xref: /netbsd-src/lib/libc/stdio/wbuf.c (revision 526d942790cc352b6ea7931f9884cc6bdbf20404)

/*	$NetBSD: wbuf.c,v 1.15 2012/03/15 18:22:31 christos Exp $	*/

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)wbuf.c	8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: wbuf.c,v 1.15 2012/03/15 18:22:31 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include "reentrant.h"
#include "local.h"

/*
 * Write the given character into the (probably full) buffer for
 * the given file.  Flush the buffer out if it is or becomes full,
 * or if c=='\n' and the file is line buffered.
 */
int
__swbuf(int c, FILE *fp)
{
	int n;

	_DIAGASSERT(fp != NULL);

	_SET_ORIENTATION(fp, -1);

	/*
	 * In case we cannot write, or longjmp takes us out early,
	 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
	 * (if line buffered) so that we will get called again.
	 * If we did not do this, a sufficient number of putc()
	 * calls might wrap _w from negative to positive.
	 */
	fp->_w = fp->_lbfsize;
	if (cantwrite(fp)) {
		errno = EBADF;
		return EOF;
	}
	c = (unsigned char)c;

	/*
	 * If it is completely full, flush it out.  Then, in any case,
	 * stuff c into the buffer.  If this causes the buffer to fill
	 * completely, or if c is '\n' and the file is line buffered,
	 * flush it (perhaps a second time).  The second flush will always
	 * happen on unbuffered streams, where _bf._size==1; fflush()
	 * guarantees that putc() will always call wbuf() by setting _w
	 * to 0, so we need not do anything else.
	 */
	_DIAGASSERT(__type_fit(int, fp->_p - fp->_bf._base));
	n = (int)(fp->_p - fp->_bf._base);
	if (n >= fp->_bf._size) {
		if (fflush(fp))
			return EOF;
		n = 0;
	}
	fp->_w--;
	*fp->_p++ = c;
	if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
		if (fflush(fp))
			return EOF;
	return c;
}