1 #include <mqueue.h>
2 #include <pthread.h>
3 #include <errno.h>
4 #include <sys/socket.h>
5 #include <signal.h>
6 #include <unistd.h>
7 #include "syscall.h"
8
9 struct args {
10 pthread_barrier_t barrier;
11 int sock;
12 const struct sigevent *sev;
13 };
14
start(void * p)15 static void *start(void *p)
16 {
17 struct args *args = p;
18 char buf[32];
19 ssize_t n;
20 int s = args->sock;
21 void (*func)(union sigval) = args->sev->sigev_notify_function;
22 union sigval val = args->sev->sigev_value;
23
24 pthread_barrier_wait(&args->barrier);
25 n = recv(s, buf, sizeof(buf), MSG_NOSIGNAL|MSG_WAITALL);
26 close(s);
27 if (n==sizeof buf && buf[sizeof buf - 1] == 1)
28 func(val);
29 return 0;
30 }
31
mq_notify(mqd_t mqd,const struct sigevent * sev)32 int mq_notify(mqd_t mqd, const struct sigevent *sev)
33 {
34 struct args args = { .sev = sev };
35 pthread_attr_t attr;
36 pthread_t td;
37 int s;
38 struct sigevent sev2;
39 static const char zeros[32];
40
41 if (!sev || sev->sigev_notify != SIGEV_THREAD)
42 return syscall(SYS_mq_notify, mqd, sev);
43
44 s = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, 0);
45 if (s < 0) return -1;
46 args.sock = s;
47
48 if (sev->sigev_notify_attributes) attr = *sev->sigev_notify_attributes;
49 else pthread_attr_init(&attr);
50 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
51 pthread_barrier_init(&args.barrier, 0, 2);
52
53 if (pthread_create(&td, &attr, start, &args)) {
54 __syscall(SYS_close, s);
55 errno = EAGAIN;
56 return -1;
57 }
58
59 pthread_barrier_wait(&args.barrier);
60 pthread_barrier_destroy(&args.barrier);
61
62 sev2.sigev_notify = SIGEV_THREAD;
63 sev2.sigev_signo = s;
64 sev2.sigev_value.sival_ptr = (void *)&zeros;
65
66 if (syscall(SYS_mq_notify, mqd, &sev2) < 0) {
67 pthread_cancel(td);
68 __syscall(SYS_close, s);
69 return -1;
70 }
71
72 return 0;
73 }
74