Re: [PATCH v2] * grub-core/fs/udf.c: Add support for UUID

[Vladimir 'phcoder' Serbinenko]

Committed with few fixes. Thanks

Le Thu, Jun 22, 2017 à 2:42 PM, Pali Rohár <address@hidden> a écrit :

Use same algorithm as in libblkid from util-linux v2.30.

1. Take first 16 bytes from UTF-8 encoded string of VolumeSetIdentifier
2. If all bytes are hexadecimal digits, convert to lowercase and use as UUID
3. If first 8 bytes are not all hexadecimal digits, convert those 8 bytes
   to their hexadecimal representation, resulting in 16 bytes for UUID
4. Otherwise, compose UUID from two parts:
   1. part: converted first 8 bytes (which are hexadecimal digits) to lowercase
   2. part: encoded following 4 bytes to their hexadecimal representation (16 bytes)

So UUID would always have 16 hexadecimal digits in lowercase variant.

According to UDF specification, first 16 Unicode characters of
VolumeSetIdentifier should be unique value and first 8 should be
hexadecimal characters.

In most cases all 16 characters are hexadecimal, but e.g. MS Windows
format.exe set only first 8 as hexadecimal and remaining as fixed
(non-unique) which violates specification.
---
Changes since v1:
* Fixed handling strings in 8 bit OSTA compressed Unicode format
* Use xdigit instead of alnum
* Compatibility with blkid from util-linux v2.30
---
 grub-core/fs/udf.c |  121 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 120 insertions(+), 1 deletion(-)

diff --git a/grub-core/fs/udf.c b/grub-core/fs/udf.c
index e7a4d4e..ce12a49 100644
--- a/grub-core/fs/udf.c
+++ b/grub-core/fs/udf.c
@@ -321,6 +321,32 @@ struct grub_udf_partmap
   };
 } GRUB_PACKED;

+struct grub_udf_pvd
+{
+  struct grub_udf_tag tag;
+  grub_uint32_t seq_num;
+  grub_uint32_t pvd_num;
+  grub_uint8_t ident[32];
+  grub_uint16_t vol_seq_num;
+  grub_uint16_t max_vol_seq_num;
+  grub_uint16_t interchange_level;
+  grub_uint16_t max_interchange_level;
+  grub_uint32_t charset_list;
+  grub_uint32_t max_charset_list;
+  grub_uint8_t volset_ident[128];
+  struct grub_udf_charspec desc_charset;
+  struct grub_udf_charspec expl_charset;
+  struct grub_udf_extent_ad vol_abstract;
+  struct grub_udf_extent_ad vol_copyright;
+  struct grub_udf_regid app_ident;
+  struct grub_udf_timestamp recording_time;
+  struct grub_udf_regid imp_ident;
+  grub_uint8_t imp_use[64];
+  grub_uint32_t pred_vds_loc;
+  grub_uint16_t flags;
+  grub_uint8_t reserved[22];
+} GRUB_PACKED;
+
 struct grub_udf_lvd
 {
   struct grub_udf_tag tag;
@@ -348,6 +374,7 @@ struct grub_udf_aed
 struct grub_udf_data
 {
   grub_disk_t disk;
+  struct grub_udf_pvd pvd;
   struct grub_udf_lvd lvd;
   struct grub_udf_pd pds[GRUB_UDF_MAX_PDS];
   struct grub_udf_partmap *pms[GRUB_UDF_MAX_PMS];
@@ -692,7 +719,17 @@ grub_udf_mount (grub_disk_t disk)
        }

       tag.tag_ident = U16 (tag.tag_ident);
-      if (tag.tag_ident == GRUB_UDF_TAG_IDENT_PD)
+      if (tag.tag_ident == GRUB_UDF_TAG_IDENT_PVD)
+       {
+         if (grub_disk_read (disk, block << lbshift, 0,
+                             sizeof (struct grub_udf_pvd),
+                             &data->pvd))
+           {
+             grub_error (GRUB_ERR_BAD_FS, "not an UDF filesystem");
+             goto fail;
+           }
+       }
+      else if (tag.tag_ident == GRUB_UDF_TAG_IDENT_PD)
        {
          if (data->npd >= GRUB_UDF_MAX_PDS)
            {
@@ -1225,6 +1262,87 @@ grub_udf_label (grub_device_t device, char **label)
   return grub_errno;
 }

+static char *
+gen_uuid_from_volset (char *volset_ident)
+{
+  grub_size_t i;
+  grub_size_t len;
+  grub_size_t nonhexpos;
+  grub_uint8_t buf[17];
+  char *uuid;
+
+  len = grub_strlen (volset_ident);
+  if (len < 8)
+    return NULL;
+
+  uuid = grub_malloc (17);
+  if (!uuid)
+    return NULL;
+
+  if (len > 16)
+    len = 16;
+
+  grub_memset (buf, 0, sizeof (buf));
+  grub_memcpy (buf, volset_ident, len);
+
+  nonhexpos = 16;
+  for (i = 0; i < 16; ++i)
+    {
+      if (!grub_isxdigit (buf[i]))
+        {
+          nonhexpos = i;
+          break;
+        }
+    }
+
+  if (nonhexpos < 8)
+    {
+      grub_snprintf (uuid, 17, "%02x%02x%02x%02x%02x%02x%02x%02x",
+                    buf[0], buf[1], buf[2], buf[3],
+                    buf[4], buf[5], buf[6], buf[7]);
+    }
+  else if (nonhexpos < 16)
+    {
+      for (i = 0; i < 8; ++i)
+        uuid[i] = grub_tolower (buf[i]);
+      grub_snprintf (uuid+8, 9, "%02x%02x%02x%02x",
+                    buf[8], buf[9], buf[10], buf[11]);
+    }
+  else
+    {
+      for (i = 0; i < 16; ++i)
+        uuid[i] = grub_tolower (buf[i]);
+      uuid[16] = 0;
+    }
+
+  return uuid;
+}
+
+static grub_err_t
+grub_udf_uuid (grub_device_t device, char **uuid)
+{
+  char *volset_ident;
+  struct grub_udf_data *data;
+  data = "" (device->disk);
+
+  if (data)
+    {
+      volset_ident = read_dstring (data->pvd.volset_ident, sizeof (data->pvd.volset_ident), 0);
+      if (volset_ident)
+        {
+          *uuid = gen_uuid_from_volset (volset_ident);
+          grub_free (volset_ident);
+        }
+      else
+        *uuid = 0;
+      grub_free (data);
+    }
+  else
+    *uuid = 0;
+
+  return grub_errno;
+}
+
 static struct grub_fs grub_udf_fs = {
   .name = "udf",
   .dir = grub_udf_dir,
@@ -1232,6 +1350,7 @@ static struct grub_fs grub_udf_fs = {
   .read = grub_udf_read,
   .close = grub_udf_close,
   .label = grub_udf_label,
+  .uuid = grub_udf_uuid,
 #ifdef GRUB_UTIL
   .reserved_first_sector = 1,
   .blocklist_install = 1,
--
1.7.9.5