/* opt.c -- general-purpose command line option parser
   Copyright (C) 2016-2017 Free Software Foundation, Inc.

   GNU Mailutils is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 3, or (at
   your option) any later version.

   GNU Mailutils is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Mailutils.  If not, see <http://www.gnu.org/licenses/>.
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <mailutils/alloc.h>
#include <mailutils/opt.h>
#include <mailutils/nls.h>
#include <mailutils/errno.h>
#include <mailutils/stdstream.h>

#define EXIT_SUCCESS 0
#define EXIT_ERROR   1

/* Option and its aliases form a contiguous array.  Option slot is used
   to preserve contiguity during sorting. */
struct opt_slot
{
  struct mu_option **opt;   /* Points to the option */
  int count;                /* Number of options in opt */
};

/* Compare pointers to two option structs */
static int
optcmp (const void *a, const void *b)
{
  struct mu_option const *ap = *(struct mu_option const **)a;
  struct mu_option const *bp = *(struct mu_option const **)b;
  
  if (!MU_OPTION_IS_VALID_SHORT_OPTION (ap)
      && MU_OPTION_IS_VALID_LONG_OPTION (ap)
      && !MU_OPTION_IS_VALID_SHORT_OPTION (bp)
      && MU_OPTION_IS_VALID_LONG_OPTION (bp))
    return strcasecmp (ap->opt_long, bp->opt_long);
  else
    {
      char afirst, bfirst;
      int res;

      afirst = ap->opt_short ? ap->opt_short : ap->opt_long ? *ap->opt_long : 0;
      bfirst = bp->opt_short ? bp->opt_short : bp->opt_long ? *bp->opt_long : 0;

      res = mu_tolower (afirst) - mu_tolower (bfirst);
      
      return res ? res : afirst - bfirst;
    }
}

/* Compare pointers to two option slots */
static int
slotcmp (const void *a, const void *b)
{
  struct opt_slot const *ap = (struct opt_slot const *)a;
  struct opt_slot const *bp = (struct opt_slot const *)b;
  return optcmp (ap->opt, bp->opt);
} 
/* Sort a group of options in OPTBUF, starting at index START (first
   option slot after a group header (if any).  The group spans up to
   next group header or end of options */
static size_t
sort_group (struct mu_option **optbuf, size_t start)
{
  size_t i, count = 0;

  /* Make sure the first option in group is not an alias. */
  optbuf[start]->opt_flags &= ~MU_OPTION_ALIAS;
  for (i = start; optbuf[i] && !MU_OPTION_IS_GROUP_HEADER (optbuf[i]); i++)
    {
      if (!(optbuf[i]->opt_flags & MU_OPTION_ALIAS))
	count++;
    }
  if (count == i - start)
    /* Inplace sort */
    qsort (&optbuf[start], count, sizeof (optbuf[0]), optcmp);
  else
    {
      /* Option group contains aliases. Split it into option slots. */
      struct mu_option **tmp;
      struct opt_slot *slots;
      size_t j, k, l;
      
      slots = mu_calloc (count, sizeof (slots[0]));
      j = 0;
      slots[0].opt = optbuf + start;
      slots[0].count = 1;
      for (k = start + 1; k < i; k++)
	{
	  if (optbuf[k]->opt_flags & MU_OPTION_ALIAS)
	    slots[j].count++;
	  else
	    {
	      j++;
	      slots[j].opt = optbuf + k;
	      slots[j].count = 1;
	    }
	}
      /* Sort the slots */
      qsort (slots, count, sizeof (slots[0]), slotcmp);
      /* Create ordered array of option pointers */
      tmp = mu_calloc (i - start, sizeof (tmp[0]));
      for (k = l = 0; k < count; k++)
	for (j = 0; j < slots[k].count; j++)
	  tmp[l++] = slots[k].opt[j];
      /* Copy ordered pointers back and free temporary memory */
      memcpy (optbuf + start, tmp, (i - start) * sizeof tmp[0]);
      free (tmp);
      free (slots);
    }
		     
  return i;
}

/* Print help summary and exit. */
static void
fn_help (struct mu_parseopt *po, struct mu_option *opt, char const *unused)
{
  mu_program_help (po, mu_strout);
  exit (EXIT_SUCCESS);
}

/* Print usage summary and exit. */
static void
fn_usage (struct mu_parseopt *po, struct mu_option *opt, char const *unused)
{
  mu_program_usage (po, 1, mu_strout);
  exit (EXIT_SUCCESS);
}

static void
fn_version (struct mu_parseopt *po, struct mu_option *opt, char const *unused)
{
  mu_program_version (po, mu_strout);
  exit (EXIT_SUCCESS);
}

/* Default options */
struct mu_option mu_default_options[] = {
  MU_OPTION_GROUP(""),
  { "help",    '?', NULL, MU_OPTION_IMMEDIATE, N_("give this help list"),
    mu_c_string, NULL, fn_help },
  { "usage",   0,   NULL, MU_OPTION_IMMEDIATE, N_("give a short usage message"),
    mu_c_string, NULL, fn_usage
  },
  MU_OPTION_END
};

struct mu_option mu_version_options[] = {
  { "version", 'V', NULL, MU_OPTION_IMMEDIATE, N_("print program version"),
    mu_c_string, NULL, fn_version },
  MU_OPTION_END
};

/* Output error message */
void
mu_parseopt_error (struct mu_parseopt *po, char const *fmt, ...)
{
  va_list ap;

  if (po->po_flags & MU_PARSEOPT_IGNORE_ERRORS)
    return;

  if (po->po_prog_name)
    fprintf (stderr, "%s: ", po->po_prog_name);
  va_start (ap, fmt);
  vfprintf (stderr, fmt, ap);
  va_end (ap);
  fputc ('\n', stderr);
}

static void
mu_option_cache_destroy (void *ptr)
{
  struct mu_option_cache *cache = ptr;
  free (cache);
}

static int parseopt_apply (void *item, void *data);

/* If OPT is an immediate option, evaluate it right away.  Otherwise,
   add option OPT with argument ARG to the cache in PO. */
void
add_option_cache (struct mu_parseopt *po, struct mu_option *opt,
		  char const *arg)
{
  struct mu_option_cache *cache = mu_alloc (sizeof (*cache));
  
  cache->cache_opt = opt;
  if (arg == NULL && opt->opt_default)
    arg = opt->opt_default;
  cache->cache_arg = arg;

  if ((po->po_flags & MU_PARSEOPT_IMMEDIATE)
       || (opt->opt_flags & MU_OPTION_IMMEDIATE))
    {
      parseopt_apply (cache, po);
      mu_option_cache_destroy (cache);
    }
  else
    {
      mu_list_append (po->po_optlist, cache);
    }
}

/* Find first option for which I is an alias */
struct mu_option *
option_unalias (struct mu_parseopt *po, int i)
{
  while (i > 0 && po->po_optv[i]->opt_flags & MU_OPTION_ALIAS)
    --i;
  return po->po_optv[i];
}

/* Find a descriptor of short option CHR */
struct mu_option *
find_short_option (struct mu_parseopt *po, int chr)
{
  size_t i;

  for (i = 0; i < po->po_optc; i++)
    {
      if (MU_OPTION_IS_VALID_SHORT_OPTION (po->po_optv[i])
	  && po->po_optv[i]->opt_short == chr)
	return option_unalias (po, i);
    }
  mu_parseopt_error (po, _("unrecognized option '-%c'"), chr);
  return NULL;
}

enum neg_match
  {
    neg_nomatch,
    neg_match_inexact,
    neg_match_exact
  };
  
static enum neg_match
negmatch (struct mu_parseopt *po, size_t i, char const *optstr, size_t optlen)
{
  if (mu_option_possible_negation (po, po->po_optv[i]))
    {
      size_t neglen = strlen (po->po_negation);
      size_t len = strlen (po->po_optv[i]->opt_long);
      if (optlen <= neglen + len
	  && memcmp (optstr, po->po_negation, neglen) == 0
	  && memcmp (optstr + neglen, po->po_optv[i]->opt_long,
		     optlen - neglen) == 0)
	{
	  return (optlen == neglen + len) ? neg_match_exact : neg_match_inexact;
	}
    }
  return neg_nomatch;
}

/* Find a descriptor of long option OPTSTR.  If it has argument, return
   it in *ARGPTR. */
struct mu_option *
find_long_option (struct mu_parseopt *po, char const *optstr,
		  struct mu_option **used_opt_ptr,
		  char **used_value,
		  char **value)
{
  size_t i;
  size_t optlen;       /* Length of the option in optstr */
  int found = 0;       /* 1 if the match was found, 2 if option is ambiguous */
  enum neg_match neg;  /* 1 if a boolean option is negated */
  struct mu_option *ret_opt = NULL;
  struct mu_option *used_opt;
  
  optlen = strcspn (optstr, "=");
  
  for (i = 0; i < po->po_optc; i++)
    {
      if (MU_OPTION_IS_VALID_LONG_OPTION (po->po_optv[i]))
	{
	  size_t len = strlen (po->po_optv[i]->opt_long);
	  struct mu_option *opt = option_unalias (po, i);
	  neg = neg_nomatch;
	  if ((optlen <= len
	       && memcmp (po->po_optv[i]->opt_long, optstr, optlen) == 0)
	      || (neg = negmatch (po, i, optstr, optlen)))
	    {
	      switch (found)
		{
		case 0:
		  used_opt = po->po_optv[i];
		  ret_opt = opt;
		  found++;
		  if (optlen == len || neg == neg_match_exact)
		    i = po->po_optc - 1; /* exact match: break the loop */
		  break;
		  
		case 1:
		  if (opt == ret_opt)
		    continue;
		  if (po->po_flags & MU_PARSEOPT_IGNORE_ERRORS)
		    return NULL;
		  mu_parseopt_error (po,
				     _("option '%s%*.*s' is ambiguous; possibilities:"),
				     po->po_long_opt_start,
				     optlen, optlen, optstr);
		  fprintf (stderr, "%s%s%s\n",
			   po->po_long_opt_start,
			   neg ? po->po_negation : "",
			   used_opt->opt_long);
		  if (neg == neg_nomatch && negmatch (po, i, optstr, optlen))
		    fprintf (stderr, "%s%s%s\n",
			     po->po_long_opt_start,
			     po->po_negation,
			     po->po_optv[i]->opt_long);
		  found++;
		  
		case 2:
		  fprintf (stderr, "%s%s%s\n",
			   po->po_long_opt_start,
			   neg ? po->po_negation : "",
			   po->po_optv[i]->opt_long);
		  if (neg == neg_nomatch && negmatch (po, i, optstr, optlen))
		    fprintf (stderr, "%s%s%s\n",
			     po->po_long_opt_start,
			     po->po_negation,
			     po->po_optv[i]->opt_long);
		}
	    }
	}
    }
  
  switch (found)
    {
    case 0:
      mu_parseopt_error (po, _("unrecognized option '%s%s'"),
			 po->po_long_opt_start, optstr);
      break;
      
    case 1:
      *used_opt_ptr = used_opt;
      if (optstr[optlen])
	++optlen;
      *used_value = (char *)(optstr + optlen);
      if (ret_opt->opt_type == mu_c_bool)
	{
	  if (neg)
	    *value = "0";
	  else
	    *value = "1";
	}
      else
	*value = NULL;
      return ret_opt;

    case 2:
      break;
    }

  return NULL;  
}

static void
permute (struct mu_parseopt *po)
{
  if (!(po->po_flags & MU_PARSEOPT_IN_ORDER) && po->po_arg_count)
    {
      /* Array to save arguments in */
      char *save[2];
      /* Number of arguments processed (at most two) */
      int n = po->po_ind - (po->po_arg_start + po->po_arg_count);
      
      if (n > 2)
	abort ();
      
      /* Store the processed elements away */
      save[0] = po->po_argv[po->po_arg_start + po->po_arg_count];
      if (n == 2)
	save[1] = po->po_argv[po->po_arg_start + po->po_arg_count + 1];

      /* Shift the array */
      memmove (po->po_argv + po->po_arg_start + n,
	       po->po_argv + po->po_arg_start,
	       po->po_arg_count * sizeof (po->po_argv[0]));
      
      /* Place stored elements in the vacating slots */
      po->po_argv[po->po_arg_start] = save[0];
      if (n == 2)
	po->po_argv[po->po_arg_start + 1] = save[1];
      
      /* Fix up start index */
      po->po_arg_start += n;
      po->po_permuted = 1;
    }
}

/* Consume next option from PO.  On success, update PO members as
   described below and return 0.  On end of options, return 1.

   If the consumed option is a short option, then 

     po_chr  keeps its option character, and
     po_cur  points to the next option character to be processed

   Otherwise, if the consumed option is a long one, then

     po_chr  is 0
     po_cur  points to the first character after --
*/   
static int
next_opt (struct mu_parseopt *po)
{
  if (!*po->po_cur)
    {
      permute (po);
      
      while (1)
	{
	  po->po_cur = po->po_argv[po->po_ind++];
	  if (!po->po_cur)
	    return 1;
	  if (po->po_cur[0] == '-' && po->po_cur[1])
	    {
	      if (*++po->po_cur == '-')
		{
		  if (*++po->po_cur == 0)
		    {
		      /* End of options */
		      permute (po);
		      ++po->po_ind;
		      return 1;
		    }
		  
		  if (po->po_flags & MU_PARSEOPT_SINGLE_DASH)
		    /* a non-optional argument */;
		  else
		    {
		      /* It's a long option */
		      po->po_chr = 0;
		      return 0;
		    }
		}
	      else if (po->po_flags & MU_PARSEOPT_SINGLE_DASH)
		{
		  /* Assume single-dash long option */
		  po->po_chr = 0;
		  return 0;
		}
	      else
		break;
	    }

	  if (!(po->po_flags & MU_PARSEOPT_IN_ORDER))
	    {
	      if (!po->po_permuted && po->po_arg_count == 0)
		po->po_arg_start = po->po_ind - 1;
	      po->po_arg_count++;
	      continue;
	    }
	  else
	    return 1;
	}
    }

  po->po_chr = *po->po_cur++;

  return 0;
}

/* Parse options */
static int
parse (struct mu_parseopt *po)
{
  int rc;

  rc = mu_list_create (&po->po_optlist);
  if (rc)
    return rc;
  mu_list_set_destroy_item (po->po_optlist, mu_option_cache_destroy);
  
  po->po_ind = 0;
  if (!(po->po_flags & MU_PARSEOPT_ARGV0))
    {
      po->po_ind++;
      if (!(po->po_flags & MU_PARSEOPT_PROG_NAME))
	{
	  char *p = strrchr (po->po_argv[0], '/');
	  if (p)
	    p++;
	  else
	    p = (char*) po->po_argv[0];
	  if (strlen (p) > 3 && memcmp (p, "lt-", 3) == 0)
	    p += 3;
	  po->po_prog_name = p;
	}
    }
  else if (!(po->po_flags & MU_PARSEOPT_PROG_NAME))
    po->po_prog_name = NULL;

  po->po_arg_start = po->po_ind;
  po->po_arg_count = 0;
  po->po_permuted = 0;
  
  po->po_cur = "";

  po->po_opterr = -1;
  
  while (next_opt (po) == 0)
    {
      struct mu_option *opt, *uopt;
      char *value;
      
      if (po->po_chr)
	{
	  opt = find_short_option (po, po->po_chr);
	  uopt = NULL;
	  value = NULL;
	}
      else
	{
	  opt = find_long_option (po, po->po_cur, &uopt, &po->po_cur, &value);
	}

      if (opt)
	{
	  char *arg = NULL;
	  
	  if (opt->opt_arg)
	    {
	      if (po->po_cur[0])
		{
		  arg = po->po_cur;
		  po->po_cur = "";
		}
	      else if (opt->opt_flags & MU_OPTION_ARG_OPTIONAL)
		/* ignore it */;
	      else if (po->po_ind < po->po_argc)
		arg = po->po_argv[po->po_ind++];
	      else
		{
		  if (uopt)
		    mu_parseopt_error (po,
				 _("option '%s%s' requires an argument"),
				       po->po_long_opt_start, uopt->opt_long);
		  else
		    mu_parseopt_error (po,
				 _("option '-%c' requires an argument"),
				       po->po_chr);
		  po->po_opterr = po->po_ind;
		  if (po->po_flags & MU_PARSEOPT_NO_ERREXIT)
		    {
		      if (!(po->po_flags & MU_PARSEOPT_IN_ORDER))
			po->po_arg_count++;
		      continue;
		    }
		  exit (po->po_exit_error);
		}	
	    }
	  else
	    {
	      if (uopt
		  && po->po_cur[0]
		  && !(po->po_flags & MU_OPTION_ARG_OPTIONAL))
		{
		  mu_parseopt_error (po,
			       _("option '%s%s' doesn't allow an argument"),
				     po->po_long_opt_start,
				     uopt->opt_long);
		  po->po_opterr = po->po_ind;
		  if (po->po_flags & MU_PARSEOPT_NO_ERREXIT)
		    {
		      if (!(po->po_flags & MU_PARSEOPT_IN_ORDER))
			po->po_arg_count++;
		      continue;
		    }
		  exit (po->po_exit_error);
		}
	      arg = NULL;
	    }

	  if (!arg && value)
	    arg = value;
	  
	  add_option_cache (po, opt, arg);
	}
      else
	{
	  po->po_opterr = po->po_ind;
	  if (po->po_flags & MU_PARSEOPT_NO_ERREXIT)
	    {
	      if (!(po->po_flags & MU_PARSEOPT_IN_ORDER))
		po->po_arg_count++;
	      continue;
	    }
	  exit (po->po_exit_error);
	}
    }

  if (!po->po_permuted)
    po->po_arg_start = po->po_ind - 1 - po->po_arg_count;
  return 0;
}

/* Initialize structure mu_parseopt with given options and flags. */
static int
parseopt_init (struct mu_parseopt *po, struct mu_option **options,
	       int flags)
{
  struct mu_option *opt;
  size_t i, j;

  po->po_argc = 0;
  po->po_argv = NULL;
  po->po_optc = 0;
  po->po_flags = flags;
    
  /* Fix up flags */
  if (flags & MU_PARSEOPT_IGNORE_ERRORS)
    flags |= MU_PARSEOPT_NO_ERREXIT;

  if (!(flags & MU_PARSEOPT_PROG_DOC))
    po->po_prog_doc = NULL;
  if (!(flags & MU_PARSEOPT_PROG_ARGS))
    po->po_prog_args = NULL;
  if (!(flags & MU_PARSEOPT_SPECIAL_ARGS))
    po->po_special_args = NULL;
  if (!(flags & MU_PARSEOPT_BUG_ADDRESS))
    po->po_bug_address = NULL;
  if (!(flags & MU_PARSEOPT_PACKAGE_NAME))
    po->po_package_name = NULL;
  if (!(flags & MU_PARSEOPT_PACKAGE_URL))
    po->po_package_url = NULL;
  if (!(flags & MU_PARSEOPT_PACKAGE_URL))
    po->po_data = NULL;
  if (!(flags & MU_PARSEOPT_EXTRA_INFO))
    po->po_extra_info = NULL;
  if (!(flags & MU_PARSEOPT_HELP_HOOK))
    po->po_help_hook = NULL;
  if (!(flags & MU_PARSEOPT_EXIT_ERROR))
    po->po_exit_error = EXIT_ERROR;
  if (!(flags & MU_PARSEOPT_VERSION_HOOK))
    po->po_version_hook = NULL;
  if (!(flags & MU_PARSEOPT_PROG_DOC_HOOK))
    po->po_prog_doc_hook = NULL;
  if (!(flags & MU_PARSEOPT_NEGATION))
    po->po_negation = NULL;
  
  if (flags & MU_PARSEOPT_SINGLE_DASH)
    po->po_long_opt_start = "-";
  else
    po->po_long_opt_start = "--";    
  
  /* Count the options */
  po->po_optc = 0;
  for (i = 0; options[i]; i++)
    for (opt = options[i]; !MU_OPTION_IS_END (opt); opt++)
      ++po->po_optc;

  if (!(flags & MU_PARSEOPT_NO_STDOPT))
    for (i = 0; !MU_OPTION_IS_END (&mu_default_options[i]); i++)
      ++po->po_optc;

  if (flags & MU_PARSEOPT_VERSION_HOOK)
    for (i = 0; !MU_OPTION_IS_END (&mu_version_options[i]); i++)
      ++po->po_optc;
  
  /* Allocate the working buffer of option pointers */
  po->po_optv = mu_calloc (po->po_optc + 1, sizeof (*po->po_optv));
  if (!po->po_optv)
    return -1;

  /* Fill in the array */
  j = 0;
  for (i = 0; options[i]; i++)
    for (opt = options[i]; !MU_OPTION_IS_END (opt); opt++, j++)
      {
	if (!opt->opt_set)
	  opt->opt_set = mu_option_set_value;
	po->po_optv[j] = opt;
      }
  
  if (!(flags & MU_PARSEOPT_NO_STDOPT))
    for (i = 0; !MU_OPTION_IS_END (&mu_default_options[i]); i++, j++)
      po->po_optv[j] = &mu_default_options[i];

  if (flags & MU_PARSEOPT_VERSION_HOOK)
    for (i = 0; !MU_OPTION_IS_END (&mu_version_options[i]); i++, j++)
      po->po_optv[j] = &mu_version_options[i];
  
  po->po_optv[j] = NULL;

  /* Ensure sane start of options. */
  po->po_optv[0]->opt_flags &= ~MU_OPTION_ALIAS;
  if (!(flags & MU_PARSEOPT_NO_SORT))
    {
      /* Sort the options */
      size_t start;

      for (start = 0; start < po->po_optc; )
	{
	  if (MU_OPTION_IS_GROUP_HEADER (po->po_optv[start]))
	    start = sort_group (po->po_optv, start + 1);
	  else 
	    start = sort_group (po->po_optv, start);
	}
    }

  po->po_ind = 0;
  po->po_opterr = 0;
  po->po_optlist = NULL;
  po->po_cur = NULL;
  po->po_chr = 0;
  po->po_arg_start = 0;
  po->po_arg_count = 0;
  po->po_permuted = 0;
  
  return 0;
}

/* Parse command line from ARGC/ARGV. Valid options are given in
   OPTIONS.  FLAGS control the parsing. */
int
mu_parseopt (struct mu_parseopt *po,
	     int argc, char **argv, struct mu_option **options,
	     int flags)
{
  int rc;

  if (flags & MU_PARSEOPT_REUSE)
    {
      mu_list_clear (po->po_optlist);
      po->po_flags = (po->po_flags & MU_PARSEOPT_IMMUTABLE_MASK)
	                | (flags & ~MU_PARSEOPT_IMMUTABLE_MASK);
    }
  else
    {
      rc = parseopt_init (po, options, flags);
      if (rc)
	return rc;
    }
  po->po_argc = argc;
  po->po_argv = argv;
  
  rc = parse (po);

  if (rc == 0)
    {
      if (po->po_opterr >= 0)
	rc = -1; 
      else
	{
	  if (po->po_flags & MU_PARSEOPT_IMMEDIATE)
	    rc = mu_parseopt_apply (po);
	}
    }

  return rc;
}

void
mu_parseopt_free (struct mu_parseopt *popt)
{
  free (popt->po_optv);
  mu_list_destroy (&popt->po_optlist);
}

static int
parseopt_apply (void *item, void *data)
{
  struct mu_option_cache *cp = item;
  struct mu_parseopt *popt = data;
  cp->cache_opt->opt_set (popt, cp->cache_opt, cp->cache_arg);
  return 0;
}

int
mu_parseopt_apply (struct mu_parseopt *popt)
{
  return mu_list_foreach (popt->po_optlist, parseopt_apply, popt);
}

void
mu_option_set_value (struct mu_parseopt *po, struct mu_option *opt,
		     char const *arg)
{
  if (opt->opt_ptr)
    {
      char *errmsg;
      int rc;
      
      if (arg == NULL)
	{
	  if (opt->opt_default)
	    /* The default value has been already assigned in add_option_cache.
	       This conditional is here in case mu_option_set_value is called
	       from the user code. */
	    arg = opt->opt_default;
	  else if (opt->opt_arg == NULL)
	    arg = "1";
	  else
	    {
	      *(void**)opt->opt_ptr = NULL;
	      return;
	    }
	}
      rc = mu_str_to_c (arg, opt->opt_type, opt->opt_ptr, &errmsg);
      if (rc)
	{
	  char const *errtext;
	  if (errmsg)
	    errtext = errmsg;
	  else
	    errtext = mu_strerror (rc);

	  if (opt->opt_long)
	    mu_parseopt_error (po, "%s%s: %s", po->po_long_opt_start,
			       opt->opt_long, errtext);
	  else
	    mu_parseopt_error (po, "-%c: %s", opt->opt_short, errtext);
	  free (errmsg);

	  if (!(po->po_flags & MU_PARSEOPT_NO_ERREXIT))
	    exit (po->po_exit_error);
	}
    }
}

int
mu_option_possible_negation (struct mu_parseopt *po, struct mu_option *opt)
{
  return po->po_negation && opt->opt_type == mu_c_bool && !opt->opt_arg;
}