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[/] [openrisc/] [tags/] [gnu-src/] [newlib-1.18.0/] [newlib-1.18.0-or32-1.0rc2/] [newlib/] [libc/] [sys/] [linux/] [linuxthreads/] [mq_notify.c] - Rev 520
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/* Copyright 2002, Red Hat Inc. */ #include <mqueue.h> #include <unistd.h> #include <errno.h> #include <sys/ipc.h> #include <sys/sem.h> #include <string.h> #include "internals.h" #include <sys/lock.h> #include "mqlocal.h" static void *mq_notify_process (void *); void __cleanup_mq_notify (struct libc_mq *info) { struct sembuf sb4 = {4, 1, 0}; /* kill notification thread and allow other processes to set a notification */ pthread_cancel ((pthread_t)info->th); semop (info->semid, &sb4, 1); } static void * mq_notify_process (void *arg) { struct libc_mq *info = (struct libc_mq *)arg; struct sembuf sb3[2] = {{3, 0, 0}, {5, 0, 0}}; struct sembuf sb4 = {4, 1, 0}; int rc; /* wait until queue is empty */ while (!(rc = semop (info->semid, sb3, 1)) && errno == EINTR) /* empty */ ; if (!rc) { /* now wait until there are 0 readers and the queue has something in it */ sb3[0].sem_op = -1; while (!(rc = semop (info->semid, sb3, 2)) && errno == EINTR) /* empty */ ; /* restore value since we have not actually performed a read */ sb3[0].sem_op = 1; semop (info->semid, sb3, 1); /* perform desired notification - either run function in this thread or pass signal */ if (!rc) { if (info->sigevent->sigev_notify == SIGEV_SIGNAL) raise (info->sigevent->sigev_signo); else if (info->sigevent->sigev_notify == SIGEV_THREAD) info->sigevent->sigev_notify_function (info->sigevent->sigev_value); /* allow other processes to now mq_notify */ semop (info->semid, &sb4, 1); } } pthread_exit (NULL); } int mq_notify (mqd_t msgid, const struct sigevent *notification) { struct libc_mq *info; struct sembuf sb4 = {4, -1, IPC_NOWAIT}; int rc; pthread_attr_t *attr = NULL; info = __find_mq (msgid); if (info == NULL) { errno = EBADF; return -1; } /* get notification lock */ rc = semop (info->semid, &sb4, 1); if (rc == -1) { errno = EBUSY; return -1; } /* to get the notification running we use a pthread - if the user has requested an action in a pthread, we use the user's attributes when setting up the thread */ info->sigevent = (struct sigevent *)notification; if (info->sigevent->sigev_notify == SIGEV_THREAD) attr = (pthread_attr_t *)info->sigevent->sigev_notify_attributes; rc = pthread_create ((pthread_t *)&info->th, attr, mq_notify_process, (void *)info); if (rc != 0) rc = -1; else info->cleanup_notify = &__cleanup_mq_notify; return rc; }