qemu

FORK: QEMU emulator
git clone https://git.neptards.moe/neptards/qemu.git
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fuse_signals.c (2556B)

      1 /*
      2  * FUSE: Filesystem in Userspace
      3  * Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
      4  *
      5  * Utility functions for setting signal handlers.
      6  *
      7  * This program can be distributed under the terms of the GNU LGPLv2.
      8  * See the file COPYING.LIB
      9  */
     10 
     11 #include "qemu/osdep.h"
     12 #include "fuse_i.h"
     13 #include "fuse_lowlevel.h"
     14 
     15 
     16 static struct fuse_session *fuse_instance;
     17 
     18 static void exit_handler(int sig)
     19 {
     20     if (fuse_instance) {
     21         fuse_session_exit(fuse_instance);
     22         if (sig <= 0) {
     23             fuse_log(FUSE_LOG_ERR, "assertion error: signal value <= 0\n");
     24             abort();
     25         }
     26         fuse_instance->error = sig;
     27     }
     28 }
     29 
     30 static void do_nothing(int sig)
     31 {
     32     (void)sig;
     33 }
     34 
     35 static int set_one_signal_handler(int sig, void (*handler)(int), int remove)
     36 {
     37     struct sigaction sa;
     38     struct sigaction old_sa;
     39 
     40     memset(&sa, 0, sizeof(struct sigaction));
     41     sa.sa_handler = remove ? SIG_DFL : handler;
     42     sigemptyset(&(sa.sa_mask));
     43     sa.sa_flags = 0;
     44 
     45     if (sigaction(sig, NULL, &old_sa) == -1) {
     46         fuse_log(FUSE_LOG_ERR, "fuse: cannot get old signal handler: %s\n",
     47                  strerror(errno));
     48         return -1;
     49     }
     50 
     51     if (old_sa.sa_handler == (remove ? handler : SIG_DFL) &&
     52         sigaction(sig, &sa, NULL) == -1) {
     53         fuse_log(FUSE_LOG_ERR, "fuse: cannot set signal handler: %s\n",
     54                  strerror(errno));
     55         return -1;
     56     }
     57     return 0;
     58 }
     59 
     60 int fuse_set_signal_handlers(struct fuse_session *se)
     61 {
     62     /*
     63      * If we used SIG_IGN instead of the do_nothing function,
     64      * then we would be unable to tell if we set SIG_IGN (and
     65      * thus should reset to SIG_DFL in fuse_remove_signal_handlers)
     66      * or if it was already set to SIG_IGN (and should be left
     67      * untouched.
     68      */
     69     if (set_one_signal_handler(SIGHUP, exit_handler, 0) == -1 ||
     70         set_one_signal_handler(SIGINT, exit_handler, 0) == -1 ||
     71         set_one_signal_handler(SIGTERM, exit_handler, 0) == -1 ||
     72         set_one_signal_handler(SIGPIPE, do_nothing, 0) == -1) {
     73         return -1;
     74     }
     75 
     76     fuse_instance = se;
     77     return 0;
     78 }
     79 
     80 void fuse_remove_signal_handlers(struct fuse_session *se)
     81 {
     82     if (fuse_instance != se) {
     83         fuse_log(FUSE_LOG_ERR,
     84                  "fuse: fuse_remove_signal_handlers: unknown session\n");
     85     } else {
     86         fuse_instance = NULL;
     87     }
     88 
     89     set_one_signal_handler(SIGHUP, exit_handler, 1);
     90     set_one_signal_handler(SIGINT, exit_handler, 1);
     91     set_one_signal_handler(SIGTERM, exit_handler, 1);
     92     set_one_signal_handler(SIGPIPE, do_nothing, 1);
     93 }