path: root/argp/argp.h

/* Hierarchical argument parsing, layered over getopt.
   Copyright (C) 1995-2025 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Written by Miles Bader <miles@gnu.ai.mit.edu>.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef _ARGP_H
#define _ARGP_H

#include <stdio.h>
#include <ctype.h>
#include <getopt.h>
#include <limits.h>
#include <errno.h>

__BEGIN_DECLS

/* error_t may or may not be available from errno.h, depending on the
   operating system.  */
#ifndef __error_t_defined
# define __error_t_defined 1
typedef int error_t;
#endif

/* A description of a particular option.  A pointer to an array of
   these is passed in the OPTIONS field of an argp structure.  Each option
   entry can correspond to one long option and/or one short option; more
   names for the same option can be added by following an entry in an option
   array with options having the OPTION_ALIAS flag set.  */
struct argp_option
{
  /* The long option name.  For more than one name for the same option, you
     can use following options with the OPTION_ALIAS flag set.  */
  const char *name;

  /* What key is returned for this option.  If > 0 and printable, then it's
     also accepted as a short option.  */
  int key;

  /* If non-NULL, this is the name of the argument associated with this
     option, which is required unless the OPTION_ARG_OPTIONAL flag is set. */
  const char *arg;

  /* OPTION_ flags.  */
  int flags;

  /* The doc string for this option.  If both NAME and KEY are 0, This string
     will be printed outdented from the normal option column, making it
     useful as a group header (it will be the first thing printed in its
     group); in this usage, it's conventional to end the string with a `:'.  */
  const char *doc;

  /* The group this option is in.  In a long help message, options are sorted
     alphabetically within each group, and the groups presented in the order
     0, 1, 2, ..., n, -m, ..., -2, -1.  Every entry in an options array with
     if this field 0 will inherit the group number of the previous entry, or
     zero if it's the first one, unless its a group header (NAME and KEY both
     0), in which case, the previous entry + 1 is the default.  Automagic
     options such as --help are put into group -1.  */
  int group;
};

/* The argument associated with this option is optional.  */
#define OPTION_ARG_OPTIONAL	0x1

/* This option isn't displayed in any help messages.  */
#define OPTION_HIDDEN	       	0x2

/* This option is an alias for the closest previous non-alias option.  This
   means that it will be displayed in the same help entry, and will inherit
   fields other than NAME and KEY from the aliased option.  */
#define OPTION_ALIAS		0x4

/* This option isn't actually an option (and so should be ignored by the
   actual option parser), but rather an arbitrary piece of documentation that
   should be displayed in much the same manner as the options.  If this flag
   is set, then the option NAME field is displayed unmodified (e.g., no `--'
   prefix is added) at the left-margin (where a *short* option would normally
   be displayed), and the documentation string in the normal place.  For
   purposes of sorting, any leading whitespace and punctuation is ignored,
   except that if the first non-whitespace character is not `-', this entry
   is displayed after all options (and OPTION_DOC entries with a leading `-')
   in the same group.  */
#define OPTION_DOC		0x8

/* This option shouldn't be included in `long' usage messages (but is still
   included in help messages).  This is mainly intended for options that are
   completely documented in an argp's ARGS_DOC field, in which case including
   the option in the generic usage list would be redundant.  For instance,
   if ARGS_DOC is "FOO BAR\n-x BLAH", and the `-x' option's purpose is to
   distinguish these two cases, -x should probably be marked
   OPTION_NO_USAGE.  */
#define OPTION_NO_USAGE		0x10

struct argp;			/* fwd declare this type */
struct argp_state;		/* " */
struct argp_child;		/* " */

/* The type of a pointer to an argp parsing function.  */
typedef error_t (*argp_parser_t) (int __key, char *__arg,
				  struct argp_state *__state);

/* What to return for unrecognized keys.  For special ARGP_KEY_ keys, such
   returns will simply be ignored.  For user keys, this error will be turned
   into EINVAL (if the call to argp_parse is such that errors are propagated
   back to the user instead of exiting); returning EINVAL itself would result
   in an immediate stop to parsing in *all* cases.  */
#define ARGP_ERR_UNKNOWN	E2BIG /* Hurd should never need E2BIG.  XXX */

/* Special values for the KEY argument to an argument parsing function.
   ARGP_ERR_UNKNOWN should be returned if they aren't understood.

   The sequence of keys to a parsing function is either (where each
   uppercased word should be prefixed by `ARGP_KEY_' and opt is a user key):

       INIT opt... NO_ARGS END SUCCESS  -- No non-option arguments at all
   or  INIT (opt | ARG)... END SUCCESS  -- All non-option args parsed
   or  INIT (opt | ARG)... SUCCESS      -- Some non-option arg unrecognized

   The third case is where every parser returned ARGP_KEY_UNKNOWN for an
   argument, in which case parsing stops at that argument (returning the
   unparsed arguments to the caller of argp_parse if requested, or stopping
   with an error message if not).

   If an error occurs (either detected by argp, or because the parsing
   function returned an error value), then the parser is called with
   ARGP_KEY_ERROR, and no further calls are made.  */

/* This is not an option at all, but rather a command line argument.  If a
   parser receiving this key returns success, the fact is recorded, and the
   ARGP_KEY_NO_ARGS case won't be used.  HOWEVER, if while processing the
   argument, a parser function decrements the NEXT field of the state it's
   passed, the option won't be considered processed; this is to allow you to
   actually modify the argument (perhaps into an option), and have it
   processed again.  */
#define ARGP_KEY_ARG		0
/* There are remaining arguments not parsed by any parser, which may be found
   starting at (STATE->argv + STATE->next).  If success is returned, but
   STATE->next left untouched, it's assumed that all arguments were consume,
   otherwise, the parser should adjust STATE->next to reflect any arguments
   consumed.  */
#define ARGP_KEY_ARGS		0x1000006
/* There are no more command line arguments at all.  */
#define ARGP_KEY_END		0x1000001
/* Because it's common to want to do some special processing if there aren't
   any non-option args, user parsers are called with this key if they didn't
   successfully process any non-option arguments.  Called just before
   ARGP_KEY_END (where more general validity checks on previously parsed
   arguments can take place).  */
#define ARGP_KEY_NO_ARGS	0x1000002
/* Passed in before any parsing is done.  Afterwards, the values of each
   element of the CHILD_INPUT field, if any, in the state structure is
   copied to each child's state to be the initial value of the INPUT field.  */
#define ARGP_KEY_INIT		0x1000003
/* Use after all other keys, including SUCCESS & END.  */
#define ARGP_KEY_FINI		0x1000007
/* Passed in when parsing has successfully been completed (even if there are
   still arguments remaining).  */
#define ARGP_KEY_SUCCESS	0x1000004
/* Passed in if an error occurs.  */
#define ARGP_KEY_ERROR		0x1000005

/* An argp structure contains a set of options declarations, a function to
   deal with parsing one, documentation string, a possible vector of child
   argp's, and perhaps a function to filter help output.  When actually
   parsing options, getopt is called with the union of all the argp
   structures chained together through their CHILD pointers, with conflicts
   being resolved in favor of the first occurrence in the chain.  */
struct argp
{
  /* An array of argp_option structures, terminated by an entry with both
     NAME and KEY having a value of 0.  */
  const struct argp_option *options;

  /* What to do with an option from this structure.  KEY is the key
     associated with the option, and ARG is any associated argument (NULL if
     none was supplied).  If KEY isn't understood, ARGP_ERR_UNKNOWN should be
     returned.  If a non-zero, non-ARGP_ERR_UNKNOWN value is returned, then
     parsing is stopped immediately, and that value is returned from
     argp_parse().  For special (non-user-supplied) values of KEY, see the
     ARGP_KEY_ definitions below.  */
  argp_parser_t parser;

  /* A string describing what other arguments are wanted by this program.  It
     is only used by argp_usage to print the `Usage:' message.  If it
     contains newlines, the strings separated by them are considered
     alternative usage patterns, and printed on separate lines (lines after
     the first are prefix by `  or: ' instead of `Usage:').  */
  const char *args_doc;

  /* If non-NULL, a string containing extra text to be printed before and
     after the options in a long help message (separated by a vertical tab
     `\v' character).  */
  const char *doc;

  /* A vector of argp_children structures, terminated by a member with a 0
     argp field, pointing to child argps should be parsed with this one.  Any
     conflicts are resolved in favor of this argp, or early argps in the
     CHILDREN list.  This field is useful if you use libraries that supply
     their own argp structure, which you want to use in conjunction with your
     own.  */
  const struct argp_child *children;

  /* If non-zero, this should be a function to filter the output of help
     messages.  KEY is either a key from an option, in which case TEXT is
     that option's help text, or a special key from the ARGP_KEY_HELP_
     defines, below, describing which other help text TEXT is.  The function
     should return either TEXT, if it should be used as-is, a replacement
     string, which should be malloced, and will be freed by argp, or NULL,
     meaning `print nothing'.  The value for TEXT is *after* any translat