libbb/getopt32.c - busybox - Git at Google

 /* vi: set sw=4 ts=4: */
 /*
  * universal getopt32 implementation for busybox
  *
  * Copyright (C) 2003-2005  Vladimir Oleynik  <dzo@simtreas.ru>
  *
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */

 #include <getopt.h>
 #include "libbb.h"

 /*      Documentation

 uint32_t
 getopt32(char **argv, const char *applet_opts, ...)

         The command line options must be declared in const char
         *applet_opts as a string of chars, for example:

         flags = getopt32(argv, "rnug");

         If one of the given options is found, a flag value is added to
         the return value (an unsigned long).

         The flag value is determined by the position of the char in
         applet_opts string.  For example, in the above case:

         flags = getopt32(argv, "rnug");

         "r" will add 1    (bit 0)
         "n" will add 2    (bit 1)
         "u" will add 4    (bit 2)
         "g" will add 8    (bit 3)

         and so on.  You can also look at the return value as a bit
         field and each option sets one bit.

         On exit, global variable optind is set so that if you
         will do argc -= optind; argv += optind; then
         argc will be equal to number of remaining non-option
         arguments, first one would be in argv[0], next in argv[1] and so on
         (options and their parameters will be moved into argv[]
         positions prior to argv[optind]).

  ":"    If one of the options requires an argument, then add a ":"
         after the char in applet_opts and provide a pointer to store
         the argument.  For example:

         char *pointer_to_arg_for_a;
         char *pointer_to_arg_for_b;
         char *pointer_to_arg_for_c;
         char *pointer_to_arg_for_d;

         flags = getopt32(argv, "a:b:c:d:",
                         &pointer_to_arg_for_a, &pointer_to_arg_for_b,
                         &pointer_to_arg_for_c, &pointer_to_arg_for_d);

         The type of the pointer (char* or llist_t*) may be controlled
         by the "::" special separator that is set in the external string
         opt_complementary (see below for more info).

  "::"   If option can have an *optional* argument, then add a "::"
         after its char in applet_opts and provide a pointer to store
         the argument.  Note that optional arguments _must_
         immediately follow the option: -oparam, not -o param.

  "+"    If the first character in the applet_opts string is a plus,
         then option processing will stop as soon as a non-option is
         encountered in the argv array.  Useful for applets like env
         which should not process arguments to subprograms:
         env -i ls -d /
         Here we want env to process just the '-i', not the '-d'.

 const char *applet_long_options

         This struct allows you to define long options:

         static const char applet_longopts[] ALIGN1 =
 		//"name\0" has_arg val
 		"verbose\0" No_argument "v"
 		;
         applet_long_options = applet_longopts;

         The last member of struct option (val) typically is set to
         matching short option from applet_opts. If there is no matching
         char in applet_opts, then:
         - return bit have next position after short options
         - if has_arg is not "No_argument", use ptr for arg also
         - opt_complementary affects it too

         Note: a good applet will make long options configurable via the
         config process and not a required feature.  The current standard
         is to name the config option CONFIG_FEATURE_<applet>_LONG_OPTIONS.

 const char *opt_complementary

  ":"    The colon (":") is used to separate groups of two or more chars
         and/or groups of chars and special characters (stating some
         conditions to be checked).

  "abc"  If groups of two or more chars are specified, the first char
         is the main option and the other chars are secondary options.
         Their flags will be turned on if the main option is found even
         if they are not specifed on the command line.  For example:

         opt_complementary = "abc";
         flags = getopt32(argv, "abcd")

         If getopt() finds "-a" on the command line, then
         getopt32's return value will be as if "-a -b -c" were
         found.

  "ww"   Adjacent double options have a counter associated which indicates
         the number of occurences of the option.
         For example the ps applet needs:
         if w is given once, GNU ps sets the width to 132,
         if w is given more than once, it is "unlimited"

         int w_counter = 0; // must be initialized!
         opt_complementary = "ww";
         getopt32(argv, "w", &w_counter);
         if (w_counter)
                 width = (w_counter == 1) ? 132 : INT_MAX;
         else
                 get_terminal_width(...&width...);

         w_counter is a pointer to an integer. It has to be passed to
         getopt32() after all other option argument sinks.

         For example: accept multiple -v to indicate the level of verbosity
         and for each -b optarg, add optarg to my_b. Finally, if b is given,
         turn off c and vice versa:

         llist_t *my_b = NULL;
         int verbose_level = 0;
         opt_complementary = "vv:b::b-c:c-b";
         f = getopt32(argv, "vb:c", &my_b, &verbose_level);
         if (f & 2)       // -c after -b unsets -b flag
                 while (my_b) dosomething_with(llist_pop(&my_b));
         if (my_b)        // but llist is stored if -b is specified
                 free_llist(my_b);
         if (verbose_level) printf("verbose level is %d\n", verbose_level);

 Special characters:

  "-"    A dash as the first char in a opt_complementary group forces
         all arguments to be treated as options, even if they have
         no leading dashes. Next char in this case can't be a digit (0-9),
         use ':' or end of line. For example:

         opt_complementary = "-:w-x:x-w";
         getopt32(argv, "wx");

         Allows any arguments to be given without a dash (./program w x)
         as well as with a dash (./program -x).

 	NB: getopt32() will leak a small amount of memory if you use
 	this option! Do not use it if there is a possibility of recursive
 	getopt32() calls.

  "--"   A double dash at the beginning of opt_complementary means the
         argv[1] string should always be treated as options, even if it isn't
         prefixed with a "-".  This is useful for special syntax in applets
         such as "ar" and "tar":
         tar xvf foo.tar

 	NB: getopt32() will leak a small amount of memory if you use
 	this option! Do not use it if there is a possibility of recursive
 	getopt32() calls.

  "-N"   A dash as the first char in a opt_complementary group followed
         by a single digit (0-9) means that at least N non-option
         arguments must be present on the command line

  "=N"   An equal sign as the first char in a opt_complementary group followed
         by a single digit (0-9) means that exactly N non-option
         arguments must be present on the command line

  "?N"   A "?" as the first char in a opt_complementary group followed
         by a single digit (0-9) means that at most N arguments must be present
         on the command line.

  "V-"   An option with dash before colon or end-of-line results in
         bb_show_usage() being called if this option is encountered.
         This is typically used to implement "print verbose usage message
         and exit" option.

  "a-b"  A dash between two options causes the second of the two
         to be unset (and ignored) if it is given on the command line.

         [FIXME: what if they are the same? like "x-x"? Is it ever useful?]

         For example:
         The du applet has the options "-s" and "-d depth".  If
         getopt32 finds -s, then -d is unset or if it finds -d
         then -s is unset.  (Note:  busybox implements the GNU
         "--max-depth" option as "-d".)  To obtain this behavior, you
         set opt_complementary = "s-d:d-s".  Only one flag value is
         added to getopt32's return value depending on the
         position of the options on the command line.  If one of the
         two options requires an argument pointer (":" in applet_opts
         as in "d:") optarg is set accordingly.

         char *smax_print_depth;

         opt_complementary = "s-d:d-s:x-x";
         opt = getopt32(argv, "sd:x", &smax_print_depth);

         if (opt & 2)
                 max_print_depth = atoi(smax_print_depth);
         if (opt & 4)
                 printf("Detected odd -x usage\n");

  "a--b" A double dash between two options, or between an option and a group
         of options, means that they are mutually exclusive.  Unlike
         the "-" case above, an error will be forced if the options
         are used together.

         For example:
         The cut applet must have only one type of list specified, so
         -b, -c and -f are mutually exclusive and should raise an error
         if specified together.  In this case you must set
         opt_complementary = "b--cf:c--bf:f--bc".  If two of the
         mutually exclusive options are found, getopt32 will call
 	bb_show_usage() and die.

  "x--x" Variation of the above, it means that -x option should occur
         at most once.

  "a+"   A plus after a char in opt_complementary means that the parameter
         for this option is a nonnegative integer. It will be processed
         with xatoi_u() - allowed range is 0..INT_MAX.

         int param;  // "unsigned param;" will also work
         opt_complementary = "p+";
         getopt32(argv, "p:", &param);

  "a::"  A double colon after a char in opt_complementary means that the
         option can occur multiple times. Each occurrence will be saved as
         a llist_t element instead of char*.

         For example:
         The grep applet can have one or more "-e pattern" arguments.
         In this case you should use getopt32() as follows:

         llist_t *patterns = NULL;

         (this pointer must be initializated to NULL if the list is empty
         as required by llist_add_to_end(llist_t **old_head, char *new_item).)

         opt_complementary = "e::";

         getopt32(argv, "e:", &patterns);
         $ grep -e user -e root /etc/passwd
         root:x:0:0:root:/root:/bin/bash
         user:x:500:500::/home/user:/bin/bash

  "a?b"  A "?" between an option and a group of options means that
         at least one of them is required to occur if the first option
         occurs in preceding command line arguments.

         For example from "id" applet:

         // Don't allow -n -r -rn -ug -rug -nug -rnug
         opt_complementary = "r?ug:n?ug:u--g:g--u";
         flags = getopt32(argv, "rnug");

         This example allowed only:
         $ id; id -u; id -g; id -ru; id -nu; id -rg; id -ng; id -rnu; id -rng

  "X"    A opt_complementary group with just a single letter means
         that this option is required. If more than one such group exists,
         at least one option is required to occur (not all of them).
         For example from "start-stop-daemon" applet:

         // Don't allow -KS -SK, but -S or -K is required
         opt_complementary = "K:S:K--S:S--K";
         flags = getopt32(argv, "KS...);


         Don't forget to use ':'. For example, "?322-22-23X-x-a"
         is interpreted as "?3:22:-2:2-2:2-3Xa:2--x" -
         max 3 args; count uses of '-2'; min 2 args; if there is
         a '-2' option then unset '-3', '-X' and '-a'; if there is
         a '-2' and after it a '-x' then error out.
         But it's far too obfuscated. Use ':' to separate groups.
 */

 /* Code here assumes that 'unsigned' is at least 32 bits wide */

 const char *const bb_argv_dash[] = { "-", NULL };

 const char *opt_complementary;

 enum {
 	PARAM_STRING,
 	PARAM_LIST,
 	PARAM_INT,
 };

 typedef struct {
 	unsigned char opt_char;
 	smallint param_type;
 	unsigned switch_on;
 	unsigned switch_off;
 	unsigned incongruously;
 	unsigned requires;
 	void **optarg;  /* char**, llist_t** or int *. */
 	int *counter;
 } t_complementary;

 /* You can set applet_long_options for parse called long options */
 #if ENABLE_GETOPT_LONG
 static const struct option bb_null_long_options[1] = {
 	{ 0, 0, 0, 0 }
 };
 const char *applet_long_options;
 #endif

 uint32_t option_mask32;

 uint32_t FAST_FUNC
 getopt32(char **argv, const char *applet_opts, ...)
 {
 	int argc;
 	unsigned flags = 0;
 	unsigned requires = 0;
 	t_complementary complementary[33]; /* last stays zero-filled */
 	int c;
 	const unsigned char *s;
 	t_complementary *on_off;
 	va_list p;
 #if ENABLE_GETOPT_LONG
 	const struct option *l_o;
 	struct option *long_options = (struct option *) &bb_null_long_options;
 #endif
 	unsigned trigger;
 	char **pargv;
 	int min_arg = 0;
 	int max_arg = -1;

 #define SHOW_USAGE_IF_ERROR     1
 #define ALL_ARGV_IS_OPTS        2
 #define FIRST_ARGV_IS_OPT       4

 	int spec_flgs = 0;

 	/* skip 0: some applets cheat: they do not actually HAVE argv[0] */
 	argc = 1;
 	while (argv[argc])
 		argc++;

 	va_start(p, applet_opts);

 	c = 0;
 	on_off = complementary;
 	memset(on_off, 0, sizeof(complementary));

 	/* skip GNU extension */
 	s = (const unsigned char *)applet_opts;
 	if (*s == '+' || *s == '-')
 		s++;
 	while (*s) {
 		if (c >= 32)
 			break;
 		on_off->opt_char = *s;
 		on_off->switch_on = (1 << c);
 		if (*++s == ':') {
 			on_off->optarg = va_arg(p, void **);
 			while (*++s == ':')
 				continue;
 		}
 		on_off++;
 		c++;
 	}

 #if ENABLE_GETOPT_LONG
 	if (applet_long_options) {
 		const char *optstr;
 		unsigned i, count;

 		count = 1;
 		optstr = applet_long_options;
 		while (optstr[0]) {
 			optstr += strlen(optstr) + 3; /* skip NUL, has_arg, val */
 			count++;
 		}
 		/* count == no. of longopts + 1 */
 		long_options = alloca(count * sizeof(*long_options));
 		memset(long_options, 0, count * sizeof(*long_options));
 		i = 0;
 		optstr = applet_long_options;
 		while (--count) {
 			long_options[i].name = optstr;
 			optstr += strlen(optstr) + 1;
 			long_options[i].has_arg = (unsigned char)(*optstr++);
 			/* long_options[i].flag = NULL; */
 			long_options[i].val = (unsigned char)(*optstr++);
 			i++;
 		}
 		for (l_o = long_options; l_o->name; l_o++) {
 			if (l_o->flag)
 				continue;
 			for (on_off = complementary; on_off->opt_char; on_off++)
 				if (on_off->opt_char == l_o->val)
 					goto next_long;
 			if (c >= 32)
 				break;
 			on_off->opt_char = l_o->val;
 			on_off->switch_on = (1 << c);
 			if (l_o->has_arg != no_argument)
 				on_off->optarg = va_arg(p, void **);
 			c++;
  next_long: ;
 		}
 	}
 #endif /* ENABLE_GETOPT_LONG */
 	for (s = (const unsigned char *)opt_complementary; s && *s; s++) {
 		t_complementary *pair;
 		unsigned *pair_switch;

 		if (*s == ':')
 			continue;
 		c = s[1];
 		if (*s == '?') {
 			if (c < '0' || c > '9') {
 				spec_flgs |= SHOW_USAGE_IF_ERROR;
 			} else {
 				max_arg = c - '0';
 				s++;
 			}
 			continue;
 		}
 		if (*s == '-') {
 			if (c < '0' || c > '9') {
 				if (c == '-') {
 					spec_flgs |= FIRST_ARGV_IS_OPT;
 					s++;
 				} else
 					spec_flgs |= ALL_ARGV_IS_OPTS;
 			} else {
 				min_arg = c - '0';
 				s++;
 			}
 			continue;
 		}
 		if (*s == '=') {
 			min_arg = max_arg = c - '0';
 			s++;
 			continue;
 		}
 		for (on_off = complementary; on_off->opt_char; on_off++)
 			if (on_off->opt_char == *s)
 				break;
 		if (c == ':' && s[2] == ':') {
 			on_off->param_type = PARAM_LIST;
 			continue;
 		}
 		if (c == '+' && (s[2] == ':' || s[2] == '\0')) {
 			on_off->param_type = PARAM_INT;
 			continue;
 		}
 		if (c == ':' || c == '\0') {
 			requires |= on_off->switch_on;
 			continue;
 		}
 		if (c == '-' && (s[2] == ':' || s[2] == '\0')) {
 			flags |= on_off->switch_on;
 			on_off->incongruously |= on_off->switch_on;
 			s++;
 			continue;
 		}
 		if (c == *s) {
 			on_off->counter = va_arg(p, int *);
 			s++;
 		}
 		pair = on_off;
 		pair_switch = &(pair->switch_on);
 		for (s++; *s && *s != ':'; s++) {
 			if (*s == '?') {
 				pair_switch = &(pair->requires);
 			} else if (*s == '-') {
 				if (pair_switch == &(pair->switch_off))
 					pair_switch = &(pair->incongruously);
 				else
 					pair_switch = &(pair->switch_off);
 			} else {
 				for (on_off = complementary; on_off->opt_char; on_off++)
 					if (on_off->opt_char == *s) {
 						*pair_switch |= on_off->switch_on;
 						break;
 					}
 			}
 		}
 		s--;
 	}
 	va_end(p);

 	if (spec_flgs & (FIRST_ARGV_IS_OPT | ALL_ARGV_IS_OPTS)) {
 		pargv = argv + 1;
 		while (*pargv) {
 			if (pargv[0][0] != '-' && pargv[0][0] != '\0') {
 				/* Can't use alloca: opts with params will
 				 * return pointers to stack!
 				 * NB: we leak these allocations... */
 				char *pp = xmalloc(strlen(*pargv) + 2);
 				*pp = '-';
 				strcpy(pp + 1, *pargv);
 				*pargv = pp;
 			}
 			if (!(spec_flgs & ALL_ARGV_IS_OPTS))
 				break;
 			pargv++;
 		}
 	}

 	/* In case getopt32 was already called:
 	 * reset the libc getopt() function, which keeps internal state.
 	 * run_nofork_applet_prime() does this, but we might end up here
 	 * also via gunzip_main() -> gzip_main(). Play safe.
 	 */
 #ifdef __GLIBC__
 	optind = 0;
 #else /* BSD style */
 	optind = 1;
 	/* optreset = 1; */
 #endif
 	/* optarg = NULL; opterr = 0; optopt = 0; - do we need this?? */

 	pargv = NULL;

 	/* Note: just "getopt() <= 0" will not work well for
 	 * "fake" short options, like this one:
 	 * wget $'-\203' "Test: test" http://kernel.org/
 	 * (supposed to act as --header, but doesn't) */
 #if ENABLE_GETOPT_LONG
 	while ((c = getopt_long(argc, argv, applet_opts,
 			long_options, NULL)) != -1) {
 #else
 	while ((c = getopt(argc, argv, applet_opts)) != -1) {
 #endif
 		/* getopt prints "option requires an argument -- X"
 		 * and returns '?' if an option has no arg, but one is reqd */
 		c &= 0xff; /* fight libc's sign extension */
 		for (on_off = complementary; on_off->opt_char != c; on_off++) {
 			/* c can be NUL if long opt has non-NULL ->flag,
 			 * but we construct long opts so that flag
 			 * is always NULL (see above) */
 			if (on_off->opt_char == '\0' /* && c != '\0' */) {
 				/* c is probably '?' - "bad option" */
 				bb_show_usage();
 			}
 		}
 		if (flags & on_off->incongruously)
 			bb_show_usage();
 		trigger = on_off->switch_on & on_off->switch_off;
 		flags &= ~(on_off->switch_off ^ trigger);
 		flags |= on_off->switch_on ^ trigger;
 		flags ^= trigger;
 		if (on_off->counter)
 			(*(on_off->counter))++;
 		if (on_off->param_type == PARAM_LIST) {
 			if (optarg)
 				llist_add_to_end((llist_t **)(on_off->optarg), optarg);
 		} else if (on_off->param_type == PARAM_INT) {
 			if (optarg)
 //TODO: xatoi_u indirectly pulls in printf machinery
 				*(unsigned*)(on_off->optarg) = xatoi_u(optarg);
 		} else if (on_off->optarg) {
 			if (optarg)
 				*(char **)(on_off->optarg) = optarg;
 		}
 		if (pargv != NULL)
 			break;
 	}

 	/* check depending requires for given options */
 	for (on_off = complementary; on_off->opt_char; on_off++) {
 		if (on_off->requires && (flags & on_off->switch_on) &&
 					(flags & on_off->requires) == 0)
 			bb_show_usage();
 	}
 	if (requires && (flags & requires) == 0)
 		bb_show_usage();
 	argc -= optind;
 	if (argc < min_arg || (max_arg >= 0 && argc > max_arg))
 		bb_show_usage();

 	option_mask32 = flags;
 	return flags;
 }
	/* vi: set sw=4 ts=4: */
	/*
	* universal getopt32 implementation for busybox
	*
	* Copyright (C) 2003-2005 Vladimir Oleynik <dzo@simtreas.ru>
	*
	* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
	*/

	#include <getopt.h>
	#include "libbb.h"

	/* Documentation

	uint32_t
	getopt32(char *argv, const char applet_opts, ...)

	The command line options must be declared in const char
	*applet_opts as a string of chars, for example:

	flags = getopt32(argv, "rnug");

	If one of the given options is found, a flag value is added to
	the return value (an unsigned long).

	The flag value is determined by the position of the char in
	applet_opts string. For example, in the above case:

	flags = getopt32(argv, "rnug");

	"r" will add 1 (bit 0)
	"n" will add 2 (bit 1)
	"u" will add 4 (bit 2)
	"g" will add 8 (bit 3)

	and so on. You can also look at the return value as a bit
	field and each option sets one bit.

	On exit, global variable optind is set so that if you
	will do argc -= optind; argv += optind; then
	argc will be equal to number of remaining non-option
	arguments, first one would be in argv[0], next in argv[1] and so on
	(options and their parameters will be moved into argv[]
	positions prior to argv[optind]).

	":" If one of the options requires an argument, then add a ":"
	after the char in applet_opts and provide a pointer to store
	the argument. For example:

	char *pointer_to_arg_for_a;
	char *pointer_to_arg_for_b;
	char *pointer_to_arg_for_c;
	char *pointer_to_arg_for_d;

	flags = getopt32(argv, "a:b:c:d:",
	&pointer_to_arg_for_a, &pointer_to_arg_for_b,
	&pointer_to_arg_for_c, &pointer_to_arg_for_d);

	The type of the pointer (char* or llist_t*) may be controlled
	by the "::" special separator that is set in the external string
	opt_complementary (see below for more info).

	"::" If option can have an optional argument, then add a "::"
	after its char in applet_opts and provide a pointer to store
	the argument. Note that optional arguments _must_
	immediately follow the option: -oparam, not -o param.

	"+" If the first character in the applet_opts string is a plus,
	then option processing will stop as soon as a non-option is
	encountered in the argv array. Useful for applets like env
	which should not process arguments to subprograms:
	env -i ls -d /
	Here we want env to process just the '-i', not the '-d'.

	const char *applet_long_options

	This struct allows you to define long options:

	static const char applet_longopts[] ALIGN1 =
	//"name\0" has_arg val
	"verbose\0" No_argument "v"
	;
	applet_long_options = applet_longopts;

	The last member of struct option (val) typically is set to
	matching short option from applet_opts. If there is no matching
	char in applet_opts, then:
	- return bit have next position after short options
	- if has_arg is not "No_argument", use ptr for arg also
	- opt_complementary affects it too

	Note: a good applet will make long options configurable via the
	config process and not a required feature. The current standard
	is to name the config option CONFIG_FEATURE_<applet>_LONG_OPTIONS.

	const char *opt_complementary

	":" The colon (":") is used to separate groups of two or more chars
	and/or groups of chars and special characters (stating some
	conditions to be checked).

	"abc" If groups of two or more chars are specified, the first char
	is the main option and the other chars are secondary options.
	Their flags will be turned on if the main option is found even
	if they are not specifed on the command line. For example:

	opt_complementary = "abc";
	flags = getopt32(argv, "abcd")

	If getopt() finds "-a" on the command line, then
	getopt32's return value will be as if "-a -b -c" were
	found.

	"ww" Adjacent double options have a counter associated which indicates
	the number of occurences of the option.
	For example the ps applet needs:
	if w is given once, GNU ps sets the width to 132,
	if w is given more than once, it is "unlimited"

	int w_counter = 0; // must be initialized!
	opt_complementary = "ww";
	getopt32(argv, "w", &w_counter);
	if (w_counter)
	width = (w_counter == 1) ? 132 : INT_MAX;
	else
	get_terminal_width(...&width...);

	w_counter is a pointer to an integer. It has to be passed to
	getopt32() after all other option argument sinks.

	For example: accept multiple -v to indicate the level of verbosity
	and for each -b optarg, add optarg to my_b. Finally, if b is given,
	turn off c and vice versa:

	llist_t *my_b = NULL;
	int verbose_level = 0;
	opt_complementary = "vv:b::b-c:c-b";
	f = getopt32(argv, "vb:c", &my_b, &verbose_level);
	if (f & 2) // -c after -b unsets -b flag
	while (my_b) dosomething_with(llist_pop(&my_b));
	if (my_b) // but llist is stored if -b is specified
	free_llist(my_b);
	if (verbose_level) printf("verbose level is %d\n", verbose_level);

	Special characters:

	"-" A dash as the first char in a opt_complementary group forces
	all arguments to be treated as options, even if they have
	no leading dashes. Next char in this case can't be a digit (0-9),
	use ':' or end of line. For example:

	opt_complementary = "-:w-x:x-w";
	getopt32(argv, "wx");

	Allows any arguments to be given without a dash (./program w x)
	as well as with a dash (./program -x).

	NB: getopt32() will leak a small amount of memory if you use
	this option! Do not use it if there is a possibility of recursive
	getopt32() calls.

	"--" A double dash at the beginning of opt_complementary means the
	argv[1] string should always be treated as options, even if it isn't
	prefixed with a "-". This is useful for special syntax in applets
	such as "ar" and "tar":
	tar xvf foo.tar

	NB: getopt32() will leak a small amount of memory if you use
	this option! Do not use it if there is a possibility of recursive
	getopt32() calls.

	"-N" A dash as the first char in a opt_complementary group followed
	by a single digit (0-9) means that at least N non-option
	arguments must be present on the command line

	"=N" An equal sign as the first char in a opt_complementary group followed
	by a single digit (0-9) means that exactly N non-option
	arguments must be present on the command line

	"?N" A "?" as the first char in a opt_complementary group followed
	by a single digit (0-9) means that at most N arguments must be present
	on the command line.

	"V-" An option with dash before colon or end-of-line results in
	bb_show_usage() being called if this option is encountered.
	This is typically used to implement "print verbose usage message
	and exit" option.

	"a-b" A dash between two options causes the second of the two
	to be unset (and ignored) if it is given on the command line.

	[FIXME: what if they are the same? like "x-x"? Is it ever useful?]

	For example:
	The du applet has the options "-s" and "-d depth". If
	getopt32 finds -s, then -d is unset or if it finds -d
	then -s is unset. (Note: busybox implements the GNU
	"--max-depth" option as "-d".) To obtain this behavior, you
	set opt_complementary = "s-d:d-s". Only one flag value is
	added to getopt32's return value depending on the
	position of the options on the command line. If one of the
	two options requires an argument pointer (":" in applet_opts
	as in "d:") optarg is set accordingly.

	char *smax_print_depth;

	opt_complementary = "s-d:d-s:x-x";
	opt = getopt32(argv, "sd:x", &smax_print_depth);

	if (opt & 2)
	max_print_depth = atoi(smax_print_depth);
	if (opt & 4)
	printf("Detected odd -x usage\n");

	"a--b" A double dash between two options, or between an option and a group
	of options, means that they are mutually exclusive. Unlike
	the "-" case above, an error will be forced if the options
	are used together.

	For example:
	The cut applet must have only one type of list specified, so
	-b, -c and -f are mutually exclusive and should raise an error
	if specified together. In this case you must set
	opt_complementary = "b--cf:c--bf:f--bc". If two of the
	mutually exclusive options are found, getopt32 will call
	bb_show_usage() and die.

	"x--x" Variation of the above, it means that -x option should occur
	at most once.

	"a+" A plus after a char in opt_complementary means that the parameter
	for this option is a nonnegative integer. It will be processed
	with xatoi_u() - allowed range is 0..INT_MAX.

	int param; // "unsigned param;" will also work
	opt_complementary = "p+";
	getopt32(argv, "p:", &param);

	"a::" A double colon after a char in opt_complementary means that the
	option can occur multiple times. Each occurrence will be saved as
	a llist_t element instead of char*.

	For example:
	The grep applet can have one or more "-e pattern" arguments.
	In this case you should use getopt32() as follows:

	llist_t *patterns = NULL;

	(this pointer must be initializated to NULL if the list is empty
	as required by llist_add_to_end(llist_t *old_head, char new_item).)

	opt_complementary = "e::";

	getopt32(argv, "e:", &patterns);
	$ grep -e user -e root /etc/passwd
	root:x:0:0:root:/root:/bin/bash
	user:x:500:500::/home/user:/bin/bash

	"a?b" A "?" between an option and a group of options means that
	at least one of them is required to occur if the first option
	occurs in preceding command line arguments.

	For example from "id" applet:

	// Don't allow -n -r -rn -ug -rug -nug -rnug
	opt_complementary = "r?ug:n?ug:u--g:g--u";
	flags = getopt32(argv, "rnug");

	This example allowed only:
	$ id; id -u; id -g; id -ru; id -nu; id -rg; id -ng; id -rnu; id -rng

	"X" A opt_complementary group with just a single letter means
	that this option is required. If more than one such group exists,
	at least one option is required to occur (not all of them).
	For example from "start-stop-daemon" applet:

	// Don't allow -KS -SK, but -S or -K is required
	opt_complementary = "K:S:K--S:S--K";
	flags = getopt32(argv, "KS...);


	Don't forget to use ':'. For example, "?322-22-23X-x-a"
	is interpreted as "?3:22:-2:2-2:2-3Xa:2--x" -
	max 3 args; count uses of '-2'; min 2 args; if there is
	a '-2' option then unset '-3', '-X' and '-a'; if there is
	a '-2' and after it a '-x' then error out.
	But it's far too obfuscated. Use ':' to separate groups.
	*/

	/* Code here assumes that 'unsigned' is at least 32 bits wide */

	const char *const bb_argv_dash[] = { "-", NULL };

	const char *opt_complementary;

	enum {
	PARAM_STRING,
	PARAM_LIST,
	PARAM_INT,
	};

	typedef struct {
	unsigned char opt_char;
	smallint param_type;
	unsigned switch_on;
	unsigned switch_off;
	unsigned incongruously;
	unsigned requires;
	void *optarg; / char, llist_t or int . /
	int *counter;
	} t_complementary;

	/* You can set applet_long_options for parse called long options */
	#if ENABLE_GETOPT_LONG
	static const struct option bb_null_long_options[1] = {
	{ 0, 0, 0, 0 }
	};
	const char *applet_long_options;
	#endif

	uint32_t option_mask32;

	uint32_t FAST_FUNC
	getopt32(char *argv, const char applet_opts, ...)
	{
	int argc;
	unsigned flags = 0;
	unsigned requires = 0;
	t_complementary complementary[33]; /* last stays zero-filled */
	int c;
	const unsigned char *s;
	t_complementary *on_off;
	va_list p;
	#if ENABLE_GETOPT_LONG
	const struct option *l_o;
	struct option long_options = (struct option ) &bb_null_long_options;
	#endif
	unsigned trigger;
	char **pargv;
	int min_arg = 0;
	int max_arg = -1;

	#define SHOW_USAGE_IF_ERROR 1
	#define ALL_ARGV_IS_OPTS 2
	#define FIRST_ARGV_IS_OPT 4

	int spec_flgs = 0;

	/* skip 0: some applets cheat: they do not actually HAVE argv[0] */
	argc = 1;
	while (argv[argc])
	argc++;

	va_start(p, applet_opts);

	c = 0;
	on_off = complementary;
	memset(on_off, 0, sizeof(complementary));

	/* skip GNU extension */
	s = (const unsigned char *)applet_opts;
	if (s == '+' \|\| s == '-')
	s++;
	while (*s) {
	if (c >= 32)
	break;
	on_off->opt_char = *s;
	on_off->switch_on = (1 << c);
	if (*++s == ':') {
	on_off->optarg = va_arg(p, void **);
	while (*++s == ':')
	continue;
	}
	on_off++;
	c++;
	}

	#if ENABLE_GETOPT_LONG
	if (applet_long_options) {
	const char *optstr;
	unsigned i, count;

	count = 1;
	optstr = applet_long_options;
	while (optstr[0]) {
	optstr += strlen(optstr) + 3; /* skip NUL, has_arg, val */
	count++;
	}
	/* count == no. of longopts + 1 */
	long_options = alloca(count * sizeof(*long_options));
	memset(long_options, 0, count * sizeof(*long_options));
	i = 0;
	optstr = applet_long_options;
	while (--count) {
	long_options[i].name = optstr;
	optstr += strlen(optstr) + 1;
	long_options[i].has_arg = (unsigned char)(*optstr++);
	/* long_options[i].flag = NULL; */
	long_options[i].val = (unsigned char)(*optstr++);
	i++;
	}
	for (l_o = long_options; l_o->name; l_o++) {
	if (l_o->flag)
	continue;
	for (on_off = complementary; on_off->opt_char; on_off++)
	if (on_off->opt_char == l_o->val)
	goto next_long;
	if (c >= 32)
	break;
	on_off->opt_char = l_o->val;
	on_off->switch_on = (1 << c);
	if (l_o->has_arg != no_argument)
	on_off->optarg = va_arg(p, void **);
	c++;
	next_long: ;
	}
	}
	#endif /* ENABLE_GETOPT_LONG */
	for (s = (const unsigned char )opt_complementary; s && s; s++) {
	t_complementary *pair;
	unsigned *pair_switch;

	if (*s == ':')
	continue;
	c = s[1];
	if (*s == '?') {
	if (c < '0' \|\| c > '9') {
	spec_flgs \|= SHOW_USAGE_IF_ERROR;
	} else {
	max_arg = c - '0';
	s++;
	}
	continue;
	}
	if (*s == '-') {
	if (c < '0' \|\| c > '9') {
	if (c == '-') {
	spec_flgs \|= FIRST_ARGV_IS_OPT;
	s++;
	} else
	spec_flgs \|= ALL_ARGV_IS_OPTS;
	} else {
	min_arg = c - '0';
	s++;
	}
	continue;
	}
	if (*s == '=') {
	min_arg = max_arg = c - '0';
	s++;
	continue;
	}
	for (on_off = complementary; on_off->opt_char; on_off++)
	if (on_off->opt_char == *s)
	break;
	if (c == ':' && s[2] == ':') {
	on_off->param_type = PARAM_LIST;
	continue;
	}
	if (c == '+' && (s[2] == ':' \|\| s[2] == '\0')) {
	on_off->param_type = PARAM_INT;
	continue;
	}
	if (c == ':' \|\| c == '\0') {
	requires \|= on_off->switch_on;
	continue;
	}
	if (c == '-' && (s[2] == ':' \|\| s[2] == '\0')) {
	flags \|= on_off->switch_on;
	on_off->incongruously \|= on_off->switch_on;
	s++;
	continue;
	}
	if (c == *s) {
	on_off->counter = va_arg(p, int *);
	s++;
	}
	pair = on_off;
	pair_switch = &(pair->switch_on);
	for (s++; s && s != ':'; s++) {
	if (*s == '?') {
	pair_switch = &(pair->requires);
	} else if (*s == '-') {
	if (pair_switch == &(pair->switch_off))
	pair_switch = &(pair->incongruously);
	else
	pair_switch = &(pair->switch_off);
	} else {
	for (on_off = complementary; on_off->opt_char; on_off++)
	if (on_off->opt_char == *s) {
	*pair_switch \|= on_off->switch_on;
	break;
	}
	}
	}
	s--;
	}
	va_end(p);

	if (spec_flgs & (FIRST_ARGV_IS_OPT \| ALL_ARGV_IS_OPTS)) {
	pargv = argv + 1;
	while (*pargv) {
	if (pargv[0][0] != '-' && pargv[0][0] != '\0') {
	/* Can't use alloca: opts with params will
	* return pointers to stack!
	* NB: we leak these allocations... */
	char pp = xmalloc(strlen(pargv) + 2);
	*pp = '-';
	strcpy(pp + 1, *pargv);
	*pargv = pp;
	}
	if (!(spec_flgs & ALL_ARGV_IS_OPTS))
	break;
	pargv++;
	}
	}

	/* In case getopt32 was already called:
	* reset the libc getopt() function, which keeps internal state.
	* run_nofork_applet_prime() does this, but we might end up here
	* also via gunzip_main() -> gzip_main(). Play safe.
	*/
	#ifdef __GLIBC__
	optind = 0;
	#else /* BSD style */
	optind = 1;
	/* optreset = 1; */
	#endif
	/* optarg = NULL; opterr = 0; optopt = 0; - do we need this?? */

	pargv = NULL;

	/* Note: just "getopt() <= 0" will not work well for
	* "fake" short options, like this one:
	* wget $'-\203' "Test: test" http://kernel.org/
	* (supposed to act as --header, but doesn't) */
	#if ENABLE_GETOPT_LONG
	while ((c = getopt_long(argc, argv, applet_opts,
	long_options, NULL)) != -1) {
	#else
	while ((c = getopt(argc, argv, applet_opts)) != -1) {
	#endif
	/* getopt prints "option requires an argument -- X"
	* and returns '?' if an option has no arg, but one is reqd */
	c &= 0xff; /* fight libc's sign extension */
	for (on_off = complementary; on_off->opt_char != c; on_off++) {
	/* c can be NUL if long opt has non-NULL ->flag,
	* but we construct long opts so that flag
	* is always NULL (see above) */
	if (on_off->opt_char == '\0' /* && c != '\0' */) {
	/* c is probably '?' - "bad option" */
	bb_show_usage();
	}
	}
	if (flags & on_off->incongruously)
	bb_show_usage();
	trigger = on_off->switch_on & on_off->switch_off;
	flags &= ~(on_off->switch_off ^ trigger);
	flags \|= on_off->switch_on ^ trigger;
	flags ^= trigger;
	if (on_off->counter)
	(*(on_off->counter))++;
	if (on_off->param_type == PARAM_LIST) {
	if (optarg)
	llist_add_to_end((llist_t **)(on_off->optarg), optarg);
	} else if (on_off->param_type == PARAM_INT) {
	if (optarg)
	//TODO: xatoi_u indirectly pulls in printf machinery
	(unsigned)(on_off->optarg) = xatoi_u(optarg);
	} else if (on_off->optarg) {
	if (optarg)
	(char *)(on_off->optarg) = optarg;
	}
	if (pargv != NULL)
	break;
	}

	/* check depending requires for given options */
	for (on_off = complementary; on_off->opt_char; on_off++) {
	if (on_off->requires && (flags & on_off->switch_on) &&
	(flags & on_off->requires) == 0)
	bb_show_usage();
	}
	if (requires && (flags & requires) == 0)
	bb_show_usage();
	argc -= optind;
	if (argc < min_arg \|\| (max_arg >= 0 && argc > max_arg))
	bb_show_usage();

	option_mask32 = flags;
	return flags;
	}