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      1 /***
      2   This file is part of libdaemon.
      3 
      4   Copyright 2003-2008 Lennart Poettering
      5 
      6   Permission is hereby granted, free of charge, to any person obtaining a copy
      7   of this software and associated documentation files (the "Software"), to deal
      8   in the Software without restriction, including without limitation the rights
      9   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     10   copies of the Software, and to permit persons to whom the Software is
     11   furnished to do so, subject to the following conditions:
     12 
     13   The above copyright notice and this permission notice shall be included in
     14   all copies or substantial portions of the Software.
     15 
     16   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     17   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     18   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     19   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     20   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     21   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     22   SOFTWARE.
     23 
     24 ***/
     25 
     26 #ifdef HAVE_CONFIG_H
     27 #include <config.h>
     28 #endif
     29 
     30 #include <fcntl.h>
     31 #include <unistd.h>
     32 #include <errno.h>
     33 #include <string.h>
     34 #include <stdarg.h>
     35 #include <signal.h>
     36 
     37 #include "dsignal.h"
     38 #include "dlog.h"
     39 #include "dnonblock.h"
     40 
     41 static int _signal_pipe[2] = { -1, -1 };
     42 
     43 static void _sigfunc(int s) {
     44     int saved_errno = errno;
     45     write(_signal_pipe[1], &s, sizeof(s));
     46     errno = saved_errno;
     47 }
     48 
     49 static int _init(void) {
     50 
     51     if (_signal_pipe[0] < 0 || _signal_pipe[1] < 0) {
     52         if (pipe(_signal_pipe) < 0) {
     53             daemon_log(LOG_ERR, "pipe(): %s", strerror(errno));
     54             return -1;
     55         }
     56 
     57         if (daemon_nonblock(_signal_pipe[0], 1) < 0 || daemon_nonblock(_signal_pipe[1], 1) < 0) {
     58             daemon_signal_done();
     59             return -1;
     60         }
     61     }
     62 
     63     return 0;
     64 }
     65 
     66 int daemon_signal_install(int s){
     67     sigset_t ss;
     68     struct sigaction sa;
     69 
     70     if (_init() < 0)
     71         return -1;
     72 
     73     if (sigemptyset(&ss) < 0) {
     74         daemon_log(LOG_ERR, "sigemptyset(): %s", strerror(errno));
     75         return -1;
     76     }
     77 
     78     if (sigaddset(&ss, s) < 0) {
     79         daemon_log(LOG_ERR, "sigaddset(): %s", strerror(errno));
     80         return -1;
     81     }
     82 
     83     if (sigprocmask(SIG_UNBLOCK, &ss, NULL) < 0) {
     84         daemon_log(LOG_ERR, "sigprocmask(): %s", strerror(errno));
     85         return -1;
     86     }
     87 
     88     memset(&sa, 0, sizeof(sa));
     89     sa.sa_handler = _sigfunc;
     90     sigemptyset(&sa.sa_mask);
     91     sa.sa_flags = SA_RESTART;
     92 
     93     if (sigaction(s, &sa, NULL) < 0) {
     94         daemon_log(LOG_ERR, "sigaction(%s, ...) failed: %s", strsignal(s), strerror(errno));
     95         return -1;
     96     }
     97 
     98     return 0;
     99 }
    100 
    101 int daemon_signal_init(int s, ...) {
    102     int sig, r = 0;
    103     va_list ap;
    104 
    105     if (_init() < 0)
    106         return -1;
    107 
    108     va_start(ap, s);
    109 
    110     sig = s;
    111     while (sig > 0) {
    112         if ((r = daemon_signal_install(sig)) < 0)
    113             break;
    114 
    115         sig = va_arg(ap, int);
    116     }
    117 
    118     va_end(ap);
    119 
    120     return r;
    121 }
    122 
    123 void daemon_signal_done(void) {
    124     int saved_errno = errno;
    125 
    126     if (_signal_pipe[0] != -1)
    127         close(_signal_pipe[0]);
    128 
    129     if (_signal_pipe[1] != -1)
    130         close(_signal_pipe[1]);
    131 
    132     _signal_pipe[0] = _signal_pipe[1] = -1;
    133 
    134     errno = saved_errno;
    135 }
    136 
    137 int daemon_signal_next(void) {
    138     int s;
    139     ssize_t r;
    140 
    141     if ((r = read(_signal_pipe[0], &s, sizeof(s))) == sizeof(s))
    142         return s;
    143 
    144     if (r < 0) {
    145 
    146         if (errno == EAGAIN)
    147             return 0;
    148         else {
    149             daemon_log(LOG_ERR, "read(signal_pipe[0], ...): %s", strerror(errno));
    150             return -1;
    151         }
    152     }
    153 
    154     daemon_log(LOG_ERR, "Short read() on signal pipe.");
    155     return -1;
    156 }
    157 
    158 int daemon_signal_fd(void) {
    159     return _signal_pipe[0];
    160 }
    161