normal/context.c

   1 /* env.c - Environment variables */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2003,2005,2006,2007,2008,2009  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/env.h>
  21 #include <grub/env_private.h>
  22 #include <grub/misc.h>
  23 #include <grub/mm.h>
  24 #include <grub/command.h>
  25 #include <grub/normal.h>
  26
  27 struct menu_pointer
  28 {
  29   grub_menu_t menu;
  30   struct menu_pointer *prev;
  31 };
  32
  33 struct menu_pointer initial_menu;
  34 struct menu_pointer *current_menu = &initial_menu;
  35
  36 void
  37 grub_env_unset_menu (void)
  38 {
  39   current_menu->menu = NULL;
  40 }
  41
  42 grub_menu_t
  43 grub_env_get_menu (void)
  44 {
  45   return current_menu->menu;
  46 }
  47
  48 void
  49 grub_env_set_menu (grub_menu_t nmenu)
  50 {
  51   current_menu->menu = nmenu;
  52 }
  53
  54 grub_err_t
  55 grub_env_context_open (int export)
  56 {
  57   struct grub_env_context *context;
  58   int i;
  59   struct menu_pointer *menu;
  60
  61   context = grub_zalloc (sizeof (*context));
  62   if (! context)
  63     return grub_errno;
  64   menu = grub_zalloc (sizeof (*menu));
  65   if (! menu)
  66     return grub_errno;
  67
  68   context->prev = grub_current_context;
  69   grub_current_context = context;
  70
  71   menu->prev = current_menu;
  72   current_menu = menu;
  73
  74   /* Copy exported variables.  */
  75   for (i = 0; i < HASHSZ; i++)
  76     {
  77       struct grub_env_var *var;
  78
  79       for (var = context->prev->vars[i]; var; var = var->next)
  80         {
  81           if (export && var->global)
  82             {
  83               if (grub_env_set (var->name, var->value) != GRUB_ERR_NONE)
  84                 {
  85                   grub_env_context_close ();
  86                   return grub_errno;
  87                 }
  88               grub_env_export (var->name);
  89               grub_register_variable_hook (var->name, var->read_hook, var->write_hook);
  90             }
  91         }
  92     }
  93
  94   return GRUB_ERR_NONE;
  95 }
  96
  97 grub_err_t
  98 grub_env_context_close (void)
  99 {
 100   struct grub_env_context *context;
 101   int i;
 102   struct menu_pointer *menu;
 103
 104   if (! grub_current_context->prev)
 105     return grub_error (GRUB_ERR_BAD_ARGUMENT,
 106                        "cannot close the initial context");
 107
 108   /* Free the variables associated with this context.  */
 109   for (i = 0; i < HASHSZ; i++)
 110     {
 111       struct grub_env_var *p, *q;
 112
 113       for (p = grub_current_context->vars[i]; p; p = q)
 114         {
 115           q = p->next;
 116           grub_free (p->name);
 117           grub_free (p->value);
 118           grub_free (p);
 119         }
 120     }
 121
 122   /* Restore the previous context.  */
 123   context = grub_current_context->prev;
 124   grub_free (grub_current_context);
 125   grub_current_context = context;
 126
 127   menu = current_menu->prev;
 128   grub_free (current_menu);
 129   current_menu = menu;
 130
 131   return GRUB_ERR_NONE;
 132 }
 133
 134 grub_err_t
 135 grub_env_export (const char *name)
 136 {
 137   struct grub_env_var *var;
 138
 139   var = grub_env_find (name);
 140   if (! var)
 141     {
 142       grub_err_t err;
 143
 144       err = grub_env_set (name, "");
 145       if (err)
 146         return err;
 147       var = grub_env_find (name);
 148     }
 149   var->global = 1;
 150
 151   return GRUB_ERR_NONE;
 152 }
 153
 154 static grub_command_t export_cmd;
 155
 156 static grub_err_t
 157 grub_cmd_export (struct grub_command *cmd __attribute__ ((unused)),
 158                  int argc, char **args)
 159 {
 160   if (argc < 1)
 161     return grub_error (GRUB_ERR_BAD_ARGUMENT,
 162                        "no environment variable specified");
 163
 164   grub_env_export (args[0]);
 165   return 0;
 166 }
 167
 168 void
 169 grub_context_init (void)
 170 {
 171   grub_env_export ("root");
 172   grub_env_export ("prefix");
 173
 174   export_cmd = grub_register_command ("export", grub_cmd_export,
 175                                       "export ENVVAR", "Export a variable.");
 176 }
 177
 178 void
 179 grub_context_fini (void)
 180 {
 181   grub_unregister_command (export_cmd);
 182 }