mips: Ensure PC update with MTC0 single-stepping
[qemu.git] / util / event_notifier-posix.c
1 /*
2 * event notifier support
3 *
4 * Copyright Red Hat, Inc. 2010
5 *
6 * Authors:
7 * Michael S. Tsirkin <mst@redhat.com>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 */
12
13 #include "qemu-common.h"
14 #include "qemu/event_notifier.h"
15 #include "sysemu/char.h"
16 #include "qemu/main-loop.h"
17
18 #ifdef CONFIG_EVENTFD
19 #include <sys/eventfd.h>
20 #endif
21
22 void event_notifier_init_fd(EventNotifier *e, int fd)
23 {
24 e->rfd = fd;
25 e->wfd = fd;
26 }
27
28 int event_notifier_init(EventNotifier *e, int active)
29 {
30 int fds[2];
31 int ret;
32
33 #ifdef CONFIG_EVENTFD
34 ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
35 #else
36 ret = -1;
37 errno = ENOSYS;
38 #endif
39 if (ret >= 0) {
40 e->rfd = e->wfd = ret;
41 } else {
42 if (errno != ENOSYS) {
43 return -errno;
44 }
45 if (qemu_pipe(fds) < 0) {
46 return -errno;
47 }
48 ret = fcntl_setfl(fds[0], O_NONBLOCK);
49 if (ret < 0) {
50 ret = -errno;
51 goto fail;
52 }
53 ret = fcntl_setfl(fds[1], O_NONBLOCK);
54 if (ret < 0) {
55 ret = -errno;
56 goto fail;
57 }
58 e->rfd = fds[0];
59 e->wfd = fds[1];
60 }
61 if (active) {
62 event_notifier_set(e);
63 }
64 return 0;
65
66 fail:
67 close(fds[0]);
68 close(fds[1]);
69 return ret;
70 }
71
72 void event_notifier_cleanup(EventNotifier *e)
73 {
74 if (e->rfd != e->wfd) {
75 close(e->rfd);
76 }
77 close(e->wfd);
78 }
79
80 int event_notifier_get_fd(EventNotifier *e)
81 {
82 return e->rfd;
83 }
84
85 int event_notifier_set_handler(EventNotifier *e,
86 EventNotifierHandler *handler)
87 {
88 return qemu_set_fd_handler(e->rfd, (IOHandler *)handler, NULL, e);
89 }
90
91 int event_notifier_set(EventNotifier *e)
92 {
93 static const uint64_t value = 1;
94 ssize_t ret;
95
96 do {
97 ret = write(e->wfd, &value, sizeof(value));
98 } while (ret < 0 && errno == EINTR);
99
100 /* EAGAIN is fine, a read must be pending. */
101 if (ret < 0 && errno != EAGAIN) {
102 return -errno;
103 }
104 return 0;
105 }
106
107 int event_notifier_test_and_clear(EventNotifier *e)
108 {
109 int value;
110 ssize_t len;
111 char buffer[512];
112
113 /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
114 value = 0;
115 do {
116 len = read(e->rfd, buffer, sizeof(buffer));
117 value |= (len > 0);
118 } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
119
120 return value;
121 }