.TH erl_nif 3erl "erts 5.9.1" "Ericsson AB" "C Library Functions"
.SH NAME
erl_nif \- API functions for an Erlang NIF library
.SH DESCRIPTION
.LP

.RS -4
.B
Note:
.RE
The NIF concept is officially supported from R14B\&. NIF source code written for earlier experimental versions might need adaption to run on R14B\&.
.LP
No incompatible changes between \fIR14B\fR\& and R14A\&.
.LP
Incompatible changes between \fIR14A\fR\& and R13B04:
.RS 2
.TP 2
*
Environment argument removed for \fIenif_alloc\fR\&, \fIenif_realloc\fR\&, \fIenif_free\fR\&, \fIenif_alloc_binary\fR\&, \fIenif_realloc_binary\fR\&, \fIenif_release_binary\fR\&, \fIenif_alloc_resource\fR\&, \fIenif_release_resource\fR\&, \fIenif_is_identical\fR\& and \fIenif_compare\fR\&\&.
.LP
.TP 2
*
Character encoding argument added to \fIenif_get_atom\fR\& and \fIenif_make_existing_atom\fR\&\&.
.LP
.TP 2
*
Module argument added to \fIenif_open_resource_type\fR\& while changing name spaces of resource types from global to module local\&.
.LP
.RE

.LP
Incompatible changes between \fIR13B04\fR\& and R13B03:
.RS 2
.TP 2
*
The function prototypes of the NIFs have changed to expect \fIargc\fR\& and \fIargv\fR\& arguments\&. The arity of a NIF is by that no longer limited to 3\&.
.LP
.TP 2
*
\fIenif_get_data\fR\& renamed as \fIenif_priv_data\fR\&\&.
.LP
.TP 2
*
\fIenif_make_string\fR\& got a third argument for character encoding\&.
.LP
.RE


.LP
A NIF library contains native implementation of some functions of an Erlang module\&. The native implemented functions (NIFs) are called like any other functions without any difference to the caller\&. Each NIF must also have an implementation in Erlang that will be invoked if the function is called before the NIF library has been successfully loaded\&. A typical such stub implementation is to throw an exception\&. But it can also be used as a fallback implementation if the NIF library is not implemented for some architecture\&.
.LP
A minimal example of a NIF library can look like this:
.LP

.LP
.nf

/* niftest.c */
#include "erl_nif.h"

static ERL_NIF_TERM hello(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    return enif_make_string(env, "Hello world!", ERL_NIF_LATIN1);
}

static ErlNifFunc nif_funcs[] =
{
    {"hello", 0, hello}
};

ERL_NIF_INIT(niftest,nif_funcs,NULL,NULL,NULL,NULL)

.fi
.LP
and the Erlang module would have to look something like this:
.LP

.LP
.nf

-module(niftest).

-export([init/0, hello/0]).

init() ->
      erlang:load_nif("./niftest", 0).

hello() ->
      "NIF library not loaded".

.fi
.LP
and compile and test something like this (on Linux):
.LP

.LP
.nf

$> gcc -fPIC -shared -o niftest.so niftest.c -I $ERL_ROOT/usr/include/
$> erl

1> c(niftest).
{ok,niftest}
2> niftest:hello().
"NIF library not loaded"
3> niftest:init().
ok
4> niftest:hello().
"Hello world!"

.fi
.LP
A better solution for a real module is to take advantage of the new directive \fBon_load\fR\& to automatically load the NIF library when the module is loaded\&.
.LP

.RS -4
.B
Note:
.RE
A NIF does not have to be exported, it can be local to the module\&. Note however that unused local stub functions will be optimized away by the compiler causing loading of the NIF library to fail\&.

.LP
A loaded NIF library is tied to the Erlang module code version that loaded it\&. If the module is upgraded with a new version, the new Erlang code will have to load its own NIF library (or maybe choose not to)\&. The new code version can however choose to load the exact same NIF library as the old code if it wants to\&. Sharing the same dynamic library will mean that static data defined by the library will be shared as well\&. To avoid unintentionally shared static data, each Erlang module code can keep its own private data\&. This private data can be set when the NIF library is loaded and then retrieved by calling \fBenif_priv_data\fR\&\&.
.LP
There is no way to explicitly unload a NIF library\&. A library will be automatically unloaded when the module code that it belongs to is purged by the code server\&.
.SH "FUNCTIONALITY"

.LP
All functions that a NIF library needs to do with Erlang are performed through the NIF API functions\&. There are functions for the following functionality:
.RS 2
.TP 2
.B
Read and write Erlang terms:
Any Erlang terms can be passed to a NIF as function arguments and be returned as function return values\&. The terms are of C-type \fBERL_NIF_TERM\fR\& and can only be read or written using API functions\&. Most functions to read the content of a term are prefixed \fIenif_get_\fR\& and usually return true (or false) if the term was of the expected type (or not)\&. The functions to write terms are all prefixed \fIenif_make_\fR\& and usually return the created \fIERL_NIF_TERM\fR\&\&. There are also some functions to query terms, like \fIenif_is_atom\fR\&, \fIenif_is_identical\fR\& and \fIenif_compare\fR\&\&.
.RS 2
.LP
All terms of type \fIERL_NIF_TERM\fR\& belong to an environment of type \fBErlNifEnv\fR\&\&. The lifetime of a term is controlled by the lifetime of its environment object\&. All API functions that read or write terms has the environment, that the term belongs to, as the first function argument\&.
.RE

.TP 2
.B
Binaries:
Terms of type binary are accessed with the help of the struct type \fBErlNifBinary\fR\& that contains a pointer (\fIdata\fR\&) to the raw binary data and the length (\fIsize\fR\&) of the data in bytes\&. Both \fIdata\fR\& and \fIsize\fR\& are read-only and should only be written using calls to API functions\&. Instances of \fIErlNifBinary\fR\& are however always allocated by the user (usually as local variables)\&.
.RS 2
.LP
The raw data pointed to by \fIdata\fR\& is only mutable after a call to \fBenif_alloc_binary\fR\& or \fBenif_realloc_binary\fR\&\&. All other functions that operates on a binary will leave the data as read-only\&. A mutable binary must in the end either be freed with \fBenif_release_binary\fR\& or made read-only by transferring it to an Erlang term with \fBenif_make_binary\fR\&\&. But it does not have to happen in the same NIF call\&. Read-only binaries do not have to be released\&.
.RE

.RS 2
.LP
\fBenif_make_new_binary\fR\& can be used as a shortcut to allocate and return a binary in the same NIF call\&.
.RE

.RS 2
.LP
Binaries are sequences of whole bytes\&. Bitstrings with an arbitrary bit length have no support yet\&.
.RE

.TP 2
.B
Resource objects:
The use of resource objects is a way to return pointers to native data structures from a NIF in a safe way\&. A resource object is just a block of memory allocated with \fBenif_alloc_resource\fR\&\&. A handle ("safe pointer") to this memory block can then be returned to Erlang by the use of \fBenif_make_resource\fR\&\&. The term returned by \fIenif_make_resource\fR\& is totally opaque in nature\&. It can be stored and passed between processes on the same node, but the only real end usage is to pass it back as an argument to a NIF\&. The NIF can then call \fBenif_get_resource\fR\& and get back a pointer to the memory block that is guaranteed to still be valid\&. A resource object will not be deallocated until the last handle term has been garbage collected by the VM and the resource has been released with \fBenif_release_resource\fR\& (not necessarily in that order)\&.
.RS 2
.LP
All resource objects are created as instances of some \fIresource type\fR\&\&. This makes resources from different modules to be distinguishable\&. A resource type is created by calling \fBenif_open_resource_type\fR\& when a library is loaded\&. Objects of that resource type can then later be allocated and \fIenif_get_resource\fR\& verifies that the resource is of the expected type\&. A resource type can have a user supplied destructor function that is automatically called when resources of that type are released (by either the garbage collector or \fIenif_release_resource\fR\&)\&. Resource types are uniquely identified by a supplied name string and the name of the implementing module\&.
.RE

.RS 2
.LP
Here is a template example of how to create and return a resource object\&.
.RE

.RS 2
.LP

.RE

.LP
.nf

    ERL_NIF_TERM term;
    MyStruct* obj = enif_alloc_resource(my_resource_type, sizeof(MyStruct));

    /* initialize struct ... */

    term = enif_make_resource(env, obj);

    if (keep_a_reference_of_our_own) {
        /* store 'obj' in static variable, private data or other resource object */
    }
    else {
        enif_release_resource(obj);
        /* resource now only owned by "Erlang" */
    }
    return term;
    
.fi
.RS 2
.LP
Note that once \fIenif_make_resource\fR\& creates the term to return to Erlang, the code can choose to either keep its own native pointer to the allocated struct and release it later, or release it immediately and rely solely on the garbage collector to eventually deallocate the resource object when it collects the term\&.
.RE

.RS 2
.LP
Another usage of resource objects is to create binary terms with user defined memory management\&. \fBenif_make_resource_binary\fR\& will create a binary term that is connected to a resource object\&. The destructor of the resource will be called when the binary is garbage collected, at which time the binary data can be released\&. An example of this can be a binary term consisting of data from a \fImmap\fR\&\&'ed file\&. The destructor can then do \fImunmap\fR\& to release the memory region\&.
.RE

.RS 2
.LP
Resource types support upgrade in runtime by allowing a loaded NIF library to takeover an already existing resource type and thereby "inherit" all existing objects of that type\&. The destructor of the new library will thereafter be called for the inherited objects and the library with the old destructor function can be safely unloaded\&. Existing resource objects, of a module that is upgraded, must either be deleted or taken over by the new NIF library\&. The unloading of a library will be postponed as long as there exist resource objects with a destructor function in the library\&.
.RE

.TP 2
.B
Threads and concurrency:
A NIF is thread-safe without any explicit synchronization as long as it acts as a pure function and only reads the supplied arguments\&. As soon as you write towards a shared state either through static variables or \fBenif_priv_data\fR\& you need to supply your own explicit synchronization\&. This includes terms in process independent environments that are shared between threads\&. Resource objects will also require synchronization if you treat them as mutable\&.
.RS 2
.LP
The library initialization callbacks \fIload\fR\&, \fIreload\fR\& and \fIupgrade\fR\& are all thread-safe even for shared state data\&.
.RE

.RS 2
.LP
Avoid doing lengthy work in NIF calls as that may degrade the responsiveness of the VM\&. NIFs are called directly by the same scheduler thread that executed the calling Erlang code\&. The calling scheduler will thus be blocked from doing any other work until the NIF returns\&.
.RE

.RE
.SH "INITIALIZATION"

.RS 2
.TP 2
.B
ERL_NIF_INIT(MODULE, ErlNifFunc funcs[], load, reload, upgrade, unload):
This is the magic macro to initialize a NIF library\&. It should be evaluated in global file scope\&.
.RS 2
.LP
\fIMODULE\fR\& is the name of the Erlang module as an identifier without string quotations\&. It will be stringified by the macro\&.
.RE

.RS 2
.LP
\fIfuncs\fR\& is a static array of function descriptors for all the implemented NIFs in this library\&.
.RE

.RS 2
.LP
\fIload\fR\&, \fIreload\fR\&, \fIupgrade\fR\& and \fIunload\fR\& are pointers to functions\&. One of \fIload\fR\&, \fIreload\fR\& or \fIupgrade\fR\& will be called to initialize the library\&. \fIunload\fR\& is called to release the library\&. They are all described individually below\&.
.RE

.TP 2
.B
int (*load)(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info):
\fIload\fR\& is called when the NIF library is loaded and there is no previously loaded library for this module\&.
.RS 2
.LP
\fI*priv_data\fR\& can be set to point to some private data that the library needs in order to keep a state between NIF calls\&. \fIenif_priv_data\fR\& will return this pointer\&. \fI*priv_data\fR\& will be initialized to NULL when \fIload\fR\& is called\&.
.RE

.RS 2
.LP
\fIload_info\fR\& is the second argument to \fBerlang:load_nif/2\fR\&\&.
.RE

.RS 2
.LP
The library will fail to load if \fIload\fR\& returns anything other than 0\&. \fIload\fR\& can be NULL in case no initialization is needed\&.
.RE

.TP 2
.B
int (*upgrade)(ErlNifEnv* env, void** priv_data, void** old_priv_data, ERL_NIF_TERM load_info):
\fIupgrade\fR\& is called when the NIF library is loaded and there is old code of this module with a loaded NIF library\&.
.RS 2
.LP
Works the same as \fIload\fR\&\&. The only difference is that \fI*old_priv_data\fR\& already contains the value set by the last call to \fIload\fR\& or \fIreload\fR\& for the old module code\&. \fI*priv_data\fR\& will be initialized to NULL when \fIupgrade\fR\& is called\&. It is allowed to write to both *priv_data and *old_priv_data\&.
.RE

.RS 2
.LP
The library will fail to load if \fIupgrade\fR\& returns anything other than 0 or if \fIupgrade\fR\& is NULL\&.
.RE

.TP 2
.B
void (*unload)(ErlNifEnv* env, void* priv_data):
\fIunload\fR\& is called when the module code that the NIF library belongs to is purged as old\&. New code of the same module may or may not exist\&. Note that \fIunload\fR\& is not called for a replaced library as a consequence of \fIreload\fR\&\&.
.TP 2
.B
int (*reload)(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info):
\fIreload\fR\& is called when the NIF library is loaded and there is already a previously loaded library for this module code\&.
.RS 2
.LP
Works the same as \fIload\fR\&\&. The only difference is that \fI*priv_data\fR\& already contains the value set by the previous call to \fIload\fR\& or \fIreload\fR\&\&.
.RE

.RS 2
.LP
The library will fail to load if \fIreload\fR\& returns anything other than 0 or if \fIreload\fR\& is NULL\&.
.RE

.RE
.SH "DATA TYPES"

.RS 2
.TP 2
.B
ERL_NIF_TERM:
Variables of type \fIERL_NIF_TERM\fR\& can refer to any Erlang term\&. This is an opaque type and values of it can only by used either as arguments to API functions or as return values from NIFs\&. All \fIERL_NIF_TERM\fR\&\&'s belong to an environment (\fBErlNifEnv\fR\&)\&. A term can not be destructed individually, it is valid until its environment is destructed\&.
.TP 2
.B
ErlNifEnv:
\fIErlNifEnv\fR\& represents an environment that can host Erlang terms\&. All terms in an environment are valid as long as the environment is valid\&. \fIErlNifEnv\fR\& is an opaque type and pointers to it can only be passed on to API functions\&. There are two types of environments; process bound and process independent\&.
.RS 2
.LP
A \fIprocess bound environment\fR\& is passed as the first argument to all NIFs\&. All function arguments passed to a NIF will belong to that environment\&. The return value from a NIF must also be a term belonging to the same environment\&. In addition a process bound environment contains transient information about the calling Erlang process\&. The environment is only valid in the thread where it was supplied as argument until the NIF returns\&. It is thus useless and dangerous to store pointers to process bound environments between NIF calls\&.
.RE

.RS 2
.LP
A \fIprocess independent environment\fR\& is created by calling \fBenif_alloc_env\fR\&\&. It can be used to store terms between NIF calls and to send terms with \fBenif_send\fR\&\&. A process independent environment with all its terms is valid until you explicitly invalidates it with \fBenif_free_env\fR\& or \fIenif_send\fR\&\&.
.RE

.RS 2
.LP
All elements of a list/tuple must belong to the same environment as the list/tuple itself\&. Terms can be copied between environments with \fBenif_make_copy\fR\&\&.
.RE

.TP 2
.B
ErlNifFunc:

.LP
.nf

typedef struct {
    const char* \fIname\fR\&;
    unsigned \fIarity\fR\&;
    ERL_NIF_TERM (*\fIfptr\fR\&)(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
} ErlNifFunc;

.fi
.RS 2
.LP
Describes a NIF by its name, arity and implementation\&. \fIfptr\fR\& is a pointer to the function that implements the NIF\&. The argument \fIargv\fR\& of a NIF will contain the function arguments passed to the NIF and \fIargc\fR\& is the length of the array, i\&.e\&. the function arity\&. \fIargv[N-1]\fR\& will thus denote the Nth argument to the NIF\&. Note that the \fIargc\fR\& argument allows for the same C function to implement several Erlang functions with different arity (but same name probably)\&.
.RE

.TP 2
.B
ErlNifBinary:

.LP
.nf

typedef struct {
    unsigned \fIsize\fR\&;
    unsigned char* \fIdata\fR\&;
} ErlNifBinary;

.fi
.RS 2
.LP
\fIErlNifBinary\fR\& contains transient information about an inspected binary term\&. \fIdata\fR\& is a pointer to a buffer of \fIsize\fR\& bytes with the raw content of the binary\&.
.RE

.RS 2
.LP
Note that \fIErlNifBinary\fR\& is a semi-opaque type and you are only allowed to read fields \fIsize\fR\& and \fIdata\fR\&\&.
.RE

.TP 2
.B
ErlNifPid:
\fIErlNifPid\fR\& is a process identifier (pid)\&. In contrast to pid terms (instances of \fIERL_NIF_TERM\fR\&), \fIErlNifPid\fR\&\&'s are self contained and not bound to any \fBenvironment\fR\&\&. \fIErlNifPid\fR\& is an opaque type\&.
.TP 2
.B
ErlNifResourceType:
Each instance of \fIErlNifResourceType\fR\& represent a class of memory managed resource objects that can be garbage collected\&. Each resource type has a unique name and a destructor function that is called when objects of its type are released\&.
.TP 2
.B
ErlNifResourceDtor:

.LP
.nf

typedef void ErlNifResourceDtor(ErlNifEnv* env, void* obj);

.fi
.RS 2
.LP
The function prototype of a resource destructor function\&. A destructor function is not allowed to call any term-making functions\&.
.RE

.TP 2
.B
ErlNifCharEncoding:

.LP
.nf

typedef enum {
    ERL_NIF_LATIN1
}ErlNifCharEncoding;

.fi
.RS 2
.LP
The character encoding used in strings and atoms\&. The only supported encoding is currently \fIERL_NIF_LATIN1\fR\& for iso-latin-1 (8-bit ascii)\&.
.RE

.TP 2
.B
ErlNifSysInfo:
Used by \fBenif_system_info\fR\& to return information about the runtime system\&. Contains currently the exact same content as \fBErlDrvSysInfo\fR\&\&.
.TP 2
.B
ErlNifSInt64:
A native signed 64-bit integer type\&.
.TP 2
.B
ErlNifUInt64:
A native unsigned 64-bit integer type\&.
.RE
.SH EXPORTS
.LP
.B
void*enif_alloc(size_t size)
.br
.RS
.LP
Allocate memory of \fIsize\fR\& bytes\&. Return NULL if allocation failed\&.
.RE

.LP
.B
intenif_alloc_binary(size_t size, ErlNifBinary* bin)
.br
.RS
.LP
Allocate a new binary of size \fIsize\fR\& bytes\&. Initialize the structure pointed to by \fIbin\fR\& to refer to the allocated binary\&. The binary must either be released by \fBenif_release_binary\fR\& or ownership transferred to an Erlang term with \fBenif_make_binary\fR\&\&. An allocated (and owned) \fIErlNifBinary\fR\& can be kept between NIF calls\&.
.LP
Return true on success or false if allocation failed\&.
.RE

.LP
.B
ErlNifEnv*enif_alloc_env()
.br
.RS
.LP
Allocate a new process independent environment\&. The environment can be used to hold terms that is not bound to any process\&. Such terms can later be copied to a process environment with \fBenif_make_copy\fR\& or be sent to a process as a message with \fBenif_send\fR\&\&.
.LP
Return pointer to the new environment\&.
.RE

.LP
.B
void*enif_alloc_resource(ErlNifResourceType* type, unsigned size)
.br
.RS
.LP
Allocate a memory managed resource object of type \fItype\fR\& and size \fIsize\fR\& bytes\&.
.RE

.LP
.B
voidenif_clear_env(ErlNifEnv* env)
.br
.RS
.LP
Free all terms in an environment and clear it for reuse\&. The environment must have been allocated with \fBenif_alloc_env\fR\&\&.
.RE

.LP
.B
intenif_compare(ERL_NIF_TERM lhs, ERL_NIF_TERM rhs)
.br
.RS
.LP
Return an integer less than, equal to, or greater than zero if \fIlhs\fR\& is found, respectively, to be less than, equal, or greater than \fIrhs\fR\&\&. Corresponds to the Erlang operators \fI==\fR\&, \fI/=\fR\&, \fI=<\fR\&, \fI<\fR\&, \fI>=\fR\& and \fI>\fR\& (but \fInot\fR\& \fI=:=\fR\& or \fI=/=\fR\&)\&.
.RE

.LP
.B
voidenif_cond_broadcast(ErlNifCond *cnd)
.br
.RS
.LP
Same as \fBerl_drv_cond_broadcast\fR\&\&.
.RE

.LP
.B
ErlNifCond*enif_cond_create(char *name)
.br
.RS
.LP
Same as \fBerl_drv_cond_create\fR\&\&.
.RE

.LP
.B
voidenif_cond_destroy(ErlNifCond *cnd)
.br
.RS
.LP
Same as \fBerl_drv_cond_destroy\fR\&\&.
.RE

.LP
.B
voidenif_cond_signal(ErlNifCond *cnd)
.br
.RS
.LP
Same as \fBerl_drv_cond_signal\fR\&\&.
.RE

.LP
.B
voidenif_cond_wait(ErlNifCond *cnd, ErlNifMutex *mtx)
.br
.RS
.LP
Same as \fBerl_drv_cond_wait\fR\&\&.
.RE

.LP
.B
intenif_equal_tids(ErlNifTid tid1, ErlNifTid tid2)
.br
.RS
.LP
Same as \fBerl_drv_equal_tids\fR\&\&.
.RE

.LP
.B
voidenif_free(void* ptr)
.br
.RS
.LP
Free memory allocated by \fIenif_alloc\fR\&\&.
.RE

.LP
.B
voidenif_free_env(ErlNifEnv* env)
.br
.RS
.LP
Free an environment allocated with \fBenif_alloc_env\fR\&\&. All terms created in the environment will be freed as well\&.
.RE

.LP
.B
intenif_get_atom(ErlNifEnv* env, ERL_NIF_TERM term, char* buf, unsigned size, ErlNifCharEncoding encode)
.br
.RS
.LP
Write a null-terminated string, in the buffer pointed to by \fIbuf\fR\& of size \fIsize\fR\&, consisting of the string representation of the atom \fIterm\fR\& with encoding \fBencode\fR\&\&. Return the number of bytes written (including terminating null character) or 0 if \fIterm\fR\& is not an atom with maximum length of \fIsize-1\fR\&\&.
.RE

.LP
.B
intenif_get_atom_length(ErlNifEnv* env, ERL_NIF_TERM term, unsigned* len, ErlNifCharEncoding encode)
.br
.RS
.LP
Set \fI*len\fR\& to the length (number of bytes excluding terminating null character) of the atom \fIterm\fR\& with encoding \fIencode\fR\&\&. Return true on success or false if \fIterm\fR\& is not an atom\&.
.RE

.LP
.B
intenif_get_double(ErlNifEnv* env, ERL_NIF_TERM term, double* dp)
.br
.RS
.LP
Set \fI*dp\fR\& to the floating point value of \fIterm\fR\&\&. Return true on success or false if \fIterm\fR\& is not a float\&.
.RE

.LP
.B
intenif_get_int(ErlNifEnv* env, ERL_NIF_TERM term, int* ip)
.br
.RS
.LP
Set \fI*ip\fR\& to the integer value of \fIterm\fR\&\&. Return true on success or false if \fIterm\fR\& is not an integer or is outside the bounds of type \fIint\fR\&\&.
.RE

.LP
.B
intenif_get_int64(ErlNifEnv* env, ERL_NIF_TERM term, ErlNifSInt64* ip)
.br
.RS
.LP
Set \fI*ip\fR\& to the integer value of \fIterm\fR\&\&. Return true on success or false if \fIterm\fR\& is not an integer or is outside the bounds of a signed 64-bit integer\&.
.RE

.LP
.B
intenif_get_local_pid(ErlNifEnv* env, ERL_NIF_TERM term, ErlNifPid* pid)
.br
.RS
.LP
If \fIterm\fR\& is the pid of a node local process, initialize the pid variable \fI*pid\fR\& from it and return true\&. Otherwise return false\&. No check if the process is alive is done\&.
.RE

.LP
.B
intenif_get_list_cell(ErlNifEnv* env, ERL_NIF_TERM list, ERL_NIF_TERM* head, ERL_NIF_TERM* tail)
.br
.RS
.LP
Set \fI*head\fR\& and \fI*tail\fR\& from \fIlist\fR\& and return true, or return false if \fIlist\fR\& is not a non-empty list\&.
.RE

.LP
.B
intenif_get_list_length(ErlNifEnv* env, ERL_NIF_TERM term, unsigned* len)
.br
.RS
.LP
Set \fI*len\fR\& to the length of list \fIterm\fR\& and return true, or return false if \fIterm\fR\& is not a list\&.
.RE

.LP
.B
intenif_get_long(ErlNifEnv* env, ERL_NIF_TERM term, long int* ip)
.br
.RS
.LP
Set \fI*ip\fR\& to the long integer value of \fIterm\fR\& and return true, or return false if \fIterm\fR\& is not an integer or is outside the bounds of type \fIlong int\fR\&\&.
.RE

.LP
.B
intenif_get_resource(ErlNifEnv* env, ERL_NIF_TERM term, ErlNifResourceType* type, void** objp)
.br
.RS
.LP
Set \fI*objp\fR\& to point to the resource object referred to by \fIterm\fR\&\&.
.LP
Return true on success or false if \fIterm\fR\& is not a handle to a resource object of type \fItype\fR\&\&.
.RE

.LP
.B
intenif_get_string(ErlNifEnv* env, ERL_NIF_TERM list, char* buf, unsigned size, ErlNifCharEncoding encode)
.br
.RS
.LP
Write a null-terminated string, in the buffer pointed to by \fIbuf\fR\& with size \fIsize\fR\&, consisting of the characters in the string \fIlist\fR\&\&. The characters are written using encoding \fBencode\fR\&\&. Return the number of bytes written (including terminating null character), or \fI-size\fR\& if the string was truncated due to buffer space, or 0 if \fIlist\fR\& is not a string that can be encoded with \fIencode\fR\& or if \fIsize\fR\& was less than 1\&. The written string is always null-terminated unless buffer \fIsize\fR\& is less than 1\&.
.RE

.LP
.B
intenif_get_tuple(ErlNifEnv* env, ERL_NIF_TERM term, int* arity, const ERL_NIF_TERM** array)
.br
.RS
.LP
If \fIterm\fR\& is a tuple, set \fI*array\fR\& to point to an array containing the elements of the tuple and set \fI*arity\fR\& to the number of elements\&. Note that the array is read-only and \fI(*array)[N-1]\fR\& will be the Nth element of the tuple\&. \fI*array\fR\& is undefined if the arity of the tuple is zero\&.
.LP
Return true on success or false if \fIterm\fR\& is not a tuple\&.
.RE

.LP
.B
intenif_get_uint(ErlNifEnv* env, ERL_NIF_TERM term, unsigned int* ip)
.br
.RS
.LP
Set \fI*ip\fR\& to the unsigned integer value of \fIterm\fR\& and return true, or return false if \fIterm\fR\& is not an unsigned integer or is outside the bounds of type \fIunsigned int\fR\&\&.
.RE

.LP
.B
intenif_get_uint64(ErlNifEnv* env, ERL_NIF_TERM term, ErlNifUInt64* ip)
.br
.RS
.LP
Set \fI*ip\fR\& to the unsigned integer value of \fIterm\fR\& and return true, or return false if \fIterm\fR\& is not an unsigned integer or is outside the bounds of an unsigned 64-bit integer\&.
.RE

.LP
.B
intenif_get_ulong(ErlNifEnv* env, ERL_NIF_TERM term, unsigned long* ip)
.br
.RS
.LP
Set \fI*ip\fR\& to the unsigned long integer value of \fIterm\fR\& and return true, or return false if \fIterm\fR\& is not an unsigned integer or is outside the bounds of type \fIunsigned long\fR\&\&.
.RE

.LP
.B
intenif_inspect_binary(ErlNifEnv* env, ERL_NIF_TERM bin_term, ErlNifBinary* bin)
.br
.RS
.LP
Initialize the structure pointed to by \fIbin\fR\& with information about the binary term \fIbin_term\fR\&\&. Return true on success or false if \fIbin_term\fR\& is not a binary\&.
.RE

.LP
.B
intenif_inspect_iolist_as_binary(ErlNifEnv* env, ERL_NIF_TERM term, ErlNifBinary* bin) 
.br
.RS
.LP
Initialize the structure pointed to by \fIbin\fR\& with one continuous buffer with the same byte content as \fIiolist\fR\&\&. As with inspect_binary, the data pointed to by \fIbin\fR\& is transient and does not need to be released\&. Return true on success or false if \fIiolist\fR\& is not an iolist\&.
.RE

.LP
.B
intenif_is_atom(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is an atom\&.
.RE

.LP
.B
intenif_is_binary(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is a binary
.RE

.LP
.B
intenif_is_empty_list(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is an empty list\&.
.RE

.LP
.B
intenif_is_exception(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is an exception\&.
.RE

.LP
.B
intenif_is_number(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is a number\&.
.RE

.LP
.B
intenif_is_fun(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is a fun\&.
.RE

.LP
.B
intenif_is_identical(ERL_NIF_TERM lhs, ERL_NIF_TERM rhs)
.br
.RS
.LP
Return true if the two terms are identical\&. Corresponds to the Erlang operators \fI=:=\fR\& and \fI=/=\fR\&\&.
.RE

.LP
.B
intenif_is_pid(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is a pid\&.
.RE

.LP
.B
intenif_is_port(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is a port\&.
.RE

.LP
.B
intenif_is_ref(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is a reference\&.
.RE

.LP
.B
intenif_is_tuple(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is a tuple\&.
.RE

.LP
.B
intenif_is_list(ErlNifEnv* env, ERL_NIF_TERM term)
.br
.RS
.LP
Return true if \fIterm\fR\& is a list\&.
.RE

.LP
.B
intenif_keep_resource(void* obj)
.br
.RS
.LP
Add a reference to resource object \fIobj\fR\& obtained from \fBenif_alloc_resource\fR\&\&. Each call to \fIenif_keep_resource\fR\& for an object must be balanced by a call to \fBenif_release_resource\fR\& before the object will be destructed\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_atom(ErlNifEnv* env, const char* name)
.br
.RS
.LP
Create an atom term from the null-terminated C-string \fIname\fR\& with iso-latin-1 encoding\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_atom_len(ErlNifEnv* env, const char* name, size_t len)
.br
.RS
.LP
Create an atom term from the string \fIname\fR\& with length \fIlen\fR\&\&. Null-characters are treated as any other characters\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_badarg(ErlNifEnv* env)
.br
.RS
.LP
Make a badarg exception to be returned from a NIF, and set an associated exception reason in \fIenv\fR\&\&. If \fIenif_make_badarg\fR\& is called, the term it returns \fImust\fR\& be returned from the function that called it\&. No other return value is allowed\&. Also, the term returned from \fIenif_make_badarg\fR\& may be passed only to \fBenif_is_exception\fR\& and not to any other NIF API function\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_binary(ErlNifEnv* env, ErlNifBinary* bin)
.br
.RS
.LP
Make a binary term from \fIbin\fR\&\&. Any ownership of the binary data will be transferred to the created term and \fIbin\fR\& should be considered read-only for the rest of the NIF call and then as released\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_copy(ErlNifEnv* dst_env, ERL_NIF_TERM src_term)
.br
.RS
.LP
Make a copy of term \fIsrc_term\fR\&\&. The copy will be created in environment \fIdst_env\fR\&\&. The source term may be located in any environment\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_double(ErlNifEnv* env, double d)
.br
.RS
.LP
Create a floating-point term from a \fIdouble\fR\&\&.
.RE

.LP
.B
intenif_make_existing_atom(ErlNifEnv* env, const char* name, ERL_NIF_TERM* atom, ErlNifCharEncoding encode)
.br
.RS
.LP
Try to create the term of an already existing atom from the null-terminated C-string \fIname\fR\& with encoding \fBencode\fR\&\&. If the atom already exists store the term in \fI*atom\fR\& and return true, otherwise return false\&.
.RE

.LP
.B
intenif_make_existing_atom_len(ErlNifEnv* env, const char* name, size_t len, ERL_NIF_TERM* atom, ErlNifCharEncoding encoding)
.br
.RS
.LP
Try to create the term of an already existing atom from the string \fIname\fR\& with length \fIlen\fR\& and encoding \fBencode\fR\&\&. Null-characters are treated as any other characters\&. If the atom already exists store the term in \fI*atom\fR\& and return true, otherwise return false\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_int(ErlNifEnv* env, int i)
.br
.RS
.LP
Create an integer term\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_int64(ErlNifEnv* env, ErlNifSInt64 i)
.br
.RS
.LP
Create an integer term from a signed 64-bit integer\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_list(ErlNifEnv* env, unsigned cnt, \&.\&.\&.)
.br
.RS
.LP
Create an ordinary list term of length \fIcnt\fR\&\&. Expects \fIcnt\fR\& number of arguments (after \fIcnt\fR\&) of type ERL_NIF_TERM as the elements of the list\&. An empty list is returned if \fIcnt\fR\& is 0\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_list1(ErlNifEnv* env, ERL_NIF_TERM e1)
.br
.B
ERL_NIF_TERMenif_make_list2(ErlNifEnv* env, ERL_NIF_TERM e1, ERL_NIF_TERM e2)
.br
.B
ERL_NIF_TERMenif_make_list3(ErlNifEnv* env, ERL_NIF_TERM e1, ERL_NIF_TERM e2, ERL_NIF_TERM e3)
.br
.B
ERL_NIF_TERMenif_make_list4(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e4)
.br
.B
ERL_NIF_TERMenif_make_list5(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e5)
.br
.B
ERL_NIF_TERMenif_make_list6(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e6)
.br
.B
ERL_NIF_TERMenif_make_list7(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e7)
.br
.B
ERL_NIF_TERMenif_make_list8(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e8)
.br
.B
ERL_NIF_TERMenif_make_list9(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e9)
.br
.RS
.LP
Create an ordinary list term with length indicated by the function name\&. Prefer these functions (macros) over the variadic \fIenif_make_list\fR\& to get a compile time error if the number of arguments does not match\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_list_cell(ErlNifEnv* env, ERL_NIF_TERM head, ERL_NIF_TERM tail)
.br
.RS
.LP
Create a list cell \fI[head | tail]\fR\&\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_list_from_array(ErlNifEnv* env, const ERL_NIF_TERM arr[], unsigned cnt)
.br
.RS
.LP
Create an ordinary list containing the elements of array \fIarr\fR\& of length \fIcnt\fR\&\&. An empty list is returned if \fIcnt\fR\& is 0\&.
.RE

.LP
.B
intenif_make_reverse_list(ErlNifEnv* env, ERL_NIF_TERM term, ERL_NIF_TERM *list)
.br
.RS
.LP
Set \fI*list\fR\& to the reverse list of the list \fIterm\fR\& and return true, or return false if \fIterm\fR\& is not a list\&. This function should only be used on short lists as a copy will be created of the list which will not be released until after the nif returns\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_long(ErlNifEnv* env, long int i)
.br
.RS
.LP
Create an integer term from a \fIlong int\fR\&\&.
.RE

.LP
.B
unsigned char*enif_make_new_binary(ErlNifEnv* env, size_t size, ERL_NIF_TERM* termp)
.br
.RS
.LP
Allocate a binary of size \fIsize\fR\& bytes and create an owning term\&. The binary data is mutable until the calling NIF returns\&. This is a quick way to create a new binary without having to use \fBErlNifBinary\fR\&\&. The drawbacks are that the binary can not be kept between NIF calls and it can not be reallocated\&.
.LP
Return a pointer to the raw binary data and set \fI*termp\fR\& to the binary term\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_pid(ErlNifEnv* env, const ErlNifPid* pid)
.br
.RS
.LP
Make a pid term from \fI*pid\fR\&\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_ref(ErlNifEnv* env)
.br
.RS
.LP
Create a reference like \fBerlang:make_ref/0\fR\&\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_resource(ErlNifEnv* env, void* obj)
.br
.RS
.LP
Create an opaque handle to a memory managed resource object obtained by \fBenif_alloc_resource\fR\&\&. No ownership transfer is done, as the resource object still needs to be released by \fBenif_release_resource\fR\&, but note that the call to \fIenif_release_resource\fR\& can occur immediately after obtaining the term from \fIenif_make_resource\fR\&, in which case the resource object will be deallocated when the term is garbage collected\&. See the \fBexample of creating and returning a resource object\fR\& for more details\&.
.LP
Note that the only defined behaviour of using a resource term in an Erlang program is to store it and send it between processes on the same node\&. Other operations such as matching or \fIterm_to_binary\fR\& will have unpredictable (but harmless) results\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_resource_binary(ErlNifEnv* env, void* obj, const void* data, size_t size)
.br
.RS
.LP
Create a binary term that is memory managed by a resource object \fIobj\fR\& obtained by \fBenif_alloc_resource\fR\&\&. The returned binary term will consist of \fIsize\fR\& bytes pointed to by \fIdata\fR\&\&. This raw binary data must be kept readable and unchanged until the destructor of the resource is called\&. The binary data may be stored external to the resource object in which case it is the responsibility of the destructor to release the data\&.
.LP
Several binary terms may be managed by the same resource object\&. The destructor will not be called until the last binary is garbage collected\&. This can be useful as a way to return different parts of a larger binary buffer\&.
.LP
As with \fBenif_make_resource\fR\&, no ownership transfer is done\&. The resource still needs to be released with \fBenif_release_resource\fR\&\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_string(ErlNifEnv* env, const char* string, ErlNifCharEncoding encoding)
.br
.RS
.LP
Create a list containing the characters of the null-terminated string \fIstring\fR\& with encoding \fBencoding\fR\&\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_string_len(ErlNifEnv* env, const char* string, size_t len, ErlNifCharEncoding encoding)
.br
.RS
.LP
Create a list containing the characters of the string \fIstring\fR\& with length \fIlen\fR\& and encoding \fBencoding\fR\&\&. Null-characters are treated as any other characters\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_sub_binary(ErlNifEnv* env, ERL_NIF_TERM bin_term, size_t pos, size_t size)
.br
.RS
.LP
Make a subbinary of binary \fIbin_term\fR\&, starting at zero-based position \fIpos\fR\& with a length of \fIsize\fR\& bytes\&. \fIbin_term\fR\& must be a binary or bitstring and \fIpos+size\fR\& must be less or equal to the number of whole bytes in \fIbin_term\fR\&\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_tuple(ErlNifEnv* env, unsigned cnt, \&.\&.\&.)
.br
.RS
.LP
Create a tuple term of arity \fIcnt\fR\&\&. Expects \fIcnt\fR\& number of arguments (after \fIcnt\fR\&) of type ERL_NIF_TERM as the elements of the tuple\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_tuple1(ErlNifEnv* env, ERL_NIF_TERM e1)
.br
.B
ERL_NIF_TERMenif_make_tuple2(ErlNifEnv* env, ERL_NIF_TERM e1, ERL_NIF_TERM e2)
.br
.B
ERL_NIF_TERMenif_make_tuple3(ErlNifEnv* env, ERL_NIF_TERM e1, ERL_NIF_TERM e2, ERL_NIF_TERM e3)
.br
.B
ERL_NIF_TERMenif_make_tuple4(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e4)
.br
.B
ERL_NIF_TERMenif_make_tuple5(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e5)
.br
.B
ERL_NIF_TERMenif_make_tuple6(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e6)
.br
.B
ERL_NIF_TERMenif_make_tuple7(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e7)
.br
.B
ERL_NIF_TERMenif_make_tuple8(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e8)
.br
.B
ERL_NIF_TERMenif_make_tuple9(ErlNifEnv* env, ERL_NIF_TERM e1, \&.\&.\&., ERL_NIF_TERM e9)
.br
.RS
.LP
Create a tuple term with length indicated by the function name\&. Prefer these functions (macros) over the variadic \fIenif_make_tuple\fR\& to get a compile time error if the number of arguments does not match\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_tuple_from_array(ErlNifEnv* env, const ERL_NIF_TERM arr[], unsigned cnt)
.br
.RS
.LP
Create a tuple containing the elements of array \fIarr\fR\& of length \fIcnt\fR\&\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_uint(ErlNifEnv* env, unsigned int i)
.br
.RS
.LP
Create an integer term from an \fIunsigned int\fR\&\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_uint64(ErlNifEnv* env, ErlNifUInt64 i)
.br
.RS
.LP
Create an integer term from an unsigned 64-bit integer\&.
.RE

.LP
.B
ERL_NIF_TERMenif_make_ulong(ErlNifEnv* env, unsigned long i)
.br
.RS
.LP
Create an integer term from an \fIunsigned long int\fR\&\&.
.RE

.LP
.B
ErlNifMutex*enif_mutex_create(char *name)
.br
.RS
.LP
Same as \fBerl_drv_mutex_create\fR\&\&.
.RE

.LP
.B
voidenif_mutex_destroy(ErlNifMutex *mtx)
.br
.RS
.LP
Same as \fBerl_drv_mutex_destroy\fR\&\&.
.RE

.LP
.B
voidenif_mutex_lock(ErlNifMutex *mtx)
.br
.RS
.LP
Same as \fBerl_drv_mutex_lock\fR\&\&.
.RE

.LP
.B
intenif_mutex_trylock(ErlNifMutex *mtx)
.br
.RS
.LP
Same as \fBerl_drv_mutex_trylock\fR\&\&.
.RE

.LP
.B
voidenif_mutex_unlock(ErlNifMutex *mtx)
.br
.RS
.LP
Same as \fBerl_drv_mutex_unlock\fR\&\&.
.RE

.LP
.B
ErlNifResourceType*enif_open_resource_type(ErlNifEnv* env, const char* module_str, const char* name, ErlNifResourceDtor* dtor, ErlNifResourceFlags flags, ErlNifResourceFlags* tried)
.br
.RS
.LP
Create or takeover a resource type identified by the string \fIname\fR\& and give it the destructor function pointed to by \fBdtor\fR\&\&. Argument \fIflags\fR\& can have the following values:
.RS 2
.TP 2
.B
\fIERL_NIF_RT_CREATE\fR\&:
Create a new resource type that does not already exist\&.
.TP 2
.B
\fIERL_NIF_RT_TAKEOVER\fR\&:
Open an existing resource type and take over ownership of all its instances\&. The supplied destructor \fIdtor\fR\& will be called both for existing instances as well as new instances not yet created by the calling NIF library\&.
.RE
.LP
The two flag values can be combined with bitwise-or\&. The name of the resource type is local to the calling module\&. Argument \fImodule_str\fR\& is not (yet) used and must be NULL\&. The \fIdtor\fR\& may be \fINULL\fR\& in case no destructor is needed\&.
.LP
On success, return a pointer to the resource type and \fI*tried\fR\& will be set to either \fIERL_NIF_RT_CREATE\fR\& or \fIERL_NIF_RT_TAKEOVER\fR\& to indicate what was actually done\&. On failure, return \fINULL\fR\& and set \fI*tried\fR\& to \fIflags\fR\&\&. It is allowed to set \fItried\fR\& to \fINULL\fR\&\&.
.LP
Note that \fIenif_open_resource_type\fR\& is only allowed to be called in the three callbacks \fBload\fR\&, \fBreload\fR\& and \fBupgrade\fR\&\&.
.RE

.LP
.B
void*enif_priv_data(ErlNifEnv* env)
.br
.RS
.LP
Return the pointer to the private data that was set by \fIload\fR\&, \fIreload\fR\& or \fIupgrade\fR\&\&.
.LP
Was previously named \fIenif_get_data\fR\&\&.
.RE

.LP
.B
intenif_realloc_binary(ErlNifBinary* bin, size_t size)
.br
.RS
.LP
Change the size of a binary \fIbin\fR\&\&. The source binary may be read-only, in which case it will be left untouched and a mutable copy is allocated and assigned to \fI*bin\fR\&\&. Return true on success, false if memory allocation failed\&.
.RE

.LP
.B
voidenif_release_binary(ErlNifBinary* bin)
.br
.RS
.LP
Release a binary obtained from \fIenif_alloc_binary\fR\&\&.
.RE

.LP
.B
voidenif_release_resource(void* obj)
.br
.RS
.LP
Remove a reference to resource object \fIobj\fR\&obtained from \fBenif_alloc_resource\fR\&\&. The resource object will be destructed when the last reference is removed\&. Each call to \fIenif_release_resource\fR\& must correspond to a previous call to \fIenif_alloc_resource\fR\& or \fBenif_keep_resource\fR\&\&. References made by \fBenif_make_resource\fR\& can only be removed by the garbage collector\&.
.RE

.LP
.B
ErlNifRWLock*enif_rwlock_create(char *name)
.br
.RS
.LP
Same as \fBerl_drv_rwlock_create\fR\&\&.
.RE

.LP
.B
voidenif_rwlock_destroy(ErlNifRWLock *rwlck)
.br
.RS
.LP
Same as \fBerl_drv_rwlock_destroy\fR\&\&.
.RE

.LP
.B
voidenif_rwlock_rlock(ErlNifRWLock *rwlck)
.br
.RS
.LP
Same as \fBerl_drv_rwlock_rlock\fR\&\&.
.RE

.LP
.B
voidenif_rwlock_runlock(ErlNifRWLock *rwlck)
.br
.RS
.LP
Same as \fBerl_drv_rwlock_runlock\fR\&\&.
.RE

.LP
.B
voidenif_rwlock_rwlock(ErlNifRWLock *rwlck)
.br
.RS
.LP
Same as \fBerl_drv_rwlock_rwlock\fR\&\&.
.RE

.LP
.B
voidenif_rwlock_rwunlock(ErlNifRWLock *rwlck)
.br
.RS
.LP
Same as \fBerl_drv_rwlock_rwunlock\fR\&\&.
.RE

.LP
.B
intenif_rwlock_tryrlock(ErlNifRWLock *rwlck)
.br
.RS
.LP
Same as \fBerl_drv_rwlock_tryrlock\fR\&\&.
.RE

.LP
.B
intenif_rwlock_tryrwlock(ErlNifRWLock *rwlck)
.br
.RS
.LP
Same as \fBerl_drv_rwlock_tryrwlock\fR\&\&.
.RE

.LP
.B
ErlNifPid*enif_self(ErlNifEnv* caller_env, ErlNifPid* pid)
.br
.RS
.LP
Initialize the pid variable \fI*pid\fR\& to represent the calling process\&. Return \fIpid\fR\&\&.
.RE

.LP
.B
intenif_send(ErlNifEnv* env, ErlNifPid* to_pid, ErlNifEnv* msg_env, ERL_NIF_TERM msg)
.br
.RS
.LP
Send a message to a process\&.
.RS 2
.TP 2
.B
\fIenv\fR\&:
The environment of the calling process\&. Must be NULL if and only if calling from a created thread\&.
.TP 2
.B
\fI*to_pid\fR\&:
The pid of the receiving process\&. The pid should refer to a process on the local node\&.
.TP 2
.B
\fImsg_env\fR\&:
The environment of the message term\&. Must be a process independent environment allocated with \fBenif_alloc_env\fR\&\&.
.TP 2
.B
\fImsg\fR\&:
The message term to send\&.
.RE
.LP
Return true on success, or false if \fI*to_pid\fR\& does not refer to an alive local process\&.
.LP
The message environment \fImsg_env\fR\& with all its terms (including \fImsg\fR\&) will be invalidated by a successful call to \fIenif_send\fR\&\&. The environment should either be freed with \fBenif_free_env\fR\& of cleared for reuse with \fBenif_clear_env\fR\&\&.
.LP
This function is only thread-safe when the emulator with SMP support is used\&. It can only be used in a non-SMP emulator from a NIF-calling thread\&.
.RE

.LP
.B
unsignedenif_sizeof_resource(void* obj)
.br
.RS
.LP
Get the byte size of a resource object \fIobj\fR\& obtained by \fBenif_alloc_resource\fR\&\&.
.RE

.LP
.B
voidenif_system_info(ErlNifSysInfo *sys_info_ptr, size_t size)
.br
.RS
.LP
Same as \fBdriver_system_info\fR\&\&.
.RE

.LP
.B
intenif_thread_create(char *name,ErlNifTid *tid,void * (*func)(void *),void *args,ErlNifThreadOpts *opts)
.br
.RS
.LP
Same as \fBerl_drv_thread_create\fR\&\&.
.RE

.LP
.B
voidenif_thread_exit(void *resp)
.br
.RS
.LP
Same as \fBerl_drv_thread_exit\fR\&\&.
.RE

.LP
.B
intenif_thread_join(ErlNifTid, void **respp)
.br
.RS
.LP
Same as \fBerl_drv_thread_join \fR\&\&.
.RE

.LP
.B
ErlNifThreadOpts*enif_thread_opts_create(char *name)
.br
.RS
.LP
Same as \fBerl_drv_thread_opts_create\fR\&\&.
.RE

.LP
.B
voidenif_thread_opts_destroy(ErlNifThreadOpts *opts)
.br
.RS
.LP
Same as \fBerl_drv_thread_opts_destroy\fR\&\&.
.RE

.LP
.B
ErlNifTidenif_thread_self(void)
.br
.RS
.LP
Same as \fBerl_drv_thread_self\fR\&\&.
.RE

.LP
.B
intenif_tsd_key_create(char *name, ErlNifTSDKey *key)
.br
.RS
.LP
Same as \fBerl_drv_tsd_key_create\fR\&\&.
.RE

.LP
.B
voidenif_tsd_key_destroy(ErlNifTSDKey key)
.br
.RS
.LP
Same as \fBerl_drv_tsd_key_destroy\fR\&\&.
.RE

.LP
.B
void*enif_tsd_get(ErlNifTSDKey key)
.br
.RS
.LP
Same as \fBerl_drv_tsd_get\fR\&\&.
.RE

.LP
.B
voidenif_tsd_set(ErlNifTSDKey key, void *data)
.br
.RS
.LP
Same as \fBerl_drv_tsd_set\fR\&\&.
.RE

.SH "SEE ALSO"

.LP
\fBerlang:load_nif/2\fR\&