File

util-src/signal.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

/*
 * signal.c -- Signal Handler Library for Lua
 *
 * Version: 1.000+changes
 *
 * Copyright (C) 2007  Patrick J. Donnelly (batrick@batbytes.com)
 *
 * This software is distributed under the same license as Lua 5.0:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
*/

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include <signal.h>
#include <stdlib.h>

#include "lua.h"
#include "lauxlib.h"

#if (LUA_VERSION_NUM < 503)
#define lua_isinteger(L, n) lua_isnumber(L, n)
#endif

#ifndef lsig

#define lsig

struct lua_signal {
	char *name; /* name of the signal */
	int sig; /* the signal */
};

#endif

#define MAX_PENDING_SIGNALS 32

#define LUA_SIGNAL "lua_signal"

static const struct lua_signal lua_signals[] = {
	/* ANSI C signals */
#ifdef SIGABRT
	{"SIGABRT", SIGABRT},
#endif
#ifdef SIGFPE
	{"SIGFPE", SIGFPE},
#endif
#ifdef SIGILL
	{"SIGILL", SIGILL},
#endif
#ifdef SIGINT
	{"SIGINT", SIGINT},
#endif
#ifdef SIGSEGV
	{"SIGSEGV", SIGSEGV},
#endif
#ifdef SIGTERM
	{"SIGTERM", SIGTERM},
#endif
	/* posix signals */
#ifdef SIGHUP
	{"SIGHUP", SIGHUP},
#endif
#ifdef SIGQUIT
	{"SIGQUIT", SIGQUIT},
#endif
#ifdef SIGTRAP
	{"SIGTRAP", SIGTRAP},
#endif
#ifdef SIGKILL
	{"SIGKILL", SIGKILL},
#endif
#ifdef SIGUSR1
	{"SIGUSR1", SIGUSR1},
#endif
#ifdef SIGUSR2
	{"SIGUSR2", SIGUSR2},
#endif
#ifdef SIGPIPE
	{"SIGPIPE", SIGPIPE},
#endif
#ifdef SIGALRM
	{"SIGALRM", SIGALRM},
#endif
#ifdef SIGCHLD
	{"SIGCHLD", SIGCHLD},
#endif
#ifdef SIGCONT
	{"SIGCONT", SIGCONT},
#endif
#ifdef SIGSTOP
	{"SIGSTOP", SIGSTOP},
#endif
#ifdef SIGTTIN
	{"SIGTTIN", SIGTTIN},
#endif
#ifdef SIGTTOU
	{"SIGTTOU", SIGTTOU},
#endif
	/* some BSD signals */
#ifdef SIGIOT
	{"SIGIOT", SIGIOT},
#endif
#ifdef SIGBUS
	{"SIGBUS", SIGBUS},
#endif
#ifdef SIGCLD
	{"SIGCLD", SIGCLD},
#endif
#ifdef SIGURG
	{"SIGURG", SIGURG},
#endif
#ifdef SIGXCPU
	{"SIGXCPU", SIGXCPU},
#endif
#ifdef SIGXFSZ
	{"SIGXFSZ", SIGXFSZ},
#endif
#ifdef SIGVTALRM
	{"SIGVTALRM", SIGVTALRM},
#endif
#ifdef SIGPROF
	{"SIGPROF", SIGPROF},
#endif
#ifdef SIGWINCH
	{"SIGWINCH", SIGWINCH},
#endif
#ifdef SIGPOLL
	{"SIGPOLL", SIGPOLL},
#endif
#ifdef SIGIO
	{"SIGIO", SIGIO},
#endif
	/* add odd signals */
#ifdef SIGSTKFLT
	{"SIGSTKFLT", SIGSTKFLT}, /* stack fault */
#endif
#ifdef SIGSYS
	{"SIGSYS", SIGSYS},
#endif
	{NULL, 0}
};

static lua_State *Lsig = NULL;
static lua_Hook Hsig = NULL;
static int Hmask = 0;
static int Hcount = 0;

static int signals[MAX_PENDING_SIGNALS];
static int nsig = 0;

static void sighook(lua_State *L, lua_Debug *ar) {
	(void)ar;
	/* restore the old hook */
	lua_sethook(L, Hsig, Hmask, Hcount);

	lua_pushstring(L, LUA_SIGNAL);
	lua_gettable(L, LUA_REGISTRYINDEX);

	for(int i = 0; i < nsig; i++) {
		lua_pushinteger(L, signals[i]);
		lua_gettable(L, -2);
		lua_call(L, 0, 0);
	};

	nsig = 0;

	lua_pop(L, 1); /* pop lua_signal table */

}

static void handle(int sig) {
	if(nsig == 0) {
		/* Store the existing debug hook (if any) and its parameters */
		Hsig = lua_gethook(Lsig);
		Hmask = lua_gethookmask(Lsig);
		Hcount = lua_gethookcount(Lsig);

		/* Set our new debug hook */
		lua_sethook(Lsig, sighook, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
	}

	if(nsig < MAX_PENDING_SIGNALS) {
		signals[nsig++] = sig;
	}
}

/*
 * l_signal == signal(signal [, func [, chook]])
 *
 * signal = signal number or string
 * func = Lua function to call
 * chook = catch within C functions
 *         if caught, Lua function _must_
 *         exit, as the stack is most likely
 *         in an unstable state.
*/

static int l_signal(lua_State *L) {
	int args = lua_gettop(L);
	int t, sig; /* type, signal */

	/* get type of signal */
	luaL_checkany(L, 1);
	t = lua_type(L, 1);

	if(t == LUA_TNUMBER) {
		sig = (int) lua_tointeger(L, 1);
	} else if(t == LUA_TSTRING) {
		lua_pushstring(L, LUA_SIGNAL);
		lua_gettable(L, LUA_REGISTRYINDEX);
		lua_pushvalue(L, 1);
		lua_gettable(L, -2);

		if(!lua_isinteger(L, -1)) {
			return luaL_error(L, "invalid signal string");
		}

		sig = (int) lua_tointeger(L, -1);
		lua_pop(L, 1); /* get rid of number we pushed */
	} else {
		luaL_checknumber(L, 1);    /* will always error, with good error msg */
		return luaL_error(L, "unreachable: invalid number was accepted");
	}

	/* set handler */
	if(args == 1 || lua_isnil(L, 2)) { /* clear handler */
		lua_pushstring(L, LUA_SIGNAL);
		lua_gettable(L, LUA_REGISTRYINDEX);
		lua_pushinteger(L, sig);
		lua_gettable(L, -2); /* return old handler */
		lua_pushinteger(L, sig);
		lua_pushnil(L);
		lua_settable(L, -4);
		lua_remove(L, -2); /* remove LUA_SIGNAL table */
		signal(sig, SIG_DFL);
	} else {
		luaL_checktype(L, 2, LUA_TFUNCTION);

		lua_pushstring(L, LUA_SIGNAL);
		lua_gettable(L, LUA_REGISTRYINDEX);

		lua_pushinteger(L, sig);
		lua_pushvalue(L, 2);
		lua_settable(L, -3);

		/* Set the state for the handler */
		Lsig = L;

		if(lua_toboolean(L, 3)) { /* c hook? */
			if(signal(sig, handle) == SIG_ERR) {
				lua_pushboolean(L, 0);
			} else {
				lua_pushboolean(L, 1);
			}
		} else { /* lua_hook */
			if(signal(sig, handle) == SIG_ERR) {
				lua_pushboolean(L, 0);
			} else {
				lua_pushboolean(L, 1);
			}
		}
	}

	return 1;
}

/*
 * l_raise == raise(signal)
 *
 * signal = signal number or string
*/

static int l_raise(lua_State *L) {
	/* int args = lua_gettop(L); */
	int t = 0; /* type */
	lua_Integer ret;

	luaL_checkany(L, 1);

	t = lua_type(L, 1);

	if(t == LUA_TNUMBER) {
		ret = (lua_Integer) raise((int) lua_tointeger(L, 1));
		lua_pushinteger(L, ret);
	} else if(t == LUA_TSTRING) {
		lua_pushstring(L, LUA_SIGNAL);
		lua_gettable(L, LUA_REGISTRYINDEX);
		lua_pushvalue(L, 1);
		lua_gettable(L, -2);

		if(!lua_isnumber(L, -1)) {
			return luaL_error(L, "invalid signal string");
		}

		ret = (lua_Integer) raise((int) lua_tointeger(L, -1));
		lua_pop(L, 1); /* get rid of number we pushed */
		lua_pushinteger(L, ret);
	} else {
		luaL_checknumber(L, 1);    /* will always error, with good error msg */
	}

	return 1;
}

#if defined(__unix__) || defined(__APPLE__)

/* define some posix only functions */

/*
 * l_kill == kill(pid, signal)
 *
 * pid = process id
 * signal = signal number or string
*/

static int l_kill(lua_State *L) {
	int t; /* type */
	lua_Integer ret; /* return value */

	luaL_checknumber(L, 1); /* must be int for pid */
	luaL_checkany(L, 2); /* check for a second arg */

	t = lua_type(L, 2);

	if(t == LUA_TNUMBER) {
		ret = (lua_Integer) kill((int) lua_tointeger(L, 1),
		                         (int) lua_tointeger(L, 2));
		lua_pushinteger(L, ret);
	} else if(t == LUA_TSTRING) {
		lua_pushstring(L, LUA_SIGNAL);
		lua_gettable(L, LUA_REGISTRYINDEX);
		lua_pushvalue(L, 2);
		lua_gettable(L, -2);

		if(!lua_isnumber(L, -1)) {
			return luaL_error(L, "invalid signal string");
		}

		ret = (lua_Integer) kill((int) lua_tointeger(L, 1),
		                         (int) lua_tointeger(L, -1));
		lua_pop(L, 1); /* get rid of number we pushed */
		lua_pushinteger(L, ret);
	} else {
		luaL_checknumber(L, 2);    /* will always error, with good error msg */
	}

	return 1;
}

#endif

static const struct luaL_Reg lsignal_lib[] = {
	{"signal", l_signal},
	{"raise", l_raise},
#if defined(__unix__) || defined(__APPLE__)
	{"kill", l_kill},
#endif
	{NULL, NULL}
};

int luaopen_prosody_util_signal(lua_State *L) {
	luaL_checkversion(L);
	int i = 0;

	/* add the library */
	lua_newtable(L);
	luaL_setfuncs(L, lsignal_lib, 0);

	/* push lua_signals table into the registry */
	/* put the signals inside the library table too,
	 * they are only a reference */
	lua_pushstring(L, LUA_SIGNAL);
	lua_newtable(L);

	while(lua_signals[i].name != NULL) {
		/* registry table */
		lua_pushstring(L, lua_signals[i].name);
		lua_pushinteger(L, lua_signals[i].sig);
		lua_settable(L, -3);
		/* signal table */
		lua_pushstring(L, lua_signals[i].name);
		lua_pushinteger(L, lua_signals[i].sig);
		lua_settable(L, -5);
		i++;
	}

	/* add newtable to the registry */
	lua_settable(L, LUA_REGISTRYINDEX);

	return 1;
}
int luaopen_util_signal(lua_State *L) {
	return luaopen_prosody_util_signal(L);
}