/* ungetc.c (emx+gcc) -- Copyright (c) 1990-1993 by Eberhard Mattes */

#include <sys/emx.h>
#include <stdio.h>
#include <errno.h>

int ungetc (int c, FILE *stream)
{
  if (!(stream->flags & _IOOPEN) || c == EOF)
    return (EOF);
  if ((stream->flags & _IOSPECIAL) && stream->flush == NULL)
    {
      /* ungetc on a string is used only by scanf, and this does an */
      /* ungetc of the recently read character, so we don't have to */
      /* write it to the (read-only!) string.                       */
      --stream->ptr;
      ++stream->rcount;
      stream->flags &= ~_IOEOF;
      return ((unsigned char)c);
    }
  if (!(stream->flags & _IOREAD))      /* File in read mode? */
    {
      stream->flags |= _IOERR;
      errno = EACCES;
      return (EOF);
    }
  if (nbuf (stream))
    _fbuf (stream);
  if (stream->ptr == stream->buffer)
    {
      if (stream->rcount != 0)
        return (EOF);                  /* multiple ungetc: no space */
      *stream->ptr = (char)c;
    }
  else
    {
      --stream->ptr;
      *stream->ptr = (char)c;
    }
  ++stream->rcount;
  stream->flags &= ~_IOEOF;
  stream->flags |= _IOREREAD;          /* for fseek */
  return ((unsigned char)c);
}