2009-12-21 Robert Millan <rmh.grub@aybabtu.com>

* util/mkisofs/msdos_partition.h: New file (based on
        include/grub/msdos_partition.h).
        * util/mkisofs/mkisofs.c (use_protective_msdos_label): New variable.
        (OPTION_PROTECTIVE_MSDOS_LABEL): New macro.
        (ld_options, main): Recognize --protective-msdos-label.
        * util/mkisofs/mkisofs.h (use_protective_msdos_label): New declaration.
        * util/mkisofs/write.c: Include `"msdos_partition.h"'.
        (padblock_write): If `use_protective_msdos_label' is set, patch a
        protective DOS-style label in the output image.

        * util/grub-mkrescue.in: Use --protective-msdos-label.

ChangeLog

@@ -1,3 +1,17 @@
+2009-12-21  Robert Millan  <rmh.grub@aybabtu.com>
+
+	* util/mkisofs/msdos_partition.h: New file (based on
+	include/grub/msdos_partition.h).
+	* util/mkisofs/mkisofs.c (use_protective_msdos_label): New variable.
+	(OPTION_PROTECTIVE_MSDOS_LABEL): New macro.
+	(ld_options, main): Recognize --protective-msdos-label.
+	* util/mkisofs/mkisofs.h (use_protective_msdos_label): New declaration.
+	* util/mkisofs/write.c: Include `"msdos_partition.h"'.
+	(padblock_write): If `use_protective_msdos_label' is set, patch a
+	protective DOS-style label in the output image.
+
+	* util/grub-mkrescue.in: Use --protective-msdos-label.
+
 2009-12-21  Robert Millan  <rmh.grub@aybabtu.com>
 
 	* util/grub-mkrescue.in: Do not zero-pad image for BIOS-based disk

util/grub-mkrescue.in

@@ -180,7 +180,7 @@ if test -e "${pc_dir}" ; then
 fi
 
 # build iso image
-grub-mkisofs ${grub_mkisofs_arguments} -o ${output_image} -r ${iso9660_dir} ${source}
+grub-mkisofs ${grub_mkisofs_arguments} --protective-msdos-label -o ${output_image} -r ${iso9660_dir} ${source}
 rm -rf ${iso9660_dir}
 
 rm -f ${embed_img}

util/mkisofs/mkisofs.c

@@ -91,6 +91,7 @@ int extension_record_size = 0;
 int use_eltorito = 0;
 int use_eltorito_emul_floppy = 0;
 int use_embedded_boot = 0;
+int use_protective_msdos_label = 0;
 int use_boot_info_table = 0;
 int use_RockRidge = 0;
 int use_Joliet = 0;
@@ -199,6 +200,8 @@ struct ld_option
 
 #define OPTION_VERSION			173
 
+#define OPTION_PROTECTIVE_MSDOS_LABEL	174
+
 static const struct ld_option ld_options[] =
 {
   { {"all-files", no_argument, NULL, 'a'},
@@ -213,6 +216,8 @@ static const struct ld_option ld_options[] =
       '\0', N_("FILE"), N_("Set Copyright filename"), ONE_DASH },
   { {"embedded-boot", required_argument, NULL, 'G'},
       'G', N_("FILE"), N_("Set embedded boot image name"), TWO_DASHES },
+  { {"protective-msdos-label", no_argument, NULL, OPTION_PROTECTIVE_MSDOS_LABEL },
+      '\0', NULL, N_("Patch a protective DOS-style label in the image"), TWO_DASHES },
   { {"eltorito-boot", required_argument, NULL, 'b'},
       'b', N_("FILE"), N_("Set El Torito boot image name"), ONE_DASH },
   { {"eltorito-catalog", required_argument, NULL, 'c'},
@@ -726,11 +731,14 @@ int FDECL2(main, int, argc, char **, argv){
 	  error (1, 0, _("Required boot image pathname missing"));
 	break;
       case 'G':
-	use_embedded_boot++;
+	use_embedded_boot = 1;
 	boot_image_embed = optarg;  /* pathname of the boot image on host filesystem */
 	if (boot_image_embed == NULL)
 	  error (1, 0, _("Required boot image pathname missing"));
 	break;
+      case OPTION_PROTECTIVE_MSDOS_LABEL:
+	use_protective_msdos_label = 1;
+	break;
       case 'c':
 	use_eltorito++;
 	boot_catalog = optarg;  /* pathname of the boot image on cd */

util/mkisofs/mkisofs.h

@@ -297,6 +297,7 @@ extern struct iso_directory_record jroot_record;
 
 extern int use_eltorito;
 extern int use_embedded_boot;
+extern int use_protective_msdos_label;
 extern int use_eltorito_emul_floppy;
 extern int use_boot_info_table;
 extern int use_RockRidge;

util/mkisofs/msdos_partition.h

@@ -0,0 +1,75 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 1999,2000,2001,2002,2004,2007  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/>.
+ */
+
+#ifndef MSDOS_PARTITION_H
+#define MSDOS_PARTITION_H	1
+
+#include <stdint.h>
+
+/* The signature.  */
+#define MSDOS_PARTITION_SIGNATURE		((0xaa << 8) | 0x55)
+
+/* This is not a flag actually, but used as if it were a flag.  */
+#define MSDOS_PARTITION_TYPE_HIDDEN_FLAG	0x10
+
+/* The partition entry.  */
+struct msdos_partition_entry
+{
+  /* If active, 0x80, otherwise, 0x00.  */
+  uint8_t flag;
+
+  /* The head of the start.  */
+  uint8_t start_head;
+
+  /* (S | ((C >> 2) & 0xC0)) where S is the sector of the start and C
+     is the cylinder of the start. Note that S is counted from one.  */
+  uint8_t start_sector;
+
+  /* (C & 0xFF) where C is the cylinder of the start.  */
+  uint8_t start_cylinder;
+
+  /* The partition type.  */
+  uint8_t type;
+
+  /* The end versions of start_head, start_sector and start_cylinder,
+     respectively.  */
+  uint8_t end_head;
+  uint8_t end_sector;
+  uint8_t end_cylinder;
+
+  /* The start sector. Note that this is counted from zero.  */
+  uint32_t start;
+
+  /* The length in sector units.  */
+  uint32_t length;
+} __attribute__ ((packed));
+
+/* The structure of MBR.  */
+struct msdos_partition_mbr
+{
+  /* The code area (actually, including BPB).  */
+  uint8_t code[446];
+
+  /* Four partition entries.  */
+  struct msdos_partition_entry entries[4];
+
+  /* The signature 0xaa55.  */
+  uint16_t signature;
+} __attribute__ ((packed));
+
+#endif

util/mkisofs/write.c

@@ -21,11 +21,10 @@
    along with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "config.h"
+
 #include <string.h>
 #include <stdlib.h>
-#include "config.h"
-#include "mkisofs.h"
-#include "iso9660.h"
 #include <time.h>
 #include <errno.h>
 
@@ -37,6 +36,10 @@
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
+
+#include "mkisofs.h"
+#include "iso9660.h"
+#include "msdos_partition.h"
  
 #ifdef __SVR4
 extern char * strdup(const char *);
@@ -1424,7 +1427,6 @@ static int FDECL1(dirtree_cleanup, FILE *, outfile)
 static int FDECL1(padblock_write, FILE *, outfile)
 {
   char *buffer;
-  int i;
 
   buffer = e_malloc (2048 * PADBLOCK_SIZE);
   memset (buffer, 0, 2048 * PADBLOCK_SIZE);
@@ -1437,6 +1439,29 @@ static int FDECL1(padblock_write, FILE *, outfile)
       fread (buffer, 2048 * PADBLOCK_SIZE, 1, fp);
     }
 
+  if (use_protective_msdos_label)
+    {
+      struct msdos_partition_mbr *mbr = (void *) buffer;
+
+      memset (mbr->entries, 0, sizeof(mbr->entries));
+
+      /* Some idiotic BIOSes refuse to boot if they don't find at least
+	 one partition with active bit set.  */
+      mbr->entries[0].flag = 0x80;
+
+      /* Doesn't really matter, as long as it's non-zero.  It seems that
+         0xCD is used elsewhere, so we follow suit.  */
+      mbr->entries[0].type = 0xcd;
+
+      /* Start immediately (sector 1).  */
+      mbr->entries[0].start = 1;
+
+      /* We don't know yet.  Let's keep it safe.  */
+      mbr->entries[0].length = UINT32_MAX;
+
+      mbr->signature = MSDOS_PARTITION_SIGNATURE;
+    }
+
   xfwrite (buffer, 1, 2048 * PADBLOCK_SIZE, outfile);
   last_extent_written += PADBLOCK_SIZE;