname[EI_MAXHOSTNAMELEN+1];
    char thisnodename[MAXNODELEN+1];
    char thisalivename[EI_MAXALIVELEN+1];
/* Currently this_ipaddr isn't used */
/*    struct in_addr this_ipaddr; */
    char ei_connect_cookie[EI_MAX_COOKIE_SIZE+1];
    short creation;
    erlang_pid self;
} ei_cnode;

typedef struct in_addr *Erl_IpAddr; 


/* A dynamic version of ei XX */

typedef struct ei_x_buff_TAG {
    char* buff;
    int buffsz;
    int index;
} ei_x_buff;


/* -------------------------------------------------------------------- */
/*    Function definitions (listed in same order as documentation)      */
/* -------------------------------------------------------------------- */

/* Handle the connection */

int ei_connect_init(ei_cnode* ec, const char* this_node_name,
		    const char *cookie, short creation);
int ei_connect_xinit (ei_cnode* ec, const char *thishostname,
		      const char *thisalivename, const char *thisnodename,
		      Erl_IpAddr thisipaddr, const char *cookie,
		      const short creation);

int ei_connect(ei_cnode* ec, char *nodename);
int ei_connect_tmo(ei_cnode* ec, char *nodename, unsigned ms);
int ei_xconnect(ei_cnode* ec, Erl_IpAddr adr, char *alivename);
int ei_xconnect_tmo(ei_cnode* ec, Erl_IpAddr adr, char *alivename, unsigned ms);

int ei_receive(int fd, unsigned char *bufp, int bufsize);
int ei_receive_tmo(int fd, unsigned char *bufp, int bufsize, unsigned ms);
int ei_receive_msg(int fd, erlang_msg* msg, ei_x_buff* x);
int ei_receive_msg_tmo(int fd, erlang_msg* msg, ei_x_buff* x, unsigned ms);
int ei_xreceive_msg(int fd, erlang_msg* msg, ei_x_buff* x);
int ei_xreceive_msg_tmo(int fd, erlang_msg* msg, ei_x_buff* x, unsigned ms);

int ei_send(int fd, erlang_pid* to, char* buf, int len);
int ei_send_tmo(int fd, erlang_pid* to, char* buf, int len, unsigned ms);
int ei_reg_send(ei_cnode* ec, int fd, char *server_name, char* buf, int len);
int ei_reg_send_tmo(ei_cnode* ec, int fd, char *server_name, char* buf, int len, unsigned ms);

int ei_rpc(ei_cnode* ec, int fd, char *mod, char *fun,
	   const char* inbuf, int inbuflen, ei_x_buff* x);
int ei_rpc_to(ei_cnode* ec, int fd, char *mod, char *fun,
	      const char* buf, int len);
int ei_rpc_from(ei_cnode* ec, int fd, int timeout, erlang_msg* msg,
		ei_x_buff* x);

int ei_publish(ei_cnode* ec, int port);
int ei_publish_tmo(ei_cnode* ec, int port, unsigned ms);
int ei_accept(ei_cnode* ec, int lfd, ErlConnect *conp);
int ei_accept_tmo(ei_cnode* ec, int lfd, ErlConnect *conp, unsigned ms);
int ei_unpublish(ei_cnode* ec);
int ei_unpublish_tmo(const char *alive, unsigned ms);

const char *ei_thisnodename(const ei_cnode* ec);
const char *ei_thishostname(const ei_cnode* ec);
const char *ei_thisalivename(const ei_cnode* ec);

erlang_pid *ei_self(ei_cnode* ec);

/* 
 * settings 
 */

void ei_set_compat_rel(unsigned rel);
void ei_set_tracelevel(int);
int ei_get_tracelevel(void);

/* 
 * We have erl_gethost*() so we include ei versions as well.
 */

#if defined(VXWORKS)

extern int h_errno;

/*
 * We need these definitions - if the user has SENS then he gets them
 * from netdb.h, otherwise we define them ourselves.
 *
 * If you are getting "multiple definition" errors here,
 * make sure you have included <netdb.h> BEFORE "erl_interface.h"
 * or define HAVE_SENS in your CFLAGS.
 */

#if !defined(HAVE_SENS) && !defined(HOST_NOT_FOUND) /* just in case */

struct	hostent {
  char	*h_name;	/* official name of host */
  char	**h_aliases;	/* alias list */
  int	h_addrtype;	/* host address type */
  int	h_length;	/* length of address */
  char	**h_addr_list;	/* list of addresses from name server */
#define	h_addr	h_addr_list[0]	/* address, for backward compatiblity */
  unsigned int unused;  /* SENS defines this as ttl */
};

#define	HOST_NOT_FOUND	1 /* Authoritative Answer Host not found */
#define	TRY_AGAIN	2 /* Non-Authoritive Host not found, or SERVERFAIL */
#define	NO_RECOVERY	3 /* Non recoverable errors, FORMERR, REFUSED, NOTIMP */
#define	NO_DATA		4 /* Valid name, no data record of requested type */
#define	NO_ADDRESS	NO_DATA		/* no address, look for MX record */

#endif /* !HAVE_SENS && !HOST_NOT_FOUND */
#endif /* VXWORKS */


struct hostent *ei_gethostbyname(const char *name);
struct hostent *ei_gethostbyaddr(const char *addr, int len, int type);
struct hostent *ei_gethostbyname_r(const char *name, 
				   struct hostent *hostp, 
				   char *buffer, 
				   int buflen, 
				   int *h_errnop);
struct hostent *ei_gethostbyaddr_r(const char *addr,
				   int length, 
				   int type, 
				   struct hostent *hostp,
				   char *buffer,  
				   int buflen, 
				   int *h_errnop);


/* Encode/decode functions */

int ei_encode_version(char *buf, int *index);
int ei_x_encode_version(ei_x_buff* x);
int ei_encode_long(char *buf, int *index, long p);
int ei_x_encode_long(ei_x_buff* x, long n);
int ei_encode_ulong(char *buf, int *index, unsigned long p);
int ei_x_encode_ulong(ei_x_buff* x, unsigned long n);
int ei_encode_double(char *buf, int *index, double p);
int ei_x_encode_double(ei_x_buff* x, double dbl);
int ei_encode_boolean(char *buf, int *index, int p);
int ei_x_encode_boolean(ei_x_buff* x, int p);
int ei_encode_char(char *buf, int *index, char p);
int ei_x_encode_char(ei_x_buff* x, char p);
int ei_encode_string(char *buf, int *index, const char *p);
int ei_encode_string_len(char *buf, int *index, const char *p, int len);
int ei_x_encode_string(ei_x_buff* x, const char* s);
int ei_x_encode_string_len(ei_x_buff* x, const char* s, int len);
int ei_encode_atom(char *buf, int *index, const char *p);
int ei_encode_atom_as(char *buf, int *index, const char *p,
		    erlang_char_encoding from, erlang_char_encoding to);
int ei_encode_atom_len(char *buf, int *index, const char *p, int len);
int ei_encode_atom_len_as(char *buf, int *index, const char *p, int len,
			erlang_char_encoding from, erlang_char_encoding to);
int ei_x_encode_atom(ei_x_buff* x, const char* s);
int ei_x_encode_atom_as(ei_x_buff* x, const char* s,
		      erlang_char_encoding from, erlang_char_encoding to);
int ei_x_encode_atom_len(ei_x_buff* x, const char* s, int len);
int ei_x_encode_atom_len_as(ei_x_buff* x, const char* s, int len,
			  erlang_char_encoding from, erlang_char_encoding to);
int ei_encode_binary(char *buf, int *index, const void *p, long len);
int ei_x_encode_binary(ei_x_buff* x, const void* s, int len);
int ei_encode_pid(char *buf, int *index, const erlang_pid *p);
int ei_x_encode_pid(ei_x_buff* x, const erlang_pid* pid);
int ei_encode_fun(char* buf, int* index, const erlang_fun* p);
int ei_x_encode_fun(ei_x_buff* x, const erlang_fun* fun);
int ei_encode_port(char *buf, int *index, const erlang_port *p);
int ei_x_encode_port(ei_x_buff* x, const erlang_port *p);
int ei_encode_ref(char *buf, int *index, const erlang_ref *p);
int ei_x_encode_ref(ei_x_buff* x, const erlang_ref *p);
int ei_encode_term(char *buf, int *index, void *t); /* ETERM* actually */
int ei_x_encode_term(ei_x_buff* x, void* t);
int ei_encode_trace(char *buf, int *index, const erlang_trace *p);
int ei_x_encode_trace(ei_x_buff* x, const erlang_trace *p);
int ei_encode_tuple_header(char *buf, int *index, int arity);
int ei_x_encode_tuple_header(ei_x_buff* x, long n);
int ei_encode_list_header(char *buf, int *index, int arity);
int ei_x_encode_list_header(ei_x_buff* x, long n);
#define ei_encode_empty_list(buf,i) ei_encode_list_header(buf,i,0)
int ei_x_encode_empty_list(ei_x_buff* x);
int ei_encode_map_header(char *buf, int *index, int arity);
int ei_x_encode_map_header(ei_x_buff* x, long n);

/* 
 * ei_get_type() returns the type and "size" of the item at
 * buf[index]. For strings and atoms, size is the number of characters
 * not including the terminating 0. For binaries, size is the number
 * of bytes. For lists and tuples, size is the arity of the
 * object. For other types, size is 0. In all cases, index is left
 * unchanged.
 */

int ei_get_type(const char *buf, const int *index, int *type, int *size);
int ei_get_type_internal(const char *buf, const int *index, int *type,
			 int *size);

/* Step through buffer, decoding the given type into the buffer
 * provided. On success, 0 is returned and index is updated to point
 * to the start of the next item in the buffer. If the type of item at
 * buf[index] is not the requested type, -1 is returned and index is
 * not updated. The buffer provided by the caller must be sufficiently
 * large to contain the decoded object.
 */
int ei_decode_version(const char *buf, int *index, int *version);
int ei_decode_long(const char *buf, int *index, long *p);
int ei_decode_ulong(const char *buf, int *index, unsigned long *p);
int ei_decode_double(const char *buf, int *index, double *p);
int ei_decode_boolean(const char *buf, int *index, int *p);
int ei_decode_char(const char *buf, int *index, char *p);
int ei_decode_string(const char *buf, int *index, char *p);
int ei_decode_atom(const char *buf, int *index, char *p);
int ei_decode_atom_as(const char *buf, int *index, char *p, int destlen, erlang_char_encoding want, erlang_char_encoding* was, erlang_char_encoding* result);
int ei_decode_binary(const char *buf, int *index, void *p, long *len);
int ei_decode_fun(const char* buf, int* index, erlang_fun* p);
void free_fun(erlang_fun* f);
int ei_decode_pid(const char *buf, int *index, erlang_pid *p);
int ei_decode_port(const char *buf, int *index, erlang_port *p);
int ei_decode_ref(const char *buf, int *index, erlang_ref *p);
int ei_decode_term(const char *buf, int *index, void *t); /* ETERM** actually */
int ei_decode_trace(const char *buf, int *index, erlang_trace *p);
int ei_decode_tuple_header(const char *buf, int *index, int *arity);
int ei_decode_list_header(const char *buf, int *index, int *arity);
int ei_decode_map_header(const char *buf, int *index, int *arity);

/* 
 * ei_decode_ei_term() returns 1 if term is decoded, 0 if term is OK,
 * but not decoded here and -1 if something is wrong.  ONLY changes
 * index if term is decoded (return value 1)!
 */

int ei_decode_ei_term(const char* buf, int* index, ei_term* term);


/*
 * ei_print_term to print out a binary coded term
 */

int ei_print_term(FILE *fp, const char* buf, int* index);
int ei_s_print_term(char** s, const char* buf, int* index);

/*
 * format to build binary format terms a bit like printf
 */

int ei_x_format(ei_x_buff* x, const char* fmt, ...);
int ei_x_format_wo_ver(ei_x_buff* x, const char *fmt, ...);

int ei_x_new(ei_x_buff* x);
int ei_x_new_with_version(ei_x_buff* x);
int ei_x_free(ei_x_buff* x);
int ei_x_append(ei_x_buff* x, const ei_x_buff* x2);
int ei_x_append_buf(ei_x_buff* x, const char* buf, int len);
int ei_skip_term(const char* buf, int* index);

/***************************************************************************
 *
 *  Hash types needed by registry types
 *
 ***************************************************************************/

#define EI_SMALLKEY 32

typedef struct bucket_s {
  int rawhash;
  const char *key;
  char keybuf[EI_SMALLKEY];
  const void *value;
  struct bucket_s *next;
} ei_bucket;

/* users of the package declare variables as pointers to this. */
typedef struct {
  ei_bucket **tab;
  int (*hash)(const char *); /* hash function for this table */
  int size; /* size of table */
  int nelem; /* nr elements */
  int npos;  /* nr occupied positions */
  ei_bucket *freelist; /* reuseable freed buckets */
} ei_hash;


/***************************************************************************
 *
 *  Registry defines, types, functions
 *
 ***************************************************************************/

/* -------------------------------------------------------------------- */
/*                               XXXXXXXXXXX                            */
/* -------------------------------------------------------------------- */

/* registry object attributes */
#define EI_DIRTY 0x01 /* dirty bit (object value differs from backup) */
#define EI_DELET 0x02 /* object is deleted */
#define EI_INT 0x10 /* object is an integer */
#define EI_FLT 0x20 /* object is a float */
#define EI_STR 0x40 /* object is a string */
#define EI_BIN 0x80 /* object is a binary, i.e. pointer to arbitrary type */


/* -------------------------------------------------------------------- */
/*                               XXXXXXXXXXX                            */
/* -------------------------------------------------------------------- */

typedef struct ei_reg_inode {
  int attr; 
  int size;
  union {
    long i;   
    double f;
    char *s;
    void *p;
  } val;
  struct ei_reg_inode *next;
} ei_reg_obj;

typedef struct {
  ei_reg_obj *freelist;
  ei_hash *tab;
} ei_reg;

struct ei_reg_stat {
  int attr;             /* object attributes (see above) */
  int size;             /* size in bytes (for STR and BIN) 0 for others */
};

struct ei_reg_tabstat {
  int size;   /* size of table */
  int nelem; /* number of stored elements */
  int npos;   /* number of occupied positions */
  int collisions; /* number of positions with more than one element */
};


/* -------------------------------------------------------------------- */
/*                               XXXXXXXXXXX                            */
/* -------------------------------------------------------------------- */

/* FIXME move comments to source */

/* open / close registry. On open, a descriptor is returned that must
 * be specified in all subsequent calls to registry functions. You can
 * open as many registries as you like.
 */
ei_reg *ei_reg_open(int size);
int ei_reg_resize(ei_reg *oldreg, int newsize);
int ei_reg_close(ei_reg *reg);

/* set values... these routines assign values to keys. If the key
 * exists, the previous value is discarded and the new one replaces
 * it.
 *
 * BIN objects require an additional argument indicating the size in
 * bytes of the stored object. This will be used when the object is
 * backed up, since it will need to be copied at that time. Remember
 * also that pointers are process-space specific and it is not
 * meaningful to back them up for later recall. If you are storing
 * binary objects for backup, make sure that they are self-contained
 * (without references to other objects).
 *
 * On success the function returns 0, otherwise a value
 * indicating the reason for failure will be returned.
 */
int ei_reg_setival(ei_reg *reg, const char *key, long i);
int ei_reg_setfval(ei_reg *reg, const char *key, double f);
int ei_reg_setsval(ei_reg *reg, const char *key, const char *s);
int ei_reg_setpval(ei_reg *reg, const char *key, const void *p, int size);

/* general set function (specifiy type via flags)
 * optional arguments are as for equivalent type-specific function,
 * i.e.:
 * ei_reg_setval(fd, path, EI_INT, int i);
 * ei_reg_setval(fd, path, EI_FLT, float f);
 * ei_reg_setval(fd, path, EI_STR, const char *s);
 * ei_reg_setval(fd, path, EI_BIN, const void *p, int size);
 */
int ei_reg_setval(ei_reg *reg, const char *key, int flags, ...);

/* get value of specific type object */
/* warning: it may be difficult to detect errors when using these
 * functions, since the error values are returned "in band"
 */
long ei_reg_getival(ei_reg *reg, const char *key);
double ei_reg_getfval(ei_reg *reg, const char *key);
const char *ei_reg_getsval(ei_reg *reg, const char *key);
const void *ei_reg_getpval(ei_reg *reg, const char *key, int *size);

/* get value of any type object (must specify) 
 * Retrieve a value from an object. The type of value expected and a
 * pointer to a large enough buffer must be provided. flags must be
 * set to the appropriate type (see type constants above) and the
 * object type must match. If (flags == 0) the pointer is *assumed* to
 * be of the correct type for the object. In any case, the actual
 * object type is always returned on success.
 *
 * The argument following flags must be one of int*, double*, const
 * char** and const void**. 
 *
 * for BIN objects an int* is needed to return the size of the object, i.e.
 * int ei_reg_getval(ei_reg *reg, const char *path, int flags, void **p, int *size);
 */
int ei_reg_getval(ei_reg *reg, const char *key, int flags, ...);

/* mark the object as dirty. Normally this operation will not be
 * necessary, as it is done automatically by all of the above 'set'
 * functions. However, if you modify the contents of an object pointed
 * to by a STR or BIN object, then the registry will not be aware of
 * the change. As a result, the object may be missed on a subsequent
 * backup operation. Use this function to set the dirty bit on the
 * object.
 */
int ei_reg_markdirty(ei_reg *reg, const char *key);

/* remove objects. The value, if any, is discarded. For STR and BIN
 * objects, the object itself is removed using free(). */
int ei_reg_delete(ei_reg *reg, const char *key);

/* get information about an object */
int ei_reg_stat(ei_reg *reg, const char *key, struct ei_reg_stat *obuf);

/* get information about table */
int ei_reg_tabstat(ei_reg *reg, struct ei_reg_tabstat *obuf);

/* dump to / restore from backup */
/* fd is open descriptor to Erlang, mntab is Mnesia table name */
/* flags here: */
#define EI_FORCE 0x1 /* dump all records (not just dirty ones) */
#define EI_NOPURGE 0x2 /* don't purge deleted records */
int ei_reg_dump(int fd, ei_reg *reg, const char *mntab, int flags);
int ei_reg_restore(int fd, ei_reg *reg, const char *mntab);
int ei_reg_purge(ei_reg *reg);


/* -------------------------------------------------------------------- */
/*            Encoding/decoding bugnums to GNU MP format                */
/* -------------------------------------------------------------------- */

/* If the user included <gmp.h> we supply some more functions */

#if defined(__GNU_MP_VERSION) \
	&& __GNU_MP_VERSION == 4 && __GNU_MP_VERSION_MINOR >= 1 

int ei_decode_bignum(const char *buf, int *index, mpz_t obj);
int ei_encode_bignum(char *buf, int *index, mpz_t obj);
int ei_x_encode_bignum(ei_x_buff *x, mpz_t obj);

#endif /* __GNU_MP_VERSION */

/* -------------------------------------------------------------------- */
/*            Function definitions not documented FIXME                 */
/* -------------------------------------------------------------------- */

/* FIXME replace this primitive type size code */

#ifdef __WIN32__
#define EI_LONGLONG __int64
#define EI_ULONGLONG unsigned __int64
#else
#define EI_LONGLONG long long
#define EI_ULONGLONG unsigned long long
#endif

#ifndef VXWORKS
int ei_decode_longlong(const char *buf, int *index, EI_LONGLONG *p);
int ei_decode_ulonglong(const char *buf, int *index, EI_ULONGLONG *p);
int ei_encode_longlong(char *buf, int *index, EI_LONGLONG p);
int ei_encode_ulonglong(char *buf, int *index, EI_ULONGLONG p);
int ei_x_encode_longlong(ei_x_buff* x, EI_LONGLONG n);
int ei_x_encode_ulonglong(ei_x_buff* x, EI_ULONGLONG n);
#endif

#ifdef USE_EI_UNDOCUMENTED

/* 
 * Decode a list of integers into an integer array (i.e. even if it is
 * encoded as a string). count gets number of items in array.
 * See "decode_intlist.c".
 */

int ei_decode_intlist(const char *buf, int *index, long *a, int *count);

/* 
 * FIXME: used in IC, document?
 * bufp = address of pointer to dynamically allocated buffer - may be reallocated by
 * this function if it is too small for the message
 * bufsz = in/out value: in=user buffer size, out=new buffer size
 * msglen = nr bytes in received message
 */
int ei_receive_encoded(int fd, char **bufp, int *bufsz, erlang_msg *to, 
		       int *msglen);
int ei_receive_encoded_tmo(int fd, char **bufp, int *bufsz, erlang_msg *to, 
			   int *msglen, unsigned ms);
int ei_send_encoded(int fd, const erlang_pid *to, char *msg, int msglen);
int ei_send_encoded_tmo(int fd, const erlang_pid *to, char *msg, int msglen,
			unsigned ms);
int ei_send_reg_encoded(int fd, const erlang_pid *from, const char *to,
			char *msg, int msglen);
int ei_send_reg_encoded_tmo(int fd, const erlang_pid *from, const char *to,
			    char *msg, int msglen, unsigned ms);

/*
 * Bacward compatibility with old undocumented but used interface...
 * FIXME use wrapper function instead?!
 */
#define ei_send_encoded_timeout(Fd,To,Msg,MsgLen,Ms) \
    ei_send_encoded_tmo((Fd),(To),(Msg),(MsgLen),(Ms))
#define ei_send_reg_encoded_timeout(Fd,From,To,Msg,MsgLen,Ms) \
    ei_send_reg_encoded_tmo((Fd),(From),(To),(Msg),(MsgLen),(Ms))


/* FIXME: is this really the best way to handle bignums? */
int ei_encode_big(char *buf, int *index, erlang_big* big);
int ei_x_encode_big(ei_x_buff* x, erlang_big* big);
int ei_decode_big(const char *buf, int *index, erlang_big* p);
int ei_big_comp(erlang_big *x, erlang_big *y);
int ei_big_to_double(erlang_big *b, double *resp);
int ei_small_to_big(int s, erlang_big *b);
erlang_big *ei_alloc_big(unsigned int arity);
void ei_free_big(erlang_big *b);

#endif /* USE_EI_UNDOCUMENTED */

#ifdef __cplusplus
}
#endif

#endif /* EI_H */