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fuse_opt.h

/*
    FUSE: Filesystem in Userspace
    Copyright (C) 2001-2006  Miklos Szeredi <miklos@szeredi.hu>

    This file is borrowed from sshfs-fuse. It provides an implementation
    of the FUSE command line parsing functions which only appear in
    later version of FUSE but are used in afuse.
    
    This file can be distributed under the terms of the GNU LGPL.
    See the file COPYING.LIB
*/

#ifndef _FUSE_OPT_H_
#define _FUSE_OPT_H_

/* This file defines the option parsing interface of FUSE */

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Option description
 *
 * This structure describes a single option, and and action associated
 * with it, in case it matches.
 *
 * More than one such match may occur, in which case the action for
 * each match is executed.
 *
 * There are three possible actions in case of a match:
 *
 * i) An integer (int or unsigned) variable determined by 'offset' is
 *    set to 'value'
 *
 * ii) The processing function is called, with 'value' as the key
 *
 * iii) An integer (any) or string (char *) variable determined by
 *    'offset' is set to the value of an option parameter
 *
 * 'offset' should normally be either set to
 *
 *  - 'offsetof(struct foo, member)'  actions i) and iii)
 *
 *  - -1                              action ii)
 *
 * The 'offsetof()' macro is defined in the <stddef.h> header.
 *
 * The template determines which options match, and also have an
 * effect on the action.  Normally the action is either i) or ii), but
 * if a format is present in the template, then action iii) is
 * performed.
 *
 * The types of templates are:
 *
 * 1) "-x", "-foo", "--foo", "--foo-bar", etc.  These match only
 *   themselves.  Invalid values are "--" and anything beginning
 *   with "-o"
 *
 * 2) "foo", "foo-bar", etc.  These match "-ofoo", "-ofoo-bar" or
 *    the relevant option in a comma separated option list
 *
 * 3) "bar=", "--foo=", etc.  These are variations of 1) and 2)
 *    which have a parameter
 *
 * 4) "bar=%s", "--foo=%lu", etc.  Same matching as above but perform
 *    action iii).
 *
 * 5) "-x ", etc.  Matches either "-xparam" or "-x param" as
 *    two separate arguments
 *
 * 6) "-x %s", etc.  Combination of 4) and 5)
 *
 * If the format is "%s", memory is allocated for the string unlike
 * with scanf().
 */
00077 struct fuse_opt {
    /** Matching template and optional parameter formatting */
00079     const char *template;

    /**
     * Offset of variable within 'data' parameter of fuse_opt_parse()
     * or -1
     */
00085     unsigned long offset;

    /**
     * Value to set the variable to, or to be passed as 'key' to the
     * processing function.  Ignored if template a format
     */
00091     int value;
};

/**
 * Key option.  In case of a match, the processing function will be
 * called with the specified key.
 */
#define FUSE_OPT_KEY(template, key) { template, -1U, key }

/**
 * Last option.  An array of 'struct fuse_opt' must end with a NULL
 * template value
 */
#define FUSE_OPT_END { .template = NULL }

/**
 * Argument list
 */
00109 struct fuse_args {
    /** Argument count */
00111     int argc;

    /** Argument vector.  NULL terminated */
00114     char **argv;

    /** Is 'argv' allocated? */
00117     int allocated;
};

/**
 * Initializer for 'struct fuse_args'
 */
#define FUSE_ARGS_INIT(argc, argv) { argc, argv, 0 }

/**
 * Key value passed to the processing function if an option did not
 * match any templated
 */
#define FUSE_OPT_KEY_OPT     -1

/**
 * Key value passed to the processing function for all non-options
 *
 * Non-options are the arguments beginning with a charater other than
 * '-' or all arguments after the special '--' option
 */
#define FUSE_OPT_KEY_NONOPT  -2

/**
 * Processing function
 *
 * This function is called if
 *    - option did not match any 'struct fuse_opt'
 *    - argument is a non-option
 *    - option did match and offset was set to -1
 *
 * The 'arg' parameter will always contain the whole argument or
 * option including the parameter if exists.  A two-argument option
 * ("-x foo") is always converted to single arguemnt option of the
 * form "-xfoo" before this function is called.
 *
 * Options of the form '-ofoo' are passed to this function without the
 * '-o' prefix.
 *
 * The return value of this function determines whether this argument
 * is to be inserted into the output argument vector, or discarded.
 *
 * @param data is the user data passed to the fuse_opt_parse() function
 * @param arg is the whole argument or option
 * @param key determines why the processing function was called
 * @param outargs the current output argument list
 * @return -1 on error, 0 if arg is to be discarded, 1 if arg should be kept
 */
typedef int (*fuse_opt_proc_t)(void *data, const char *arg, int key,
                               struct fuse_args *outargs);

/**
 * Option parsing function
 *
 * If 'args' was returned from a previous call to fuse_opt_parse() or
 * it was constructed from
 *
 * A NULL 'args' is equivalent to an empty argument vector
 *
 * A NULL 'opts' is equivalent to an 'opts' array containing a single
 * end marker
 *
 * A NULL 'proc' is equivalent to a processing function always
 * returning '1'
 *
 * @param args is the input and output argument list
 * @param data is the user data
 * @param opts is the option description array
 * @param proc is the processing function
 * @return -1 on error, 0 on success
 */
int fuse_opt_parse(struct fuse_args *args, void *data,
                   const struct fuse_opt opts[], fuse_opt_proc_t proc);

/**
 * Add an option to a comma separated option list
 *
 * @param opts is a pointer to an option list, may point to a NULL value
 * @param opt is the option to add
 * @return -1 on allocation error, 0 on success
 */
int fuse_opt_add_opt(char **opts, const char *opt);

/**
 * Add an argument to a NULL terminated argument vector
 *
 * @param args is the structure containing the current argument list
 * @param arg is the new argument to add
 * @return -1 on allocation error, 0 on success
 */
int fuse_opt_add_arg(struct fuse_args *args, const char *arg);

/**
 * Free the contents of argument list
 *
 * The structure itself is not freed
 *
 * @param args is the structure containing the argument list
 */
void fuse_opt_free_args(struct fuse_args *args);


/**
 * Check if an option matches
 *
 * @param opts is the option description array
 * @param opt is the option to match
 * @return 1 if a match is found, 0 if not
 */
int fuse_opt_match(const struct fuse_opt opts[], const char *opt);

#ifdef __cplusplus
}
#endif

#endif /* _FUSE_OPT_H_ */

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