/*-
 * 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 <sys/types.h>
#include <sys/file.h>
#include <stdio.h>
#include <errno.h>

#include "local.h"

/*
 * Return the (stdio) flags for a given mode.  Store the flags
 * to be passed to an _open() syscall through *optr.
 * Return 0 on error.
 */
int
__sflags(const char *mode, int *optr)
{
        int ret, m, o, known;

        switch (*mode++) {

        case 'r':       /* open for reading */
                ret = __SRD;
                m = O_RDONLY;
                o = 0;
                break;

        case 'w':       /* open for writing */
                ret = __SWR;
                m = O_WRONLY;
                o = O_CREAT | O_TRUNC;
                break;

        case 'a':       /* open for appending */
                ret = __SWR;
                m = O_WRONLY;
                o = O_CREAT | O_APPEND;
                break;

        default:        /* illegal mode */
                errno = EINVAL;
                return (0);
        }

        do {
                known = 1;
                switch (*mode++) {
                case 'b':
                        /* 'b' (binary) is ignored */
                        break;
                case '+':
                        /* [rwa][b]\+ means read and write */
                        ret = __SRW;
                        m = O_RDWR;
                        break;
                case 'x':
                        /* 'x' means exclusive (fail if the file exists) */
                        o |= O_EXCL;
                        break;
                case 'e':
                        /* set close-on-exec */
                        o |= O_CLOEXEC;
                        break;
                case 'v':
                        /* verify */
                        o |= O_VERIFY;
                        break;
                default:
                        known = 0;
                        break;
                }
        } while (known);

        if ((o & O_EXCL) != 0 && m == O_RDONLY) {
                errno = EINVAL;
                return (0);
        }

        *optr = m | o;
        return (ret);
}