/*

 * POSIX library for Lua 5.1, 5.2 & 5.3.

 * (c) Gary V. Vaughan <gary@vaughan.pe>, 2013-2015

 * (c) Reuben Thomas <rrt@sc3d.org> 2010-2013

 * (c) Natanael Copa <natanael.copa@gmail.com> 2008-2010

 * Clean up and bug fixes by Leo Razoumov <slonik.az@gmail.com> 2006-10-11

 * Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br> 07 Apr 2006 23:17:49

 * Based on original by Claudio Terra for Lua 3.x.

 * With contributions by Roberto Ierusalimschy.

 * With documentation from Steve Donovan 2012

 */

/***

 Sys V Message Queue Operations.

 Where supported by the underlying system, functions to send and receive

 interprocess messages.  If the module loads successfully, but there is

 no system support, then `posix.sys.msg.version` will be set, but the

 unsupported APIs wil be `nil`.

@module posix.sys.msg

*/

#include <config.h>

#include "_helpers.c"	/* For LPOSIX_2001_COMPLIANT */

#if HAVE_SYSV_MESSAGING

#include <sys/ipc.h>

#include <sys/msg.h>

#include <sys/types.h>

/***

Get a message queue identifier

@function msgget

@int key message queue id, or `IPC_PRIVATE` for a new queue

@int[opt=0] flags bitwise OR of zero or more from `IPC_CREAT` and `IPC_EXCL`,

  and access permissions `S_IRUSR`, `S_IWUSR`, `S_IRGRP`, `S_IWGRP`, `S_IROTH`

  and `S_IWOTH` (from @{posix.sys.stat})

@treturn[1] int message queue identifier, if successful

@return[2] nil

@treturn[2] string error message

@treturn[2] int errnum

@see msgget(2)

*/

static int

Pmsgget(lua_State *L)

{

	checknargs (L, 2);

	return pushresult(L, msgget(checkint(L, 1), optint(L, 2, 0)), "msgget");

}

/***

Send message to a message queue

@function msgsnd

@int id message queue identifier returned by @{msgget}

@int type arbitrary message type

@string message content

@int[opt=0] flags optionally `IPC_NOWAIT`

@treturn int 0, if successful

@return[2] nil

@treturn[2] string error message

@treturn[2] int errnum

@see msgsnd(2)

 */

static int

Pmsgsnd(lua_State *L)

{

	void *ud;

	lua_Alloc lalloc = lua_getallocf(L, &ud);

	struct {

		long mtype;

		char mtext[0];

	} *msg;

	size_t len;

	size_t msgsz;

	ssize_t r;

	int msgid = checkint(L, 1);

	long msgtype = checklong(L, 2);

	const char *msgp = luaL_checklstring(L, 3, &len;;

	int msgflg = optint(L, 4, 0);

	checknargs(L, 4);

	msgsz = sizeof(long) + len;

	if ((msg = lalloc(ud, NULL, 0, msgsz)) == NULL)

		return pusherror(L, "lalloc");

	msg->mtype = msgtype;

	memcpy(msg->mtext, msgp, len);

	r = msgsnd(msgid, msg, msgsz, msgflg);

	lua_pushinteger(L, r);

	lalloc(ud, msg, msgsz, 0);

	return (r == -1 ? pusherror(L, NULL) : 1);

}

/***

Receive message from a message queue

@function msgrcv

@int id message queue identifier returned by @{msgget}

@int size maximum message size

@int type message type (optional, default - 0)

@int[opt=0] flags bitwise OR of zero or more of `IPC_NOWAIT`, `MSG_EXCEPT`

  and `MSG_NOERROR`

@treturn[1] int message type from @{msgsnd}

@treturn[1] string message text, if successful

@return[2] nil

@treturn[2] string error message

@treturn[2] int errnum

@see msgrcv(2)

 */

static int

Pmsgrcv(lua_State *L)

{

	int msgid = checkint(L, 1);

	size_t msgsz = checkint(L, 2);

	long msgtyp = optint(L, 3, 0);

	int msgflg = optint(L, 4, 0);

	void *ud;

	lua_Alloc lalloc;

	struct {

		long mtype;

		char mtext[0];

	} *msg;

	checknargs(L, 4);

	lalloc = lua_getallocf(L, &ud);

	if ((msg = lalloc(ud, NULL, 0, msgsz)) == NULL)

		return pusherror(L, "lalloc");

	int res = msgrcv(msgid, msg, msgsz, msgtyp, msgflg);

	if (res != -1)

	{

		lua_pushinteger(L, msg->mtype);

		lua_pushlstring(L, msg->mtext, res - sizeof(long));

	}

	lalloc(ud, msg, msgsz, 0);

	return (res == -1) ? pusherror(L, NULL) : 2;

}

#endif /*!HAVE_SYSV_MESSAGING*/

static const luaL_Reg posix_sys_msg_fns[] =

{

#if HAVE_SYSV_MESSAGING

	LPOSIX_FUNC( Pmsgget		),

	LPOSIX_FUNC( Pmsgsnd		),

	LPOSIX_FUNC( Pmsgrcv		),

#endif

	{NULL, NULL}

};

/***

Constants.

@section constants

*/

/***

Message constants.

Any constants not available in the underlying system will be `nil` valued.

@table posix.sys.msg

@int IPC_CREAT create entry if key does not exist

@int IPC_EXCL fail if key exists

@int IPC_PRIVATE private key

@int IPC_NOWAIT error if request must wait

@int MSG_EXCEPT read messages with differing type

@int MSG_NOERROR truncate received message rather than erroring

@usage

  -- Print msg constants supported on this host.

  for name, value in pairs (require "posix.sys.msg") do

    if type (value) == "number" then

      print (name, value)

     end

  end

*/

LUALIB_API int

luaopen_posix_sys_msg(lua_State *L)

{

	luaL_register(L, "posix.sys.msg", posix_sys_msg_fns);

	lua_pushliteral(L, "posix.sys.msg for " LUA_VERSION " / " PACKAGE_STRING);

	lua_setfield(L, -2, "version");

#if HAVE_SYSV_MESSAGING

	LPOSIX_CONST( IPC_CREAT		);

	LPOSIX_CONST( IPC_EXCL		);

	LPOSIX_CONST( IPC_PRIVATE	);

	LPOSIX_CONST( IPC_NOWAIT	);

#  ifdef MSG_EXCEPT

	LPOSIX_CONST( MSG_EXCEPT	);

#  endif

#  ifdef MSG_NOERROR

	LPOSIX_CONST( MSG_NOERROR	);

#  endif

#endif

	return 1;

}