compiler/clib/ungetc.c

   1 /*
   2     Copyright © 1995-2012, 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 "__fdesc.h"
  14
  15 /*****************************************************************************
  16
  17     NAME */
  18 #include <stdio.h>
  19
  20         int ungetc (
  21
  22 /*  SYNOPSIS */
  23         int    c,
  24         FILE * stream)
  25
  26 /*  FUNCTION
  27         Push the character c character back into the stream.
  28
  29     INPUTS
  30         c - Put this character back into the stream. The next read will
  31                 return this character. If you push back more than one
  32                 character, then they will be returned in reverse order.
  33                 The function gurantees that one character can be
  34                 pushed back but no more. It is possible to push the EOF
  35                 character back into the stream.
  36         stream - Read from this stream
  37
  38     RESULT
  39         c or EOF on error.
  40
  41     NOTES
  42
  43     EXAMPLE
  44
  45     BUGS
  46
  47     SEE ALSO
  48         fgetc(), getc(), fputc(), putc()
  49
  50     INTERNALS
  51
  52 ******************************************************************************/
  53 {
  54     fdesc *fdesc = __getfdesc(stream->fd);
  55
  56     if (!fdesc)
  57     {
  58         stream->flags |= _STDIO_ERROR;
  59         errno = EBADF;
  60         return EOF;
  61     }
  62
  63     /* Note: changes here might require changes in vfscanf.c!! */
  64
  65     if (c < -1)
  66         c = (unsigned int)c;
  67
  68     if (!UnGetC ((BPTR)fdesc->fcb->fh, c))
  69     {
  70         errno = __arosc_ioerr2errno (IoErr ());
  71
  72         if (errno)
  73             stream->flags |= _STDIO_ERROR;
  74         else
  75             stream->flags |= _STDIO_EOF;
  76
  77         c = EOF;
  78     }
  79
  80     return c;
  81 } /* ungetc */
  82