svn commit: r1679686 - /subversion/branches/1.9-cache-improvements/subversion/libsvn_subr/cache-membuffer.c

[st...@apache.org]

Author: stefan2
Date: Sat May 16 05:13:49 2015
New Revision: 1679686

URL: http://svn.apache.org/r1679686
Log:
On the 1.9-cache-improvements branch: 
Fix another instance of the key length handling issue.  This one is
specific to this branch and does not apply to the 1.10-cache-improvements
branch.

* subversion/libsvn_subr/cache-membuffer.c
  (combine_key): Handle super-long keys the similarly to what we do in
                 combine_long_key.

Modified:
    subversion/branches/1.9-cache-improvements/subversion/libsvn_subr/cache-membuffer.c

Modified: subversion/branches/1.9-cache-improvements/subversion/libsvn_subr/cache-membuffer.c
URL: http://svn.apache.org/viewvc/subversion/branches/1.9-cache-improvements/subversion/libsvn_subr/cache-membuffer.c?rev=1679686&r1=1679685&r2=1679686&view=diff
==============================================================================
--- subversion/branches/1.9-cache-improvements/subversion/libsvn_subr/cache-membuffer.c (original)
+++ subversion/branches/1.9-cache-improvements/subversion/libsvn_subr/cache-membuffer.c Sat May 16 05:13:49 2015
@@ -2670,20 +2670,34 @@ combine_key(svn_membuffer_cache_t *cache
   /* short, fixed-size keys are the most common case */
   if (key_len != APR_HASH_KEY_STRING && key_len <= 16)
     {
-      const apr_size_t prefix_len = cache->prefix.entry_key.key_len;
+      const apr_uint32_t prefix_len = cache->prefix.entry_key.key_len;
+
       /* Copy of *key, padded with 0.
        * We put it just behind the prefix already copied into the COMBINED_KEY.
        * The buffer space has been allocated when the cache was created. */
       apr_uint64_t *data = (void *)((char *)cache->combined_key.full_key.data + 
                                     prefix_len);
-      assert(prefix_len + 16 <= cache->combined_key.full_key.size);
+      assert(prefix_len <= cache->combined_key.full_key.size - 16);
+
+      /* Paranoia: Ridiculously long keys.
+       *
+       * We can't cache combined keys of 4GB and longer anyways.  So, putting
+       * a cap on them just above the maximum cachable value keeps them still
+       * non-cachable but allows us to cast to u32.
+       */
+      assert(MAX_ITEM_SIZE < APR_UINT32_MAX);
+      if (APR_UINT32_MAX - 16 < prefix_len)
+        {
+          /* Non-cachable. Cap values. No data alignment needed.
+           * Even the combined key will not be used. */
+          cache->combined_key.entry_key.key_len = APR_UINT32_MAX;
+          return;
+        }
 
       data[0] = 0;
       data[1] = 0;
       memcpy(data, key, key_len);
 
-      cache->combined_key.entry_key.key_len = prefix_len + 16;
-
       /* scramble key DATA.  All of this must be reversible to prevent key
        * collisions.  So, we limit ourselves to xor and permutations. */
       data[1] = (data[1] << 27) | (data[1] >> 37);