/*

 * 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

 */

/***

 Synchronous I/O Multiplexing.

 Examine file descriptors for events, such as readyness for I/O.

@module posix.poll

*/

#include <config.h>

#include <poll.h>

#include "_helpers.c"

static struct {

	short       bit;

	const char *name;

} poll_event_map[] = {

#define MAP(_NAME) \

	{POLL##_NAME, #_NAME}

	MAP(IN),

	MAP(PRI),

	MAP(OUT),

	MAP(ERR),

	MAP(HUP),

	MAP(NVAL),

#undef MAP

};

#define PPOLL_EVENT_NUM (sizeof(poll_event_map) / sizeof(*poll_event_map))

static void

poll_events_createtable(lua_State *L)

{

	lua_createtable(L, 0, PPOLL_EVENT_NUM);

}

static short

poll_events_from_table(lua_State *L, int table)

{

	short events = 0;

	size_t i;

	/* Convert to absolute index */

	if (table < 0)

		table = lua_gettop(L) + table + 1;

	for (i = 0; i < PPOLL_EVENT_NUM; i++)

	{

		lua_getfield(L, table, poll_event_map[i].name);

		if (lua_toboolean(L, -1))

			events |= poll_event_map[i].bit;

		lua_pop(L, 1);

	}

	return events;

}

static void

poll_events_to_table(lua_State *L, int table, short events)

{

	size_t i;

	/* Convert to absolute index */

	if (table < 0)

		table = lua_gettop(L) + table + 1;

	for (i = 0; i < PPOLL_EVENT_NUM; i++)

	{

		lua_pushboolean(L, events & poll_event_map[i].bit);

		lua_setfield(L, table, poll_event_map[i].name);

	}

}

static nfds_t

poll_fd_list_check_table(lua_State *L, int table)

{

	nfds_t fd_num = 0;

	/*

	 * Assume table is an argument number.

	 * Should be an assert(table > 0).

	 */

	luaL_checktype(L, table, LUA_TTABLE);

	/* Nil key - the one before first */

	lua_pushnil(L);

	/* Push each key/value pair, popping previous key */

	while (lua_next(L, 1) != 0)

	{

		/* Verify the fd key */

		luaL_argcheck(L, lua_isinteger(L, -2), table,

					  "contains non-integer key(s)");

		/* Verify the table value */

		luaL_argcheck(L, lua_istable(L, -1), table,

					  "contains non-table value(s)");

		lua_getfield(L, -1, "events");

		luaL_argcheck(L, lua_istable(L, -1), table,

					  "contains invalid value table(s)");

		lua_pop(L, 1);

		lua_getfield(L, -1, "revents");

		luaL_argcheck(L, lua_isnil(L, -1) || lua_istable(L, -1), table,

					  "contains invalid value table(s)");

		lua_pop(L, 1);

		/* Remove value (but leave the key) */

		lua_pop(L, 1);

		/* Count the fds */

		fd_num++;

	}

	return fd_num;

}

static void

poll_fd_list_from_table(lua_State *L, int table, struct pollfd *fd_list)

{

	struct pollfd *pollfd = fd_list;

	/*

	 * Assume the table didn't change since

	 * the call to poll_fd_list_check_table

	 */

	/* Convert to absolute index */

	if (table < 0)

		table = lua_gettop(L) + table + 1;

	/* Nil key - the one before first */

	lua_pushnil(L);

	/* Push each key/value pair, popping previous key */

	while (lua_next(L, table) != 0)

	{

		/* Transfer the fd key */

		pollfd->fd = lua_tointeger(L, -2);

		/* Transfer "events" field from the value */

		lua_getfield(L, -1, "events");

		pollfd->events = poll_events_from_table(L, -1);

		lua_pop(L, 1);

		/* Remove value (but leave the key) */

		lua_pop(L, 1);

		/* Proceed to next fd */

		pollfd++;

	}

}

static void

poll_fd_list_to_table(lua_State *L, int table, const struct pollfd *fd_list)

{

	const struct pollfd *pollfd = fd_list;

	/*

	 * Assume the table didn't change since

	 * the call to poll_fd_list_check_table.

	 */

	/* Convert to absolute index */

	if (table < 0)

		table = lua_gettop(L) + table + 1;

	/* Nil key - the one before first */

	lua_pushnil(L);

	/* Push each key/value pair, popping previous key */

	while (lua_next(L, 1) != 0)

	{

		/* Transfer "revents" field to the value */

		lua_getfield(L, -1, "revents");

		if (lua_isnil(L, -1))

		{

			lua_pop(L, 1);

			poll_events_createtable(L);

			lua_pushvalue(L, -1);

			lua_setfield(L, -3, "revents");

		}

		poll_events_to_table(L, -1, pollfd->revents);

		lua_pop(L, 1);

		/* Remove value (but leave the key) */

		lua_pop(L, 1);

		/* Proceed to next fd */

		pollfd++;

	}

}

/***

Wait for events on multiple file descriptors.

@function poll

@tparam table fds list of file descriptors

@int[opt=-1] timeout maximum timeout in milliseconds, or -1 to block indefinitely

@treturn[1] int 0 if timed out, 1 if *fd* is ready

@return[2] nil

@treturn[2] string error message

@treturn[2] int errnum

@see poll(2)

@see rpoll

@see poll.lua

*/

static int

Ppoll(lua_State *L)

{

	struct pollfd *fd_list, static_fd_list[16];

	nfds_t fd_num = poll_fd_list_check_table(L, 1);

	int r, timeout = optint(L, 2, -1);

	checknargs(L, 2);

	fd_list = (fd_num <= sizeof(static_fd_list) / sizeof(*static_fd_list))

					? static_fd_list

					: lua_newuserdata(L, sizeof(*fd_list) * fd_num);

	poll_fd_list_from_table(L, 1, fd_list);

	r = poll(fd_list, fd_num, timeout);

	/* If any of the descriptors changed state */

	if (r > 0)

		poll_fd_list_to_table(L, 1, fd_list);

	return pushresult(L, r, NULL);

}

/***

Wait for some event on a file descriptor.

Based on [http://lua-users.org/lists/lua-l/2007-11/msg00346.html]().

@function rpoll

@int fd file descriptor

@int[opt=-1] timeout maximum timeout in milliseconds, or -1 to block indefinitely

@treturn[1] int 0 if timed out, 1 if *fd* is ready

@return[2] nil

@return[2] error message

@treturn[2] int errnum

@see poll

@usage

fh = io.open "one"

while true do

  r = rpoll (fh, 500)

  if r == 0 then

    print 'timeout'

  elseif r == 1 then

    print (fh:read ())

  else

    print "finish!"

    break

  end

end

*/

static int

Prpoll(lua_State *L)

{

	struct pollfd fds;

	int file = checkint(L, 1);

	int timeout = checkint(L, 2);

	checknargs(L, 2);

	fds.fd = file;

	fds.events = POLLIN;

	return pushresult(L, poll(&fds, 1, timeout), NULL);

}

static const luaL_Reg posix_poll_fns[] =

{

	LPOSIX_FUNC( Ppoll		),

	LPOSIX_FUNC( Prpoll		),

	{NULL, NULL}

};

LUALIB_API int

luaopen_posix_poll(lua_State *L)

{

	luaL_register(L, "posix.poll", posix_poll_fns);

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

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

	return 1;

}