From 639817de90dafbc8cc98a63ff05a7a5ade5dffc1 Mon Sep 17 00:00:00 2001
From: luben <karavelov@spnet.net>
Date: Mon, 16 Aug 2010 18:34:46 +0300
Subject: [PATCH 9/9] Important fixes

* make hash again work with N_BUCKETS(X) != X
* fix memory allocation problems catched by
  more strict allocators. libhoard catched some
  use-after-free bugs.
* realocate pointers in linear scan - it's faster
---
 src/hash.c |   88 ++++++++++++++++++++++++++++++++++--------------------------
 1 files changed, 50 insertions(+), 38 deletions(-)

diff --git a/src/hash.c b/src/hash.c
index 07a9b18..145cea5 100644
--- a/src/hash.c
+++ b/src/hash.c
@@ -781,15 +781,17 @@ static void
 expand_hash(PARROT_INTERP, ARGMOD(Hash *hash))
 {
     ASSERT_ARGS(expand_hash)
-    HashBucket  **old_index, **new_index;
-    HashBucket   *old_buckets,*new_buckets, *bucket;
-    HashBucket * const old_offset = (HashBucket *)((char *)hash + sizeof (Hash));
+
+    HashBucket  **new_index,  **index;
+    HashBucket   *new_buckets, *bucket;
+
+    HashBucket * const initial_offset = (HashBucket *)((char *)hash + sizeof (Hash));
 
     void *        new_mem;
     void * const  old_mem    = hash->buckets;
     const UINTVAL old_size   = hash->mask + 1;
-    const UINTVAL new_size   = old_size << 1; /* Double. Right-shift is 2x */
-    const UINTVAL new_mask   = new_size - 1 ;
+    const UINTVAL new_size   = old_size  << 1; /* Double. Right-shift is 2x */
+    const UINTVAL new_mask   = new_size   - 1;
     size_t        offset, i;
 
     /*
@@ -804,46 +806,57 @@ expand_hash(PARROT_INTERP, ARGMOD(Hash *hash))
     */
 
     /* resize mem */
-    if (old_offset != old_mem) {
+    if (initial_offset != old_mem) {
         /* This buffer has been reallocated at least once before. */
-        new_mem = Parrot_gc_reallocate_memory_chunk_with_interior_pointers(
-                interp, old_mem, HASH_ALLOC_SIZE(new_size), HASH_ALLOC_SIZE(old_size));
-    }
+        new_mem   = Parrot_gc_reallocate_memory_chunk_with_interior_pointers(
+                interp, old_mem, 
+                HASH_ALLOC_SIZE(new_size), 
+                HASH_ALLOC_SIZE(old_size));
+
+        new_buckets = (HashBucket *)  new_mem;
+        new_index   = (HashBucket **)(new_buckets + N_BUCKETS(new_size));
+
+        offset = (char *)new_mem - (char *)old_mem;
+
+        /* old index is here */
+        index  = (HashBucket **)(new_buckets + N_BUCKETS(old_size));
+        /* reallocate index */
+        mem_sys_memcopy(new_index, index, sizeof(HashBucket *) * old_size);
+
+        /* clear second half of the buckets, freed by old the index */
+        memset(new_buckets + N_BUCKETS(old_size), 0, 
+                sizeof (HashBucket *) * old_size);
+    } 
     else {
         /* Allocate a new buffer. */
         new_mem = Parrot_gc_allocate_memory_chunk_with_interior_pointers(
                 interp, HASH_ALLOC_SIZE(new_size));
-        memcpy(new_mem, old_mem, HASH_ALLOC_SIZE(old_size));
+
+        new_buckets = (HashBucket *)  new_mem;
+        new_index   = (HashBucket **)(new_buckets + N_BUCKETS(new_size));
+
+        offset = (char *)new_buckets - (char *)hash->buckets;
+        
+        mem_sys_memcopy(new_buckets, hash->buckets ,
+                N_BUCKETS(old_size) * sizeof (HashBucket));
+        mem_sys_memcopy(new_index,   hash->index, 
+                sizeof(HashBucket *) * old_size);
     }
 
     /*
          +---+---+---+---+---+---+-+-+-+-+-+-+-+-+
-         |  buckets  | old_index    |  new_index       |
+         |  buckets  | old_index    |  new_index |
          +---+---+---+---+---+---+-+-+-+-+-+-+-+-+
          ^                       ^
          | new_mem               | hash->index
     */
 
-    old_buckets = hash->buckets;
-    old_index   = hash->index;
-
-    new_buckets = (HashBucket *) new_mem;
-    new_index   = (HashBucket **)(new_buckets + N_BUCKETS(new_size));
-
-    /* things can have moved by this offset */
-    offset = (char *)new_buckets - (char *)old_buckets;
-
-    /* relocate the bucket index */
-    mem_sys_memmove(new_index, old_index, old_size * sizeof (HashBucket *));
 
     /* update hash data */
     hash->index     = new_index;
     hash->buckets   = new_buckets;
     hash->mask      = new_mask;
 
-    /* clear freshly allocated bucket index */
-    memset(new_index + old_size, 0, sizeof (HashBucket *) * old_size);
-
     /*
      * reloc pointers - this part would be also needed, if we
      * allocate hash memory from GC movable memory, and then
@@ -851,33 +864,32 @@ expand_hash(PARROT_INTERP, ARGMOD(Hash *hash))
      * as expand_hash is only called for that case).
      */
     if (offset) {
-        size_t j;
-        for (j = 0; j < old_size; ++j) {
-            HashBucket **next_p = new_index + j;
-            while (*next_p) {
-                *next_p = (HashBucket *)((char *)*next_p + offset);
-                bucket  = *next_p;
-                next_p  = &bucket->next;
+        for (i = 0; i < old_size; ++i) {
+            index = new_index + i;
+            while (*index) {
+                *index = (HashBucket *)((char *)*index + offset);
+                bucket = *index;
+                index  = &bucket->next;
             }
         }
     }
 
     /* recalc bucket index */
     for (i = 0; i < old_size; ++i) {
-        HashBucket **next_p = new_index + i;
+        index = new_index + i;
 
-        while ((bucket = *next_p) != NULL) {
+        while ((bucket = *index) != NULL) {
             /* rehash the bucket */
             const size_t new_loc =
                 get_hash_val(interp, hash, bucket->key) & new_mask;
 
             if (i != new_loc) {
-                *next_p             = bucket->next;
-                bucket->next        = new_index[new_loc];
-                new_index[new_loc]  = bucket;
+                *index             = bucket->next;
+                bucket->next       = new_index[new_loc];
+                new_index[new_loc] = bucket;
             }
             else
-                next_p = &bucket->next;
+                index = &bucket->next;
         }
     }
 
-- 
1.7.1