/*-

 * Copyright (c) 2003-2008 Tim Kientzle

 * 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.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``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(S) 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.

 */

/*

 * Command line parser for tar.

 */

#include "bsdcat_platform.h"

__FBSDID("$FreeBSD$");

#ifdef HAVE_ERRNO_H

#include <errno.h>

#endif

#ifdef HAVE_STDLIB_H

#include <stdlib.h>

#endif

#ifdef HAVE_STRING_H

#include <string.h>

#endif

#include "bsdcat.h"

#include "err.h"

/*

 * Short options for tar.  Please keep this sorted.

 */

static const char *short_options = "h";

/*

 * Long options for tar.  Please keep this list sorted.

 *

 * The symbolic names for options that lack a short equivalent are

 * defined in bsdcat.h.  Also note that so far I've found no need

 * to support optional arguments to long options.  That would be

 * a small change to the code below.

 */

static const struct bsdcat_option {

	const char *name;

	int required;      /* 1 if this option requires an argument. */

	int equivalent;    /* Equivalent short option. */

} tar_longopts[] = {

	{ "help",                 0, 'h' },

	{ "version",              0, OPTION_VERSION },

	{ NULL, 0, 0 }

};

/*

 * This getopt implementation has two key features that common

 * getopt_long() implementations lack.  Apart from those, it's a

 * straightforward option parser, considerably simplified by not

 * needing to support the wealth of exotic getopt_long() features.  It

 * has, of course, been shamelessly tailored for bsdcat.  (If you're

 * looking for a generic getopt_long() implementation for your

 * project, I recommend Gregory Pietsch's public domain getopt_long()

 * implementation.)  The two additional features are:

 *

 * Old-style tar arguments: The original tar implementation treated

 * the first argument word as a list of single-character option

 * letters.  All arguments follow as separate words.  For example,

 *    tar xbf 32 /dev/tape

 * Here, the "xbf" is three option letters, "32" is the argument for

 * "b" and "/dev/tape" is the argument for "f".  We support this usage

 * if the first command-line argument does not begin with '-'.  We

 * also allow regular short and long options to follow, e.g.,

 *    tar xbf 32 /dev/tape -P --format=pax

 *

 * -W long options: There's an obscure GNU convention (only rarely

 * supported even there) that allows "-W option=argument" as an

 * alternative way to support long options.  This was supported in

 * early bsdcat as a way to access long options on platforms that did

 * not support getopt_long() and is preserved here for backwards

 * compatibility.  (Of course, if I'd started with a custom

 * command-line parser from the beginning, I would have had normal

 * long option support on every platform so that hack wouldn't have

 * been necessary.  Oh, well.  Some mistakes you just have to live

 * with.)

 *

 * TODO: We should be able to use this to pull files and intermingled

 * options (such as -C) from the command line in write mode.  That

 * will require a little rethinking of the argument handling in

 * bsdcat.c.

 *

 * TODO: If we want to support arbitrary command-line options from -T

 * input (as GNU tar does), we may need to extend this to handle option

 * words from sources other than argv/argc.  I'm not really sure if I

 * like that feature of GNU tar, so it's certainly not a priority.

 */

int

bsdcat_getopt(struct bsdcat *bsdcat)

{

	enum { state_start = 0, state_old_tar, state_next_word,

	       state_short, state_long };

	const struct bsdcat_option *popt, *match = NULL, *match2 = NULL;

	const char *p, *long_prefix = "--";

	size_t optlength;

	int opt = '?';

	int required = 0;

	bsdcat->argument = NULL;

	/* First time through, initialize everything. */

	if (bsdcat->getopt_state == state_start) {

		/* Skip program name. */

		++bsdcat->argv;

		--bsdcat->argc;

		if (*bsdcat->argv == NULL)

			return (-1);

		/* Decide between "new style" and "old style" arguments. */

		bsdcat->getopt_state = state_next_word;

	}

	/*

	 * We're ready to look at the next word in argv.

	 */

	if (bsdcat->getopt_state == state_next_word) {

		/* No more arguments, so no more options. */

		if (bsdcat->argv[0] == NULL)

			return (-1);

		/* Doesn't start with '-', so no more options. */

		if (bsdcat->argv[0][0] != '-')

			return (-1);

		/* "--" marks end of options; consume it and return. */

		if (strcmp(bsdcat->argv[0], "--") == 0) {

			++bsdcat->argv;

			--bsdcat->argc;

			return (-1);

		}

		/* Get next word for parsing. */

		bsdcat->getopt_word = *bsdcat->argv++;

		--bsdcat->argc;

		if (bsdcat->getopt_word[1] == '-') {

			/* Set up long option parser. */

			bsdcat->getopt_state = state_long;

			bsdcat->getopt_word += 2; /* Skip leading '--' */

		} else {

			/* Set up short option parser. */

			bsdcat->getopt_state = state_short;

			++bsdcat->getopt_word;  /* Skip leading '-' */

		}

	}

	/*

	 * We're parsing a group of POSIX-style single-character options.

	 */

	if (bsdcat->getopt_state == state_short) {

		/* Peel next option off of a group of short options. */

		opt = *bsdcat->getopt_word++;

		if (opt == '\0') {

			/* End of this group; recurse to get next option. */

			bsdcat->getopt_state = state_next_word;

			return bsdcat_getopt(bsdcat);

		}

		/* Does this option take an argument? */

		p = strchr(short_options, opt);

		if (p == NULL)

			return ('?');

		if (p[1] == ':')

			required = 1;

		/* If it takes an argument, parse that. */

		if (required) {

			/* If arg is run-in, bsdcat->getopt_word already points to it. */

			if (bsdcat->getopt_word[0] == '\0') {

				/* Otherwise, pick up the next word. */

				bsdcat->getopt_word = *bsdcat->argv;

				if (bsdcat->getopt_word == NULL) {

					lafe_warnc(0,

					    "Option -%c requires an argument",

					    opt);

					return ('?');

				}

				++bsdcat->argv;

				--bsdcat->argc;

			}

			if (opt == 'W') {

				bsdcat->getopt_state = state_long;

				long_prefix = "-W "; /* For clearer errors. */

			} else {

				bsdcat->getopt_state = state_next_word;

				bsdcat->argument = bsdcat->getopt_word;

			}

		}

	}

	/* We're reading a long option, including -W long=arg convention. */

	if (bsdcat->getopt_state == state_long) {

		/* After this long option, we'll be starting a new word. */

		bsdcat->getopt_state = state_next_word;

		/* Option name ends at '=' if there is one. */

		p = strchr(bsdcat->getopt_word, '=');

		if (p != NULL) {

			optlength = (size_t)(p - bsdcat->getopt_word);

			bsdcat->argument = (char *)(uintptr_t)(p + 1);

		} else {

			optlength = strlen(bsdcat->getopt_word);

		}

		/* Search the table for an unambiguous match. */

		for (popt = tar_longopts; popt->name != NULL; popt++) {

			/* Short-circuit if first chars don't match. */

			if (popt->name[0] != bsdcat->getopt_word[0])

				continue;

			/* If option is a prefix of name in table, record it.*/

			if (strncmp(bsdcat->getopt_word, popt->name, optlength) == 0) {

				match2 = match; /* Record up to two matches. */

				match = popt;

				/* If it's an exact match, we're done. */

				if (strlen(popt->name) == optlength) {

					match2 = NULL; /* Forget the others. */

					break;

				}

			}

		}

		/* Fail if there wasn't a unique match. */

		if (match == NULL) {

			lafe_warnc(0,

			    "Option %s%s is not supported",

			    long_prefix, bsdcat->getopt_word);

			return ('?');

		}

		if (match2 != NULL) {

			lafe_warnc(0,

			    "Ambiguous option %s%s (matches --%s and --%s)",

			    long_prefix, bsdcat->getopt_word, match->name, match2->name);

			return ('?');

		}

		/* We've found a unique match; does it need an argument? */

		if (match->required) {

			/* Argument required: get next word if necessary. */

			if (bsdcat->argument == NULL) {

				bsdcat->argument = *bsdcat->argv;

				if (bsdcat->argument == NULL) {

					lafe_warnc(0,

					    "Option %s%s requires an argument",

					    long_prefix, match->name);

					return ('?');

				}

				++bsdcat->argv;

				--bsdcat->argc;

			}

		} else {

			/* Argument forbidden: fail if there is one. */

			if (bsdcat->argument != NULL) {

				lafe_warnc(0,

				    "Option %s%s does not allow an argument",

				    long_prefix, match->name);

				return ('?');

			}

		}

		return (match->equivalent);

	}

	return (opt);

}