kern/main.c

   1 /* main.c - the kernel main routine */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2002,2003,2005,2006,2008  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/kernel.h>
  21 #include <grub/misc.h>
  22 #include <grub/symbol.h>
  23 #include <grub/dl.h>
  24 #include <grub/term.h>
  25 #include <grub/rescue.h>
  26 #include <grub/file.h>
  27 #include <grub/device.h>
  28 #include <grub/env.h>
  29
  30 void
  31 grub_module_iterate (int (*hook) (struct grub_module_header *header))
  32 {
  33   struct grub_module_info *modinfo;
  34   struct grub_module_header *header;
  35   grub_addr_t modbase;
  36
  37   modbase = grub_arch_modules_addr ();
  38   modinfo = (struct grub_module_info *) modbase;
  39
  40   /* Check if there are any modules.  */
  41   if ((modinfo == 0) || modinfo->magic != GRUB_MODULE_MAGIC)
  42     return;
  43
  44   for (header = (struct grub_module_header *) (modbase + modinfo->offset);
  45        header < (struct grub_module_header *) (modbase + modinfo->size);
  46        header = (struct grub_module_header *) ((char *) header + header->size))
  47     {
  48       if (hook (header))
  49         break;
  50     }
  51 }
  52
  53 /* Load all modules in core.  */
  54 static void
  55 grub_load_modules (void)
  56 {
  57   auto int hook (struct grub_module_header *);
  58   int hook (struct grub_module_header *header)
  59     {
  60       /* Not an ELF module, skip.  */
  61       if (header->type != OBJ_TYPE_ELF)
  62         return 0;
  63
  64       if (! grub_dl_load_core ((char *) header + sizeof (struct grub_module_header),
  65                                (header->size - sizeof (struct grub_module_header))))
  66         grub_fatal ("%s", grub_errmsg);
  67
  68       return 0;
  69     }
  70
  71   grub_module_iterate (hook);
  72 }
  73
  74 /* Write hook for the environment variables of root. Remove surrounding
  75    parentheses, if any.  */
  76 static char *
  77 grub_env_write_root (struct grub_env_var *var __attribute__ ((unused)),
  78                      const char *val)
  79 {
  80   /* XXX Is it better to check the existence of the device?  */
  81   grub_size_t len = grub_strlen (val);
  82
  83   if (val[0] == '(' && val[len - 1] == ')')
  84     return grub_strndup (val + 1, len - 2);
  85
  86   return grub_strdup (val);
  87 }
  88
  89 /* Set the root device according to the dl prefix.  */
  90 static void
  91 grub_set_root_dev (void)
  92 {
  93   const char *prefix;
  94
  95   grub_register_variable_hook ("root", 0, grub_env_write_root);
  96   grub_env_export ("root");
  97
  98   prefix = grub_env_get ("prefix");
  99
 100   if (prefix)
 101     {
 102       char *dev;
 103
 104       dev = grub_file_get_device_name (prefix);
 105       if (dev)
 106         {
 107           grub_env_set ("root", dev);
 108           grub_free (dev);
 109         }
 110     }
 111 }
 112
 113 /* Load the normal mode module and execute the normal mode if possible.  */
 114 static void
 115 grub_load_normal_mode (void)
 116 {
 117   /* Load the module.  */
 118   grub_dl_load ("normal");
 119
 120   /* Something went wrong.  Print errors here to let user know why we're entering rescue mode.  */
 121   grub_print_error ();
 122 }
 123
 124 /* The main routine.  */
 125 void
 126 grub_main (void)
 127 {
 128   /* First of all, initialize the machine.  */
 129   grub_machine_init ();
 130
 131   /* Hello.  */
 132   grub_setcolorstate (GRUB_TERM_COLOR_HIGHLIGHT);
 133   grub_printf ("Welcome to GRUB!\n\n");
 134   grub_setcolorstate (GRUB_TERM_COLOR_STANDARD);
 135
 136   /* Load pre-loaded modules and free the space.  */
 137   grub_register_exported_symbols ();
 138   grub_load_modules ();
 139
 140   /* It is better to set the root device as soon as possible,
 141      for convenience.  */
 142   grub_machine_set_prefix ();
 143   grub_env_export ("prefix");
 144   grub_set_root_dev ();
 145
 146   /* Load the normal mode module.  */
 147   grub_load_normal_mode ();
 148
 149   /* Enter the rescue mode.  */
 150   grub_enter_rescue_mode ();
 151 }