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
exit_handler(int sig)22 static void exit_handler(int sig)
23 {
24 if (fuse_instance) {
25 fuse_session_exit(fuse_instance);
26 if(sig <= 0) {
27 fuse_log(FUSE_LOG_ERR, "assertion error: signal value <= 0\n");
28 abort();
29 }
30 fuse_instance->error = sig;
31 }
32 }
33
do_nothing(int sig)34 static void do_nothing(int sig)
35 {
36 (void) sig;
37 }
38
set_one_signal_handler(int sig,void (* handler)(int),int remove)39 static int set_one_signal_handler(int sig, void (*handler)(int), int remove)
40 {
41 struct sigaction sa;
42 struct sigaction old_sa;
43
44 memset(&sa, 0, sizeof(struct sigaction));
45 sa.sa_handler = remove ? SIG_DFL : handler;
46 sigemptyset(&(sa.sa_mask));
47 sa.sa_flags = 0;
48
49 if (sigaction(sig, NULL, &old_sa) == -1) {
50 perror("fuse: cannot get old signal handler");
51 return -1;
52 }
53
54 if (old_sa.sa_handler == (remove ? handler : SIG_DFL) &&
55 sigaction(sig, &sa, NULL) == -1) {
56 perror("fuse: cannot set signal handler");
57 return -1;
58 }
59 return 0;
60 }
61
fuse_set_signal_handlers(struct fuse_session * se)62 int fuse_set_signal_handlers(struct fuse_session *se)
63 {
64 /* If we used SIG_IGN instead of the do_nothing function,
65 then we would be unable to tell if we set SIG_IGN (and
66 thus should reset to SIG_DFL in fuse_remove_signal_handlers)
67 or if it was already set to SIG_IGN (and should be left
68 untouched. */
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 fuse_instance = se;
76 return 0;
77 }
78
fuse_remove_signal_handlers(struct fuse_session * se)79 void fuse_remove_signal_handlers(struct fuse_session *se)
80 {
81 if (fuse_instance != se)
82 fuse_log(FUSE_LOG_ERR,
83 "fuse: fuse_remove_signal_handlers: unknown session\n");
84 else
85 fuse_instance = NULL;
86
87 set_one_signal_handler(SIGHUP, exit_handler, 1);
88 set_one_signal_handler(SIGINT, exit_handler, 1);
89 set_one_signal_handler(SIGTERM, exit_handler, 1);
90 set_one_signal_handler(SIGPIPE, do_nothing, 1);
91 }
92