From 8f0658cdd063b762ece37c8159a3cb1551526a7f Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Thu, 31 May 2012 21:45:39 +0200
Subject: [PATCH] BITOP bug when called against non existing keys fixed.

In the issue #529 an user reported a bug that can be triggered with the
following code:

flushdb
set a
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
bitop or x a b

The bug was introduced with the speed optimization in commit 8bbc076
that specializes every BITOP operation loop up to the minimum length of
the input strings.

However the computation of the minimum length contained an error when a
non existing key was present in the input, after a key that was non zero
length.

This commit fixes the bug and adds a regression test for it.
---
 src/bitops.c          | 1 +
 tests/unit/bitops.tcl | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/src/bitops.c b/src/bitops.c
index d309b7af..00192b92 100644
--- a/src/bitops.c
+++ b/src/bitops.c
@@ -197,6 +197,7 @@ void bitopCommand(redisClient *c) {
             objects[j] = NULL;
             src[j] = NULL;
             len[j] = 0;
+            minlen = 0;
             continue;
         }
         /* Return an error if one of the keys is not a string. */
diff --git a/tests/unit/bitops.tcl b/tests/unit/bitops.tcl
index c8f58ef1..0e3403bf 100644
--- a/tests/unit/bitops.tcl
+++ b/tests/unit/bitops.tcl
@@ -160,4 +160,10 @@ start_server {tags {"bitops"}} {
         catch {r bitop xor dest a b c d} e
         set e
     } {*ERR*}
+
+    test {BITOP with empty string after non empty string (issue #529)} {
+        r flushdb
+        r set a "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+        r bitop or x a b
+    } {32}
 }
-- 
2.45.2