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#include <mqueue.h>
#include <pthread.h>
#include <errno.h>
#include <sys/socket.h>
#include <signal.h>
#include <unistd.h>
#include "syscall.h"
struct args {
pthread_barrier_t barrier;
int sock;
const struct sigevent *sev;
};
static void *start(void *p)
{
struct args *args = p;
char buf[32];
ssize_t n;
int s = args->sock;
void (*func)(union sigval) = args->sev->sigev_notify_function;
union sigval val = args->sev->sigev_value;
pthread_barrier_wait(&args->barrier);
n = recv(s, buf, sizeof(buf), MSG_NOSIGNAL|MSG_WAITALL);
close(s);
if (n==sizeof buf && buf[sizeof buf - 1] == 1)
func(val);
return 0;
}
int mq_notify(mqd_t mqd, const struct sigevent *sev)
{
struct args args = { .sev = sev };
pthread_attr_t attr;
pthread_t td;
int s;
struct sigevent sev2;
static const char zeros[32];
if (!sev || sev->sigev_notify != SIGEV_THREAD)
return syscall(SYS_mq_notify, mqd, sev);
s = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, 0);
if (s < 0) return -1;
args.sock = s;
if (sev->sigev_notify_attributes) attr = *sev->sigev_notify_attributes;
else pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
pthread_barrier_init(&args.barrier, 0, 2);
if (pthread_create(&td, &attr, start, &args)) {
__syscall(SYS_close, s);
errno = EAGAIN;
return -1;
}
pthread_barrier_wait(&args.barrier);
pthread_barrier_destroy(&args.barrier);
sev2.sigev_notify = SIGEV_THREAD;
sev2.sigev_signo = s;
sev2.sigev_value.sival_ptr = (void *)&zeros;
if (syscall(SYS_mq_notify, mqd, &sev2) < 0) {
pthread_cancel(td);
__syscall(SYS_close, s);
return -1;
}
return 0;
}
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