usr/src/lib/libc/stdio/setvbuf.c

/*-
 * Copyright (c) 1990 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)setvbuf.c   5.2 (Berkeley) 2/1/91";
#endif /* LIBC_SCCS and not lint */

#include <stdio.h>
#include <stdlib.h>
#include "local.h"

/*
 * Set one of the three kinds of buffering, optionally including
 * a buffer.
 */
setvbuf(fp, buf, mode, size)
        register FILE *fp;
        char *buf;
        register int mode;
        register size_t size;
{

        /*
         * Verify arguments.  The `int' limit on `size' is due to this
         * particular implementation.
         */
        if ((mode != _IOFBF && mode != _IOLBF && mode != _IONBF) ||
            (int)size < 0)
                return (EOF);

        /*
         * Write current buffer, if any; drop read count, if any.
         * Make sure putc() will not think fp is line buffered.
         * Free old buffer if it was from malloc().  Clear line and
         * non buffer flags, and clear malloc flag.
         */
        (void) __sflush(fp);
        fp->_r = 0;
        fp->_lbfsize = 0;
        if (fp->_flags & __SMBF)
                free((void *)fp->_bf._base);
        fp->_flags &= ~(__SLBF|__SNBF|__SMBF);

        /*
         * Now put back whichever flag is needed, and fix _lbfsize
         * if line buffered.  Ensure output flush on exit if the
         * stream will be buffered at all.
         */
        switch (mode) {

        case _IONBF:
                fp->_flags |= __SNBF;
                fp->_bf._base = fp->_p = fp->_nbuf;
                fp->_bf._size = 1;
                break;

        case _IOLBF:
                fp->_flags |= __SLBF;
                fp->_lbfsize = -size;
                /* FALLTHROUGH */

        case _IOFBF:
                /* no flag */
                __cleanup = _cleanup;
                fp->_bf._base = fp->_p = (unsigned char *)buf;
                fp->_bf._size = size;
                break;
        }

        /*
         * Patch up write count if necessary.
         */
        if (fp->_flags & __SWR)
                fp->_w = fp->_flags & (__SLBF|__SNBF) ? 0 : size;

        return (0);
}