text: /*
   * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by John Birrell.
   * 4. Neither the name of the author nor the names of any co-contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   * $FreeBSD: src/lib/libc_r/uthread/uthread_read.c,v 1.14 2002/08/29 23:06:07 deischen Exp $
   *
   */
  #include <sys/types.h>
  #include <sys/fcntl.h>
  #include <sys/uio.h>
  #include <errno.h>
  #include <unistd.h>
  #include <pthread.h>
  #include "pthread_private.h"
  
  __weak_reference(__read, read);
  
  ssize_t
  _read(int fd, void *buf, size_t nbytes)
  {
  	struct pthread	*curthread = _get_curthread();
  	int	ret;
  	int	type;
  
  	/* POSIX says to do just this: */
  	if (nbytes == 0) {
  		return (0);
  	}
  
  	/* Lock the file descriptor for read: */
  	if ((ret = _FD_LOCK(fd, FD_READ, NULL)) == 0) {
  		/* Get the read/write mode type: */
  		type = _thread_fd_getflags(fd) & O_ACCMODE;
  
  		/* Check if the file is not open for read: */
  		if (type != O_RDONLY && type != O_RDWR) {
  			/* File is not open for read: */
  			errno = EBADF;
  			_FD_UNLOCK(fd, FD_READ);
  			return (-1);
  		}
  
  		/* Perform a non-blocking read syscall: */
  		while ((ret = __sys_read(fd, buf, nbytes)) < 0) {
  			if ((_thread_fd_getflags(fd) & O_NONBLOCK) == 0 &&
  			    (errno == EWOULDBLOCK || errno == EAGAIN)) {
  				curthread->data.fd.fd = fd;
  				_thread_kern_set_timeout(NULL);
  
  				/* Reset the interrupted operation flag: */
  				curthread->interrupted = 0;
  
  				_thread_kern_sched_state(PS_FDR_WAIT,
  				    __FILE__, __LINE__);
  
  				/*
  				 * Check if the operation was
  				 * interrupted by a signal
  				 */
  				if (curthread->interrupted) {
  					errno = EINTR;
  					ret = -1;
  					break;
  				}
  			} else {
  				break;
  			}
  		}
  		_FD_UNLOCK(fd, FD_READ);
  	}
  	return (ret);
  }
  
  ssize_t
  __read(int fd, void *buf, size_t nbytes)
  {
  	ssize_t	ret;
  
  	_thread_enter_cancellation_point();
  	ret = _read(fd, buf, nbytes);
  	_thread_leave_cancellation_point();
  
  	return ret;
  }
  