[PATCH] UUID for FAT

[Robert Millan <rmh@aybabtu.com>]

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This patch implements UUID support for FAT (both 12/16 and 32).

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What good is a phone call… if you are unable to speak?
(as seen on /.)

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2008-05-31  Robert Millan  <rmh@aybabtu.com>

	* fs/fat.c (struct grub_fat_bpb): Move fat32-specific fields into a
	union with fat12/fat16-specific ones.  Add some new fields, including
	`num_serial' for both versions.
	(struct grub_fat_data): Add `uuid' member.
	(grub_fat_mount): Refer to fat32-specific fields in `bpb' by their new
	names.  Initialize `data->uuid' using `num_serial'.
	(grub_fat_uuid): New function.
	(grub_fat_fs): Reference grub_fat_uuid() in `uuid' struct member.

diff -x configure -x config.h.in -x CVS -x '*~' -x '*.mk' -urp ../grub2/fs/fat.c ./fs/fat.c
--- ../grub2/fs/fat.c	2007-08-02 20:40:36.000000000 +0200
+++ ./fs/fat.c	2008-05-31 22:59:11.000000000 +0200
@@ -61,14 +61,34 @@ struct grub_fat_bpb
   grub_uint16_t num_heads;
   grub_uint32_t num_hidden_sectors;
   grub_uint32_t num_total_sectors_32;
-  
-  /* The following fields are only used by FAT32.  */
-  grub_uint32_t sectors_per_fat_32;
-  grub_uint16_t extended_flags;
-  grub_uint16_t fs_version;
-  grub_uint32_t root_cluster;
-  grub_uint16_t fs_info;
-  grub_uint16_t backup_boot_sector;
+  union
+  {
+    struct
+    {
+      grub_uint8_t num_ph_drive;
+      grub_uint8_t reserved;
+      grub_uint8_t boot_sig;
+      grub_uint32_t num_serial;
+      grub_uint8_t label[11];
+      grub_uint8_t fstype[8];
+    } __attribute__ ((packed)) fat12_or_fat16;
+    struct
+    {
+      grub_uint32_t sectors_per_fat_32;
+      grub_uint16_t extended_flags;
+      grub_uint16_t fs_version;
+      grub_uint32_t root_cluster;
+      grub_uint16_t fs_info;
+      grub_uint16_t backup_boot_sector;
+      grub_uint8_t reserved[12];
+      grub_uint8_t num_ph_drive;
+      grub_uint8_t reserved1;
+      grub_uint8_t boot_sig;
+      grub_uint32_t num_serial;
+      grub_uint8_t label[11];
+      grub_uint8_t fstype[8];
+    } __attribute__ ((packed)) fat32;
+  } __attribute__ ((packed)) version_specific;
 } __attribute__ ((packed));
 
 struct grub_fat_dir_entry
@@ -122,6 +142,8 @@ struct grub_fat_data
   grub_uint32_t file_cluster;
   grub_uint32_t cur_cluster_num;
   grub_uint32_t cur_cluster;
+
+  grub_uint16_t uuid[2];
 };
 
 #ifndef GRUB_UTIL
@@ -183,7 +205,7 @@ grub_fat_mount (grub_disk_t disk)
 
   data->sectors_per_fat = ((bpb.sectors_per_fat_16
 			    ? grub_le_to_cpu16 (bpb.sectors_per_fat_16)
-			    : grub_le_to_cpu32 (bpb.sectors_per_fat_32))
+			    : grub_le_to_cpu32 (bpb.version_specific.fat32.sectors_per_fat_32))
 			   << data->logical_sector_bits);
   if (data->sectors_per_fat == 0)
     goto fail;
@@ -219,9 +241,9 @@ grub_fat_mount (grub_disk_t disk)
   if (! bpb.sectors_per_fat_16)
     {
       /* FAT32.  */
-      grub_uint16_t flags = grub_le_to_cpu16 (bpb.extended_flags);
+      grub_uint16_t flags = grub_le_to_cpu16 (bpb.version_specific.fat32.extended_flags);
       
-      data->root_cluster = grub_le_to_cpu32 (bpb.root_cluster);
+      data->root_cluster = grub_le_to_cpu32 (bpb.version_specific.fat32.root_cluster);
       data->fat_size = 32;
       data->cluster_eof_mark = 0x0ffffff8;
       
@@ -236,7 +258,7 @@ grub_fat_mount (grub_disk_t disk)
 	  data->fat_sector += active_fat * data->sectors_per_fat;
 	}
 
-      if (bpb.num_root_entries != 0 || bpb.fs_version != 0)
+      if (bpb.num_root_entries != 0 || bpb.version_specific.fat32.fs_version != 0)
 	goto fail;
     }
   else
@@ -286,6 +308,12 @@ grub_fat_mount (grub_disk_t disk)
       first_fat &= 0x00000fff;
       magic = 0x0f00;
     }
+
+  /* Serial number.  */
+  if (bpb.sectors_per_fat_16)
+    *((grub_uint32_t *) &data->uuid) = grub_le_to_cpu32 (bpb.version_specific.fat12_or_fat16.num_serial);
+  else
+    *((grub_uint32_t *) &data->uuid) = grub_le_to_cpu32 (bpb.version_specific.fat32.num_serial);
   
   /* Ignore the 3rd bit, because some BIOSes assigns 0xF0 to the media
      descriptor, even if it is a so-called superfloppy (e.g. an USB key).
@@ -797,6 +825,34 @@ grub_fat_label (grub_device_t device, ch
   return grub_errno;
 }
 
+static grub_err_t
+grub_fat_uuid (grub_device_t device, char **uuid)
+{
+  struct grub_fat_data *data;
+  grub_disk_t disk = device->disk;
+
+#ifndef GRUB_UTIL
+  grub_dl_ref (my_mod);
+#endif
+
+  data = grub_fat_mount (disk);
+  if (data)
+    {
+      *uuid = grub_malloc (40 + sizeof ('\0'));
+      grub_sprintf (*uuid, "%04x-%04x", data->uuid[1], data->uuid[0]);
+    }
+  else
+    *uuid = NULL;
+
+#ifndef GRUB_UTIL
+  grub_dl_unref (my_mod);
+#endif
+
+  grub_free (data);
+
+  return grub_errno;
+}
+
 static struct grub_fs grub_fat_fs =
   {
     .name = "fat",
@@ -805,6 +861,7 @@ static struct grub_fs grub_fat_fs =
     .read = grub_fat_read,
     .close = grub_fat_close,
     .label = grub_fat_label,
+    .uuid = grub_fat_uuid,
     .next = 0
   };