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Re: [GRUB PARTUUID PATCH V3 4/5] Support both EFI and NT Disk Signature


From: Vladimir 'phcoder' Serbinenko
Subject: Re: [GRUB PARTUUID PATCH V3 4/5] Support both EFI and NT Disk Signature for passing to kernel as root=PARTUUID=$val
Date: Mon, 27 Feb 2017 00:35:56 +0000



On Sun, Feb 26, 2017, 16:22 Nicholas Vinson <address@hidden> wrote:
From: Steve Kenton <address@hidden>
Please avoid resubmitting patches made by someone else in most cases. It obscures proper attribution. We can review his patch in his thread

---
 grub-core/commands/probe.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/grub-core/commands/probe.c b/grub-core/commands/probe.c
index cf2793e1d..5dd1a6bc5 100644
--- a/grub-core/commands/probe.c
+++ b/grub-core/commands/probe.c
@@ -16,6 +16,7 @@
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */

+#include <stddef.h>
 #include <grub/types.h>
 #include <grub/misc.h>
 #include <grub/mm.h>
@@ -24,6 +25,8 @@
 #include <grub/device.h>
 #include <grub/disk.h>
 #include <grub/partition.h>
+#include <grub/gpt_partition.h>
+#include <grub/i386/pc/boot.h>
 #include <grub/net.h>
 #include <grub/fs.h>
 #include <grub/file.h>
@@ -45,6 +48,7 @@ static const struct grub_arg_option options[] =
     {"fs",             'f', 0, N_("Determine filesystem type."), 0, 0},
     {"fs-uuid",                'u', 0, N_("Determine filesystem UUID."), 0, 0},
     {"label",          'l', 0, N_("Determine filesystem label."), 0, 0},
+    {"partuuid",       'g', 0, N_("Determine partition GUID/UUID."), 0, 0}, /* GUID but Linux kernel calls it "PARTUUID" */
     {0, 0, 0, 0, 0, 0}
   };

@@ -154,6 +158,61 @@ grub_cmd_probe (grub_extcmd_context_t ctxt, int argc, char **args)
       grub_device_close (dev);
       return GRUB_ERR_NONE;
     }
+  if (state[6].set)
+    {
+      char *partuuid = NULL; /* NULL to silence a spurious GCC warning */
+      /* Nested partitions are not supported for now. */
+      /* Non-nested partitions must have dev->disk->partition->parent == NULL */
+      if (dev->disk && dev->disk->partition && dev->disk->partition->parent == NULL)
+       {
+        grub_partition_t p = dev->disk->partition;
+        if (grub_strcmp (p->partmap->name, "msdos") == 0)
+          {
+             /* little-endian 4-byte NT disk id "GUID" in the MBR */
+             grub_uint8_t diskid[4];
+            dev->disk->partition = p->parent;
+            grub_uint32_t nt_disk_sig;
+            err = grub_disk_read (dev->disk, 0, GRUB_BOOT_MACHINE_WINDOWS_NT_MAGIC, sizeof(diskid), diskid);
+            dev->disk->partition = p;
+            if (err)
+              return grub_errno;
+            /* partition numbers are one-based */
+            partuuid = grub_xasprintf ("%02x%02x%02x%02x-%02x",
+                                       diskid[3], diskid[2], diskid[1], disk[0],
+                                       p->number + 1);
+          }
+        else if (grub_strcmp (p->partmap->name, "gpt") == 0)
+          {
+            struct grub_gpt_partentry e;
+            dev->disk->partition = p->parent;
+            err = grub_disk_read (dev->disk, p->offset, p->index, sizeof e, &e);
+            dev->disk->partition = p;
+            if (err)
+              return grub_errno;
+
+            partuuid = grub_xasprintf ("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+                                       e.guid[3], e.guid[2], e.guid[1], e.guid[0],
+                                       e.guid[5], e.guid[4],
+                                       e.guid[7], e.guid[6],
+                                       e.guid[8], e.guid[9],
+                                       e.guid[10], e.guid[11], e.guid[12], e.guid[13], e.guid[14], e.guid[15]);
+          }
+        else
+          return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
+                             N_("partition map %s does not support partition UUIDs"),
+                             dev->disk->partition->partmap->name);
+       }
+      else
+       partuuid = grub_strdup (""); /* a freeable empty string */
+
+      if (state[0].set)
+       grub_env_set (state[0].arg, partuuid);
+      else
+       grub_printf ("%s", partuuid);
+      grub_free (partuuid);
+      grub_device_close (dev);
+      return GRUB_ERR_NONE;
+    }
   grub_device_close (dev);
   return grub_error (GRUB_ERR_BAD_ARGUMENT, "unrecognised target");
 }
--
2.12.0


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