ALL_OPT(3) LAM INTERNALS ALL_OPT(3)NAME
all_opt - general purpose command-line options parsing (LAM)
SYNOPSIS
#include <all_opt.h>
char *ao_argv0(OPT *aod);
OPT *ao_init(void);
char *ao_chosen(OPT *od, const char *opt);
void ao_free(OPT *od);
int ao_intparam(OPT *od, const char *opt,
int inst, int idx, int *inum);
int ao_ninsts(OPT *od, const char *opt);
int ao_nparams(OPT *od, const char *opt, int inst);
int ao_ntaken(OPT *od);
char *ao_param(OPT *od, const char *opt, int inst, int idx);
int ao_parse(OPT *od, int *argc, char **argv);
int ao_setflags(OPT *aod, int flags);
int ao_setopt(OPT *od, const char *opt,
const char *mutex, int nparams, int flags);
int ao_setopt1(OPT *od, const char *opt,
const char *mutex, int nparams, int flags);
int ao_tail(OPT *od, int *tailc, char ***tailv);
int ao_taken(OPT *od, const char *opt);
int ao_unused(OPT *aod, int *unusedc, char ***unusedv);
DESCRIPTION
The all_opt package provides general purpose command-line option pars‐
ing. It parses multi-letter option strings with varying numbers of
parameters and invocations. Options can be made mandatory as well as
grouped into mutually exclusive sets. all_opt can handle multiple com‐
mand-line parsing invocations by maintaining a separate option descrip‐
tor for each one.
An option descriptor is created and initialized by the ao_init() func‐
tion. It returns a pointer to a new descriptor, typedef OPT (defined
in <all_opt.h>). This descriptor pointer is used as the first argument
to all the other functions. When no longer needed, a descriptor can be
destroyed by calling ao_free().
Once a descriptor is created, the user declares each valid command-line
option string by calling ao_setopt(). The function's arguments are:
ad, the option descriptor; opt, the option string being declared;
mutex, an option string in the set of mutually exclusive options (or
NULL if not used); nparams, the number of parameters expected to follow
this option (or AOVARNUM if variable); and flags, a bit-mapped field of
flags controlling other characteristics of the option. The flags value
is constructed by ORing flags from the following list:
AOINT All arguments following the option are integers.
AOMUST The option is mandatory and must be taken. If the option is
part of a mutually exclusive set, all options in the set must
also have this flag set.
ao_setopt1() is a convenience function that interprets the opt argument
as a string of single letter options and calls ao_setopt() for each
letter with the other arguments given.
The option string "#" is reserved to represent the special case of the
"-#" option (i.e. a dash followed by an integer). The integer can be
either decimal, octal, or hexadecimal. This option implies that the
AOINT flag is set and that the nparams argument is 1.
Optional flags may be set on the descriptor with ao_setflags(). Cur‐
rently, the only flag that is supported is:
AOPRESERVE_ARGV
When this flag is set, the argc and argv that are passed into
ao_parse() (see below) are not modified. Instead, a copy is
made of argv and its results are stored internally in the
descriptor. All operations are then performed on that inter‐
nal copy. Using this flag also enables the use of the
ao_unused() function, which will return the unused tokens
after parsing (i.e., tokens that were not recognized options
and were not part of the tail).
After all valid options are declared, the command line arguments are
parsed by calling ao_parse(). The argc and argv parameters are those
passed to main(). Note that argc is passed by reference. Option
strings in the command-line (prefixed with the dash character '-') and
any parameters following them, are parsed and deleted from the argc,
argv structure, leaving in it any additional strings that are neither
options nor parameters. Options can be invoked multiple times,
ao_parse() maintains a count of these instances as well as potential
parameters for each option. A "--" argument notifies ao_parse() to
avoid processing the arguments that follow it. These unprocessed argu‐
ments at the tail end of the command-line can be retrieved by calling
ao_tail(). ao_parse() checks the command-line for invalid options and
parameters, and verifies that mutual exclusion is satisfied and manda‐
tory options are taken. Once the command-line options are parsed, the
user can make queries to check which options were actually taken and
what parameters were supplied.
Option Queries
The function ao_ntaken() returns the number of options taken, i.e. that
appeared on the command-line. ao_taken() checks if the given option
opt was taken, returning 1 (true) or 0 (false). The ao_chosen() func‐
tion simplifies the task of locating the single option taken in a mutu‐
ally exclusive set. The set is identified by setting opt to any of
member options in it. ao_chosen() returns the option taken or NULL if
none was chosen.
ao_ninsts() returns the number of times (instances) an option was
invoked on the command-line. This number can be helpful if an option
accepts parameters. It allows the user to request the different param‐
eters of each instance. Instances are numbered sequentially starting
with 0. If the option accepts a variable number of parameters,
ao_nparams() returns the number of parameters provided for an option's
given instance number inst. Parameters are identified by sequential
index values starting with 0. If the option takes integer parameters,
ao_intparam() can be used to retrieve a specific parameter given its
instance number inst and its index value idx. The parameter is
returned by reference in the inum variable. If the option parameters
are strings, ao_param() is used to return a specific parameter given
its instance and index values.
The tail end of the command-line, formed by all arguments to the right
of the "--" special option, can be retrieved by calling IR ao_tail() .
The tail is returned in the standard argc, argv format through the
tailc and tailv parameters passed by reference.
EXAMPLE
The following example code demonstrates how all_opt can be used to
parse command-lines. The hypothetical tool accepts two mutually exclu‐
sive options: "foo", "bar". The "foo" option requires 2 string parame‐
ters and can only be invoked once. For simplicity, error checking is
not done.
#include <all_opt.h>
main(int argc, char *argv[])
{
OPT *ad;
char *opt;
ad = ao_init();
ao_setopt(ad, "foo", NULL, 2, 0);
ao_setopt(ad, "bar", "foo", 0, 0);
ao_parse(ad, &argc, argv);
opt = ao_chosen(ad, "foo");
if (strcmp(opt, "foo") == 0) {
if (ao_ninsts(ad, "foo") > 1) { /* error */ }
printf("foo chosen: %s %s\n",
ao_param(ad, "foo", 0, 0),
ao_param(ad, "foo", 0, 1));
} else {
printf("bar taken %d times\n",
ao_ninsts(ad, "bar"));
}
ao_free(ad);
}
RETURN VALUES
In case of an error, ao_init() returns a NULL descriptor, ao_chosen()
and ao_param() return NULL strings, and ao_intparam(), ao_parse(),
ao_setopt(), ao_setopt1(), and ao_tail() return -1. In addition, the
global variable errno is set to indicate the error.
ERRORS
EUSAGE The command-line violates the option rules.
EBADASCIINUMB A string representing an integer has an invalid format.
LAM 7.1.2 March, 2006 ALL_OPT(3)