compiler/clib/ungetc.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     ANSI C function ungetc().
   6 */
   7
   8 #include <errno.h>
   9 #include <dos/dos.h>
  10 #include <dos/dosextens.h>
  11 #include <proto/exec.h>
  12 #include <proto/dos.h>
  13 #include "__errno.h"
  14 #include "__open.h"
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <stdio.h>
  20
  21         int ungetc (
  22
  23 /*  SYNOPSIS */
  24         int    c,
  25         FILE * stream)
  26
  27 /*  FUNCTION
  28         Puch the character c character back into the stream.
  29
  30     INPUTS
  31         c - Put this character back into the stream. The next read will
  32                 return this character. If you push back more than one
  33                 character, then they will be returned in reverse order.
  34                 The function gurantees that one character can be
  35                 pushed back but no more. It is possible to push the EOF
  36                 character back into the stream.
  37         stream - Read from this stream
  38
  39     RESULT
  40         c or EOF on error.
  41
  42     NOTES
  43
  44     EXAMPLE
  45
  46     BUGS
  47
  48     SEE ALSO
  49         fgetc(), getc(), fputc(), putc()
  50
  51     INTERNALS
  52
  53 ******************************************************************************/
  54 {
  55     fdesc *fdesc = __getfdesc(stream->fd);
  56
  57     if (!fdesc)
  58     {
  59         stream->flags |= _STDIO_ERROR;
  60         errno = EBADF;
  61         return EOF;
  62     }
  63
  64     /* Note: changes here might require changes in vfscanf.c!! */
  65
  66     if (c < -1)
  67         c = (unsigned int)c;
  68
  69     if (!UnGetC ((BPTR)fdesc->fh, c))
  70     {
  71         errno = IoErr2errno (IoErr ());
  72
  73         if (errno)
  74             stream->flags |= _STDIO_ERROR;
  75         else
  76             stream->flags |= _STDIO_EOF;
  77
  78         c = EOF;
  79     }
  80
  81     return c;
  82 } /* ungetc */
  83