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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [sys/] [linux/] [mq_receive.c] - Blame information for rev 258

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Line No. Rev Author Line
1 207 jeremybenn
/* Copyright 2002, Red Hat Inc. */
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#include <mqueue.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#include <string.h>
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#define _LIBC 1
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#include <sys/lock.h>
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#undef _LIBC
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#include "mqlocal.h"
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__LOCK_INIT(static, mq_rdbuf_lock);
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ssize_t
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mq_receive (mqd_t msgid, char *msg, size_t msg_len, unsigned int *msg_prio)
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{
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  struct libc_mq *info;
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  struct sembuf sb2 = {2, 1, 0};
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  struct sembuf sb3 = {3, -1, IPC_NOWAIT};
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  struct sembuf sb5 = {5, 1, IPC_NOWAIT};
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  ssize_t num_bytes;
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  int ipcflag;
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  info = __find_mq (msgid);
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  if (info == NULL || (info->oflag & O_ACCMODE) == O_WRONLY)
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    {
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      errno = EBADF;
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      return -1;
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    }
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  if (msg_len < info->attr->mq_msgsize)
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    {
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      errno = EMSGSIZE;
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      return -1;
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    }
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  __lock_acquire (mq_rdbuf_lock);
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  ipcflag = (info->attr->mq_flags & O_NONBLOCK) ? IPC_NOWAIT : 0;
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  semop (info->semid, &sb5, 1); /* increase number of readers */
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  num_bytes = msgrcv (info->msgqid, info->rdbuf, msg_len, -MQ_PRIO_MAX, ipcflag);
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  sb5.sem_op = -1;
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  semop (info->semid, &sb5, 1); /* decrease number of readers */
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  if (num_bytes != (ssize_t)-1)
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    {
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      semop (info->semid, &sb2, 1); /* add one to messages left to write */
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      semop (info->semid, &sb3, 1); /* subtract one from messages to read */
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      memcpy (msg, info->rdbuf->text, num_bytes);
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      if (msg_prio != NULL)
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        *msg_prio = MQ_PRIO_MAX - info->rdbuf->type;
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    }
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  __lock_release (mq_rdbuf_lock);
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  return num_bytes;
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}
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