File

util-src/poll.c @ 11928:16cf863b36c0

mod_csi_simple: Skip initiating flush in all but inactive state Both in the flushing and active states the right thing to do is skip directly to returning the data. Also in any unknown state, like if the filter is somehow left behind on module unload.
author Kim Alvefur <zash@zash.se>
date Sat, 20 Nov 2021 23:54:43 +0100
parent 10921:6eb5d2bb11af
child 12314:898554323338
line wrap: on
line source


/*
 * Lua polling library
 * Copyright (C) 2017-2018 Kim Alvefur
 *
 * This project is MIT licensed. Please see the
 * COPYING file in the source package for more information.
 *
 */

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

#ifdef __linux__
#define USE_EPOLL
#endif

#ifdef USE_EPOLL
#include <sys/epoll.h>
#ifndef MAX_EVENTS
#define MAX_EVENTS 64
#endif
#else
#include <sys/select.h>
#endif

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

#ifdef USE_EPOLL
#define STATE_MT "util.poll<epoll>"
#else
#define STATE_MT "util.poll<select>"
#endif

#if (LUA_VERSION_NUM == 501)
#define luaL_setmetatable(L, tname) luaL_getmetatable(L, tname); lua_setmetatable(L, -2)
#endif
#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];
#else
	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;

#else

	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;
	}

#else

	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;
	}

#else

	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;
	}

#else

	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);
#else
	/*
	 * 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;
#else
	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;
#else
	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_util_poll(lua_State *L) {
#if (LUA_VERSION_NUM > 501)
	luaL_checkversion(L);
#endif

	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(ENOENT);

	}
	return 1;
}