/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2002 Todd C. Miller <Todd.Miller@courtesan.com>
 * All rights reserved.
 *
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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.
 */
/*
 * Copyright (c) 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Dieter Baron and Thomas Klausner.
 *
 * 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 NetBSD
 *      Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#pragma weak _getopt_clip = getopt_clip
#pragma weak _getopt_long = getopt_long
#pragma weak _getopt_long_only = getopt_long_only

#include "lint.h"
#include <getopt.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include "_libc_gettext.h"

static int optreset = 0;        /* keep track of first entry to getopt() */
#define PRINT_ERROR     ((opterr) && (*options != ':'))
#define FLAG_IS_SET(flag)       ((flags & flag) != 0)   /* is flag turned on? */

/* Determine if an argument is required for this long option */
#define LONGOPT_REQUIRES_ARG(longopt) \
                ((((longopt).has_arg == optional_argument) && \
                        (!FLAG_IS_SET(FLAG_OPTIONAL_ARGS))) || \
                        ((longopt).has_arg == required_argument))

#define FLAG_PERMUTE    0x01    /* permute non-options to the end of argv */
#define FLAG_ALLARGS    0x02    /* treat non-options as args to option "1" */
#define FLAG_LONGONLY   0x04    /* operate as getopt_long_only() */
#define FLAG_OPTIONAL_ARGS 0x08 /* allow optional arguments to options */
#define FLAG_REQUIRE_EQUIVALENTS 0x10 /* require short<->long equivalents */
#define FLAG_ABBREV     0x20    /* long option abbreviation allowed. */
#define FLAG_W_SEMICOLON 0x40   /* Support for W; in optstring */
#define FLAG_PLUS_DASH_START 0x80       /* leading '+' or '-' in optstring */

/* return values */
#define BADCH           (int)'?'
#define BADARG          ((*options == ':') ? (int)':' : (int)'?')
#define INORDER         (int)1

#define EMSG            ""

static int getopt_internal(int, char * const *, const char *,
                                const struct option *, int *, uint_t);
static int parse_long_options(int nargc, char * const *nargv, const char *,
                                const struct option *, int *, int,
                                uint_t flags);
static int gcd(int, int);
static void permute_args(int, int, int, char * const *);

static char *place = EMSG; /* option letter processing */

/* XXX: set optreset to 1 rather than these two */
static int nonopt_start = -1; /* first non option argument (for permute) */
static int nonopt_end = -1;   /* first option after non options (for permute) */

/*
 * Generalized error message output.
 *
 * NOTE ON ERROR MESSAGES: All the error messages in this file
 * use %s (not %c) because they are all routed through warnx_getopt(),
 * which takes a string argument. Character arguments passed
 * to warnxchar() are converted to strings automatically before
 * being passed to warnx_getopt().
 */
static void
warnx_getopt(const char *argv0, const char *msg, const char *arg)
{
        char errbuf[256];
        (void) snprintf(errbuf, sizeof (errbuf), msg, argv0, arg);
        (void) write(2, errbuf, strlen(errbuf));
        (void) write(2, "\n", 1);
}

/*
 * Generalized error message output.
 */
static void
warnxchar(const char *argv0, const char *msg, const char c)
{
        char charbuf[2];
        charbuf[0] = c;
        charbuf[1] = '\0';
        warnx_getopt(argv0, msg, charbuf);
}

/*
 * Generalized error message output.
 */
static void
warnxlen(const char *argv0, const char *msg, int argLen, const char *arg)
{
        char argbuf[256];
        (void) strncpy(argbuf, arg, argLen);
        argbuf[argLen < (sizeof (argbuf)-1)? argLen:(sizeof (argbuf)-1)] = '\0';
        warnx_getopt(argv0, msg, argbuf);
}

/*
 * Compute the greatest common divisor of a and b.
 */
static int
gcd(int a, int b)
{
        int c;

        c = a % b;
        while (c != 0) {
                a = b;
                b = c;
                c = a % b;
        }

        return (b);
}

/*
 * Exchange the block from nonopt_start to nonopt_end with the block
 * from nonopt_end to opt_end (keeping the same order of arguments
 * in each block).
 */
static void
permute_args(int panonopt_start, int panonopt_end, int opt_end,
    char * const *nargv)
{
        int cstart, cyclelen, i, j, ncycle, nnonopts, nopts, pos;
        char *swap;

        /*
         * compute lengths of blocks and number and size of cycles
         */
        nnonopts = panonopt_end - panonopt_start;
        nopts = opt_end - panonopt_end;
        ncycle = gcd(nnonopts, nopts);
        cyclelen = (opt_end - panonopt_start) / ncycle;

        for (i = 0; i < ncycle; i++) {
                cstart = panonopt_end+i;
                pos = cstart;
                for (j = 0; j < cyclelen; j++) {
                        if (pos >= panonopt_end)
                                pos -= nnonopts;
                        else
                                pos += nopts;
                        swap = nargv[pos];
                        ((char **)nargv)[pos] = nargv[cstart];
                        ((char **)nargv)[cstart] = swap;
                }
        }
} /* permute_args() */

/*
 * Verify that each short option (character flag) has a long equivalent,
 * and that each long option has a short option equivalent. Note that
 * multiple long options can map to the same character.
 *
 * This behavior is defined by Sun's CLIP specification (11/12/02),
 * and currently getopt_clip() is the only getopt variant that
 * requires it.
 *
 * If error output is enabled and an error is found, this function
 * prints ONE error message (the first error found) and returns an
 * error value.
 *
 * ASSUMES: options != NULL
 * ASSUMES: long_options may be NULL
 *
 * Returns < 0 if an error is found
 * Returns >= 0 on success
 */
static int
verify_short_long_equivalents(int nargc __unused, char *const *nargv,
    const char *options, const struct option *long_options, uint_t flags)
{
        int short_i = 0;
        int long_i = 0;
        int equivFound = 0;
        int ch = 0;

        /*
         * Find a long option for each short option
         */
        equivFound = 1;
        for (short_i = 0; equivFound && (options[short_i] != 0); ++short_i) {
                ch = options[short_i];

                if (ch == ':') {
                        continue;
                }
                if (FLAG_IS_SET(FLAG_W_SEMICOLON) &&
                    (ch == 'W') && (options[short_i+1] == ';')) {
                        /* W; is a special case */
                        ++short_i;
                        continue;
                }

                equivFound = 0;
                if (long_options != NULL) {
                        for (long_i = 0; ((!equivFound) &&
                            (long_options[long_i].name != NULL));
                            ++long_i) {
                                equivFound = (ch == long_options[long_i].val);
                        }
                }
                if ((!equivFound) && (PRINT_ERROR)) {
                        warnxchar(nargv[0],
                            _libc_gettext(
                            "%s: equivalent long option required -- %s"),
                            ch);
                }
        } /* short_i */

        /*
         * Find a short option for each long option. Note that if we came
         * out of the above loop with equivFound==0, we are already done.
         */
        if (equivFound && (long_options != NULL)) {
                for (long_i = 0; (equivFound &&
                    (long_options[long_i].name != NULL));
                    ++long_i) {
                        equivFound = ((long_options[long_i].val != 0) &&
                            (strchr(options, long_options[long_i].val)
                            != NULL));

                        if ((!equivFound) && (PRINT_ERROR)) {
                                warnx_getopt(nargv[0],
                                    _libc_gettext("%s: equivalent short "
                                    "option required -- %s"),
                                    long_options[long_i].name);
                        }
                } /* for long_i */
        }

        return (equivFound? 0:-1);
} /* verify_short_long_equivalents() */

/*
 * parse_long_options --
 *      Parse long options in argc/argv argument vector.
 * Returns -1 if short_too is set and the option does not match long_options.
 */
static int
parse_long_options(int nargc, char * const *nargv, const char *options,
    const struct option *long_options, int *idx, int short_too,
    uint_t flags)
{
        char *current_argv = NULL;
        char *argv_equal_ptr = NULL;
        size_t current_argv_len = 0;
        size_t long_option_len = 0;
        int i = 0;
        int match = 0;

        current_argv = place;
        match = -1;

        optind++;

        if ((argv_equal_ptr = strchr(current_argv, '=')) != NULL) {
                /* argument found (--option=arg) */
                current_argv_len = (argv_equal_ptr - current_argv);
                argv_equal_ptr++;
        } else {
                current_argv_len = strlen(current_argv);
        }

        for (i = 0; (long_options[i].name != NULL); i++) {

                /* find matching long option */
                if (strncmp(current_argv, long_options[i].name,
                    current_argv_len) != 0) {
                        continue;       /* no match  */
                }
                long_option_len = strlen(long_options[i].name);
                if ((!FLAG_IS_SET(FLAG_ABBREV)) &&
                    (long_option_len > current_argv_len)) {
                        continue;       /* Abbreviations are disabled */
                }

                if (long_option_len == current_argv_len) {
                        /* exact match */
                        match = i;
                        break;
                }
                /*
                 * If this is a known short option, don't allow
                 * a partial match of a single character.
                 */
                if (short_too && current_argv_len == 1)
                        continue;

                if (match == -1)        /* partial match */
                        match = i;
                else {
                        /* ambiguous abbreviation */
                        if (PRINT_ERROR) {
                                warnxlen(nargv[0],
                                    _libc_gettext(
                                    "%s: ambiguous option -- %s"),
                                    (int)current_argv_len,
                                    current_argv);
                        }
                        optopt = 0;
                        return (BADCH);
                }
        } /* for i */
        if (match != -1) {              /* option found */
                if ((long_options[match].has_arg == no_argument) &&
                    (argv_equal_ptr != NULL)) {
                        if (PRINT_ERROR) {
                                warnxlen(nargv[0],
                                    _libc_gettext(
                                "%s: option doesn't take an argument -- %s"),
                                    (int)current_argv_len,
                                    current_argv);
                        }
                        /*
                         * XXX: GNU sets optopt to val regardless of flag
                         */
                        if (long_options[match].flag == NULL)
                                optopt = long_options[match].val;
                        else
                                optopt = 0;
                        return (BADARG);
                }
                if (long_options[match].has_arg == required_argument ||
                    long_options[match].has_arg == optional_argument) {
                        if (argv_equal_ptr != NULL) {
                                optarg = argv_equal_ptr;
                        } else if (LONGOPT_REQUIRES_ARG(long_options[match])) {
                                /* The next argv must be the option argument */
                                if (optind < nargc) {
                                        optarg = nargv[optind];
                                }
                                ++optind; /* code below depends on this */
                        }
                }
                if (LONGOPT_REQUIRES_ARG(long_options[match]) &&
                    (optarg == NULL)) {
                        /*
                         * Missing argument; leading ':' indicates no error
                         * should be generated.
                         */
                        if (PRINT_ERROR) {
                                warnx_getopt(nargv[0],
                                    _libc_gettext(
                                "%s: option requires an argument -- %s"),
                                    current_argv);
                        }
                        /*
                         * XXX: GNU sets optopt to val regardless of flag
                         */
                        if (long_options[match].flag == NULL)
                                optopt = long_options[match].val;
                        else
                                optopt = 0;
                        --optind;
                        return (BADARG);
                }
        } else {                        /* unknown option */
                if (short_too) {
                        --optind;
                        return (-1);
                }
                if (PRINT_ERROR) {
                        warnx_getopt(nargv[0],
                            _libc_gettext("%s: illegal option -- %s"),
                            current_argv);
                }
                optopt = 0;
                return (BADCH);
        }
        if (idx)
                *idx = match;
        if (long_options[match].flag != NULL) {
                *long_options[match].flag = long_options[match].val;
                return (0);
        } else {
                optopt = long_options[match].val;
                return (optopt);
        }
} /* parse_long_options() */

/*
 * getopt_internal() --
 *      Parse argc/argv argument vector.  Called by user level routines.
 *
 * This implements all of the getopt_long(), getopt_long_only(),
 * getopt_clip() variants.
 */
static int
getopt_internal(int nargc, char * const *nargv, const char *options,
    const struct option *long_options, int *idx, uint_t flags)
{
        char *oli;                              /* option letter list index */
        int optchar, short_too;
        static int posixly_correct = -1;

        if (options == NULL)
                return (-1);

        /*
         * Disable GNU extensions if POSIXLY_CORRECT is set or options
         * string begins with a '+'.
         */
        if (posixly_correct == -1) {
                posixly_correct = (getenv("POSIXLY_CORRECT") != NULL);
        }
        if (FLAG_IS_SET(FLAG_PLUS_DASH_START)) {
                /*
                 * + or - at start of optstring takes precedence
                 * over POSIXLY_CORRECT.
                 */
                if (*options == '+') {
                        /*
                         * leading + means POSIX-compliant; first non-option
                         * ends option list. Therefore, don't permute args.
                         */
                        posixly_correct = 1;
                } else if (*options == '-') {
                        posixly_correct = 0;
                        flags |= FLAG_ALLARGS;
                }
                if ((*options == '+') || (*options == '-')) {
                        options++;
                }
        } /* if FLAG_PLUS_DASH_START */

        if (posixly_correct) {
                flags &= ~FLAG_PERMUTE;
                flags &= ~FLAG_ALLARGS;
        }

        /*
         * Some programs (like GNU cvs) set optind to 0 to restart
         * option processing. Work around this braindamage.
         *
         * The above problem comes from using global variables. We
         * should avoid their use in the future.
         */
        if (optind == 0) {
                optind = optreset = 1;
        }

        optarg = NULL;
        optopt = 0;

        if (optreset) {
                nonopt_start = nonopt_end = -1;
        }

        /*
         * On the first call, make sure that there is a short equivalent
         * for each long option, and vice versa. This is required by
         * Sun's CLIP specification (11/12/02).
         */
        if ((optind == 1) && FLAG_IS_SET(FLAG_REQUIRE_EQUIVALENTS)) {
                if (verify_short_long_equivalents(
                    nargc, nargv, options, long_options, flags) < 0) {
                        /* function printed any necessary messages */
                        errno = EINVAL;         /* invalid argument */
                        return (-1);
                }
        }

start:
        if (optreset || !*place) {              /* update scanning pointer */
                optreset = 0;
                if (optind >= nargc) {          /* end of argument vector */
                        place = EMSG;
                        if (nonopt_end != -1) {
                                /* do permutation, if we have to */
                                permute_args(nonopt_start, nonopt_end,
                                    optind, nargv);
                                optind -= nonopt_end - nonopt_start;

                        } else if (nonopt_start != -1) {
                                /*
                                 * If we skipped non-options, set optind
                                 * to the first of them.
                                 */
                                optind = nonopt_start;
                        }
                        nonopt_start = nonopt_end = -1;
                        return (-1);
                }
                if ((*(place = nargv[optind]) != '-') || (place[1] == '\0')) {
                        place = EMSG;           /* found non-option */
                        if (flags & FLAG_ALLARGS) {
                                /*
                                 * GNU extension:
                                 * return non-option as argument to option '\1'
                                 */
                                optarg = nargv[optind++];
                                return (INORDER);
                        }
                        if (!(flags & FLAG_PERMUTE)) {
                                /*
                                 * If no permutation wanted, stop parsing
                                 * at first non-option.
                                 */
                                return (-1);
                        }
                        /* do permutation */
                        if (nonopt_start == -1)
                                nonopt_start = optind;
                        else if (nonopt_end != -1) {
                                permute_args(nonopt_start, nonopt_end,
                                    optind, nargv);
                                nonopt_start = optind -
                                    (nonopt_end - nonopt_start);
                                nonopt_end = -1;
                        }
                        optind++;
                        /* process next argument */
                        goto start;
                }
                if (nonopt_start != -1 && nonopt_end == -1)
                        nonopt_end = optind;

                /*
                 * Check for "--" or "--foo" with no long options
                 * but if place is simply "-" leave it unmolested.
                 */
                if (place[1] != '\0' && *++place == '-' &&
                    (place[1] == '\0' || long_options == NULL)) {
                        optind++;
                        place = EMSG;
                        /*
                         * We found an option (--), so if we skipped
                         * non-options, we have to permute.
                         */
                        if (nonopt_end != -1) {
                                permute_args(nonopt_start, nonopt_end,
                                    optind, nargv);
                                optind -= nonopt_end - nonopt_start;
                        }
                        nonopt_start = nonopt_end = -1;
                        return (-1);
                }
        }

        /*
         * Check long options if:
         *  1) we were passed some
         *  2) the arg is not just "-"
         *  3) either the arg starts with -- or we are getopt_long_only()
         */
        if (long_options != NULL && place != nargv[optind] &&
            (*place == '-' || (FLAG_IS_SET(FLAG_LONGONLY)))) {
                short_too = 0;
                if (*place == '-')
                        place++;                /* --foo long option */
                else if (*place != ':' && strchr(options, *place) != NULL)
                        short_too = 1;          /* could be short option too */

                optchar = parse_long_options(nargc, nargv, options,
                    long_options, idx, short_too, flags);
                if (optchar != -1) {
                        place = EMSG;
                        return (optchar);
                }
        }

        if ((optchar = (int)*place++) == (int)':' ||
            (oli = strchr(options, optchar)) == NULL) {
                /*
                 * If the user didn't specify '-' as an option,
                 * assume it means -1 as POSIX specifies.
                 */
                if (optchar == (int)'-')
                        return (-1);
                /* option letter unknown or ':' */
                if (!*place)
                        ++optind;
                if (PRINT_ERROR)
                        warnxchar(nargv[0],
                            _libc_gettext("%s: illegal option -- %s"),
                            optchar);
                optopt = optchar;
                return (BADCH);
        }
        if (FLAG_IS_SET(FLAG_W_SEMICOLON) &&
            (long_options != NULL) && (optchar == 'W') && (oli[1] == ';')) {
                /* -W long-option */
                /* LINTED: statement has no consequent: if */
                if (*place) {                   /* no space */
                        /* NOTHING */;
                } else if (++optind >= nargc) { /* no long-option after -W */
                        place = EMSG;
                        if (PRINT_ERROR)
                                warnxchar(nargv[0],
                                    _libc_gettext(
                                "%s: option requires an argument -- %s"),
                                    optchar);
                        optopt = optchar;
                        return (BADARG);
                } else {                        /* white space */
                        place = nargv[optind];
                }
                optchar = parse_long_options(
                    nargc, nargv, options, long_options,
                    idx, 0, flags);

                /*
                 * PSARC 2003/645 - Match GNU behavior, set optarg to
                 * the long-option.
                 */
                if (optarg == NULL) {
                        optarg = nargv[optind-1];
                }
                place = EMSG;
                return (optchar);
        }
        if (*++oli != ':') {                    /* doesn't take argument */
                if (!*place)
                        ++optind;
        } else {                                /* takes (optional) argument */
                optarg = NULL;
                if (*place) {                   /* no white space */
                        optarg = place;
                /* XXX: disable test for :: if PC? (GNU doesn't) */
                } else if (!(FLAG_IS_SET(FLAG_OPTIONAL_ARGS) &&
                    (oli[1] == ':'))) {
                        /* arg is required (not optional) */

                        if (++optind >= nargc) {        /* no arg */
                                place = EMSG;
                                if (PRINT_ERROR) {
                                        warnxchar(nargv[0],
                                            _libc_gettext(
                                "%s: option requires an argument -- %s"),
                                            optchar);
                                }
                                optopt = optchar;
                                return (BADARG);
                        } else
                                optarg = nargv[optind];
                }
                place = EMSG;
                ++optind;
        }
        /* return valid option letter */
        optopt = optchar;               /* preserve getopt() behavior */
        return (optchar);
} /* getopt_internal() */

/*
 * getopt_long() --
 *      Parse argc/argv argument vector.
 *
 * Requires that long options be preceded with a two dashes
 * (e.g., --longoption).
 */
int
getopt_long(int nargc, char *const *nargv,
    const char *optstring,
    const struct option *long_options, int *long_index)
{

        return (getopt_internal(
            nargc, nargv, optstring, long_options, long_index,
            FLAG_PERMUTE
            | FLAG_OPTIONAL_ARGS
            | FLAG_ABBREV
            | FLAG_W_SEMICOLON
            | FLAG_PLUS_DASH_START));
} /* getopt_long() */

/*
 * getopt_long_only() --
 *      Parse argc/argv argument vector.
 *
 * Long options may be preceded with a single dash (e.g., -longoption)
 */
int
getopt_long_only(int nargc, char *const *nargv,
    const char *optstring,
    const struct option *long_options, int *long_index)
{

        return (getopt_internal(
            nargc, nargv, optstring, long_options, long_index,
            FLAG_PERMUTE
            | FLAG_OPTIONAL_ARGS
            | FLAG_ABBREV
            | FLAG_W_SEMICOLON
            | FLAG_PLUS_DASH_START
            | FLAG_LONGONLY));
} /* getopt_long_only() */

/*
 * getopt_clip() --
 *      Parse argc/argv argument vector, requiring compliance with
 *      Sun's CLIP specification (11/12/02)
 *
 * o Does not allow arguments to be optional (optional_argument is
 *   treated as required_argument).
 *
 * o Does not allow long options to be abbreviated on the command line
 *
 * o Does not allow long argument to be preceded by a single dash
 *   (Double-dash '--' is required)
 *
 * o Stops option processing at the first non-option
 *
 * o Requires that every long option have a short-option (single
 *   character) equivalent and vice-versa. If a short option or
 *   long option without an equivalent is found, an error message
 *   is printed and -1 is returned on the first call, and errno
 *   is set to EINVAL.
 *
 * o Leading + or - in optstring is ignored, and opstring is
 *   treated as if it began after the + or - .
 */
int
getopt_clip(int nargc, char *const *nargv, const char *optstring,
    const struct option *long_options, int *long_index)
{
        return getopt_internal(
            nargc, nargv, optstring, long_options, long_index,
                /*
                 * no permutation,
                 * no optional args,
                 * no long-only,
                 * no abbreviations
                 * no support for +- at start of optstring
                 * yes support for "W;" in optstring
                 */
            FLAG_W_SEMICOLON
            | FLAG_REQUIRE_EQUIVALENTS);
} /* getopt_clip() */