text: /*
   * kernel/command/cmd-help.c
   *
   * Copyright(c) 2007-2019 Jianjun Jiang <8192542@qq.com>
   * Official site: http://xboot.org
   * Mobile phone: +86-18665388956
   * QQ: 8192542
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   *
   */
  
  #include <xboot.h>
  #include <command/command.h>
  
  static void usage(void)
  {
  	printf("usage:\r\n");
  	printf("    help [command ...]\r\n");
  }
  
  static int do_help(int argc, char ** argv)
  {
  	struct command_t * pos, * n;
  	struct command_t * c;
  	struct slist_t * sl, * e;
  	int i, j, k = 0;
  
  	if(argc == 1)
  	{
  		sl = slist_alloc();
  		list_for_each_entry_safe(pos, n, &__command_list, list)
  		{
  			j = strlen(pos->name);
  			if(j > k)
  				k = j;
  			slist_add(sl, pos, "%s", pos->name);
  		}
  		slist_sort(sl);
  		slist_for_each_entry(e, sl)
  		{
  			pos = (struct command_t *)e->priv;
  			printf(" %s%*s - %s\r\n", pos->name, k - strlen(pos->name), "", pos->desc);
  		}
  		slist_free(sl);
  	}
  	else
  	{
  		for(i = 1; i < argc; i++)
  		{
  			c = search_command(argv[i]);
  			if(c)
  			{
  				printf("%s - %s\r\n", c->name, c->desc);
  				if(c->usage)
  					c->usage();
  			}
  			else
  			{
  				printf("unknown command '%s' - try 'help' for list all of commands\r\n", argv[i]);
  			}
  		}
  	}
  	return 0;
  }
  
  static struct command_t cmd_help = {
  	.name	= "help",
  	.desc	= "show online help about command",
  	.usage	= usage,
  	.exec	= do_help,
  };
  
  static __init void help_cmd_init(void)
  {
  	register_command(&cmd_help);
  }
  
  static __exit void help_cmd_exit(void)
  {
  	unregister_command(&cmd_help);
  }
  
  command_initcall(help_cmd_init);
  command_exitcall(help_cmd_exit);
  