Re: getopt reinvocation/reentrancy

[Gregory Pietsch <gpietsch at comcast dot net>]

I tried to add the reentrant functions to the getopt implementation. 
Please check it out and if it's okay, patch away. -- Gregory Pietsch

Joel Sherrill wrote:
> Hi,
>
> We have been working on the RTEMS Shell and
> I noticed something that I don't know how to
> properly deal with.  I am sure it is beyond
> the requirements of opengroup.
>
> RTEMS applications are usually a single statically
> linked executable so there can only be one main.
> So we have main's for each command (e.g. main_cat(),
> main_cp(), main_cpuuse(), etc.).  Each main_XXX
> is passed an argc, argv set and may use getopt()
> to interpret it.
>
> The problem is that newlib's getopt() uses global
> variables to hold state as the arguments are parsed.
> That is the crux of the reentrancy issue.
>
> If you invoke getopt() to parse a second set of
> options, the state information on the second set
> is left over from the end of parsing the first set.
>
> In the case I discovered this, I was doing this:
>
> netstats -c -u -i
> netstats -t
>
> On the second netstats invocation, the state pointed
> passed the end of the set of arguments so nothing
> was parsed.
>
> I am looking for suggestions on how to enhance
> getopt to support this type of usage.  I do not
> see getopt_r in /usr/include on Fedora 8 but Google
> shows that glibc had this type of functionality at
> one point.  I think the minimum requirement is a
> parallel set of getoptXXX_r with a state variable that
> can be initialized by the user.
>
> I also noticed that stdlib/getopt.c has multiple
> public API functions in it.  Should these be broken
> out?  I know they are individually small but....
>
> Any thoughts?

/****************************************************************************

getopt.c - Read command line options

AUTHOR: Gregory Pietsch
CREATED Fri Jan 10 21:13:05 1997

DESCRIPTION:

The getopt() function parses the command line arguments.  Its arguments argc
and argv are the argument count and array as passed to the main() function
on program invocation.  The argument optstring is a list of available option
characters.  If such a character is followed by a colon (`:'), the option
takes an argument, which is placed in optarg.  If such a character is
followed by two colons, the option takes an optional argument, which is
placed in optarg.  If the option does not take an argument, optarg is NULL.

The external variable optind is the index of the next array element of argv
to be processed; it communicates from one call to the next which element to
process.

The getopt_long() function works like getopt() except that it also accepts
long options started by two dashes `--'.  If these take values, it is either
in the form

--arg=value

 or

--arg value

It takes the additional arguments longopts which is a pointer to the first
element of an array of type struct option.  The last element of the array
has to be filled with NULL for the name field.

The longind pointer points to the index of the current long option relative
to longopts if it is non-NULL.

The getopt() function returns the option character if the option was found
successfully, `:' if there was a missing parameter for one of the options,
`?' for an unknown option character, and EOF for the end of the option list.

The getopt_long() function's return value is described in the header file.

The function getopt_long_only() is identical to getopt_long(), except that a
plus sign `+' can introduce long options as well as `--'.

The following describes how to deal with options that follow non-option
argv-elements.

If the caller did not specify anything, the default is REQUIRE_ORDER if the
environment variable POSIXLY_CORRECT is defined, PERMUTE otherwise.

REQUIRE_ORDER means don't recognize them as options; stop option processing
when the first non-option is seen.  This is what Unix does.  This mode of
operation is selected by either setting the environment variable
POSIXLY_CORRECT, or using `+' as the first character of the optstring
parameter.

PERMUTE is the default.  We permute the contents of ARGV as we scan, so that
eventually all the non-options are at the end.  This allows options to be
given in any order, even with programs that were not written to expect this.

RETURN_IN_ORDER is an option available to programs that were written to
expect options and other argv-elements in any order and that care about the
ordering of the two.  We describe each non-option argv-element as if it were
the argument of an option with character code 1.  Using `-' as the first
character of the optstring parameter selects this mode of operation.

The special argument `--' forces an end of option-scanning regardless of the
value of ordering.  In the case of RETURN_IN_ORDER, only `--' can cause
getopt() and friends to return EOF with optind != argc.

COPYRIGHT NOTICE AND DISCLAIMER:

Copyright (C) 1997 Gregory Pietsch

This file and the accompanying getopt.h header file are hereby placed in the 
public domain without restrictions.  Just give the author credit, don't
claim you wrote it or prevent anyone else from using it.

Gregory Pietsch's current e-mail address:
gpietsch@comcast.net
****************************************************************************/


/* include files */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>

/* macros */

/* types */
typedef enum GETOPT_ORDERING_T
{
  PERMUTE,
  RETURN_IN_ORDER,
  REQUIRE_ORDER
} GETOPT_ORDERING_T;

/* globally-defined variables */
char *optarg = 0;
int optind = 0;
int opterr = 1;
int optopt = '?';

/* static variables */
static int optwhere = 0;

/* functions */

/* reverse_argv_elements:  reverses num elements starting at argv */
static void
reverse_argv_elements (char **argv, int num)
{
  int i;
  char *tmp;

  for (i = 0; i < (num >> 1); i++)
    {
      tmp = argv[i];
      argv[i] = argv[num - i - 1];
      argv[num - i - 1] = tmp;
    }
}

/* permute: swap two blocks of argv-elements given their lengths */
static void
permute (char *const argv[], int len1, int len2)
{
  reverse_argv_elements ((char **) argv, len1);
  reverse_argv_elements ((char **) argv, len1 + len2);
  reverse_argv_elements ((char **) argv, len2);
}

/* is_option: is this argv-element an option or the end of the option list? */
static int
is_option (char *argv_element, int only)
{
  return ((argv_element == 0)
	  || (argv_element[0] == '-') || (only && argv_element[0] == '+'));
}

/* read_globals: read the values from the globals into a getopt_data 
   structure */
static void
read_globals (struct getopt_data *data)
{
  data->optarg = optarg;
  data->optind = optind;
  data->opterr = opterr;
  data->optopt = optopt;
  data->optwhere = optwhere;
}

/* write_globals: write the values into the globals from a getopt_data
   structure */
static void
write_globals (struct getopt_data *data)
{
  optarg = data->optarg;
  optind = data->optind;
  opterr = data->opterr;
  optopt = data->optopt;
  optwhere = data->optwhere;
}

/* getopt_internal:  the function that does all the dirty work */
static int
getopt_internal (int argc, char *const argv[], const char *shortopts,
		 const struct option *longopts, int *longind, int only,
		 struct getopt_data *data)
{
  GETOPT_ORDERING_T ordering = PERMUTE;
  size_t permute_from = 0;
  int num_nonopts = 0;
  int optindex = 0;
  size_t match_chars = 0;
  char *possible_arg = 0;
  int longopt_match = -1;
  int has_arg = -1;
  char *cp = 0;
  int arg_next = 0;

  /* first, deal with silly parameters and easy stuff */
  if (argc == 0 || argv == 0 || (shortopts == 0 && longopts == 0)
      || data->optind >= argc || argv[data->optind] == 0)
    return EOF;
  if (strcmp (argv[data->optind], "--") == 0)
    {
      data->optind++;
      return EOF;
    }

  /* if this is our first time through */
  if (data->optind == 0)
    data->optind = data->optwhere = 1;

  /* define ordering */
  if (shortopts != 0 && (*shortopts == '-' || *shortopts == '+'))
    {
      ordering = (*shortopts == '-') ? RETURN_IN_ORDER : REQUIRE_ORDER;
      shortopts++;
    }
  else
    ordering = (getenv ("POSIXLY_CORRECT") != 0) ? REQUIRE_ORDER : PERMUTE;

  /*
   * based on ordering, find our next option, if we're at the beginning of
   * one
   */
  if (data->optwhere == 1)
    {
      switch (ordering)
	{
	default:		/* shouldn't happen */
	case PERMUTE:
	  permute_from = data->optind;
	  num_nonopts = 0;
	  while (!is_option (argv[data->optind], only))
	    {
	      data->optind++;
	      num_nonopts++;
	    }
	  if (argv[data->optind] == 0)
	    {
	      /* no more options */
	      data->optind = permute_from;
	      return EOF;
	    }
	  else if (strcmp (argv[data->optind], "--") == 0)
	    {
	      /* no more options, but have to get `--' out of the way */
	      permute (argv + permute_from, num_nonopts, 1);
	      data->optind = permute_from + 1;
	      return EOF;
	    }
	  break;
	case RETURN_IN_ORDER:
	  if (!is_option (argv[data->optind], only))
	    {
	      data->optarg = argv[data->optind++];
	      return (optopt = 1);
	    }
	  break;
	case REQUIRE_ORDER:
	  if (!is_option (argv[data->optind], only))
	    return EOF;
	  break;
	}
    }
  /* we've got an option, so parse it */

  /* first, is it a long option? */
  if (longopts != 0
      && (memcmp (argv[data->optind], "--", 2) == 0
	  || (only && argv[data->optind][0] == '+')) && data->optwhere == 1)
    {
      /* handle long options */
      if (memcmp (argv[data->optind], "--", 2) == 0)
	data->optwhere = 2;
      longopt_match = -1;
      possible_arg = strchr (argv[data->optind] + data->optwhere, '=');
      if (possible_arg == 0)
	{
	  /* no =, so next argv might be arg */
	  match_chars = strlen (argv[data->optind]);
	  possible_arg = argv[data->optind] + match_chars;
	  match_chars = match_chars - data->optwhere;
	}
      else
	match_chars = (possible_arg - argv[data->optind]) - data->optwhere;
      for (optindex = 0; longopts[optindex].name != 0; ++optindex)
	{
	  if (memcmp
	      (argv[data->optind] + data->optwhere, longopts[optindex].name,
	       match_chars) == 0)
	    {
	      /* do we have an exact match? */
	      if (match_chars == (int) (strlen (longopts[optindex].name)))
		{
		  longopt_match = optindex;
		  break;
		}
	      /* do any characters match? */
	      else
		{
		  if (longopt_match < 0)
		    longopt_match = optindex;
		  else
		    {
		      /* we have ambiguous options */
		      if (data->opterr)
			fprintf (stderr, "%s: option `%s' is ambiguous "
				 "(could be `--%s' or `--%s')\n",
				 argv[0],
				 argv[data->optind],
				 longopts[longopt_match].name,
				 longopts[optindex].name);
		      return (data->optopt = '?');
		    }
		}
	    }
	}
      if (longopt_match >= 0)
	has_arg = longopts[longopt_match].has_arg;
    }

  /* if we didn't find a long option, is it a short option? */
  if (longopt_match < 0 && shortopts != 0)
    {
      cp = strchr (shortopts, argv[data->optind][data->optwhere]);
      if (cp == 0)
	{
	  /* couldn't find option in shortopts */
	  if (data->opterr)
	    fprintf (stderr,
		     "%s: invalid option -- `-%c'\n",
		     argv[0], argv[data->optind][data->optwhere]);
	  data->optwhere++;
	  if (argv[data->optind][data->optwhere] == '\0')
	    {
	      data->optind++;
	      data->optwhere = 1;
	    }
	  return (data->optopt = '?');
	}
      has_arg = ((cp[1] == ':')
		 ? ((cp[2] == ':') ? OPTIONAL_ARG : REQUIRED_ARG) : NO_ARG);
      possible_arg = argv[data->optind] + data->optwhere + 1;
      data->optopt = *cp;
    }

  /* get argument and reset data->optwhere */
  arg_next = 0;
  switch (has_arg)
    {
    case OPTIONAL_ARG:
      if (*possible_arg == '=')
	possible_arg++;
      data->optarg = (*possible_arg != '\0') ? possible_arg : 0;
      data->optwhere = 1;
      break;
    case REQUIRED_ARG:
      if (*possible_arg == '=')
	possible_arg++;
      if (*possible_arg != '\0')
	{
	  data->optarg = possible_arg;
	  data->optwhere = 1;
	}
      else if (data->optind + 1 >= argc)
	{
	  if (data->opterr)
	    {
	      fprintf (stderr, "%s: argument required for option `", argv[0]);
	      if (longopt_match >= 0)
		fprintf (stderr, "--%s'\n", longopts[longopt_match].name);
	      else
		fprintf (stderr, "-%c'\n", *cp);
	    }
	  data->optind++;
	  return (data->optopt = ':');
	}
      else
	{
	  data->optarg = argv[data->optind + 1];
	  arg_next = 1;
	  data->optwhere = 1;
	}
      break;
    default:			/* shouldn't happen */
    case NO_ARG:
      if (longopt_match < 0)
	{
	  data->optwhere++;
	  if (argv[data->optind][data->optwhere] == '\0')
	    data->optwhere = 1;
	}
      else
	data->optwhere = 1;
      data->optarg = 0;
      break;
    }

  /* do we have to permute or otherwise modify data->optind? */
  if (ordering == PERMUTE && data->optwhere == 1 && num_nonopts != 0)
    {
      permute (argv + permute_from, num_nonopts, 1 + arg_next);
      data->optind = permute_from + 1 + arg_next;
    }
  else if (data->optwhere == 1)
    data->optind = data->optind + 1 + arg_next;

  /* finally return */
  if (longopt_match >= 0)
    {
      if (longind != 0)
	*longind = longopt_match;
      if (longopts[longopt_match].flag != 0)
	{
	  *(longopts[longopt_match].flag) = longopts[longopt_match].val;
	  return 0;
	}
      else
	return longopts[longopt_match].val;
    }
  else
    return optopt;
}

int
getopt (int argc, char *const argv[], const char *optstring)
{
  struct getopt_data data;
  int r;

  read_globals (&data);
  r = getopt_internal (argc, argv, optstring, 0, 0, 0, &data);
  write_globals (&data);
  return r;
}

int
getopt_long (int argc, char *const argv[], const char *shortopts,
	     const struct option *longopts, int *longind)
{
  struct getopt_data data;
  int r;

  read_globals (&data);
  r = getopt_internal (argc, argv, shortopts, longopts, longind, 0, &data);
  write_globals (&data);
  return r;
}

int
getopt_long_only (int argc, char *const argv[], const char *shortopts,
		  const struct option *longopts, int *longind)
{
  struct getopt_data data;
  int r;

  read_globals (&data);
  r = getopt_internal (argc, argv, shortopts, longopts, longind, 1, &data);
  write_globals (&data);
  return r;
}

int
getopt_r (int argc, char *const argv[], const char *optstring,
	  struct getopt_data *data)
{
  return getopt_internal (argc, argv, optstring, 0, 0, 0, data);
}

int
getopt_long_r (int argc, char *const argv[], const char *shortopts,
	       const struct option *longopts, int *longind,
	       struct getopt_data *data)
{
  return getopt_internal (argc, argv, shortopts, longopts, longind, 0, data);
}

int
getopt_long_only_r (int argc, char *const argv[], const char *shortopts,
		    const struct option *longopts, int *longind,
		    struct getopt_data *data)
{
  return getopt_internal (argc, argv, shortopts, longopts, longind, 1, data);
}

/* end of file GETOPT.C */

/****************************************************************************

getopt.h - Read command line options

AUTHOR: Gregory Pietsch
CREATED Thu Jan 09 22:37:00 1997

DESCRIPTION:

The getopt() function parses the command line arguments.  Its arguments argc
and argv are the argument count and array as passed to the main() function
on program invocation.  The argument optstring is a list of available option
characters.  If such a character is followed by a colon (`:'), the option
takes an argument, which is placed in optarg.  If such a character is
followed by two colons, the option takes an optional argument, which is
placed in optarg.  If the option does not take an argument, optarg is NULL.

The external variable optind is the index of the next array element of argv
to be processed; it communicates from one call to the next which element to
process.

The getopt_long() function works like getopt() except that it also accepts
long options started by two dashes `--'.  If these take values, it is either
in the form

--arg=value

 or

--arg value

It takes the additional arguments longopts which is a pointer to the first
element of an array of type GETOPT_LONG_OPTION_T, defined below.  The last
element of the array has to be filled with NULL for the name field.

The longind pointer points to the index of the current long option relative
to longopts if it is non-NULL.

The getopt() function returns the option character if the option was found
successfully, `:' if there was a missing parameter for one of the options,
`?' for an unknown option character, and EOF for the end of the option list.

The getopt_long() function's return value is described below.

The function getopt_long_only() is identical to getopt_long(), except that a
plus sign `+' can introduce long options as well as `--'.

Describe how to deal with options that follow non-option ARGV-elements.

If the caller did not specify anything, the default is REQUIRE_ORDER if the
environment variable POSIXLY_CORRECT is defined, PERMUTE otherwise.

REQUIRE_ORDER means don't recognize them as options; stop option processing
when the first non-option is seen.  This is what Unix does.  This mode of
operation is selected by either setting the environment variable
POSIXLY_CORRECT, or using `+' as the first character of the optstring
parameter.

PERMUTE is the default.  We permute the contents of ARGV as we scan, so that
eventually all the non-options are at the end.  This allows options to be
given in any order, even with programs that were not written to expect this.

RETURN_IN_ORDER is an option available to programs that were written to
expect options and other ARGV-elements in any order and that care about the
ordering of the two.  We describe each non-option ARGV-element as if it were
the argument of an option with character code 1.  Using `-' as the first
character of the optstring parameter selects this mode of operation.

The special argument `--' forces an end of option-scanning regardless of the
value of `ordering'.  In the case of RETURN_IN_ORDER, only `--' can cause
getopt() and friends to return EOF with optind != argc.

COPYRIGHT NOTICE AND DISCLAIMER:

Copyright (C) 1997 Gregory Pietsch

This file and the accompanying getopt.c implementation file are hereby 
placed in the public domain without restrictions.  Just give the author 
credit, don't claim you wrote it or prevent anyone else from using it.

Gregory Pietsch's current e-mail address:
gpietsch@comcast.net
****************************************************************************/


#ifndef GETOPT_H
#define GETOPT_H

#include <_ansi.h>

/* include files needed by this include file */

/* macros defined by this include file */
#define NO_ARG          	0
#define REQUIRED_ARG    	1
#define OPTIONAL_ARG    	2
  /* The GETOPT_DATA_INITIALIZER macro is used to initialize a statically-
     allocated variable of type struct getopt_data.  */
#define GETOPT_DATA_INITIALIZER	{0,0,0,0,0}

#ifdef __cplusplus
extern "C"
{

#endif				/* __cplusplus */

/* types defined by this include file */
  struct option
  {
    char *name;			/* the name of the long option */
    int has_arg;		/* one of the above macros */
    int *flag;			/* determines if getopt_long() returns a
				 * value for a long option; if it is
				 * non-NULL, 0 is returned as a function
				 * value and the value of val is stored in
				 * the area pointed to by flag.  Otherwise,
				 * val is returned. */
    int val;			/* determines the value to return if flag is
				 * NULL. */

  };

  /* The getopt_data structure is for reentrancy. Its members are similar to
     the externally-defined variables.  */
  typedef struct getopt_data
  {
    char *optarg;
    int optind, opterr, optopt, optwhere;
  } getopt_data;

  /* externally-defined variables */
  extern char *optarg;

  extern int optind;

  extern int opterr;

  extern int optopt;

  /* function prototypes */
  int _EXFUN (getopt,
	      (int __argc, char *const __argv[], const char *__optstring));

  int _EXFUN (getopt_long,
	      (int __argc, char *const __argv[], const char *__shortopts,
	       const struct option * __longopts, int *__longind));

  int _EXFUN (getopt_long_only,
	      (int __argc, char *const __argv[], const char *__shortopts,
	       const struct option * __longopts, int *__longind));

  int _EXFUN (getopt_r,
	      (int __argc, char *const __argv[], const char *__optstring,
	       struct getopt_data * __data));

  int _EXFUN (getopt_long_r,
	      (int __argc, char *const __argv[], const char *__shortopts,
	       const struct option * __longopts, int *__longind,
	       struct getopt_data * __data));

  int _EXFUN (getopt_long_only_r,
	      (int __argc, char *const __argv[], const char *__shortopts,
	       const struct option * __longopts, int *__longind,
	       struct getopt_data * __data));

#ifdef __cplusplus
};

#endif /* __cplusplus  */

#endif /* GETOPT_H */

/* END OF FILE getopt.h */