Function fz_getopt_long 

pub unsafe extern "C" fn fz_getopt_long(
    nargc: c_int,
    nargv: *const *mut c_char,
    ostr: *const c_char,
    longopts: *const fz_getopt_long_options,
) -> c_int

Simple functions/variables for use in tools.

ostr = option string. Comprises single letter options, followed by : if there
is an argument to the option.

longopts: NULL (indicating no long options), or a pointer to an array of
longoptions, terminated by an entry with option == NULL.

In the event of matching a single char option, this function will normally
return the char. The exception to this is when the option requires an
argument and none is supplied; in this case we return ‘:’.

In the event of matching a long option, this function returns 0, with fz_optlong
set to point to the matching option.

A long option entry may be followed with : to indicate there is an argument to the
option. If the need for an argument is specified in this way, and no argument is
given, an error will be displayed and argument processing will stop. If an argument
is given, and the long option record contains a non-null flag pointer, then the code
will decode the argument and fill in that flag pointer. Specifically,
case-insensitive matches to ‘yes’, ‘no’, ‘true’ and ‘false’ will cause a value of 0
or 1 as appropriate to be written; failing this the arg will be interpreted as a
decimal integer using atoi.

A long option entry may be followed by an list of options (e.g. myoption=foo|bar|baz)
and the option will be passed to fz_opt_from_list. The return value of that will be
placed in fz_optitem. If the return value of that function is -1, then an error will
be displayed and argument processing will stop.

In the event of reaching the end of the arg list or ‘–’, this function returns EOF.

In the event of failing to match anything, an error is printed, and we return ‘?’.

If an argument is expected for the option, then fz_optarg will be returned pointing
at the start of the argument. Examples of supported argument formats: ‘-r500’, ‘-r 500’,
‘–resolution 500’, ‘–resolution=500’.