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