This file is getopts.def, from which is created getopts.c.
It implements the builtin "getopts" in Bash.

Copyright (C) 1987-2019 Free Software Foundation, Inc.

This file is part of GNU Bash, the Bourne Again SHell.

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it under the terms of the GNU General Public License as published by
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(at your option) any later version.

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but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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$PRODUCES getopts.c

$BUILTIN getopts
$FUNCTION getopts_builtin
$SHORT_DOC getopts optstring name [arg ...]
Parse option arguments.

Getopts is used by shell procedures to parse positional parameters
as options.

OPTSTRING contains the option letters to be recognized; if a letter
is followed by a colon, the option is expected to have an argument,
which should be separated from it by white space.

Each time it is invoked, getopts will place the next option in the
shell variable $name, initializing name if it does not exist, and
the index of the next argument to be processed into the shell
variable OPTIND.  OPTIND is initialized to 1 each time the shell or
a shell script is invoked.  When an option requires an argument,
getopts places that argument into the shell variable OPTARG.

getopts reports errors in one of two ways.  If the first character
of OPTSTRING is a colon, getopts uses silent error reporting.  In
this mode, no error messages are printed.  If an invalid option is
seen, getopts places the option character found into OPTARG.  If a
required argument is not found, getopts places a ':' into NAME and
sets OPTARG to the option character found.  If getopts is not in
silent mode, and an invalid option is seen, getopts places '?' into
NAME and unsets OPTARG.  If a required argument is not found, a '?'
is placed in NAME, OPTARG is unset, and a diagnostic message is
printed.

If the shell variable OPTERR has the value 0, getopts disables the
printing of error messages, even if the first character of
OPTSTRING is not a colon.  OPTERR has the value 1 by default.

Getopts normally parses the positional parameters, but if arguments
are supplied as ARG values, they are parsed instead.

Exit Status:
Returns success if an option is found; fails if the end of options is
encountered or an error occurs.
$END

#include <config.h>

#include <stdio.h>

#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/types.h>
#  endif
#  include <unistd.h>
#endif

#include "../bashansi.h"
#include "../bashintl.h"

#include "../shell.h"
#include "../execute_cmd.h"
#include "common.h"
#include "bashgetopt.h"
#include "getopt.h"

#define G_EOF		-1
#define G_INVALID_OPT	-2
#define G_ARG_MISSING	-3

static int getopts_unbind_variable PARAMS((char *));
static int getopts_bind_variable PARAMS((char *, char *));
static int dogetopts PARAMS((int, char **));

/* getopts_reset is magic code for when OPTIND is reset.  N is the
   value that has just been assigned to OPTIND. */
void
getopts_reset (newind)
     int newind;
{
  sh_optind = newind;
  sh_badopt = 0;
}

static int
getopts_unbind_variable (name)
     char *name;
{
#if 0
  return (unbind_variable (name));
#else
  return (unbind_variable_noref (name));
#endif
}

static int
getopts_bind_variable (name, value)
     char *name, *value;
{
  SHELL_VAR *v;

  if (legal_identifier (name))
    {
      v = bind_variable (name, value, 0);
      if (v && (readonly_p (v) || noassign_p (v)))
	return (EX_MISCERROR);
      return (v ? EXECUTION_SUCCESS : EXECUTION_FAILURE);
    }
  else
    {
      sh_invalidid (name);
      return (EXECUTION_FAILURE);
    }
}

/* Error handling is now performed as specified by Posix.2, draft 11
   (identical to that of ksh-88).  The special handling is enabled if
   the first character of the option string is a colon; this handling
   disables diagnostic messages concerning missing option arguments
   and invalid option characters.  The handling is as follows.

   INVALID OPTIONS:
        name -> "?"
        if (special_error) then
                OPTARG = option character found
                no error output
        else
                OPTARG unset
                diagnostic message
        fi
 
  MISSING OPTION ARGUMENT;
        if (special_error) then
                name -> ":"
                OPTARG = option character found
        else
                name -> "?"
                OPTARG unset
                diagnostic message
        fi
 */

static int
dogetopts (argc, argv)
     int argc;
     char **argv;
{
  int ret, special_error, old_opterr, i, n;
  char strval[2], numval[16];
  char *optstr;			/* list of options */
  char *name;			/* variable to get flag val */
  char *t;

  if (argc < 3)
    {
      builtin_usage ();
      return (EX_USAGE);
    }

  /* argv[0] is "getopts". */

  optstr = argv[1];
  name = argv[2];
  argc -= 2;
  argv += 2;

  special_error = optstr[0] == ':';

  if (special_error)
    {
      old_opterr = sh_opterr;
      optstr++;
      sh_opterr = 0;		/* suppress diagnostic messages */
    }

  if (argc > 1)
    {
      sh_getopt_restore_state (argv);
      t = argv[0];
      argv[0] = dollar_vars[0];
      ret = sh_getopt (argc, argv, optstr);
      argv[0] = t;
    }
  else if (rest_of_args == (WORD_LIST *)NULL)
    {
      for (i = 0; i < 10 && dollar_vars[i]; i++)
	;

      sh_getopt_restore_state (dollar_vars);
      ret = sh_getopt (i, dollar_vars, optstr);
    }
  else
    {
      register WORD_LIST *words;
      char **v;

      i = number_of_args () + 1;	/* +1 for $0 */
      v = strvec_create (i + 1);
      for (i = 0; i < 10 && dollar_vars[i]; i++)
	v[i] = dollar_vars[i];
      for (words = rest_of_args; words; words = words->next, i++)
	v[i] = words->word->word;
      v[i] = (char *)NULL;
      sh_getopt_restore_state (v);
      ret = sh_getopt (i, v, optstr);
      free (v);
    }

  if (special_error)
    sh_opterr = old_opterr;

  /* Set the OPTIND variable in any case, to handle "--" skipping.  It's
     highly unlikely that 14 digits will be too few. */
  if (sh_optind < 10)
    {
      numval[14] = sh_optind + '0';
      numval[15] = '\0';
      i = 14;
    }
  else
    {
      numval[i = 15] = '\0';
      n = sh_optind;
      do
	{
	  numval[--i] = (n % 10) + '0';
	}
      while (n /= 10);
    }
  bind_variable ("OPTIND", numval + i, 0);

  /* If an error occurred, decide which one it is and set the return
     code appropriately.  In all cases, the option character in error
     is in OPTOPT.  If an invalid option was encountered, OPTARG is
     NULL.  If a required option argument was missing, OPTARG points
     to a NULL string (that is, sh_optarg[0] == 0). */
  if (ret == '?')
    {
      if (sh_optarg == NULL)
	ret = G_INVALID_OPT;
      else if (sh_optarg[0] == '\0')
	ret = G_ARG_MISSING;
    }
	    
  if (ret == G_EOF)
    {
      getopts_unbind_variable ("OPTARG");
      getopts_bind_variable (name, "?");
      return (EXECUTION_FAILURE);
    }

  if (ret == G_INVALID_OPT)
    {
      /* Invalid option encountered. */
      ret = getopts_bind_variable (name, "?");

      if (special_error)
	{
	  strval[0] = (char)sh_optopt;
	  strval[1] = '\0';
	  bind_variable ("OPTARG", strval, 0);
	}
      else
	getopts_unbind_variable ("OPTARG");

      return (ret);
    }

  if (ret == G_ARG_MISSING)
    {
      /* Required argument missing. */
      if (special_error)
	{
	  ret = getopts_bind_variable (name, ":");

	  strval[0] = (char)sh_optopt;
	  strval[1] = '\0';
	  bind_variable ("OPTARG", strval, 0);
	}
      else
	{
	  ret = getopts_bind_variable (name, "?");
	  getopts_unbind_variable ("OPTARG");
	}
      return (ret);
    }			

  bind_variable ("OPTARG", sh_optarg, 0);

  strval[0] = (char) ret;
  strval[1] = '\0';
  return (getopts_bind_variable (name, strval));
}

/* The getopts builtin.  Build an argv, and call dogetopts with it. */
int
getopts_builtin (list)
     WORD_LIST *list;
{
  char **av;
  int ac, ret;

  if (list == 0)
    {
      builtin_usage ();
      return EX_USAGE;
    }

  reset_internal_getopt ();
  if ((ret = internal_getopt (list, "")) != -1)
    {
      if (ret == GETOPT_HELP)
	builtin_help ();
      else
	builtin_usage ();
      return (EX_USAGE);
    }
  list = loptend;

  av = make_builtin_argv (list, &ac);
  ret = dogetopts (ac, av);
  free ((char *)av);

  return (ret);
}