grub-savannah-mirror/grub-core/kern/command.c

/* command.c - support basic command */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2009  Free Software Foundation, Inc.
 *
 *  GRUB 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 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/lockdown.h>
#include <grub/mm.h>
#include <grub/command.h>

grub_command_t grub_command_list;

grub_command_t
grub_register_command_prio (const char *name,
			    grub_command_func_t func,
			    const char *summary,
			    const char *description,
			    int prio)
{
  grub_command_t cmd;
  int inactive = 0;

  grub_command_t *p, q;

  cmd = (grub_command_t) grub_zalloc (sizeof (*cmd));
  if (! cmd)
    return 0;

  cmd->name = name;
  cmd->func = func;
  cmd->summary = (summary) ? summary : "";
  cmd->description = description;

  cmd->flags = 0;
  cmd->prio = prio;

  for (p = &grub_command_list, q = *p; q; p = &(q->next), q = q->next)
    {
      int r;

      r = grub_strcmp (cmd->name, q->name);
      if (r < 0)
	break;
      if (r > 0)
	continue;

      if (cmd->prio >= (q->prio & GRUB_COMMAND_PRIO_MASK))
	{
	  q->prio &= ~GRUB_COMMAND_FLAG_ACTIVE;
	  break;
	}

      inactive = 1;
    }

  *p = cmd;
  cmd->next = q;
  if (q)
    q->prev = &cmd->next;
  cmd->prev = p;

  if (! inactive)
    cmd->prio |= GRUB_COMMAND_FLAG_ACTIVE;

  return cmd;
}

static grub_err_t
grub_cmd_lockdown (grub_command_t cmd __attribute__ ((unused)),
                   int argc __attribute__ ((unused)),
                   char **argv __attribute__ ((unused)))

{
  return grub_error (GRUB_ERR_ACCESS_DENIED,
                     N_("%s: the command is not allowed when lockdown is enforced"),
                     cmd->name);
}

grub_command_t
grub_register_command_lockdown (const char *name,
                                grub_command_func_t func,
                                const char *summary,
                                const char *description)
{
  if (grub_is_lockdown () == GRUB_LOCKDOWN_ENABLED)
    func = grub_cmd_lockdown;

  return grub_register_command_prio (name, func, summary, description, 0);
}

void
grub_unregister_command (grub_command_t cmd)
{
  if ((cmd->prio & GRUB_COMMAND_FLAG_ACTIVE) && (cmd->next))
    cmd->next->prio |= GRUB_COMMAND_FLAG_ACTIVE;
  grub_list_remove (GRUB_AS_LIST (cmd));
  grub_free (cmd);
}