glibc/sysdeps/standalone/read.c

/* Copyright (C) 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
   Ported to standalone by Joel Sherrill jsherril@redstone-emh2.army.mil,
     On-Line Applications Research Corporation.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <unistd.h>
#include <stddef.h>

#include "filedesc.h"
#include <fcntl.h>
#include <standalone.h>

/* Read NBYTES into BUF from FD.  Return the number read or -1.  */
ssize_t
__libc_read (int fd, void *buf, size_t nbytes)
{
  char *buffer = (char *) buf;
  int data;
  int poll;

  __set_errno (0);

  if (nbytes == 0)
    return 0;

  if ( !__FD_Is_valid( fd ) || !__FD_Table[ fd ].in_use )
    {
      __set_errno (EBADF);
      return -1;
    }
  if (buf == NULL)
    {
      __set_errno (EINVAL);
      return -1;
    }

  if ( __FD_Table[ fd ].flags & O_WRONLY )  /* is it write only? */
    {
      __set_errno (EBADF);
      return -1;
    }

  /* If this is a non-blocking fd, then we want to poll the console.  */

  poll = ( __FD_Table[ fd ].flags & O_NONBLOCK ) ? 1 : 0;

  /* Read a single character.  This is a cheap way to insure that the
     upper layers get every character because _Console_Getc can't timeout
     or otherwise know when to stop.  */


  data = _Console_Getc(poll);

  if ( data == -1 )                 /* if no data return */
    return -1;

  (void) _Console_Putc(data);       /* echo the character */

  if ( data == '\r' ) {		/* translate CR -> CR/LF */
    (void) _Console_Putc('\n');
    data = '\n';
  }

  *buffer = data;
  return 1;
}

weak_alias (__libc_read, __read)
weak_alias (__libc_read, read)