sysdeps/standalone/read.c

   1 /* Copyright (C) 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
   2    Ported to standalone by Joel Sherrill jsherril@redstone-emh2.army.mil,
   3      On-Line Applications Research Corporation.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <errno.h>
  22 #include <unistd.h>
  23 #include <stddef.h>
  24
  25 #include "filedesc.h"
  26 #include <fcntl.h>
  27 #include <standalone.h>
  28
  29 /* Read NBYTES into BUF from FD.  Return the number read or -1.  */
  30 ssize_t
  31 __libc_read (int fd, void *buf, size_t nbytes)
  32 {
  33   char *buffer = (char *) buf;
  34   int data;
  35   int poll;
  36
  37   __set_errno (0);
  38
  39   if (nbytes == 0)
  40     return 0;
  41
  42   if ( !__FD_Is_valid( fd ) || !__FD_Table[ fd ].in_use )
  43     {
  44       __set_errno (EBADF);
  45       return -1;
  46     }
  47   if (buf == NULL)
  48     {
  49       __set_errno (EINVAL);
  50       return -1;
  51     }
  52
  53   if ( __FD_Table[ fd ].flags & O_WRONLY )  /* is it write only? */
  54     {
  55       __set_errno (EBADF);
  56       return -1;
  57     }
  58
  59   /* If this is a non-blocking fd, then we want to poll the console.  */
  60
  61   poll = ( __FD_Table[ fd ].flags & O_NONBLOCK ) ? 1 : 0;
  62
  63   /* Read a single character.  This is a cheap way to insure that the
  64      upper layers get every character because _Console_Getc can't timeout
  65      or otherwise know when to stop.  */
  66
  67
  68   data = _Console_Getc(poll);
  69
  70   if ( data == -1 )                 /* if no data return */
  71     return -1;
  72
  73   (void) _Console_Putc(data);       /* echo the character */
  74
  75   if ( data == '\r' ) {         /* translate CR -> CR/LF */
  76     (void) _Console_Putc('\n');
  77     data = '\n';
  78   }
  79
  80   *buffer = data;
  81   return 1;
  82 }
  83
  84 weak_alias (__libc_read, __read)
  85 weak_alias (__libc_read, read)