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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /stdio/ungetc.c
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initial import
Diffstat (limited to 'stdio/ungetc.c')
-rw-r--r--stdio/ungetc.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/stdio/ungetc.c b/stdio/ungetc.c
new file mode 100644
index 0000000..7b22a20
--- /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;
+}