1 /* Argp example #3 -- a program with options and arguments using argp
2 Copyright (C) 1991-2023 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or
5 modify it under the terms of the GNU General Public License
6 as published by the Free Software Foundation; either version 2
7 of the License, or (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, see <https://www.gnu.org/licenses/>.
16 */
17
18 /* This program uses the same features as example 2, and uses options and
19 arguments.
20
21 We now use the first four fields in ARGP, so here's a description of them:
22 OPTIONS -- A pointer to a vector of struct argp_option (see below)
23 PARSER -- A function to parse a single option, called by argp
24 ARGS_DOC -- A string describing how the non-option arguments should look
25 DOC -- A descriptive string about this program; if it contains a
26 vertical tab character (\v), the part after it will be
27 printed *following* the options
28
29 The function PARSER takes the following arguments:
30 KEY -- An integer specifying which option this is (taken
31 from the KEY field in each struct argp_option), or
32 a special key specifying something else; the only
33 special keys we use here are ARGP_KEY_ARG, meaning
34 a non-option argument, and ARGP_KEY_END, meaning
35 that all arguments have been parsed
36 ARG -- For an option KEY, the string value of its
37 argument, or NULL if it has none
38 STATE-- A pointer to a struct argp_state, containing
39 various useful information about the parsing state; used here
40 are the INPUT field, which reflects the INPUT argument to
41 argp_parse, and the ARG_NUM field, which is the number of the
42 current non-option argument being parsed
43 It should return either 0, meaning success, ARGP_ERR_UNKNOWN, meaning the
44 given KEY wasn't recognized, or an errno value indicating some other
45 error.
46
47 Note that in this example, main uses a structure to communicate with the
48 parse_opt function, a pointer to which it passes in the INPUT argument to
49 argp_parse. Of course, it's also possible to use global variables
50 instead, but this is somewhat more flexible.
51
52 The OPTIONS field contains a pointer to a vector of struct argp_option's;
53 that structure has the following fields (if you assign your option
54 structures using array initialization like this example, unspecified
55 fields will be defaulted to 0, and need not be specified):
56 NAME -- The name of this option's long option (may be zero)
57 KEY -- The KEY to pass to the PARSER function when parsing this option,
58 *and* the name of this option's short option, if it is a
59 printable ascii character
60 ARG -- The name of this option's argument, if any
61 FLAGS -- Flags describing this option; some of them are:
62 OPTION_ARG_OPTIONAL -- The argument to this option is optional
63 OPTION_ALIAS -- This option is an alias for the
64 previous option
65 OPTION_HIDDEN -- Don't show this option in --help output
66 DOC -- A documentation string for this option, shown in --help output
67
68 An options vector should be terminated by an option with all fields zero. */
69
70 #include <stdlib.h>
71 #include <argp.h>
72
73 const char *argp_program_version =
74 "argp-ex3 1.0";
75 const char *argp_program_bug_address =
76 "<bug-gnu-utils@@gnu.org>";
77
78 /* Program documentation. */
79 static char doc[] =
80 "Argp example #3 -- a program with options and arguments using argp";
81
82 /* A description of the arguments we accept. */
83 static char args_doc[] = "ARG1 ARG2";
84
85 /* The options we understand. */
86 static struct argp_option options[] = {
87 {"verbose", 'v', 0, 0, "Produce verbose output" },
88 {"quiet", 'q', 0, 0, "Don't produce any output" },
89 {"silent", 's', 0, OPTION_ALIAS },
90 {"output", 'o', "FILE", 0,
91 "Output to FILE instead of standard output" },
92 { 0 }
93 };
94
95 /* Used by @code{main} to communicate with @code{parse_opt}. */
96 struct arguments
97 {
98 char *args[2]; /* @var{arg1} & @var{arg2} */
99 int silent, verbose;
100 char *output_file;
101 };
102
103 /* Parse a single option. */
104 static error_t
105 parse_opt (int key, char *arg, struct argp_state *state)
106 {
107 /* Get the @var{input} argument from @code{argp_parse}, which we
108 know is a pointer to our arguments structure. */
109 struct arguments *arguments = state->input;
110
111 switch (key)
112 {
113 case 'q': case 's':
114 arguments->silent = 1;
115 break;
116 case 'v':
117 arguments->verbose = 1;
118 break;
119 case 'o':
120 arguments->output_file = arg;
121 break;
122
123 case ARGP_KEY_ARG:
124 if (state->arg_num >= 2)
125 /* Too many arguments. */
126 argp_usage (state);
127
128 arguments->args[state->arg_num] = arg;
129
130 break;
131
132 case ARGP_KEY_END:
133 if (state->arg_num < 2)
134 /* Not enough arguments. */
135 argp_usage (state);
136 break;
137
138 default:
139 return ARGP_ERR_UNKNOWN;
140 }
141 return 0;
142 }
143
144 /* Our argp parser. */
145 static struct argp argp = { options, parse_opt, args_doc, doc };
146
147 int
148 main (int argc, char **argv)
149 {
150 struct arguments arguments;
151
152 /* Default values. */
153 arguments.silent = 0;
154 arguments.verbose = 0;
155 arguments.output_file = "-";
156
157 /* Parse our arguments; every option seen by @code{parse_opt} will
158 be reflected in @code{arguments}. */
159 argp_parse (&argp, argc, argv, 0, 0, &arguments);
160
161 printf ("ARG1 = %s\nARG2 = %s\nOUTPUT_FILE = %s\n"
162 "VERBOSE = %s\nSILENT = %s\n",
163 arguments.args[0], arguments.args[1],
164 arguments.output_file,
165 arguments.verbose ? "yes" : "no",
166 arguments.silent ? "yes" : "no");
167
168 exit (0);
169 }