disas: Clean up CPUDebug initialization
[qemu.git] / tools / virtiofsd / 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 "qemu/osdep.h"
12 #include "fuse_i.h"
13 #include "fuse_lowlevel.h"
14
15 #include <errno.h>
16 #include <signal.h>
17 #include <stdio.h>
18 #include <stdlib.h>
19 #include <string.h>
20
21 static struct fuse_session *fuse_instance;
22
23 static void exit_handler(int sig)
24 {
25 if (fuse_instance) {
26 fuse_session_exit(fuse_instance);
27 if (sig <= 0) {
28 fuse_log(FUSE_LOG_ERR, "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 fuse_log(FUSE_LOG_ERR, "fuse: cannot get old signal handler: %s\n",
52 strerror(errno));
53 return -1;
54 }
55
56 if (old_sa.sa_handler == (remove ? handler : SIG_DFL) &&
57 sigaction(sig, &sa, NULL) == -1) {
58 fuse_log(FUSE_LOG_ERR, "fuse: cannot set signal handler: %s\n",
59 strerror(errno));
60 return -1;
61 }
62 return 0;
63 }
64
65 int fuse_set_signal_handlers(struct fuse_session *se)
66 {
67 /*
68 * If we used SIG_IGN instead of the do_nothing function,
69 * then we would be unable to tell if we set SIG_IGN (and
70 * thus should reset to SIG_DFL in fuse_remove_signal_handlers)
71 * or if it was already set to SIG_IGN (and should be left
72 * untouched.
73 */
74 if (set_one_signal_handler(SIGHUP, exit_handler, 0) == -1 ||
75 set_one_signal_handler(SIGINT, exit_handler, 0) == -1 ||
76 set_one_signal_handler(SIGTERM, exit_handler, 0) == -1 ||
77 set_one_signal_handler(SIGPIPE, do_nothing, 0) == -1) {
78 return -1;
79 }
80
81 fuse_instance = se;
82 return 0;
83 }
84
85 void fuse_remove_signal_handlers(struct fuse_session *se)
86 {
87 if (fuse_instance != se) {
88 fuse_log(FUSE_LOG_ERR,
89 "fuse: fuse_remove_signal_handlers: unknown session\n");
90 } else {
91 fuse_instance = NULL;
92 }
93
94 set_one_signal_handler(SIGHUP, exit_handler, 1);
95 set_one_signal_handler(SIGINT, exit_handler, 1);
96 set_one_signal_handler(SIGTERM, exit_handler, 1);
97 set_one_signal_handler(SIGPIPE, do_nothing, 1);
98 }