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From: Alex Elder <aelder@sgi.com>
To: xfs@oss.sgi.com
Subject: [PATCH 05/12] xfsprogs: eliminate a pointless loop in generate_obfuscated_name()
Date: Thu, 30 Dec 2010 14:40:49 -0600	[thread overview]
Message-ID: <1293741649.2294.357.camel@doink> (raw)

Eliminate a now pointless loop.  Done as a separate patch to
make the effects of upcoming changes more clear.

Signed-off-by: Alex Elder <aelder@sgi.com>

---
 db/metadump.c |  146 ++++++++++++++++++++++++++++------------------------------
 1 file changed, 71 insertions(+), 75 deletions(-)

Index: b/db/metadump.c
===================================================================
--- a/db/metadump.c
+++ b/db/metadump.c
@@ -450,89 +450,85 @@ generate_obfuscated_name(
 	if (*name == '/')
 	    	name++;
 	do {
+		uchar_t	high_bit;
+
 		dup = 0;
-		for (;;) {
-			uchar_t	high_bit;
 
-		    	/*
-			 * The beginning of the obfuscated name can
-			 * be pretty much anything, so fill it in
-			 * with random characters.  Accumulate its
-			 * new hash value as we go.
-			 */
-			newhash = 0;
-			for (i = 0; i < namelen - 5; i++) {
-				newp[i] = random_filename_char();
-				newhash = newp[i] ^ rol32(newhash, 7);
-			}
+		/*
+		 * The beginning of the obfuscated name can be
+		 * pretty much anything, so fill it in with random
+		 * characters.  Accumulate its new hash value as we
+		 * go.
+		 */
+		newhash = 0;
+		for (i = 0; i < namelen - 5; i++) {
+			newp[i] = random_filename_char();
+			newhash = newp[i] ^ rol32(newhash, 7);
+		}
 
-			/*
-			 * Compute which five bytes need to be used
-			 * at the end of the name so the hash of the
-			 * obfuscated name is the same as the hash
-			 * of the original.  If any result in an
-			 * invalid character, flip a bit and arrange
-			 * for a corresponding bit in a neighboring
-			 * byte to be flipped as well.  For the last
-			 * byte, the "neighbor" to change is the
-			 * first byte we're computing here.
-			 */
-			newhash = rol32(newhash, 3) ^ hash;
+		/*
+		 * Compute which five bytes need to be used at the
+		 * end of the name so the hash of the obfuscated
+		 * name is the same as the hash of the original.  If
+		 * any result in an invalid character, flip a bit
+		 * and arrange for a corresponding bit in a
+		 * neighboring byte to be flipped as well.  For the
+		 * last byte, the "neighbor" to change is the first
+		 * byte we're computing here.
+		 */
+		newhash = rol32(newhash, 3) ^ hash;
 
+		high_bit = 0;
+
+		newp[namelen - 5] = ((newhash >> 28) & 0x7f) ^ high_bit;
+		if (is_invalid_char(newp[namelen - 5])) {
+			newp[namelen - 5] ^= 1;
+			high_bit = 0x80;
+		} else
 			high_bit = 0;
 
-			newp[namelen - 5] = ((newhash >> 28) & 0x7f) ^ high_bit;
-			if (is_invalid_char(newp[namelen - 5])) {
-				newp[namelen - 5] ^= 1;
-				high_bit = 0x80;
-			} else
-				high_bit = 0;
-
-			newp[namelen - 4] = ((newhash >> 21) & 0x7f) ^ high_bit;
-			if (is_invalid_char(newp[namelen - 4])) {
-				newp[namelen - 4] ^= 1;
-				high_bit = 0x80;
-			} else
-				high_bit = 0;
-
-			newp[namelen - 3] = ((newhash >> 14) & 0x7f) ^ high_bit;
-			if (is_invalid_char(newp[namelen - 3])) {
-				newp[namelen - 3] ^= 1;
-				high_bit = 0x80;
-			} else
-				high_bit = 0;
-
-			newp[namelen - 2] = ((newhash >> 7) & 0x7f) ^ high_bit;
-			if (is_invalid_char(newp[namelen - 2])) {
-				newp[namelen - 2] ^= 1;
-				high_bit = 0x80;
-			} else
-				high_bit = 0;
-
-			newp[namelen - 1] = ((newhash >> 0) & 0x7f) ^ high_bit;
-			if (is_invalid_char(newp[namelen - 1])) {
-				newp[namelen - 1] ^= 1;
-				high_bit = 0x80;
-			} else
-				high_bit = 0;
+		newp[namelen - 4] = ((newhash >> 21) & 0x7f) ^ high_bit;
+		if (is_invalid_char(newp[namelen - 4])) {
+			newp[namelen - 4] ^= 1;
+			high_bit = 0x80;
+		} else
+			high_bit = 0;
 
-			/*
-			 * If we flipped a bit on the last byte, we
-			 * need to fix up the first one we computed.
-			 * That could make that first character
-			 * invalid, in which case we flip one more
-			 * bit in both bytes.
-			 */
-			if (high_bit) {
-			    	newp[namelen - 5] ^= 0x10;
-			    	if (is_invalid_char(newp[namelen - 5])) {
-					newp[namelen - 1] ^= 2;
-					newp[namelen - 5] ^= 0x20;
-					ASSERT(!is_invalid_char(newp[namelen - 1]));
-					ASSERT(!is_invalid_char(newp[namelen - 5]));
-				}
+		newp[namelen - 3] = ((newhash >> 14) & 0x7f) ^ high_bit;
+		if (is_invalid_char(newp[namelen - 3])) {
+			newp[namelen - 3] ^= 1;
+			high_bit = 0x80;
+		} else
+			high_bit = 0;
+
+		newp[namelen - 2] = ((newhash >> 7) & 0x7f) ^ high_bit;
+		if (is_invalid_char(newp[namelen - 2])) {
+			newp[namelen - 2] ^= 1;
+			high_bit = 0x80;
+		} else
+			high_bit = 0;
+
+		newp[namelen - 1] = ((newhash >> 0) & 0x7f) ^ high_bit;
+		if (is_invalid_char(newp[namelen - 1])) {
+			newp[namelen - 1] ^= 1;
+			high_bit = 0x80;
+		} else
+			high_bit = 0;
+
+		/*
+		 * If we flipped a bit on the last byte, we need to
+		 * fix up the first one we computed.  That could
+		 * make that first character invalid, in which case
+		 * we flip one more bit in both bytes.
+		 */
+		if (high_bit) {
+			newp[namelen - 5] ^= 0x10;
+			if (is_invalid_char(newp[namelen - 5])) {
+				newp[namelen - 1] ^= 2;
+				newp[namelen - 5] ^= 0x20;
+				ASSERT(!is_invalid_char(newp[namelen - 1]));
+				ASSERT(!is_invalid_char(newp[namelen - 5]));
 			}
-			break;
 		}
 
 		ASSERT(libxfs_da_hashname((char *) newname, namelen) == hash);


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                 reply	other threads:[~2010-12-30 20:38 UTC|newest]

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