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Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +00001/*
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +00002 * 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 */
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000010
Dr. David Alan Gilbert09863eb2019-02-08 11:48:42 +000011#include "qemu/osdep.h"
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000012#include "fuse_i.h"
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000013#include "fuse_lowlevel.h"
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000014
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000015
16static struct fuse_session *fuse_instance;
17
18static void exit_handler(int sig)
19{
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000020 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 }
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000028}
29
30static void do_nothing(int sig)
31{
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000032 (void)sig;
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000033}
34
35static int set_one_signal_handler(int sig, void (*handler)(int), int remove)
36{
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000037 struct sigaction sa;
38 struct sigaction old_sa;
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000039
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000040 memset(&sa, 0, sizeof(struct sigaction));
41 sa.sa_handler = remove ? SIG_DFL : handler;
42 sigemptyset(&(sa.sa_mask));
43 sa.sa_flags = 0;
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000044
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000045 if (sigaction(sig, NULL, &old_sa) == -1) {
Eryu Guanfc1aed02019-08-09 16:25:36 +080046 fuse_log(FUSE_LOG_ERR, "fuse: cannot get old signal handler: %s\n",
47 strerror(errno));
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000048 return -1;
49 }
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000050
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000051 if (old_sa.sa_handler == (remove ? handler : SIG_DFL) &&
52 sigaction(sig, &sa, NULL) == -1) {
Eryu Guanfc1aed02019-08-09 16:25:36 +080053 fuse_log(FUSE_LOG_ERR, "fuse: cannot set signal handler: %s\n",
54 strerror(errno));
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000055 return -1;
56 }
57 return 0;
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000058}
59
60int fuse_set_signal_handlers(struct fuse_session *se)
61{
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000062 /*
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 }
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000075
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000076 fuse_instance = se;
77 return 0;
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000078}
79
80void fuse_remove_signal_handlers(struct fuse_session *se)
81{
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000082 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 }
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000088
Dr. David Alan Gilbert73878632019-12-09 19:53:47 +000089 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);
Dr. David Alan Gilbertffcf8d92019-11-28 12:22:49 +000093}