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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * getopt.h - a simple getopt(3) implementation.
4 *
5 * Copyright (C) 2020 Sean Anderson <seanga2@gmail.com>
6 * Copyright (c) 2007 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
7 */
8
9#ifndef __GETOPT_H
10#define __GETOPT_H
11
12#include <stdbool.h>
13
14/**
15 * struct getopt_state - Saved state across getopt() calls
16 */
17struct getopt_state {
18 /**
19 * @index: Index of the next unparsed argument of @argv. If getopt() has
20 * parsed all of @argv, then @index will equal @argc.
21 */
22 int index;
23 /** @arg_index: Index within the current argument */
24 int arg_index;
25 union {
26 /**
27 * @opt: Option being parsed when an error occurs. @opt is only
28 * valid when getopt() returns ``?`` or ``:``.
29 */
30 int opt;
31 /**
32 * @arg: The argument to an option, NULL if there is none. @arg
33 * is only valid when getopt() returns an option character.
34 */
35 char *arg;
36 };
37};
38
39/**
40 * getopt_init_state() - Initialize a &struct getopt_state
41 * @gs: The state to initialize
42 *
43 * This must be called before using @gs with getopt().
44 */
45void getopt_init_state(struct getopt_state *gs);
46
47int __getopt(struct getopt_state *gs, int argc, char *const argv[],
48 const char *optstring, bool silent);
49
50/**
51 * getopt() - Parse short command-line options
52 * @gs: Internal state and out-of-band return arguments. This must be
53 * initialized with getopt_init_context() beforehand.
54 * @argc: Number of arguments, not including the %NULL terminator
55 * @argv: Argument list, terminated by %NULL
56 * @optstring: Option specification, as described below
57 *
58 * getopt() parses short options. Short options are single characters. They may
59 * be followed by a required argument or an optional argument. Arguments to
60 * options may occur in the same argument as an option (like ``-larg``), or
61 * in the following argument (like ``-l arg``). An argument containing
62 * options begins with a ``-``. If an option expects no arguments, then it may
63 * be immediately followed by another option (like ``ls -alR``).
64 *
65 * @optstring is a list of accepted options. If an option is followed by ``:``
66 * in @optstring, then it expects a mandatory argument. If an option is followed
67 * by ``::`` in @optstring, it expects an optional argument. @gs.arg points
68 * to the argument, if one is parsed.
69 *
70 * getopt() stops parsing options when it encounters the first non-option
71 * argument, when it encounters the argument ``--``, or when it runs out of
72 * arguments. For example, in ``ls -l foo -R``, option parsing will stop when
73 * getopt() encounters ``foo``, if ``l`` does not expect an argument. However,
74 * the whole list of arguments would be parsed if ``l`` expects an argument.
75 *
76 * An example invocation of getopt() might look like::
77 *
78 * char *argv[] = { "program", "-cbx", "-a", "foo", "bar", 0 };
79 * int opt, argc = ARRAY_SIZE(argv) - 1;
80 * struct getopt_state gs;
81 *
82 * getopt_init_state(&gs);
83 * while ((opt = getopt(&gs, argc, argv, "a::b:c")) != -1)
84 * printf("opt = %c, index = %d, arg = \"%s\"\n", opt, gs.index, gs.arg);
85 * printf("%d argument(s) left\n", argc - gs.index);
86 *
87 * and would produce an output of::
88 *
89 * opt = c, index = 1, arg = "<NULL>"
90 * opt = b, index = 2, arg = "x"
91 * opt = a, index = 4, arg = "foo"
92 * 1 argument(s) left
93 *
94 * For further information, refer to the getopt(3) man page.
95 *
96 * Return:
97 * * An option character if an option is found. @gs.arg is set to the
98 * argument if there is one, otherwise it is set to ``NULL``.
99 * * ``-1`` if there are no more options, if a non-option argument is
100 * encountered, or if an ``--`` argument is encountered.
101 * * ``'?'`` if we encounter an option not in @optstring. @gs.opt is set to
102 * the unknown option.
103 * * ``':'`` if an argument is required, but no argument follows the
104 * option. @gs.opt is set to the option missing its argument.
105 *
106 * @gs.index is always set to the index of the next unparsed argument in @argv.
107 */
108static inline int getopt(struct getopt_state *gs, int argc,
109 char *const argv[], const char *optstring)
110{
111 return __getopt(gs, argc, argv, optstring, false);
112}
113
114/**
115 * getopt_silent() - Parse short command-line options silently
116 * @gs: State
117 * @argc: Argument count
118 * @argv: Argument list
119 * @optstring: Option specification
120 *
121 * Same as getopt(), except no error messages are printed.
122 */
123static inline int getopt_silent(struct getopt_state *gs, int argc,
124 char *const argv[], const char *optstring)
125{
126 return __getopt(gs, argc, argv, optstring, true);
127}
128
129#endif /* __GETOPT_H */