commands/help.c

   1 /* help.c - command to show a help text.  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2005,2007,2008  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/dl.h>
  21 #include <grub/misc.h>
  22 #include <grub/term.h>
  23 #include <grub/extcmd.h>
  24
  25 static grub_err_t
  26 grub_cmd_help (grub_extcmd_t ext __attribute__ ((unused)), int argc,
  27                char **args)
  28 {
  29   int cnt = 0;
  30   char *currarg;
  31
  32   auto int print_command_info (grub_command_t cmd);
  33   auto int print_command_help (grub_command_t cmd);
  34
  35   int print_command_info (grub_command_t cmd)
  36     {
  37       if ((cmd->prio & GRUB_PRIO_LIST_FLAG_ACTIVE) &&
  38           (cmd->flags & GRUB_COMMAND_FLAG_CMDLINE))
  39         {
  40           char description[GRUB_TERM_WIDTH / 2];
  41           int desclen = grub_strlen (cmd->summary);
  42
  43           /* Make a string with a length of GRUB_TERM_WIDTH / 2 - 1 filled
  44              with the description followed by spaces.  */
  45           grub_memset (description, ' ', GRUB_TERM_WIDTH / 2 - 1);
  46           description[GRUB_TERM_WIDTH / 2 - 1] = '\0';
  47           grub_memcpy (description, cmd->summary,
  48                        (desclen < GRUB_TERM_WIDTH / 2 - 1
  49                         ? desclen : GRUB_TERM_WIDTH / 2 - 1));
  50
  51           grub_printf ("%s%s", description, (cnt++) % 2 ? "\n" : " ");
  52         }
  53       return 0;
  54     }
  55
  56   int print_command_help (grub_command_t cmd)
  57     {
  58       if (cmd->prio & GRUB_PRIO_LIST_FLAG_ACTIVE)
  59         {
  60           if (! grub_strncmp (cmd->name, currarg, grub_strlen (currarg)))
  61             {
  62               if (cnt++ > 0)
  63                 grub_printf ("\n\n");
  64
  65               if (cmd->flags & GRUB_COMMAND_FLAG_EXTCMD)
  66                 grub_arg_show_help ((grub_extcmd_t) cmd->data);
  67               else
  68                 grub_printf ("Usage: %s\n%s\b", cmd->summary,
  69                              cmd->description);
  70             }
  71         }
  72       return 0;
  73     }
  74
  75   if (argc == 0)
  76     grub_command_iterate (print_command_info);
  77   else
  78     {
  79       int i;
  80
  81       for (i = 0; i < argc; i++)
  82         {
  83           currarg = args[i];
  84           grub_command_iterate (print_command_help);
  85         }
  86     }
  87
  88   return 0;
  89 }
  90
  91 static grub_extcmd_t cmd;
  92 \f
  93 GRUB_MOD_INIT(help)
  94 {
  95   cmd = grub_register_extcmd ("help", grub_cmd_help,
  96                               GRUB_COMMAND_FLAG_CMDLINE,
  97                               "help [PATTERN ...]",
  98                               "Show a help message.", 0);
  99 }
 100
 101 GRUB_MOD_FINI(help)
 102 {
 103   grub_unregister_extcmd (cmd);
 104 }