/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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 "namespace.h"
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include "un-namespace.h"

#include "libc_private.h"
#include "local.h"

static int lflush(FILE *);

static int
lflush(FILE *fp)
{
        int     ret = 0;

        if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) {
                FLOCKFILE_CANCELSAFE(fp);
                ret = __sflush(fp);
                FUNLOCKFILE_CANCELSAFE();
        }
        return (ret);
}

/*
 * Refill a stdio buffer.
 * Return EOF on eof or error, 0 otherwise.
 */
int
__srefill(FILE *fp)
{

        /* make sure stdio is set up */
        if (!__sdidinit)
                __sinit();

        ORIENT(fp, -1);

        fp->_r = 0;             /* largely a convenience for callers */

        /* SysV does not make this test; take it out for compatibility */
        if (fp->_flags & __SEOF)
                return (EOF);

        /* if not already reading, have to be reading and writing */
        if ((fp->_flags & __SRD) == 0) {
                if ((fp->_flags & __SRW) == 0) {
                        errno = EBADF;
                        fp->_flags |= __SERR;
                        return (EOF);
                }
                /* switch to reading */
                if (fp->_flags & __SWR) {
                        if (__sflush(fp))
                                return (EOF);
                        fp->_flags &= ~__SWR;
                        fp->_w = 0;
                        fp->_lbfsize = 0;
                }
                fp->_flags |= __SRD;
        } else {
                /*
                 * We were reading.  If there is an ungetc buffer,
                 * we must have been reading from that.  Drop it,
                 * restoring the previous buffer (if any).  If there
                 * is anything in that buffer, return.
                 */
                if (HASUB(fp)) {
                        FREEUB(fp);
                        if ((fp->_r = fp->_ur) != 0) {
                                fp->_p = fp->_up;
                                return (0);
                        }
                }
        }

        if (fp->_bf._base == NULL)
                __smakebuf(fp);

        /*
         * Before reading from a line buffered or unbuffered file,
         * flush all line buffered output files, per the ANSI C
         * standard.
         */
        if (fp->_flags & (__SLBF|__SNBF)) {
                /* Ignore this file in _fwalk to avoid potential deadlock. */
                fp->_flags |= __SIGN;
                (void) _fwalk(lflush);
                fp->_flags &= ~__SIGN;

                /* Now flush this file without locking it. */
                if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
                        __sflush(fp);
        }
        fp->_p = fp->_bf._base;
        fp->_r = _sread(fp, (char *)fp->_p, fp->_bf._size);
        fp->_flags &= ~__SMOD;  /* buffer contents are again pristine */
        if (fp->_r <= 0) {
                if (fp->_r == 0)
                        fp->_flags |= __SEOF;
                else {
                        fp->_r = 0;
                        fp->_flags |= __SERR;
                }
                return (EOF);
        }
        return (0);
}