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[PATCH v3, 05/16] xfsprogs: metadump: eliminate a pointless loop in gene

To: xfs@xxxxxxxxxxx
Subject: [PATCH v3, 05/16] xfsprogs: metadump: eliminate a pointless loop in generate_obfuscated_name()
From: Alex Elder <aelder@xxxxxxx>
Date: Fri, 18 Feb 2011 15:21:01 -0600
User-agent: Heirloom mailx 12.5 7/5/10
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@xxxxxxx>

No significant changes in this version from the last one posted.

---
 db/metadump.c |  144 ++++++++++++++++++++++++++++------------------------------
 1 file changed, 70 insertions(+), 74 deletions(-)

Index: b/db/metadump.c
===================================================================
--- a/db/metadump.c
+++ b/db/metadump.c
@@ -472,87 +472,83 @@ generate_obfuscated_name(
 
        hash = libxfs_da_hashname(name, namelen);
        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 - 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 - 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 - 3] = ((newhash >> 14) & 0x7f) ^ high_bit;
+               if (is_invalid_char(newp[namelen - 3])) {
+                       newp[namelen - 3] ^= 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 first byte had 0's in its upper four
-                        * bits (it's the result of shifting a
-                        * 32-bit unsigned value Right by 28 bits),
-                        * so we don't need to worry about it
-                        * becoming invalid as a result.
-                        */
-                       if (high_bit) {
-                               newp[namelen - 5] ^= 0x10;
-                               ASSERT(!is_invalid_char(newp[namelen - 5]));
-                       }
-                       break;
+               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 first byte had 0's in its upper four bits
+                * (it's the result of shifting a 32-bit unsigned
+                * value Right by 28 bits), so we don't need to
+                * worry about it becoming invalid as a result.
+                */
+               if (high_bit) {
+                       newp[namelen - 5] ^= 0x10;
+                       ASSERT(!is_invalid_char(newp[namelen - 5]));
                }
 
                ASSERT(libxfs_da_hashname(newname, namelen) == hash);

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