getopt.c

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/*
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/*
 * This file was copied from the following newsgroup posting:
 *
 * Newsgroups: mod.std.unix
 * Subject: public domain AT&T getopt source
 * Date: 3 Nov 85 19:34:15 GMT
 *
 * Here's something you've all been waiting for:  the AT&T public domain
 * source for getopt(3).  It is the code which was given out at the 1985
 * UNIFORUM conference in Dallas.  I obtained it by electronic mail
 * directly from AT&T.  The people there assure me that it is indeed
 * in the public domain.
 */

#include <stdio.h>
#include <string.h>

static int opterr = 1;
static int optind = 1;
static int optopt;
static char *optarg;

static int getopt(int argc, char *argv[], char *opts)
{
    static int sp = 1;
    int c;
    char *cp;

    if (sp == 1) {
        if (optind >= argc ||
            argv[optind][0] != '-' || argv[optind][1] == '\0')
            return EOF;
        else if (!strcmp(argv[optind], "--")) {
            optind++;
            return EOF;
        }
    }
    optopt = c = argv[optind][sp];
    if (c == ':' || !(cp = strchr(opts, c))) {
        fprintf(stderr, ": illegal option -- %c\n", c);
        if (argv[optind][++sp] == '\0') {
            optind++;
            sp = 1;
        }
        return '?';
    }
    if (*++cp == ':') {
        if (argv[optind][sp+1] != '\0')
            optarg = &argv[optind++][sp+1];
        else if(++optind >= argc) {
            fprintf(stderr, ": option requires an argument -- %c\n", c);
            sp = 1;
            return '?';
        } else
            optarg = argv[optind++];
        sp = 1;
    } else {
        if (argv[optind][++sp] == '\0') {
            sp = 1;
            optind++;
        }
        optarg = NULL;
    }

    return c;
}