From 2164da6b25efcc410b9624c8b95aaabd7340b82e Mon Sep 17 00:00:00 2001
From: Colin Watson <cjwatson@ubuntu.com>
Date: Thu, 17 Jun 2010 12:15:37 +0100
Subject: [PATCH] Fix i386-pc prefix handling with nested partitions (Debian
 bug #585068).  Note that the case where the core image is booted using
 multiboot and relocated from its original location still requires more work.
 * kern/i386/pc/init.c (make_install_device): If the prefix starts with "(,",
 fill the boot drive in between those two characters, but expect that a full
 partition specification including partition map names will follow. *
 util/i386/pc/grub-setup.c (setup): Unless an explicit prefix was specified,
 write a prefix without the drive name but including a full partition
 specification.

---
 ChangeLog                 | 15 +++++++++++++++
 kern/i386/pc/init.c       |  8 ++++++++
 util/i386/pc/grub-setup.c | 15 +++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 88e1e43d6..e2f240f40 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2010-06-17  Colin Watson  <cjwatson@ubuntu.com>
+
+	Fix i386-pc prefix handling with nested partitions (Debian bug
+	#585068).  Note that the case where the core image is booted using
+	multiboot and relocated from its original location still requires
+	more work.
+
+	* kern/i386/pc/init.c (make_install_device): If the prefix starts
+	with "(,", fill the boot drive in between those two characters, but
+	expect that a full partition specification including partition map
+	names will follow.
+	* util/i386/pc/grub-setup.c (setup): Unless an explicit prefix was
+	specified, write a prefix without the drive name but including a
+	full partition specification.
+
 2010-06-16  Colin Watson  <cjwatson@ubuntu.com>
 
 	* util/grub-mkconfig.in: Ignore non-option arguments, for
diff --git a/kern/i386/pc/init.c b/kern/i386/pc/init.c
index d81b1e117..8cbc757b2 100644
--- a/kern/i386/pc/init.c
+++ b/kern/i386/pc/init.c
@@ -83,6 +83,14 @@ make_install_device (void)
       grub_snprintf (ptr, sizeof (dev) - (ptr - dev), ")%s", grub_prefix);
       grub_strcpy (grub_prefix, dev);
     }
+  else if (grub_prefix[1] == ',' || grub_prefix[1] == ')')
+    {
+      /* We have a prefix, but still need to fill in the boot drive.  */
+      grub_snprintf (dev, sizeof (dev),
+		     "(%cd%u%s", (grub_boot_drive & 0x80) ? 'h' : 'f',
+		     grub_boot_drive & 0x7f, grub_prefix + 1);
+      grub_strcpy (grub_prefix, dev);
+    }
 
   return grub_prefix;
 }
diff --git a/util/i386/pc/grub-setup.c b/util/i386/pc/grub-setup.c
index f0baf1c89..454fba9fa 100644
--- a/util/i386/pc/grub-setup.c
+++ b/util/i386/pc/grub-setup.c
@@ -99,6 +99,7 @@ setup (const char *dir,
   struct grub_boot_blocklist *first_block, *block;
   grub_int32_t *install_dos_part, *install_bsd_part;
   grub_int32_t dos_part, bsd_part;
+  char *prefix;
   char *tmp_img;
   int i;
   grub_disk_addr_t first_sector;
@@ -230,6 +231,8 @@ setup (const char *dir,
 				       + GRUB_KERNEL_MACHINE_INSTALL_DOS_PART);
   install_bsd_part = (grub_int32_t *) (core_img + GRUB_DISK_SECTOR_SIZE
 				       + GRUB_KERNEL_MACHINE_INSTALL_BSD_PART);
+  prefix = (char *) (core_img + GRUB_DISK_SECTOR_SIZE +
+		     GRUB_KERNEL_MACHINE_PREFIX);
 
   /* Open the root device and the destination device.  */
   root_dev = grub_device_open (root);
@@ -305,6 +308,18 @@ setup (const char *dir,
 	      dos_part = root_dev->disk->partition->number;
  	      bsd_part = -1;
  	    }
+
+	  if (prefix[0] != '(')
+	    {
+	      char *root_part_name, *new_prefix;
+
+	      root_part_name =
+		grub_partition_get_name (root_dev->disk->partition);
+	      new_prefix = xasprintf ("(,%s)%s", root_part_name, prefix);
+	      strcpy (prefix, new_prefix);
+	      free (new_prefix);
+	      free (root_part_name);
+	    }
 	}
       else
 	dos_part = bsd_part = -1;