X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/5117c20ab5558e5d68b1a3c7751610cd6c4279db..af0b220756571bc8faf57a0c7b7389dd86a60376:/src/ziplist.c

diff --git a/src/ziplist.c b/src/ziplist.c
index 8ada7c42..d4ac4f9b 100644
--- a/src/ziplist.c
+++ b/src/ziplist.c
@@ -69,6 +69,36 @@
  * |11111111| - End of ziplist.
  *
  * All the integers are represented in little endian byte order.
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2009-2012, Pieter Noordhuis <pcnoordhuis at gmail dot com>
+ * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include <stdio.h>
@@ -500,12 +530,13 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
     totlen = p-first.p;
     if (totlen > 0) {
         if (p[0] != ZIP_END) {
-            /* Tricky: storing the prevlen in this entry might reduce or
-             * increase the number of bytes needed, compared to the current
-             * prevlen. Note that we can always store this length because
-             * it was previously stored by an entry that is being deleted. */
+            /* Storing `prevrawlen` in this entry may increase or decrease the
+             * number of bytes required compare to the current `prevrawlen`.
+             * There always is room to store this, because it was previously
+             * stored by an entry that is now being deleted. */
             nextdiff = zipPrevLenByteDiff(p,first.prevrawlen);
-            zipPrevEncodeLength(p-nextdiff,first.prevrawlen);
+            p -= nextdiff;
+            zipPrevEncodeLength(p,first.prevrawlen);
 
             /* Update offset for tail */
             ZIPLIST_TAIL_OFFSET(zl) =
@@ -521,8 +552,8 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
             }
 
             /* Move tail to the front of the ziplist */
-            memmove(first.p,p-nextdiff,
-                intrev32ifbe(ZIPLIST_BYTES(zl))-(p-zl)-1+nextdiff);
+            memmove(first.p,p,
+                intrev32ifbe(ZIPLIST_BYTES(zl))-(p-zl)-1);
         } else {
             /* The entire tail was deleted. No need to move memory. */
             ZIPLIST_TAIL_OFFSET(zl) =