From d8ba647d0d983c5b13ab47469f9ac0ec3d1586c9 Mon Sep 17 00:00:00 2001
From: Pali Rohár
Date: Wed, 17 May 2017 20:36:40 +0200
Subject: libblkid: udf: Change algorithm for reporting UUID

Ensure that reported UUID always contains only lowercase hexadecimal digits
and is always 16 characters length, padded with zero digits.

Volume Set Identifier is converted to UTF-8 before generating UUID from it.
As it could potentially contain any Unicode character. So correctly handle
both 8bit and 16bit OSTA Compressed Unicode encodings.

Disks which have only lowercase hexadecimal digits in Volume Set Identifier
would have same UUID as before this patch.
---
 libblkid/src/superblocks/udf.c | 51 +++++++++++++++++++++---------------------
 1 file changed, 25 insertions(+), 26 deletions(-)

(limited to 'libblkid/src/superblocks')

diff --git a/libblkid/src/superblocks/udf.c b/libblkid/src/superblocks/udf.c
index 96254d881..f908001ad 100644
--- a/libblkid/src/superblocks/udf.c
+++ b/libblkid/src/superblocks/udf.c
@@ -80,43 +80,41 @@ static inline int gen_uuid_from_volset_id(unsigned char uuid[17], struct dstring
 {
 	size_t i;
 	size_t len;
-	size_t binpos;
-	unsigned char buf[128];
+	size_t nonhexpos;
+	unsigned char buf[17];
+
+	memset(buf, 0, sizeof(buf));
 
 	if (volset_id->clen == 8)
-		memcpy(buf, volset_id->c, 16);
+		len = blkid_encode_to_utf8(BLKID_ENC_LATIN1, buf, sizeof(buf), volset_id->c, 127);
 	else if (volset_id->clen == 16)
-		blkid_encode_to_utf8(BLKID_ENC_UTF16BE, buf, sizeof(buf), volset_id->c, 127);
+		len = blkid_encode_to_utf8(BLKID_ENC_UTF16BE, buf, sizeof(buf), volset_id->c, 127);
 	else
 		return -1;
 
-	buf[16] = 0;
-	len = strlen((char *) buf);
-
 	if (len < 8)
 		return -1;
 
-	for (i = len; i < 16; ++i)
-		buf[i] = 0;
-
-	binpos = 16;
-	for (i = 0; i < len; ++i) {
-		if (!isalnum(buf[i])) {
-			binpos = i;
+	nonhexpos = 16;
+	for (i = 0; i < 16; ++i) {
+		if (!isxdigit(buf[i])) {
+			nonhexpos = i;
 			break;
 		}
 	}
 
-	if (binpos < 8) {
+	if (nonhexpos < 8) {
 		snprintf((char *) 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 (binpos < 16) {
-		memcpy(uuid, buf, 8);
+	} else if (nonhexpos < 16) {
+		for (i = 0; i < 8; ++i)
+			uuid[i] = tolower(buf[i]);
 		snprintf((char *) uuid + 8, 9, "%02x%02x%02x%02x",
 			buf[8], buf[9], buf[10], buf[11]);
 	} else {
-		memcpy(uuid, buf, 16);
+		for (i = 0; i < 16; ++i)
+			uuid[i] = tolower(buf[i]);
 		uuid[16] = 0;
 	}
 
@@ -246,14 +244,15 @@ real_blksz:
 				 * =================================================================================
 				 *
 				 * Implementation in libblkid:
-				 * The first 16 characters of VolumeSetIdentifier are used to generate UUID.
-				 * If all 16 characters are alphanumeric then they are used unchanged as UUID.
-				 * If one of first 8 characters (time value) is not alphanumeric then first
-				 * 8 characters are encoded to their hexadecimal values in 16 characters and
-				 * set as UUID. If all first 8 characters (time value) are alphanumeric but
-				 * some other remaining character is not then first 8 characters are unchanged
-				 * (set as first part of UUID string), next 4 characters are encoded to their
-				 * hexadecimal values (in 8 characters) and set as second part of UUID string.
+				 * The first 16 (Unicode) characters of VolumeSetIdentifier are encoded to UTF-8
+				 * and then first 16 UTF-8 bytes are used to generate UUID. If all 16 bytes are
+				 * hexadecimal digits then their lowercase variants are used as UUID. If one of
+				 * the first 8 bytes (time value) is not hexadecimal digit then first 8 bytes are
+				 * encoded to their hexadecimal representations, resulting in 16 characters and
+				 * set as UUID. If all first 8 bytes (time value) are hexadecimal digits but some
+				 * remaining not then lowercase variant of the first 8 bytes are used as first
+				 * part of UUID and next 4 bytes encoded in hexadecimal representations (resulting
+				 * in 8 characters) are used as second part of UUID string.
 				 */
 				unsigned char uuid[17];
 				if (gen_uuid_from_volset_id(uuid, &vd->type.primary.volset_id) == 0)
-- 
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