mirror of
https://github.com/octoleo/lsyncd.git
synced 2024-11-12 00:06:26 +00:00
181 lines
3.5 KiB
C
181 lines
3.5 KiB
C
/*
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| singal.c from Lsyncd -- the Live (Mirror) Syncing Demon
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| Albeit this signal handling system at first seems to violate
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| rentry rules things are evened out by sigmasks taking care
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| only one signal at a time can enter the core.
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| License: GPLv2 (see COPYING) or any later version
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| Authors: Axel Kittenberger <axkibe@gmail.com>
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*/
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#include "feature.h"
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <string.h>
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#define LUA_USE_APICHECK 1
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#include <lua.h>
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#include <lualib.h>
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#include <lauxlib.h>
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#include "log.h"
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#include "mem.h"
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static volatile sig_atomic_t * queue;
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static int queue_len;
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static int queue_pos;
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/*
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| Set by TERM or HUP signal handler
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| telling Lsyncd should end or reset ASAP.
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*/
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volatile sig_atomic_t hup = 0;
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volatile sig_atomic_t term = 0;
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volatile sig_atomic_t sigcode = 0;
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/*
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| signal handler
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*/
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static void
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signal_child( int sig )
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{
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// Nothing!
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//
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// This signal handler is just installed so the kernel
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// keeps finished child processes as zombies waiting to be reaped.
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}
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/*
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| signal handler
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*/
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static void
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signal_handler( int sig )
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{
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// looks if this signal is already queued
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for( int i = 0; i < queue_pos; i++ )
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{
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// if so it is dropped
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if( queue[ i ] == sig ) return;
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}
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if( queue_pos + 1 >= queue_len )
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{
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// this should never ever happen
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logstring( "Error", "Signal queue overflow!" );
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exit( -1 );
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}
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queue[ queue_pos++ ] = sig;
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}
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/*
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| Initializes signal handling.
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| Listens to SIGCHLD, but blocks it until pselect( )
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| opens the signal handler up.
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*/
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void
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signal_init( )
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{
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queue_len = 5;
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queue = s_malloc( queue_len * sizeof( sig_atomic_t ) );
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queue_pos = 0;
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}
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/*
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| Registers (or deregisters) a signal handlers.
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| Params on Lua stack:
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| 1: table of all signal handlers
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| Returns on Lua stack:
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| true if the signal could be registered with the kernel/libc
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| false if they denied it
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*/
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int
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l_onsignal( lua_State *L )
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{
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int sigc = 0;
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int ok;
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// the block mask includes all signals that have registered handlers.
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// it is used to block all signals outside the select() call
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// and also during the core signal handler runs.
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sigset_t blockmask;
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sigemptyset( &blockmask );
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sigaddset( &blockmask, SIGCHLD );
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// first time iterates the signal handler table to build
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// the blockmask
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lua_pushnil( L );
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while( lua_next( L, -2 ) )
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{
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int htype = lua_type( L, -1 ); // the handle
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// pops the value, leaves the key on stack
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lua_pop( L, 1 );
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// not a handler function (probably false)
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if( htype != LUA_TFUNCTION ) continue;
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int signum = lua_tointegerx( L, -1 , &ok );
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if( !ok ) continue;
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sigc++;
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}
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// and block those signals
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sigprocmask( SIG_BLOCK, &blockmask, NULL );
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// if there are more signal handlers than
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// the signal queue allows, it is enlarged.
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if( sigc >= queue_len )
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{
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while( sigc >= queue_len ) queue_len *= 2;
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queue = s_realloc( (sig_atomic_t *)( queue ), queue_len * sizeof( sig_atomic_t ) );
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}
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// now iterates the signal handler table
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// once again to register the signal handlers.
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struct sigaction act;
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memset (&act, '\0', sizeof(act));
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act.sa_mask = blockmask;
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lua_pushnil( L );
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while( lua_next( L, -2 ) )
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{
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int htype = lua_type( L, -1 ); // the handle
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act.sa_handler = &signal_handler;
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// pops the value, leaves the key on stack
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lua_pop( L, 1 );
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// not a handler function (probably false)
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if( htype != LUA_TFUNCTION ) continue;
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int signum = lua_tointegerx( L, -1 , &ok );
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if( !ok ) continue;
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sigaction( signum, &act, 0 );
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}
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return 0;
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}
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