1 files changed, 58 insertions, 0 deletions
diff --git a/stdio/ungetc.c b/stdio/ungetc.c
new file mode 100644
index 0000000000..7b22a200f6
--- /dev/null
+++ b/stdio/ungetc.c
@@ -0,0 +1,58 @@
+/* Copyright (C) 1991, 1993 Free Software Foundation, Inc.
+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 Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <errno.h>
+#include <stdio.h>
+
+
+/* Push the character C back onto the input stream of STREAM.  */
+int
+DEFUN(ungetc, (c, stream), register int c AND register FILE *stream)
+{
+  if (!__validfp(stream) || !stream->__mode.__read)
+    {
+      errno = EINVAL;
+      return EOF;
+    }
+
+  if (c == EOF)
+    return EOF;
+
+  if (stream->__pushed_back)
+    /* There is already a char pushed back.  */
+    return EOF;
+
+  if ((stream->__linebuf_active || stream->__put_limit > stream->__buffer) &&
+      /* This is a read-write stream with something in its buffer.
+	 Flush the stream.  */
+      __flshfp (stream, EOF) == EOF)
+    return EOF;
+
+  stream->__pushback = (unsigned char) c;
+  /* Tell __fillbf we've pushed back a char.  */
+  stream->__pushed_back = 1;
+  stream->__pushback_bufp = stream->__bufp;
+  /* Make the next getc call __fillbf.  It will return C.  */
+  stream->__bufp = stream->__get_limit;
+
+  /* We just gave it another character to read, so it's not at EOF.  */
+  stream->__eof = 0;
+
+  return stream->__pushback;
+}