index-pack: fix race condition with duplicate bases

diff --git a/object.c b/object.c
index d8a4b1ffbe68d6e9f720e979168f9d010c9c5a06..584f7acb36b68d17678b3fd6251105241794ea48 100644 (file)
--- a/object.c
+++ b/object.c
@@ -43,16 +43,17 @@ int type_from_string(const char *str)
        die("invalid object type \"%s\"", str);
 }
 
-static unsigned int hash_obj(struct object *obj, unsigned int n)
+static unsigned int hash_obj(const unsigned char *sha1, unsigned int n)
 {
        unsigned int hash;
-       memcpy(&hash, obj->sha1, sizeof(unsigned int));
-       return hash % n;
+       memcpy(&hash, sha1, sizeof(unsigned int));
+       /* Assumes power-of-2 hash sizes in grow_object_hash */
+       return hash & (n - 1);
 }
 
 static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
 {
-       unsigned int j = hash_obj(obj, size);
+       unsigned int j = hash_obj(obj->sha1, size);
 
        while (hash[j]) {
                j++;
@@ -62,13 +63,6 @@ static void insert_obj_hash(struct object *obj, struct object **hash, unsigned i
        hash[j] = obj;
 }
 
-static unsigned int hashtable_index(const unsigned char *sha1)
-{
-       unsigned int i;
-       memcpy(&i, sha1, sizeof(unsigned int));
-       return i % obj_hash_size;
-}
-
 struct object *lookup_object(const unsigned char *sha1)
 {
        unsigned int i, first;
@@ -77,7 +71,7 @@ struct object *lookup_object(const unsigned char *sha1)
        if (!obj_hash)
                return NULL;
 
-       first = i = hashtable_index(sha1);
+       first = i = hash_obj(sha1, obj_hash_size);
        while ((obj = obj_hash[i]) != NULL) {
                if (!hashcmp(sha1, obj->sha1))
                        break;
@@ -101,6 +95,10 @@ struct object *lookup_object(const unsigned char *sha1)
 static void grow_object_hash(void)
 {
        int i;
+       /*
+        * Note that this size must always be power-of-2 to match hash_obj
+        * above.
+        */
        int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
        struct object **new_hash;
 
@@ -264,18 +262,16 @@ int object_list_contains(struct object_list *list, struct object *obj)
        return 0;
 }
 
-void add_object_array(struct object *obj, const char *name, struct object_array *array)
-{
-       add_object_array_with_mode(obj, name, array, S_IFINVALID);
-}
-
 /*
  * A zero-length string to which object_array_entry::name can be
  * initialized without requiring a malloc/free.
  */
 static char object_array_slopbuf[1];
 
-void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
+static void add_object_array_with_mode_context(struct object *obj, const char *name,
+                                              struct object_array *array,
+                                              unsigned mode,
+                                              struct object_context *context)
 {
        unsigned nr = array->nr;
        unsigned alloc = array->alloc;
@@ -298,9 +294,28 @@ void add_object_array_with_mode(struct object *obj, const char *name, struct obj
        else
                entry->name = xstrdup(name);
        entry->mode = mode;
+       entry->context = context;
        array->nr = ++nr;
 }
 
+void add_object_array(struct object *obj, const char *name, struct object_array *array)
+{
+       add_object_array_with_mode(obj, name, array, S_IFINVALID);
+}
+
+void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
+{
+       add_object_array_with_mode_context(obj, name, array, mode, NULL);
+}
+
+void add_object_array_with_context(struct object *obj, const char *name, struct object_array *array, struct object_context *context)
+{
+       if (context)
+               add_object_array_with_mode_context(obj, name, array, context->mode, context);
+       else
+               add_object_array_with_mode_context(obj, name, array, S_IFINVALID, context);
+}
+
 void object_array_filter(struct object_array *array,
                         object_array_each_func_t want, void *cb_data)
 {