libfuse: fuse-3.2.1/lib/fuse_signals.c Source File

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 }
fuse_remove_signal_handlers
void fuse_remove_signal_handlers(struct fuse_session *se)
Definition: fuse_signals.c:80
fuse_set_signal_handlers
int fuse_set_signal_handlers(struct fuse_session *se)
Definition: fuse_signals.c:63
fuse_session_exit
void fuse_session_exit(struct fuse_session *se)
Definition: fuse_lowlevel.c:2993