usr/src/lib/libc/stdio/fflush.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.
 *
 * %sccs.include.redist.c%
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fflush.c    5.1 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/errno.h>
#include <stdio.h>
#include "local.h"

/* Flush a single file, or (if fp is NULL) all files.  */
fflush(fp)
        register FILE *fp;
{
        if (fp == NULL)
                return (_fwalk(__sflush));

        if ((fp->_flags & __SWR) == 0) {
                errno = EBADF;
                return (EOF);
        }
        return (__sflush(fp));
}

__sflush(fp)
        register FILE *fp;
{
        register unsigned char *p;
        register int n, t;

        t = fp->_flags;
        if ((t & __SWR) == 0)
                return (0);

        if ((p = fp->_bf._base) == NULL)
                return (0);

        n = fp->_p - p;         /* write this much */

        /*
         * Set these immediately to avoid problems with longjmp and to allow
         * exchange buffering (via setvbuf) in user write function.
         */
        fp->_p = p;
        fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;

        for (; n > 0; n -= t, p += t) {
                t = (*fp->_write)(fp->_cookie, (char *)p, n);
                if (t <= 0) {
                        fp->_flags |= __SERR;
                        return (EOF);
                }
        }
        return (0);
}