libfuse
fuse_signals.c
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 "config.h"
12 #include "fuse_lowlevel.h"
13 #include "fuse_i.h"
14 
15 #include <stdio.h>
16 #include <string.h>
17 #include <signal.h>
18 #include <stdlib.h>
19 
20 static struct fuse_session *fuse_instance;
21 
22 static void exit_handler(int sig)
23 {
24  (void) sig;
25  if (fuse_instance) {
26  fuse_session_exit(fuse_instance);
27  if(sig <= 0) {
28  fprintf(stderr, "assertion error: signal value <= 0\n");
29  abort();
30  }
31  fuse_instance->error = sig;
32  }
33 }
34 
35 static void do_nothing(int sig)
36 {
37  (void) sig;
38 }
39 
40 static int set_one_signal_handler(int sig, void (*handler)(int), int remove)
41 {
42  struct sigaction sa;
43  struct sigaction old_sa;
44 
45  memset(&sa, 0, sizeof(struct sigaction));
46  sa.sa_handler = remove ? SIG_DFL : handler;
47  sigemptyset(&(sa.sa_mask));
48  sa.sa_flags = 0;
49 
50  if (sigaction(sig, NULL, &old_sa) == -1) {
51  perror("fuse: cannot get old signal handler");
52  return -1;
53  }
54 
55  if (old_sa.sa_handler == (remove ? handler : SIG_DFL) &&
56  sigaction(sig, &sa, NULL) == -1) {
57  perror("fuse: cannot set signal handler");
58  return -1;
59  }
60  return 0;
61 }
62 
63 int fuse_set_signal_handlers(struct fuse_session *se)
64 {
65  /* If we used SIG_IGN instead of the do_nothing function,
66  then we would be unable to tell if we set SIG_IGN (and
67  thus should reset to SIG_DFL in fuse_remove_signal_handlers)
68  or if it was already set to SIG_IGN (and should be left
69  untouched. */
70  if (set_one_signal_handler(SIGHUP, exit_handler, 0) == -1 ||
71  set_one_signal_handler(SIGINT, exit_handler, 0) == -1 ||
72  set_one_signal_handler(SIGTERM, exit_handler, 0) == -1 ||
73  set_one_signal_handler(SIGPIPE, do_nothing, 0) == -1)
74  return -1;
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  fprintf(stderr,
84  "fuse: fuse_remove_signal_handlers: unknown session\n");
85  else
86  fuse_instance = NULL;
87 
88  set_one_signal_handler(SIGHUP, exit_handler, 1);
89  set_one_signal_handler(SIGINT, exit_handler, 1);
90  set_one_signal_handler(SIGTERM, exit_handler, 1);
91  set_one_signal_handler(SIGPIPE, do_nothing, 1);
92 }
void fuse_remove_signal_handlers(struct fuse_session *se)
Definition: fuse_signals.c:80
int fuse_set_signal_handlers(struct fuse_session *se)
Definition: fuse_signals.c:63
void fuse_session_exit(struct fuse_session *se)