[PATCH 1/1 V2] add --partuuid to probe

[Steve Kenton]

Signed-off-by: Steve Kenton <address@hidden>
---
V2 coding style changes as suggested in feedback
In V1 I was treating p->index as an offset into the partition table instead
of an index from 0-15 of the partition table slot needing to be multipled
by the size of a gtp partition table entry. Is this correct? There are two
temporary comments about the include files used to remove the magic numbers,
If you would prefer others just let me know.

 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 cf2793e..662c0a3 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 */
+      grub_uint8_t diskbuf[16];
+      if (dev->disk && dev->disk->partition)
+       {
+         grub_partition_t p = dev->disk->partition;
+         if (grub_strcmp (p->partmap->name, "msdos") == 0)
+           {
+             /* 440 location of NT Volume Label in MBR 
./include/grub/i386/pc/boot.h */
+             const int diskid_offset = GRUB_BOOT_MACHINE_WINDOWS_NT_MAGIC;
+             dev->disk->partition = p->parent;
+             /* little-endian 4-byte NT disk id */
+             err = grub_disk_read (dev->disk, 0, diskid_offset, 4, diskbuf);
+             dev->disk->partition = p;
+             if (err)
+               return grub_errno;
+             partuuid = grub_xasprintf ("%02x%02x%02x%02x-%02x",
+                                        diskbuf[3], diskbuf[2], diskbuf[1], 
diskbuf[0],
+                                        p->number + 1); /* one based partition 
number */
+           }
+         else if (grub_strcmp (p->partmap->name, "gpt") == 0)
+           {
+             const int guid_offset = p->index * sizeof(struct 
grub_gpt_partentry) + 
+             /* 16 location of GUID in entry ./include/grub/gpt_partition.h */
+                                     offsetof(struct grub_gpt_partentry, guid);
+             dev->disk->partition = p->parent;
+             /* little-endian 16-byte EFI partition GUID */
+             err = grub_disk_read (dev->disk, p->offset, guid_offset, 16, 
diskbuf);
+             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",
+                                        diskbuf[3], diskbuf[2], diskbuf[1], 
diskbuf[0],
+                                        diskbuf[5], diskbuf[4],
+                                        diskbuf[7], diskbuf[6],
+                                        diskbuf[8], diskbuf[9],
+                                        diskbuf[10], diskbuf[11], diskbuf[12], 
diskbuf[13], diskbuf[14], diskbuf[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");
 }
-- 
2.9.0.137.gcf4c2cf