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
20struct sigfd_compat_info
21{
22    sigset_t mask;
23    int fd;
24};
25
26static void *sigwait_compat(void *opaque)
27{
28    struct sigfd_compat_info *info = opaque;
29    int err;
30    sigset_t all;
31
32    sigfillset(&all);
33    sigprocmask(SIG_BLOCK, &all, NULL);
34
35    do {
36	siginfo_t siginfo;
37
38	err = sigwaitinfo(&info->mask, &siginfo);
39	if (err == -1 && errno == EINTR) {
40            err = 0;
41            continue;
42        }
43
44	if (err > 0) {
45	    char buffer[128];
46	    size_t offset = 0;
47
48	    memcpy(buffer, &err, sizeof(err));
49	    while (offset < sizeof(buffer)) {
50		ssize_t len;
51
52		len = write(info->fd, buffer + offset,
53			    sizeof(buffer) - offset);
54		if (len == -1 && errno == EINTR)
55		    continue;
56
57		if (len <= 0) {
58		    err = -1;
59		    break;
60		}
61
62		offset += len;
63	    }
64	}
65    } while (err >= 0);
66
67    return NULL;
68}
69
70static 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    memcpy(&info->mask, mask, sizeof(*mask));
89    info->fd = fds[1];
90
91    pthread_attr_init(&attr);
92    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
93
94    pthread_create(&tid, &attr, sigwait_compat, info);
95
96    pthread_attr_destroy(&attr);
97
98    return fds[0];
99}
100
101int qemu_signalfd(const sigset_t *mask)
102{
103#if defined(SYS_signalfd)
104    int ret;
105
106    ret = syscall(SYS_signalfd, -1, mask, _NSIG / 8);
107    if (!(ret == -1 && errno == ENOSYS))
108	return ret;
109#endif
110
111    return qemu_signalfd_compat(mask);
112}
113
114int qemu_eventfd(int *fds)
115{
116#if defined(SYS_eventfd)
117    int ret;
118
119    ret = syscall(SYS_eventfd, 0);
120    if (ret >= 0) {
121	fds[0] = fds[1] = ret;
122	return 0;
123    } else if (!(ret == -1 && errno == ENOSYS))
124	return ret;
125#endif
126
127    return pipe(fds);
128}
129