loader/multiboot_loader.c

   1 /* multiboot_loader.c - boot multiboot 1 or 2 OS image */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 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/machine/machine.h>
  21 #include <grub/multiboot.h>
  22 #include <grub/multiboot2.h>
  23 #include <multiboot2.h>
  24 #include <grub/elf.h>
  25 #include <grub/file.h>
  26 #include <grub/err.h>
  27 #include <grub/dl.h>
  28 #include <grub/mm.h>
  29 #include <grub/misc.h>
  30 #include <grub/gzio.h>
  31 #include <grub/command.h>
  32
  33 grub_dl_t my_mod;
  34
  35 /* This tracks which version of multiboot to use when using
  36  * the module command. By default use multiboot version 1.
  37  * values:
  38  *      1 - Multiboot version 1
  39  *      2 - Multiboot version 2
  40  */
  41
  42 static unsigned int module_version_status = 1;
  43
  44 static int
  45 find_multi_boot1_header (grub_file_t file)
  46 {
  47   struct grub_multiboot_header *header;
  48   char buffer[MULTIBOOT_SEARCH];
  49   int found_status = 0;
  50   grub_ssize_t len;
  51
  52   len = grub_file_read (file, buffer, MULTIBOOT_SEARCH);
  53   if (len < 32)
  54     return found_status;
  55
  56   /* Look for the multiboot header in the buffer.  The header should
  57      be at least 12 bytes and aligned on a 4-byte boundary.  */
  58   for (header = (struct grub_multiboot_header *) buffer;
  59       ((char *) header <= buffer + len - 12) || (header = 0);
  60       header = (struct grub_multiboot_header *) ((char *) header + 4))
  61     {
  62       if (header->magic == MULTIBOOT_MAGIC
  63           && !(header->magic + header->flags + header->checksum))
  64         {
  65            found_status = 1;
  66            break;
  67         }
  68      }
  69
  70    return found_status;
  71 }
  72
  73 static int
  74 find_multi_boot2_header (grub_file_t file)
  75 {
  76   struct multiboot_header *header;
  77   char buffer[MULTIBOOT_SEARCH];
  78   int found_status = 0;
  79   grub_ssize_t len;
  80
  81   len = grub_file_read (file, buffer, MULTIBOOT_SEARCH);
  82   if (len < 32)
  83     return found_status;
  84
  85   /* Look for the multiboot header in the buffer.  The header should
  86      be at least 8 bytes and aligned on a 8-byte boundary.  */
  87   for (header = (struct multiboot_header *) buffer;
  88       ((char *) header <= buffer + len - 8) || (header = 0);
  89       header = (struct multiboot_header *) ((char *) header + 8))
  90     {
  91       if (header->magic == MULTIBOOT2_HEADER_MAGIC)
  92         {
  93            found_status = 1;
  94            break;
  95         }
  96      }
  97
  98    return found_status;
  99 }
 100
 101 static grub_err_t
 102 grub_cmd_multiboot_loader (grub_command_t cmd __attribute__ ((unused)),
 103                            int argc, char *argv[])
 104 {
 105   grub_file_t file = 0;
 106   int header_multi_ver_found = 0;
 107
 108   grub_dl_ref (my_mod);
 109
 110   if (argc == 0)
 111     {
 112       grub_error (GRUB_ERR_BAD_ARGUMENT, "No kernel specified");
 113       goto fail;
 114     }
 115
 116   file = grub_gzfile_open (argv[0], 1);
 117   if (! file)
 118     {
 119       grub_error (GRUB_ERR_BAD_ARGUMENT, "Couldn't open file");
 120       goto fail;
 121     }
 122
 123   /* find which header is in the file */
 124   if (find_multi_boot1_header (file))
 125     header_multi_ver_found = 1;
 126   else if (find_multi_boot2_header (file))
 127     header_multi_ver_found = 2;
 128   else
 129     {
 130       grub_error (GRUB_ERR_BAD_OS, "Multiboot header not found");
 131       goto fail;
 132     }
 133
 134   /* close file before calling functions */
 135   if (file)
 136     grub_file_close (file);
 137
 138   /* Launch multi boot with header */
 139
 140   /* XXX Find a better way to identify this.
 141      This is for i386-pc */
 142 #if defined(GRUB_MACHINE_PCBIOS) || defined(GRUB_MACHINE_LINUXBIOS)
 143   if (header_multi_ver_found == 1)
 144     {
 145       grub_dprintf ("multiboot_loader",
 146                     "Launching multiboot 1 grub_multiboot() function\n");
 147       grub_multiboot (argc, argv);
 148       module_version_status = 1;
 149     }
 150 #endif
 151   if (header_multi_ver_found == 0 || header_multi_ver_found == 2)
 152     {
 153       grub_dprintf ("multiboot_loader",
 154                     "Launching multiboot 2 grub_multiboot2() function\n");
 155       grub_multiboot2 (argc, argv);
 156       module_version_status = 2;
 157     }
 158
 159   return grub_errno;
 160
 161 fail:
 162   if (file)
 163     grub_file_close (file);
 164
 165   grub_dl_unref (my_mod);
 166
 167   return grub_errno;
 168 }
 169
 170 static grub_err_t
 171 grub_cmd_module_loader (grub_command_t cmd __attribute__ ((unused)),
 172                         int argc, char *argv[])
 173 {
 174
 175 #if defined(GRUB_MACHINE_PCBIOS) || defined(GRUB_MACHINE_LINUXBIOS)
 176   if (module_version_status == 1)
 177     {
 178       grub_dprintf("multiboot_loader",
 179            "Launching multiboot 1 grub_module() function\n");
 180       grub_module (argc, argv);
 181     }
 182 #endif
 183   if (module_version_status == 2)
 184     {
 185       grub_dprintf("multiboot_loader",
 186           "Launching multiboot 2 grub_module2() function\n");
 187       grub_module2 (argc, argv);
 188     }
 189
 190   return grub_errno;
 191 }
 192
 193 static grub_command_t cmd_multiboot, cmd_module;
 194
 195 GRUB_MOD_INIT(multiboot)
 196 {
 197   cmd_multiboot =
 198     grub_register_command ("multiboot", grub_cmd_multiboot_loader,
 199                            0, "load a multiboot kernel");
 200   cmd_module =
 201     grub_register_command ("module", grub_cmd_module_loader,
 202                            0, "load a multiboot module");
 203
 204   my_mod = mod;
 205 }
 206
 207 GRUB_MOD_FINI(multiboot)
 208 {
 209   grub_unregister_command (cmd_multiboot);
 210   grub_unregister_command (cmd_module);
 211 }