2009-09-10  Colin Watson  <address@hidden>

	* disk/loopback.c (struct grub_loopback): Add `root' member.
	(delete_loopback): Free `dev->root'.
	(grub_cmd_loopback): Save the `root' environment variable.
	(grub_loopback_open): Set the `root' environment variable
	temporarily to that which was in effect when the `loopback' command
	was run.

Index: disk/loopback.c
===================================================================
--- disk/loopback.c	(revision 2584)
+++ disk/loopback.c	(working copy)
@@ -23,10 +23,12 @@
 #include <grub/disk.h>
 #include <grub/mm.h>
 #include <grub/extcmd.h>
+#include <grub/env.h>
 
 struct grub_loopback
 {
   char *devname;
+  char *root;
   char *filename;
   int has_partitions;
   struct grub_loopback *next;
@@ -62,6 +64,7 @@
   *prev = dev->next;
 
   grub_free (dev->devname);
+  grub_free (dev->root);
   grub_free (dev->filename);
   grub_free (dev);
 
@@ -125,6 +128,13 @@
       return grub_errno;
     }
 
+  newdev->root = grub_strdup (grub_env_get ("root"));
+  if (! newdev->root)
+    {
+      grub_free (newdev);
+      return grub_errno;
+    }
+
   newdev->filename = grub_strdup (args[1]);
   if (! newdev->filename)
     {
@@ -161,6 +171,7 @@
 {
   grub_file_t file;
   struct grub_loopback *dev;
+  char *save_root;
 
   for (dev = loopback_list; dev; dev = dev->next)
     if (grub_strcmp (dev->devname, name) == 0)
@@ -169,9 +180,16 @@
   if (! dev)
     return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "Can't open device");
 
+  save_root = grub_strdup (grub_env_get ("root"));
+  grub_env_set ("root", dev->root);
+
   file = grub_file_open (dev->filename);
   if (! file)
-    return grub_errno;
+    {
+      grub_env_set ("root", save_root);
+      grub_free (save_root);
+      return grub_errno;
+    }
 
   /* Use the filesize for the disk size, round up to a complete sector.  */
   disk->total_sectors = ((file->size + GRUB_DISK_SECTOR_SIZE - 1)
@@ -181,6 +199,9 @@
   disk->has_partitions = dev->has_partitions;
   disk->data = file;
 
+  grub_env_set ("root", save_root);
+  grub_free (save_root);
+
   return 0;
 }