getopt.c

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/*
 * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

FILE_LICENCE ( GPL2_OR_LATER );

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

/** @file
 *
 * Parse command-line options
 *
 */

/**
 * Option argument
 *
 * This will point to the argument for the most recently returned
 * option, if applicable.
 */
char *optarg;

/**
 * Current option index
 *
 * This is an index into the argv[] array.  When getopt() returns -1,
 * @c optind is the index to the first element that is not an option.
 */
int optind;

/**
 * Current option character index
 *
 * This is an index into the current element of argv[].
 */
int nextchar;

/**
 * Unrecognised option
 *
 * When an unrecognised option is encountered, the actual option
 * character is stored in @c optopt.
 */
int optopt;

/**
 * Get option argument from argv[] array
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @ret argument        Option argument, or NULL
 *
 * Grab the next element of argv[], if it exists and is not an option.
 */
static const char * get_argv_argument ( int argc, char * const argv[] ) {
        char *arg;

        /* Don't overrun argv[] */
        if ( optind >= argc )
                return NULL;
        arg = argv[optind];

        /* If next argv element is an option, then it's not usable as
         * an argument.
         */
        if ( *arg == '-' )
                return NULL;

        /** Consume this argv element, and return it */
        optind++;
        return arg;
}

/**
 * Match long option
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @v opttext           Option text within current argv[] element
 * @v longopt           Long option specification
 * @ret option          Option to return from getopt()
 * @ret matched         Found a match for this long option
 */
static int match_long_option ( int argc, char * const argv[],
                               const char *opttext,
                               const struct option *longopt, int *option ) {
        size_t optlen;
        const char *argument = NULL;

        /* Compare option name */
        optlen = strlen ( longopt->name );
        if ( strncmp ( opttext, longopt->name, optlen ) != 0 )
                return 0;

        /* Check for inline argument */
        if ( opttext[optlen] == '=' ) {
                argument = &opttext[ optlen + 1 ];
        } else if ( opttext[optlen] ) {
                /* Long option with trailing garbage - no match */
                return 0;
        }

        /* Consume this argv element */
        optind++;

        /* If we want an argument but don't have one yet, try to grab
         * the next argv element
         */
        if ( ( longopt->has_arg != no_argument ) && ( ! argument ) )
                argument = get_argv_argument ( argc, argv );

        /* If we need an argument but don't have one, sulk */
        if ( ( longopt->has_arg == required_argument ) && ( ! argument ) ) {
                printf ( "Option \"%s\" requires an argument\n",
                         longopt->name );
                *option = ':';
                return 1;
        }

        /* If we have an argument where we shouldn't have one, sulk */
        if ( ( longopt->has_arg == no_argument ) && argument ) {
                printf ( "Option \"%s\" takes no argument\n", longopt->name );
                *option = ':';
                return 1;
        }

        /* Store values and return success */
        optarg = ( char * ) argument;
        if ( longopt->flag ) {
                *(longopt->flag) = longopt->val;
                *option = 0;
        } else {
                *option = longopt->val;
        }
        return 1;
}

/**
 * Match short option
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @v opttext           Option text within current argv[] element
 * @v shortopt          Option character from option specification
 * @ret option          Option to return from getopt()
 * @ret matched         Found a match for this short option
 */
static int match_short_option ( int argc, char * const argv[],
                                const char *opttext, int shortopt,
                                enum getopt_argument_requirement has_arg,
                                int *option ) {
        const char *argument = NULL;

        /* Compare option character */
        if ( *opttext != shortopt )
                return 0;

        /* Consume option character */
        opttext++;
        nextchar++;
        if ( *opttext ) {
                if ( has_arg != no_argument ) {
                        /* Consume remainder of element as inline argument */
                        argument = opttext;
                        optind++;
                        nextchar = 0;
                }
        } else {
                /* Reached end of argv element */
                optind++;
                nextchar = 0;
        }

        /* If we want an argument but don't have one yet, try to grab
         * the next argv element
         */
        if ( ( has_arg != no_argument ) && ( ! argument ) )
                argument = get_argv_argument ( argc, argv );

        /* If we need an argument but don't have one, sulk */
        if ( ( has_arg == required_argument ) && ( ! argument ) ) {
                printf ( "Option \"%c\" requires an argument\n", shortopt );
                *option = ':';
                return 1;
        }

        /* Store values and return success */
        optarg = ( char * ) argument;
        *option = shortopt;
        return 1;
}

/**
 * Parse command-line options
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @v optstring         Option specification string
 * @v longopts          Long option specification table
 * @ret longindex       Index of long option (or NULL)
 * @ret option          Option found, or -1 for no more options
 *
 * Note that the caller must arrange for reset_getopt() to be called
 * before each set of calls to getopt_long().  In Etherboot, this is
 * done automatically by execv().
 */
int getopt_long ( int argc, char * const argv[], const char *optstring,
                  const struct option *longopts, int *longindex ) {
        const char *opttext = argv[optind];
        const struct option *longopt;
        int shortopt;
        enum getopt_argument_requirement has_arg;
        int option;

        /* Check for end of argv array */
        if ( optind >= argc )
                return -1;

        /* Check for end of options */
        if ( *(opttext++) != '-' )
                return -1;

        /* Check for long options */
        if ( *(opttext++) == '-' ) {
                for ( longopt = longopts ; longopt->name ; longopt++ ) {
                        if ( ! match_long_option ( argc, argv, opttext,
                                                   longopt, &option ) )
                                continue;
                        if ( longindex )
                                *longindex = ( longopt - longopts );
                        return option;
                }
                optopt = '?';
                printf ( "Unrecognised option \"--%s\"\n", opttext );
                return '?';
        }

        /* Check for short options */
        if ( nextchar < 1 )
                nextchar = 1;
        opttext = ( argv[optind] + nextchar );
        while ( ( shortopt = *(optstring++) ) ) {
                has_arg = no_argument;
                while ( *optstring == ':' ) {
                        has_arg++;
                        optstring++;
                }
                if ( match_short_option ( argc, argv, opttext, shortopt,
                                          has_arg, &option ) ) {
                        return option;
                }
        }
        optopt = *opttext;
        printf ( "Unrecognised option \"-%c\"\n", optopt );
        return '?';
}