File

util-src/poll.c @ 12983:4533c9b906b0

util.format: Tweak serialization of %q formatted entries Improves serialization of function references especially, the built-in default handling of that in util.serialization is not the most informative. Now, along with the function metatable from util.startup, the actual function can be found by filename and line number.
author Kim Alvefur <zash@zash.se>
date Sun, 26 Mar 2023 00:18:05 +0100
parent 12976:a187600ec7d6
line wrap: on
line source


/*
 * Lua polling library
 * Copyright (C) 2017-2022 Kim Alvefur
 *
 * This project is MIT licensed. Please see the
 * COPYING file in the source package for more information.
 *
 */

#include <string.h>
#include <errno.h>

#if defined(__linux__)
#define USE_EPOLL
#define POLL_BACKEND "epoll"
#elif defined(__unix__)
#define USE_POLL
#define POLL_BACKEND "poll"
#else
#define USE_SELECT
#define POLL_BACKEND "select"
#endif

#ifdef USE_EPOLL
#include <unistd.h>
#include <sys/epoll.h>
#ifndef MAX_EVENTS
#define MAX_EVENTS 64
#endif
#endif
#ifdef USE_POLL
#include <poll.h>
#ifndef MAX_EVENTS
#define MAX_EVENTS 10000
#endif
#endif
#ifdef USE_SELECT
#include <sys/select.h>
#endif

#include <lualib.h>
#include <lauxlib.h>

#define STATE_MT "util.poll<" POLL_BACKEND ">"

#if (LUA_VERSION_NUM < 504)
#define luaL_pushfail lua_pushnil
#endif

/*
 * Structure to keep state for each type of API
 */
typedef struct Lpoll_state {
	int processed;
#ifdef USE_EPOLL
	int epoll_fd;
	struct epoll_event events[MAX_EVENTS];
#endif
#ifdef USE_POLL
	nfds_t count;
	struct pollfd events[MAX_EVENTS];
#endif
#ifdef USE_SELECT
	fd_set wantread;
	fd_set wantwrite;
	fd_set readable;
	fd_set writable;
	fd_set all;
	fd_set err;
#endif
} Lpoll_state;

/*
 * Add an FD to be watched
 */
static int Ladd(lua_State *L) {
	struct Lpoll_state *state = luaL_checkudata(L, 1, STATE_MT);
	int fd = luaL_checkinteger(L, 2);

	int wantread = lua_toboolean(L, 3);
	int wantwrite = lua_toboolean(L, 4);

	if(fd < 0) {
		luaL_pushfail(L);
		lua_pushstring(L, strerror(EBADF));
		lua_pushinteger(L, EBADF);
		return 3;
	}

#ifdef USE_EPOLL
	struct epoll_event event;
	event.data.fd = fd;
	event.events = (wantread ? EPOLLIN : 0) | (wantwrite ? EPOLLOUT : 0);

	event.events |= EPOLLERR | EPOLLHUP | EPOLLRDHUP;

	int ret = epoll_ctl(state->epoll_fd, EPOLL_CTL_ADD, fd, &event);

	if(ret < 0) {
		ret = errno;
		luaL_pushfail(L);
		lua_pushstring(L, strerror(ret));
		lua_pushinteger(L, ret);
		return 3;
	}

	lua_pushboolean(L, 1);
	return 1;

#endif
#ifdef USE_POLL

	for(nfds_t i = 0; i < state->count; i++) {
		if(state->events[i].fd == fd) {
			luaL_pushfail(L);
			lua_pushstring(L, strerror(EEXIST));
			lua_pushinteger(L, EEXIST);
			return 3;
		}
	}

	if(state->count >= MAX_EVENTS) {
		luaL_pushfail(L);
		lua_pushstring(L, strerror(EMFILE));
		lua_pushinteger(L, EMFILE);
		return 3;
	}

	state->events[state->count].fd = fd;
	state->events[state->count].events = (wantread ? POLLIN : 0) | (wantwrite ? POLLOUT : 0);
	state->events[state->count].revents = 0;
	state->count++;

	lua_pushboolean(L, 1);
	return 1;
#endif
#ifdef USE_SELECT

	if(fd > FD_SETSIZE) {
		luaL_pushfail(L);
		lua_pushstring(L, strerror(EBADF));
		lua_pushinteger(L, EBADF);
		return 3;
	}

	if(FD_ISSET(fd, &state->all)) {
		luaL_pushfail(L);
		lua_pushstring(L, strerror(EEXIST));
		lua_pushinteger(L, EEXIST);
		return 3;
	}

	FD_CLR(fd, &state->readable);
	FD_CLR(fd, &state->writable);
	FD_CLR(fd, &state->err);

	FD_SET(fd, &state->all);

	if(wantread) {
		FD_SET(fd, &state->wantread);
	}
	else {
		FD_CLR(fd, &state->wantread);
	}

	if(wantwrite) {
		FD_SET(fd, &state->wantwrite);
	}
	else {
		FD_CLR(fd, &state->wantwrite);
	}

	lua_pushboolean(L, 1);
	return 1;
#endif
}

/*
 * Set events to watch for, readable and/or writable
 */
static int Lset(lua_State *L) {
	struct Lpoll_state *state = luaL_checkudata(L, 1, STATE_MT);
	int fd = luaL_checkinteger(L, 2);

#ifdef USE_EPOLL

	int wantread = lua_toboolean(L, 3);
	int wantwrite = lua_toboolean(L, 4);

	struct epoll_event event;
	event.data.fd = fd;
	event.events = (wantread ? EPOLLIN : 0) | (wantwrite ? EPOLLOUT : 0);

	event.events |= EPOLLERR | EPOLLHUP | EPOLLRDHUP;

	int ret = epoll_ctl(state->epoll_fd, EPOLL_CTL_MOD, fd, &event);

	if(ret == 0) {
		lua_pushboolean(L, 1);
		return 1;
	}
	else {
		ret = errno;
		luaL_pushfail(L);
		lua_pushstring(L, strerror(ret));
		lua_pushinteger(L, ret);
		return 3;
	}

#endif
#ifdef USE_POLL
	int wantread = lua_toboolean(L, 3);
	int wantwrite = lua_toboolean(L, 4);

	for(nfds_t i = 0; i < state->count; i++) {
		struct pollfd *event =  &state->events[i];

		if(event->fd == fd) {
			event->events = (wantread ? POLLIN : 0) | (wantwrite ? POLLOUT : 0);
			lua_pushboolean(L, 1);
			return 1;
		} else if(event->fd == -1) {
			break;
		}
	}

	luaL_pushfail(L);
	lua_pushstring(L, strerror(ENOENT));
	lua_pushinteger(L, ENOENT);
	return 3;
#endif
#ifdef USE_SELECT

	if(!FD_ISSET(fd, &state->all)) {
		luaL_pushfail(L);
		lua_pushstring(L, strerror(ENOENT));
		lua_pushinteger(L, ENOENT);
		return 3;
	}

	if(!lua_isnoneornil(L, 3)) {
		if(lua_toboolean(L, 3)) {
			FD_SET(fd, &state->wantread);
		}
		else {
			FD_CLR(fd, &state->wantread);
		}
	}

	if(!lua_isnoneornil(L, 4)) {
		if(lua_toboolean(L, 4)) {
			FD_SET(fd, &state->wantwrite);
		}
		else {
			FD_CLR(fd, &state->wantwrite);
		}
	}

	lua_pushboolean(L, 1);
	return 1;
#endif
}

/*
 * Remove FDs
 */
static int Ldel(lua_State *L) {
	struct Lpoll_state *state = luaL_checkudata(L, 1, STATE_MT);
	int fd = luaL_checkinteger(L, 2);

#ifdef USE_EPOLL

	struct epoll_event event;
	event.data.fd = fd;

	int ret = epoll_ctl(state->epoll_fd, EPOLL_CTL_DEL, fd, &event);

	if(ret == 0) {
		lua_pushboolean(L, 1);
		return 1;
	}
	else {
		ret = errno;
		luaL_pushfail(L);
		lua_pushstring(L, strerror(ret));
		lua_pushinteger(L, ret);
		return 3;
	}

#endif
#ifdef USE_POLL

	if(state->count == 0) {
		luaL_pushfail(L);
		lua_pushstring(L, strerror(ENOENT));
		lua_pushinteger(L, ENOENT);
		return 3;
	}

	/*
	 * Move the last item on top of the removed one
	 */
	struct pollfd *last = &state->events[state->count - 1];

	for(nfds_t i = 0; i < state->count; i++) {
		struct pollfd *event = &state->events[i];

		if(event->fd == fd) {
			event->fd = last->fd;
			event->events = last->events;
			event->revents = last->revents;
			last->fd = -1;
			state->count--;

			lua_pushboolean(L, 1);
			return 1;
		}
	}

	luaL_pushfail(L);
	lua_pushstring(L, strerror(ENOENT));
	lua_pushinteger(L, ENOENT);
	return 3;
#endif
#ifdef USE_SELECT

	if(!FD_ISSET(fd, &state->all)) {
		luaL_pushfail(L);
		lua_pushstring(L, strerror(ENOENT));
		lua_pushinteger(L, ENOENT);
		return 3;
	}

	FD_CLR(fd, &state->wantread);
	FD_CLR(fd, &state->wantwrite);
	FD_CLR(fd, &state->readable);
	FD_CLR(fd, &state->writable);
	FD_CLR(fd, &state->all);
	FD_CLR(fd, &state->err);

	lua_pushboolean(L, 1);
	return 1;
#endif
}


/*
 * Check previously manipulated event state for FDs ready for reading or writing
 */
static int Lpushevent(lua_State *L, struct Lpoll_state *state) {
#ifdef USE_EPOLL

	if(state->processed > 0) {
		state->processed--;
		struct epoll_event event = state->events[state->processed];
		lua_pushinteger(L, event.data.fd);
		lua_pushboolean(L, event.events & (EPOLLIN | EPOLLHUP | EPOLLRDHUP | EPOLLERR));
		lua_pushboolean(L, event.events & EPOLLOUT);
		return 3;
	}

#endif
#ifdef USE_POLL

	for(int i = state->processed - 1; i >= 0; i--) {
		struct pollfd *event = &state->events[i];

		if(event->fd != -1 && event->revents != 0) {
			lua_pushinteger(L, event->fd);
			lua_pushboolean(L, event->revents & (POLLIN | POLLHUP | POLLERR));
			lua_pushboolean(L, event->revents & POLLOUT);
			event->revents = 0;
			state->processed = i;
			return 3;
		}
	}

#endif
#ifdef USE_SELECT

	for(int fd = state->processed + 1; fd < FD_SETSIZE; fd++) {
		if(FD_ISSET(fd, &state->readable) || FD_ISSET(fd, &state->writable) || FD_ISSET(fd, &state->err)) {
			lua_pushinteger(L, fd);
			lua_pushboolean(L, FD_ISSET(fd, &state->readable) | FD_ISSET(fd, &state->err));
			lua_pushboolean(L, FD_ISSET(fd, &state->writable));
			FD_CLR(fd, &state->readable);
			FD_CLR(fd, &state->writable);
			FD_CLR(fd, &state->err);
			state->processed = fd;
			return 3;
		}
	}

#endif
	return 0;
}

/*
 * Wait for event
 */
static int Lwait(lua_State *L) {
	struct Lpoll_state *state = luaL_checkudata(L, 1, STATE_MT);

	int ret = Lpushevent(L, state);

	if(ret != 0) {
		return ret;
	}

	lua_Number timeout = luaL_checknumber(L, 2);
	luaL_argcheck(L, timeout >= 0, 1, "positive number expected");

#ifdef USE_EPOLL
	ret = epoll_wait(state->epoll_fd, state->events, MAX_EVENTS, timeout * 1000);
#endif
#ifdef USE_POLL
	ret = poll(state->events, state->count, timeout * 1000);
#endif
#ifdef USE_SELECT
	/*
	 * select(2) mutates the fd_sets passed to it so in order to not
	 * have to recreate it manually every time a copy is made.
	 */
	memcpy(&state->readable, &state->wantread, sizeof(fd_set));
	memcpy(&state->writable, &state->wantwrite, sizeof(fd_set));
	memcpy(&state->err, &state->all, sizeof(fd_set));

	struct timeval tv;
	tv.tv_sec = (time_t)timeout;
	tv.tv_usec = ((suseconds_t)(timeout * 1000000)) % 1000000;

	ret = select(FD_SETSIZE, &state->readable, &state->writable, &state->err, &tv);
#endif

	if(ret == 0) {
		/* Is this an error? */
		lua_pushnil(L);
		lua_pushstring(L, "timeout");
		return 2;
	}
	else if(ret < 0 && errno == EINTR) {
		/* Is this an error? */
		lua_pushnil(L);
		lua_pushstring(L, "signal");
		return 2;
	}
	else if(ret < 0) {
		ret = errno;
		luaL_pushfail(L);
		lua_pushstring(L, strerror(ret));
		lua_pushinteger(L, ret);
		return 3;
	}

	/*
	 * Search for the first ready FD and return it
	 */
#ifdef USE_EPOLL
	state->processed = ret;
#endif
#ifdef USE_POLL
	state->processed = state->count;
#endif
#ifdef USE_SELECT
	state->processed = -1;
#endif
	return Lpushevent(L, state);
}

#ifdef USE_EPOLL
/*
 * Return Epoll FD
 */
static int Lgetfd(lua_State *L) {
	struct Lpoll_state *state = luaL_checkudata(L, 1, STATE_MT);
	lua_pushinteger(L, state->epoll_fd);
	return 1;
}

/*
 * Close epoll FD
 */
static int Lgc(lua_State *L) {
	struct Lpoll_state *state = luaL_checkudata(L, 1, STATE_MT);

	if(state->epoll_fd == -1) {
		return 0;
	}

	if(close(state->epoll_fd) == 0) {
		state->epoll_fd = -1;
	}
	else {
		lua_pushstring(L, strerror(errno));
		lua_error(L);
	}

	return 0;
}
#endif

/*
 * String representation
 */
static int Ltos(lua_State *L) {
	struct Lpoll_state *state = luaL_checkudata(L, 1, STATE_MT);
	lua_pushfstring(L, "%s: %p", STATE_MT, state);
	return 1;
}

/*
 * Create a new context
 */
static int Lnew(lua_State *L) {
	/* Allocate state */
	Lpoll_state *state = lua_newuserdata(L, sizeof(Lpoll_state));
	luaL_setmetatable(L, STATE_MT);

	/* Initialize state */
#ifdef USE_EPOLL
	state->epoll_fd = -1;
	state->processed = 0;

	int epoll_fd = epoll_create1(EPOLL_CLOEXEC);

	if(epoll_fd <= 0) {
		luaL_pushfail(L);
		lua_pushstring(L, strerror(errno));
		lua_pushinteger(L, errno);
		return 3;
	}

	state->epoll_fd = epoll_fd;
#endif
#ifdef USE_POLL
	state->processed = -1;
	state->count = 0;

	for(nfds_t i = 0; i < MAX_EVENTS; i++) {
		state->events[i].fd = -1;
		state->events[i].events = 0;
		state->events[i].revents = 0;
	}

#endif
#ifdef USE_SELECT
	FD_ZERO(&state->wantread);
	FD_ZERO(&state->wantwrite);
	FD_ZERO(&state->readable);
	FD_ZERO(&state->writable);
	FD_ZERO(&state->all);
	FD_ZERO(&state->err);
	state->processed = FD_SETSIZE;
#endif

	return 1;
}

/*
 * Open library
 */
int luaopen_prosody_util_poll(lua_State *L) {
	luaL_checkversion(L);

	luaL_newmetatable(L, STATE_MT);
	{

		lua_pushliteral(L, STATE_MT);
		lua_setfield(L, -2, "__name");

		lua_pushcfunction(L, Ltos);
		lua_setfield(L, -2, "__tostring");

		lua_createtable(L, 0, 2);
		{
			lua_pushcfunction(L, Ladd);
			lua_setfield(L, -2, "add");
			lua_pushcfunction(L, Lset);
			lua_setfield(L, -2, "set");
			lua_pushcfunction(L, Ldel);
			lua_setfield(L, -2, "del");
			lua_pushcfunction(L, Lwait);
			lua_setfield(L, -2, "wait");
#ifdef USE_EPOLL
			lua_pushcfunction(L, Lgetfd);
			lua_setfield(L, -2, "getfd");
#endif
		}
		lua_setfield(L, -2, "__index");

#ifdef USE_EPOLL
		lua_pushcfunction(L, Lgc);
		lua_setfield(L, -2, "__gc");
#endif
	}

	lua_createtable(L, 0, 3);
	{
		lua_pushcfunction(L, Lnew);
		lua_setfield(L, -2, "new");

#define push_errno(named_error) lua_pushinteger(L, named_error);\
		lua_setfield(L, -2, #named_error);

		push_errno(EEXIST);
		push_errno(EMFILE);
		push_errno(ENOENT);

		lua_pushliteral(L, POLL_BACKEND);
		lua_setfield(L, -2, "api");

	}
	return 1;
}

/* COMPAT */
int luaopen_util_poll(lua_State *L) {
	return luaopen_prosody_util_poll(L);
}