goption.c

/* goption.c - Option parser
 *
 *  Copyright (C) 1999, 2003 Red Hat Software
 *  Copyright (C) 2004       Anders Carlsson <andersca@gnome.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

/**
 * SECTION:option
 * @Short_description: parses commandline options
 * @Title: Commandline option parser
 *
 * The GOption commandline parser is intended to be a simpler replacement
 * for the popt library. It supports short and long commandline options,
 * as shown in the following example:
 *
 * `testtreemodel -r 1 --max-size 20 --rand --display=:1.0 -vb -- file1 file2`
 *
 * The example demonstrates a number of features of the GOption
 * commandline parser:
 *
 * - Options can be single letters, prefixed by a single dash.
 *
 * - Multiple short options can be grouped behind a single dash.
 *
 * - Long options are prefixed by two consecutive dashes.
 *
 * - Options can have an extra argument, which can be a number, a string or
 *   a filename. For long options, the extra argument can be appended with
 *   an equals sign after the option name, which is useful if the extra
 *   argument starts with a dash, which would otherwise cause it to be
 *   interpreted as another option.
 *
 * - Non-option arguments are returned to the application as rest arguments.
 *
 * - An argument consisting solely of two dashes turns off further parsing,
 *   any remaining arguments (even those starting with a dash) are returned
 *   to the application as rest arguments.
 *
 * Another important feature of GOption is that it can automatically
 * generate nicely formatted help output. Unless it is explicitly turned
 * off with g_option_context_set_help_enabled(), GOption will recognize
 * the `--help`, `-?`, `--help-all` and `--help-groupname` options
 * (where `groupname` is the name of a #GOptionGroup) and write a text
 * similar to the one shown in the following example to stdout.
 *
 * |[
 * Usage:
 *   testtreemodel [OPTION...] - test tree model performance
 *  
 * Help Options:
 *   -h, --help               Show help options
 *   --help-all               Show all help options
 *   --help-gtk               Show GTK+ Options
 *  
 * Application Options:
 *   -r, --repeats=N          Average over N repetitions
 *   -m, --max-size=M         Test up to 2^M items
 *   --display=DISPLAY        X display to use
 *   -v, --verbose            Be verbose
 *   -b, --beep               Beep when done
 *   --rand                   Randomize the data
 * ]|
 *
 * GOption groups options in #GOptionGroups, which makes it easy to
 * incorporate options from multiple sources. The intended use for this is
 * to let applications collect option groups from the libraries it uses,
 * add them to their #GOptionContext, and parse all options by a single call
 * to g_option_context_parse(). See gtk_get_option_group() for an example.
 *
 * If an option is declared to be of type string or filename, GOption takes
 * care of converting it to the right encoding; strings are returned in
 * UTF-8, filenames are returned in the GLib filename encoding. Note that
 * this only works if setlocale() has been called before
 * g_option_context_parse().
 *
 * Here is a complete example of setting up GOption to parse the example
 * commandline above and produce the example help output.
 * |[<!-- language="C" --> 
 * static gint repeats = 2;
 * static gint max_size = 8;
 * static gboolean verbose = FALSE;
 * static gboolean beep = FALSE;
 * static gboolean randomize = FALSE;
 *
 * static GOptionEntry entries[] =
 * {
 *   { "repeats", 'r', 0, G_OPTION_ARG_INT, &repeats, "Average over N repetitions", "N" },
 *   { "max-size", 'm', 0, G_OPTION_ARG_INT, &max_size, "Test up to 2^M items", "M" },
 *   { "verbose", 'v', 0, G_OPTION_ARG_NONE, &verbose, "Be verbose", NULL },
 *   { "beep", 'b', 0, G_OPTION_ARG_NONE, &beep, "Beep when done", NULL },
 *   { "rand", 0, 0, G_OPTION_ARG_NONE, &randomize, "Randomize the data", NULL },
 *   { NULL }
 * };
 *
 * int
 * main (int argc, char *argv[])
 * {
 *   GError *error = NULL;
 *   GOptionContext *context;
 *
 *   context = g_option_context_new ("- test tree model performance");
 *   g_option_context_add_main_entries (context, entries, GETTEXT_PACKAGE);
 *   g_option_context_add_group (context, gtk_get_option_group (TRUE));
 *   if (!g_option_context_parse (context, &argc, &argv, &error))
 *     {
 *       g_print ("option parsing failed: %s\n", error->message);
 *       exit (1);
 *     }
 *
 *   ...
 *
 * }
 * ]|
 *
 * On UNIX systems, the argv that is passed to main() has no particular
 * encoding, even to the extent that different parts of it may have
 * different encodings.  In general, normal arguments and flags will be
 * in the current locale and filenames should be considered to be opaque
 * byte strings.  Proper use of %G_OPTION_ARG_FILENAME vs
 * %G_OPTION_ARG_STRING is therefore important.
 *
 * Note that on Windows, filenames do have an encoding, but using
 * #GOptionContext with the argv as passed to main() will result in a
 * program that can only accept commandline arguments with characters
 * from the system codepage.  This can cause problems when attempting to
 * deal with filenames containing Unicode characters that fall outside
 * of the codepage.
 *
 * A solution to this is to use g_win32_get_command_line() and
 * g_option_context_parse_strv() which will properly handle full Unicode
 * filenames.  If you are using #GApplication, this is done
 * automatically for you.
 *
 * The following example shows how you can use #GOptionContext directly
 * in order to correctly deal with Unicode filenames on Windows:
 *
 * |[<!-- language="C" --> 
 * int
 * main (int argc, char **argv)
 * {
 *   GError *error = NULL;
 *   GOptionContext *context;
 *   gchar **args;
 *
 * #ifdef G_OS_WIN32
 *   args = g_win32_get_command_line ();
 * #else
 *   args = g_strdupv (argv);
 * #endif
 *
 *   // set up context
 *
 *   if (!g_option_context_parse_strv (context, &args, &error))
 *     {
 *       // error happened
 *     }
 *
 *   ...
 *
 *   g_strfreev (args);
 *
 *   ...
 * }
 * ]|
 */

#include "config.h"

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

#if defined __OpenBSD__
#include <unistd.h>
#include <sys/sysctl.h>
#endif

#include "goption.h"

#include "gprintf.h"
#include "glibintl.h"

#define TRANSLATE(group, str) (((group)->translate_func ? (* (group)->translate_func) ((str), (group)->translate_data) : (str)))

#define NO_ARG(entry) ((entry)->arg == G_OPTION_ARG_NONE ||       \
                       ((entry)->arg == G_OPTION_ARG_CALLBACK &&  \
                        ((entry)->flags & G_OPTION_FLAG_NO_ARG)))

#define OPTIONAL_ARG(entry) ((entry)->arg == G_OPTION_ARG_CALLBACK &&  \
                       (entry)->flags & G_OPTION_FLAG_OPTIONAL_ARG)

typedef struct
{
  GOptionArg arg_type;
  gpointer arg_data;
  union
  {
    gboolean bool;
    gint integer;
    gchar *str;
    gchar **array;
    gdouble dbl;
    gint64 int64;
  } prev;
  union
  {
    gchar *str;
    struct
    {
      gint len;
      gchar **data;
    } array;
  } allocated;
} Change;

typedef struct
{
  gchar **ptr;
  gchar *value;
} PendingNull;

struct _GOptionContext
{
  GList           *groups;

  gchar           *parameter_string;
  gchar           *summary;
  gchar           *description;

  GTranslateFunc   translate_func;
  GDestroyNotify   translate_notify;
  gpointer         translate_data;

  guint            help_enabled   : 1;
  guint            ignore_unknown : 1;
  guint            strv_mode      : 1;
  guint            strict_posix   : 1;

  GOptionGroup    *main_group;

  /* We keep a list of change so we can revert them */
  GList           *changes;

  /* We also keep track of all argv elements
   * that should be NULLed or modified.
   */
  GList           *pending_nulls;
};

struct _GOptionGroup
{
  gchar           *name;
  gchar           *description;
  gchar           *help_description;

  gint             ref_count;

  GDestroyNotify   destroy_notify;
  gpointer         user_data;

  GTranslateFunc   translate_func;
  GDestroyNotify   translate_notify;
  gpointer         translate_data;

  GOptionEntry    *entries;
  gint             n_entries;

  GOptionParseFunc pre_parse_func;
  GOptionParseFunc post_parse_func;
  GOptionErrorFunc error_func;
};

static void free_changes_list (GOptionContext *context,
                               gboolean        revert);
static void free_pending_nulls (GOptionContext *context,
                                gboolean        perform_nulls);


static int
_g_unichar_get_width (gunichar c)
{
  if (G_UNLIKELY (g_unichar_iszerowidth (c)))
    return 0;

  /* we ignore the fact that we should call g_unichar_iswide_cjk() under
   * some locales (legacy East Asian ones) */
  if (g_unichar_iswide (c))
    return 2;

  return 1;
}

static glong
_g_utf8_strwidth (const gchar *p)
{
  glong len = 0;
  g_return_val_if_fail (p != NULL, 0);

  while (*p)
    {
      len += _g_unichar_get_width (g_utf8_get_char (p));
      p = g_utf8_next_char (p);
    }

  return len;
}

G_DEFINE_QUARK (g-option-context-error-quark, g_option_error)

/**
 * g_option_context_new:
 * @parameter_string: (nullable): a string which is displayed in
 *    the first line of `--help` output, after the usage summary
 *    `programname [OPTION...]`
 *
 * Creates a new option context.
 *
 * The @parameter_string can serve multiple purposes. It can be used
 * to add descriptions for "rest" arguments, which are not parsed by
 * the #GOptionContext, typically something like "FILES" or
 * "FILE1 FILE2...". If you are using #G_OPTION_REMAINING for
 * collecting "rest" arguments, GLib handles this automatically by
 * using the @arg_description of the corresponding #GOptionEntry in
 * the usage summary.
 *
 * Another usage is to give a short summary of the program
 * functionality, like " - frob the strings", which will be displayed
 * in the same line as the usage. For a longer description of the
 * program functionality that should be displayed as a paragraph
 * below the usage line, use g_option_context_set_summary().
 *
 * Note that the @parameter_string is translated using the
 * function set with g_option_context_set_translate_func(), so
 * it should normally be passed untranslated.
 *
 * Returns: a newly created #GOptionContext, which must be
 *    freed with g_option_context_free() after use.
 *
 * Since: 2.6
 */
GOptionContext *
g_option_context_new (const gchar *parameter_string)

{
  GOptionContext *context;

  context = g_new0 (GOptionContext, 1);

  context->parameter_string = g_strdup (parameter_string);
  context->strict_posix = FALSE;
  context->help_enabled = TRUE;
  context->ignore_unknown = FALSE;

  return context;
}

/**
 * g_option_context_free:
 * @context: a #GOptionContext
 *
 * Frees context and all the groups which have been
 * added to it.
 *
 * Please note that parsed arguments need to be freed separately (see
 * #GOptionEntry).
 *
 * Since: 2.6
 */
void g_option_context_free (GOptionContext *context)
{
  g_return_if_fail (context != NULL);

  g_list_free_full (context->groups, (GDestroyNotify) g_option_group_unref);

  if (context->main_group)
    g_option_group_unref (context->main_group);

  free_changes_list (context, FALSE);
  free_pending_nulls (context, FALSE);

  g_free (context->parameter_string);
  g_free (context->summary);
  g_free (context->description);

  if (context->translate_notify)
    (* context->translate_notify) (context->translate_data);

  g_free (context);
}


/**
 * g_option_context_set_help_enabled:
 * @context: a #GOptionContext
 * @help_enabled: %TRUE to enable `--help`, %FALSE to disable it
 *
 * Enables or disables automatic generation of `--help` output.
 * By default, g_option_context_parse() recognizes `--help`, `-h`,
 * `-?`, `--help-all` and `--help-groupname` and creates suitable
 * output to stdout.
 *
 * Since: 2.6
 */
void g_option_context_set_help_enabled (GOptionContext *context,
                                        gboolean        help_enabled)

{
  g_return_if_fail (context != NULL);

  context->help_enabled = help_enabled;
}

/**
 * g_option_context_get_help_enabled:
 * @context: a #GOptionContext
 *
 * Returns whether automatic `--help` generation
 * is turned on for @context. See g_option_context_set_help_enabled().
 *
 * Returns: %TRUE if automatic help generation is turned on.
 *
 * Since: 2.6
 */
gboolean
g_option_context_get_help_enabled (GOptionContext *context)
{
  g_return_val_if_fail (context != NULL, FALSE);

  return context->help_enabled;
}

/**
 * g_option_context_set_ignore_unknown_options:
 * @context: a #GOptionContext
 * @ignore_unknown: %TRUE to ignore unknown options, %FALSE to produce
 *    an error when unknown options are met
 *
 * Sets whether to ignore unknown options or not. If an argument is
 * ignored, it is left in the @argv array after parsing. By default,
 * g_option_context_parse() treats unknown options as error.
 *
 * This setting does not affect non-option arguments (i.e. arguments
 * which don't start with a dash). But note that GOption cannot reliably
 * determine whether a non-option belongs to a preceding unknown option.
 *
 * Since: 2.6
 **/
void
g_option_context_set_ignore_unknown_options (GOptionContext *context,
                                             gboolean        ignore_unknown)
{
  g_return_if_fail (context != NULL);

  context->ignore_unknown = ignore_unknown;
}

/**
 * g_option_context_get_ignore_unknown_options:
 * @context: a #GOptionContext
 *
 * Returns whether unknown options are ignored or not. See
 * g_option_context_set_ignore_unknown_options().
 *
 * Returns: %TRUE if unknown options are ignored.
 *
 * Since: 2.6
 **/
gboolean
g_option_context_get_ignore_unknown_options (GOptionContext *context)
{
  g_return_val_if_fail (context != NULL, FALSE);

  return context->ignore_unknown;
}

/**
 * g_option_context_set_strict_posix:
 * @context: a #GOptionContext
 * @strict_posix: the new value
 *
 * Sets strict POSIX mode.
 *
 * By default, this mode is disabled.
 *
 * In strict POSIX mode, the first non-argument parameter encountered
 * (eg: filename) terminates argument processing.  Remaining arguments
 * are treated as non-options and are not attempted to be parsed.
 *
 * If strict POSIX mode is disabled then parsing is done in the GNU way
 * where option arguments can be freely mixed with non-options.
 *
 * As an example, consider "ls foo -l".  With GNU style parsing, this
 * will list "foo" in long mode.  In strict POSIX style, this will list
 * the files named "foo" and "-l".
 *
 * It may be useful to force strict POSIX mode when creating "verb
 * style" command line tools.  For example, the "gsettings" command line
 * tool supports the global option "--schemadir" as well as many
 * subcommands ("get", "set", etc.) which each have their own set of
 * arguments.  Using strict POSIX mode will allow parsing the global
 * options up to the verb name while leaving the remaining options to be
 * parsed by the relevant subcommand (which can be determined by
 * examining the verb name, which should be present in argv[1] after
 * parsing).
 *
 * Since: 2.44
 **/
void
g_option_context_set_strict_posix (GOptionContext *context,
                                   gboolean        strict_posix)
{
  g_return_if_fail (context != NULL);

  context->strict_posix = strict_posix;
}

/**
 * g_option_context_get_strict_posix:
 * @context: a #GOptionContext
 *
 * Returns whether strict POSIX code is enabled.
 *
 * See g_option_context_set_strict_posix() for more information.
 *
 * Returns: %TRUE if strict POSIX is enabled, %FALSE otherwise.
 *
 * Since: 2.44
 **/
gboolean
g_option_context_get_strict_posix (GOptionContext *context)
{
  g_return_val_if_fail (context != NULL, FALSE);

  return context->strict_posix;
}

/**
 * g_option_context_add_group:
 * @context: a #GOptionContext
 * @group: (transfer full): the group to add
 *
 * Adds a #GOptionGroup to the @context, so that parsing with @context
 * will recognize the options in the group. Note that this will take
 * ownership of the @group and thus the @group should not be freed.
 *
 * Since: 2.6
 **/
void
g_option_context_add_group (GOptionContext *context,
                            GOptionGroup   *group)
{
  GList *list;

  g_return_if_fail (context != NULL);
  g_return_if_fail (group != NULL);
  g_return_if_fail (group->name != NULL);
  g_return_if_fail (group->description != NULL);
  g_return_if_fail (group->help_description != NULL);

  for (list = context->groups; list; list = list->next)
    {
      GOptionGroup *g = (GOptionGroup *)list->data;

      if ((group->name == NULL && g->name == NULL) ||
          (group->name && g->name && strcmp (group->name, g->name) == 0))
        g_warning ("A group named \"%s\" is already part of this GOptionContext",
                   group->name);
    }

  context->groups = g_list_append (context->groups, group);
}

/**
 * g_option_context_set_main_group:
 * @context: a #GOptionContext
 * @group: (transfer full): the group to set as main group
 *
 * Sets a #GOptionGroup as main group of the @context.
 * This has the same effect as calling g_option_context_add_group(),
 * the only difference is that the options in the main group are
 * treated differently when generating `--help` output.
 *
 * Since: 2.6
 **/
void
g_option_context_set_main_group (GOptionContext *context,
                                 GOptionGroup   *group)
{
  g_return_if_fail (context != NULL);
  g_return_if_fail (group != NULL);

  if (context->main_group)
    {
      g_warning ("This GOptionContext already has a main group");

      return;
    }

  context->main_group = group;
}

/**
 * g_option_context_get_main_group:
 * @context: a #GOptionContext
 *
 * Returns a pointer to the main group of @context.
 *
 * Returns: (transfer none): the main group of @context, or %NULL if
 *  @context doesn't have a main group. Note that group belongs to
 *  @context and should not be modified or freed.
 *
 * Since: 2.6
 **/
GOptionGroup *
g_option_context_get_main_group (GOptionContext *context)
{
  g_return_val_if_fail (context != NULL, NULL);

  return context->main_group;
}

/**
 * g_option_context_add_main_entries:
 * @context: a #GOptionContext
 * @entries: a %NULL-terminated array of #GOptionEntrys
 * @translation_domain: (nullable): a translation domain to use for translating
 *    the `--help` output for the options in @entries
 *    with gettext(), or %NULL
 *
 * A convenience function which creates a main group if it doesn't
 * exist, adds the @entries to it and sets the translation domain.
 *
 * Since: 2.6
 **/
void
g_option_context_add_main_entries (GOptionContext      *context,
                                   const GOptionEntry  *entries,
                                   const gchar         *translation_domain)
{
  g_return_if_fail (entries != NULL);

  if (!context->main_group)
    context->main_group = g_option_group_new (NULL, NULL, NULL, NULL, NULL);

  g_option_group_add_entries (context->main_group, entries);
  g_option_group_set_translation_domain (context->main_group, translation_domain);
}

static gint
calculate_max_length (GOptionGroup *group,
                      GHashTable   *aliases)
{
  GOptionEntry *entry;
  gint i, len, max_length;
  const gchar *long_name;

  max_length = 0;

  for (i = 0; i < group->n_entries; i++)
    {
      entry = &group->entries[i];

      if (entry->flags & G_OPTION_FLAG_HIDDEN)
        continue;

      long_name = g_hash_table_lookup (aliases, &entry->long_name);
      if (!long_name)
        long_name = entry->long_name;
      len = _g_utf8_strwidth (long_name);

      if (entry->short_name)
        len += 4;

      if (!NO_ARG (entry) && entry->arg_description)
        len += 1 + _g_utf8_strwidth (TRANSLATE (group, entry->arg_description));

      max_length = MAX (max_length, len);
    }

  return max_length;
}

static void
print_entry (GOptionGroup       *group,
             gint                max_length,
             const GOptionEntry *entry,
             GString            *string,
             GHashTable         *aliases)
{
  GString *str;
  const gchar *long_name;

  if (entry->flags & G_OPTION_FLAG_HIDDEN)
    return;

  if (entry->long_name[0] == 0)
    return;

  long_name = g_hash_table_lookup (aliases, &entry->long_name);
  if (!long_name)
    long_name = entry->long_name;

  str = g_string_new (NULL);

  if (entry->short_name)
    g_string_append_printf (str, "  -%c, --%s", entry->short_name, long_name);
  else
    g_string_append_printf (str, "  --%s", long_name);

  if (entry->arg_description)
    g_string_append_printf (str, "=%s", TRANSLATE (group, entry->arg_description));

  g_string_append_printf (string, "%s%*s %s\n", str->str,
                          (int) (max_length + 4 - _g_utf8_strwidth (str->str)), "",
                          entry->description ? TRANSLATE (group, entry->description) : "");
  g_string_free (str, TRUE);
}

static gboolean
group_has_visible_entries (GOptionContext *context,
                           GOptionGroup *group,
                           gboolean      main_entries)
{
  GOptionFlags reject_filter = G_OPTION_FLAG_HIDDEN;
  GOptionEntry *entry;
  gint i, l;
  gboolean main_group = group == context->main_group;

  if (!main_entries)
    reject_filter |= G_OPTION_FLAG_IN_MAIN;

  for (i = 0, l = (group ? group->n_entries : 0); i < l; i++)
    {
      entry = &group->entries[i];

      if (main_entries && !main_group && !(entry->flags & G_OPTION_FLAG_IN_MAIN))
        continue;
      if (entry->long_name[0] == 0) /* ignore rest entry */
        continue;
      if (!(entry->flags & reject_filter))
        return TRUE;
    }

  return FALSE;
}

static gboolean
group_list_has_visible_entries (GOptionContext *context,
                                GList          *group_list,
                                gboolean       main_entries)
{
  while (group_list)
    {
      if (group_has_visible_entries (context, group_list->data, main_entries))
        return TRUE;

      group_list = group_list->next;
    }

  return FALSE;
}

static gboolean
context_has_h_entry (GOptionContext *context)
{
  gsize i;
  GList *list;

  if (context->main_group)
    {
      for (i = 0; i < context->main_group->n_entries; i++)
        {
          if (context->main_group->entries[i].short_name == 'h')
            return TRUE;
        }
    }

  for (list = context->groups; list != NULL; list = g_list_next (list))
    {
     GOptionGroup *group;

      group = (GOptionGroup*)list->data;
      for (i = 0; i < group->n_entries; i++)
        {
          if (group->entries[i].short_name == 'h')
            return TRUE;
        }
    }
  return FALSE;
}

/**
 * g_option_context_get_help:
 * @context: a #GOptionContext
 * @main_help: if %TRUE, only include the main group
 * @group: (nullable): the #GOptionGroup to create help for, or %NULL
 *
 * Returns a formatted, translated help text for the given context.
 * To obtain the text produced by `--help`, call
 * `g_option_context_get_help (context, TRUE, NULL)`.
 * To obtain the text produced by `--help-all`, call
 * `g_option_context_get_help (context, FALSE, NULL)`.
 * To obtain the help text for an option group, call
 * `g_option_context_get_help (context, FALSE, group)`.
 *
 * Returns: A newly allocated string containing the help text
 *
 * Since: 2.14
 */
gchar *
g_option_context_get_help (GOptionContext *context,
                           gboolean        main_help,
                           GOptionGroup   *group)
{
  GList *list;
  gint max_length = 0, len;
  gint i;
  GOptionEntry *entry;
  GHashTable *shadow_map;
  GHashTable *aliases;
  gboolean seen[256];
  const gchar *rest_description;
  GString *string;
  guchar token;

  string = g_string_sized_new (1024);

  rest_description = NULL;
  if (context->main_group)
    {

      for (i = 0; i < context->main_group->n_entries; i++)
        {
          entry = &context->main_group->entries[i];
          if (entry->long_name[0] == 0)
            {
              rest_description = TRANSLATE (context->main_group, entry->arg_description);
              break;
            }
        }
    }

  g_string_append_printf (string, "%s\n  %s", _("Usage:"), g_get_prgname ());
  if (context->help_enabled ||
      (context->main_group && context->main_group->n_entries > 0) ||
      context->groups != NULL)
    g_string_append_printf (string, " %s", _("[OPTION…]"));

  if (rest_description)
    {
      g_string_append (string, " ");
      g_string_append (string, rest_description);
    }

  if (context->parameter_string)
    {
      g_string_append (string, " ");
      g_string_append (string, TRANSLATE (context, context->parameter_string));
    }

  g_string_append (string, "\n\n");

  if (context->summary)
    {
      g_string_append (string, TRANSLATE (context, context->summary));
      g_string_append (string, "\n\n");
    }

  memset (seen, 0, sizeof (gboolean) * 256);
  shadow_map = g_hash_table_new (g_str_hash, g_str_equal);
  aliases = g_hash_table_new_full (NULL, NULL, NULL, g_free);

  if (context->main_group)
    {
      for (i = 0; i < context->main_group->n_entries; i++)
        {
          entry = &context->main_group->entries[i];
          g_hash_table_insert (shadow_map,
                               (gpointer)entry->long_name,
                               entry);

          if (seen[(guchar)entry->short_name])
            entry->short_name = 0;
          else
            seen[(guchar)entry->short_name] = TRUE;
        }
    }

  list = context->groups;
  while (list != NULL)
    {
      GOptionGroup *g = list->data;
      for (i = 0; i < g->n_entries; i++)
        {
          entry = &g->entries[i];
          if (g_hash_table_lookup (shadow_map, entry->long_name) &&
              !(entry->flags & G_OPTION_FLAG_NOALIAS))
            {
              g_hash_table_insert (aliases, &entry->long_name,
                                   g_strdup_printf ("%s-%s", g->name, entry->long_name));
            }
          else
            g_hash_table_insert (shadow_map, (gpointer)entry->long_name, entry);

          if (seen[(guchar)entry->short_name] &&
              !(entry->flags & G_OPTION_FLAG_NOALIAS))
            entry->short_name = 0;
          else
            seen[(guchar)entry->short_name] = TRUE;
        }
      list = list->next;
    }

  g_hash_table_destroy (shadow_map);

  list = context->groups;

  if (context->help_enabled)
    {
      max_length = _g_utf8_strwidth ("-?, --help");

      if (list)
        {
          len = _g_utf8_strwidth ("--help-all");
          max_length = MAX (max_length, len);
        }
    }

  if (context->main_group)
    {
      len = calculate_max_length (context->main_group, aliases);
      max_length = MAX (max_length, len);
    }

  while (list != NULL)
    {
      GOptionGroup *g = list->data;

      if (context->help_enabled)
        {
          /* First, we check the --help-<groupname> options */
          len = _g_utf8_strwidth ("--help-") + _g_utf8_strwidth (g->name);
          max_length = MAX (max_length, len);
        }

      /* Then we go through the entries */
      len = calculate_max_length (g, aliases);
      max_length = MAX (max_length, len);

      list = list->next;
    }

  /* Add a bit of padding */
  max_length += 4;