1 /*
2 * signalfd/eventfd compatibility
3 *
4 * Copyright IBM, Corp. 2008
5 *
6 * Authors:
7 * Anthony Liguori <aliguori@us.ibm.com>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2. See
10 * the COPYING file in the top-level directory.
11 *
12 */
13
14 #include "qemu-common.h"
15 #include "compatfd.h"
16
17 #include <sys/syscall.h>
18 #include <pthread.h>
19
20 struct sigfd_compat_info
21 {
22 sigset_t mask;
23 int fd;
24 };
25
sigwait_compat(void * opaque)26 static void *sigwait_compat(void *opaque)
27 {
28 struct sigfd_compat_info *info = opaque;
29 sigset_t all;
30
31 sigfillset(&all);
32 sigprocmask(SIG_BLOCK, &all, NULL);
33
34 while (1) {
35 int sig;
36 int err;
37
38 err = sigwait(&info->mask, &sig);
39 if (err != 0) {
40 if (errno == EINTR) {
41 continue;
42 } else {
43 return NULL;
44 }
45 } else {
46 struct qemu_signalfd_siginfo buffer;
47 size_t offset = 0;
48
49 memset(&buffer, 0, sizeof(buffer));
50 buffer.ssi_signo = sig;
51
52 while (offset < sizeof(buffer)) {
53 ssize_t len;
54
55 len = write(info->fd, (char *)&buffer + offset,
56 sizeof(buffer) - offset);
57 if (len == -1 && errno == EINTR)
58 continue;
59
60 if (len <= 0) {
61 return NULL;
62 }
63
64 offset += len;
65 }
66 }
67 }
68 }
69
qemu_signalfd_compat(const sigset_t * mask)70 static int qemu_signalfd_compat(const sigset_t *mask)
71 {
72 pthread_attr_t attr;
73 pthread_t tid;
74 struct sigfd_compat_info *info;
75 int fds[2];
76
77 info = malloc(sizeof(*info));
78 if (info == NULL) {
79 errno = ENOMEM;
80 return -1;
81 }
82
83 if (pipe(fds) == -1) {
84 free(info);
85 return -1;
86 }
87
88 qemu_set_cloexec(fds[0]);
89 qemu_set_cloexec(fds[1]);
90
91 memcpy(&info->mask, mask, sizeof(*mask));
92 info->fd = fds[1];
93
94 pthread_attr_init(&attr);
95 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
96
97 pthread_create(&tid, &attr, sigwait_compat, info);
98
99 pthread_attr_destroy(&attr);
100
101 return fds[0];
102 }
103
qemu_signalfd(const sigset_t * mask)104 int qemu_signalfd(const sigset_t *mask)
105 {
106 #if defined(CONFIG_SIGNALFD)
107 int ret;
108
109 ret = syscall(SYS_signalfd, -1, mask, _NSIG / 8);
110 if (ret != -1) {
111 qemu_set_cloexec(ret);
112 return ret;
113 }
114 #endif
115
116 return qemu_signalfd_compat(mask);
117 }
118