[PATCHv2] hurd: Use part: qualifier

[Samuel Thibault]

When using userland drivers such as rumpdisk, we'd rather make ext2fs use
parted-based libstore partitioning support. That can be used for kernelland
drivers as well, so we can just make grub always use the part: qualifier to
switch ext2fs to it.

grub_util_find_hurd_root_device then has to understand this syntax and translate
it into the /dev/ entry name.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

---
Difference with v2: rebase on master

Index: grub2-2.06/util/grub.d/10_hurd.in
===================================================================
--- grub2-2.06.orig/util/grub.d/10_hurd.in
+++ grub2-2.06/util/grub.d/10_hurd.in
@@ -128,9 +128,11 @@ EOF
   else
       opts=
   fi
+  device=device:${GRUB_DEVICE#/dev/}
+  device=$(echo "$device" | sed -e 
's/^device:\(.*[0-9]\+\)s\([0-9]\+\)$/part:\2:device:\1'/)
   sed "s/^/$submenu_indentation/" << EOF
        echo            '$(echo "$message" | grub_quote)'
-       multiboot       ${kernel} root=device:${GRUB_DEVICE#/dev/} $opts 
${GRUB_CMDLINE_GNUMACH}
+       multiboot       ${kernel} root=$device $opts ${GRUB_CMDLINE_GNUMACH}
 EOF
 
   if [ x$type != xrecovery ] ; then
Index: grub2-2.06/grub-core/osdep/hurd/getroot.c
===================================================================
--- grub2-2.06.orig/grub-core/osdep/hurd/getroot.c
+++ grub2-2.06/grub-core/osdep/hurd/getroot.c
@@ -109,6 +109,16 @@ grub_util_find_hurd_root_device (const c
     grub_util_error (_("translator `%s' for path `%s' is given only options, "
                        "cannot find device part"), argz, path);
 
+  int part = -1;
+  if (strncmp (name, "part:", sizeof ("part:") - 1) == 0)
+    {
+      char *next = strchr (name + sizeof ("part:") - 1, ':');
+      if (next)
+        {
+          part = atoi (name + sizeof ("part:") - 1);
+          name = next + 1;
+        }
+    }
   if (strncmp (name, "device:", sizeof ("device:") - 1) == 0)
     {
       char *dev_name = name + sizeof ("device:") - 1;
@@ -123,10 +133,10 @@ grub_util_find_hurd_root_device (const c
             dev_name = next_name + 1;
         }
 
-      size = sizeof ("/dev/") - 1 + strlen (dev_name) + 1;
-      ret = xmalloc (size);
-      next = stpncpy (ret, "/dev/", size);
-      stpncpy (next, dev_name, size - (next - ret));
+      if (part >= 0)
+        ret = xasprintf("/dev/%ss%u", dev_name, part);
+      else
+        ret = xasprintf("/dev/%s", dev_name);
     }
   else if (!strncmp (name, "file:", sizeof ("file:") - 1))
     ret = strdup (name + sizeof ("file:") - 1);