From 228cfb40bf9f6fa70cdb6c8aa7304efe9f558870 Mon Sep 17 00:00:00 2001
From: Vladimir 'phcoder' Serbinenko <phcoder@gmail.com>
Date: Thu, 2 Dec 2010 14:26:46 +0100
Subject: [PATCH] support bind and subvolume mount

---
 grub-core/kern/emu/getroot.c | 23 ++++++++---------------
 grub-core/kern/emu/misc.c    | 28 ++++++++++++++++++++++++++++
 include/grub/emu/misc.h      |  2 ++
 3 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/grub-core/kern/emu/getroot.c b/grub-core/kern/emu/getroot.c
index f51dcd770..373834127 100644
--- a/grub-core/kern/emu/getroot.c
+++ b/grub-core/kern/emu/getroot.c
@@ -103,8 +103,8 @@ xgetcwd (void)
    can't deal with the multiple-device case yet, but in the meantime, we can
    at least cope with the single-device case by scanning
    /proc/self/mountinfo.  */
-static char *
-find_root_device_from_mountinfo (const char *dir)
+char *
+grub_find_root_device_from_mountinfo (const char *dir, char **relroot)
 {
   FILE *fp;
   char *buf = NULL;
@@ -115,6 +115,9 @@ find_root_device_from_mountinfo (const char *dir)
   if (! fp)
     return NULL; /* fall through to other methods */
 
+  if (relroot)
+    *relroot = NULL;
+
   while (getline (&buf, &len, fp) > 0)
     {
       int mnt_id, parent_mnt_id;
@@ -131,9 +134,6 @@ find_root_device_from_mountinfo (const char *dir)
 		  &count) < 6)
 	continue;
 
-      if (strcmp (enc_root, "/") != 0)
-	continue; /* only a subtree is mounted */
-
       enc_path_len = strlen (enc_path);
       if (strncmp (dir, enc_path, enc_path_len) != 0 ||
 	  (dir[enc_path_len] && dir[enc_path_len] != '/'))
@@ -147,9 +147,6 @@ find_root_device_from_mountinfo (const char *dir)
       free (ret);
       ret = NULL;
 
-      if (major != 0)
-	continue; /* not a virtual device */
-
       sep = strstr (buf + count, " - ");
       if (!sep)
 	continue;
@@ -158,13 +155,9 @@ find_root_device_from_mountinfo (const char *dir)
       if (sscanf (sep, "%s %s", fstype, device) != 2)
 	continue;
 
-      if (stat (device, &st) < 0)
-	continue;
-
-      if (!S_ISBLK (st.st_mode))
-	continue; /* not a block device */
-
       ret = strdup (device);
+      if (relroot)
+	*relroot = strdup (enc_root);
     }
 
   free (buf);
@@ -531,7 +524,7 @@ grub_guess_root_device (const char *dir)
   struct stat st;
 
 #ifdef __linux__
-  os_dev = find_root_device_from_mountinfo (dir);
+  os_dev = grub_find_root_device_from_mountinfo (dir, NULL);
   if (os_dev)
     return os_dev;
 #endif /* __linux__ */
diff --git a/grub-core/kern/emu/misc.c b/grub-core/kern/emu/misc.c
index c8b95443b..44c40b010 100644
--- a/grub-core/kern/emu/misc.c
+++ b/grub-core/kern/emu/misc.c
@@ -415,6 +415,18 @@ grub_make_system_path_relative_to_its_root (const char *path)
 	  if (offset == 0)
 	    {
 	      free (buf);
+#ifdef __linux__
+	      {
+		char *bind;
+		grub_free (grub_find_root_device_from_mountinfo (buf2, &bind));
+		if (bind && bind[0] && bind[1])
+		  {
+		    buf3 = bind;
+		    goto parsedir;
+		  }
+		grub_free (bind);
+	      }
+#endif
 	      free (buf2);
 #if defined(HAVE_LIBZFS) && defined(HAVE_LIBNVPAIR)
 	      if (poolfs)
@@ -437,6 +449,21 @@ grub_make_system_path_relative_to_its_root (const char *path)
     }
   free (buf);
   buf3 = xstrdup (buf2 + offset);
+  buf2[offset] = 0;
+#ifdef __linux__
+  {
+    char *bind;
+    grub_free (grub_find_root_device_from_mountinfo (buf2, &bind));
+    if (bind && bind[0] && bind[1])
+      {
+	char *temp = buf3;
+	buf3 = grub_xasprintf ("%s%s%s", bind, buf3[0] == '/' ?"":"/", buf3);
+	grub_free (temp);
+      }
+    grub_free (bind);
+  }
+#endif
+  
   free (buf2);
 
 #ifdef __CYGWIN__
@@ -452,6 +479,7 @@ grub_make_system_path_relative_to_its_root (const char *path)
     }
 #endif
 
+ parsedir:
   /* Remove trailing slashes, return empty string if root directory.  */
   len = strlen (buf3);
   while (len > 0 && buf3[len - 1] == '/')
diff --git a/include/grub/emu/misc.h b/include/grub/emu/misc.h
index ef0d18300..d4ebcb0d1 100644
--- a/include/grub/emu/misc.h
+++ b/include/grub/emu/misc.h
@@ -78,4 +78,6 @@ extern char * canonicalize_file_name (const char *path);
 int grub_device_mapper_supported (void);
 #endif
 
+char *grub_find_root_device_from_mountinfo (const char *dir, char **relroot);
+
 #endif /* GRUB_EMU_MISC_H */