C bindings: Implement _DeepCopy() & some unittests.

mojo/public/c/bindings/lib/array.c

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/public/c/bindings/array.h"
 
 #include <assert.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <string.h>
 
 #include "mojo/public/c/bindings/buffer.h"
 #include "mojo/public/c/bindings/interface.h"
 #include "mojo/public/c/bindings/lib/type_descriptor.h"
 #include "mojo/public/c/bindings/lib/util.h"
 #include "mojo/public/c/bindings/union.h"
 
 struct MojomArrayHeader* MojomArray_New(struct MojomBuffer* buf,
                                         uint32_t num_elements,
                                         uint32_t element_byte_size) {
@@ skipping 189 matching lines @@
         elem_data,
         in_array_size - (uint32_t)(elem_data - (char*)in_array),
         in_num_handles,
         inout_context);
     if (result != MOJOM_VALIDATION_ERROR_NONE)
       return result;
   }
 
   return MOJOM_VALIDATION_ERROR_NONE;
 }
+
+struct MojomArrayHeader* MojomArray_DeepCopy(
+    struct MojomBuffer* buffer,
+    const struct MojomTypeDescriptorArray* in_type_desc,
+    struct MojomArrayHeader* in_array) {
+  assert(in_type_desc);
+  assert(in_array);
+
+  struct MojomArrayHeader* out_array =
+      MojomBuffer_Allocate(buffer, in_array->num_bytes);

[viettrungluu, 2016/08/02 20:15:06]

E.g., this could fail. Though at least here you can still bail (and return null)
without a problem.

+  memcpy(out_array, in_array, in_array->num_bytes);
+
+  // Nothing else to copy for POD types.
+  if (in_type_desc->elem_type == MOJOM_TYPE_DESCRIPTOR_TYPE_POD)
+    return out_array;
+
+  for (size_t i = 0; i < in_array->num_elements; i++) {
+    void* in_elem_data =
+        array_index_by_type(in_array, in_type_desc->elem_type, i);
+    void* out_elem_data =
+        array_index_by_type(out_array, in_type_desc->elem_type, i);
+
+    MojomType_DispatchDeepCopy(buffer, in_type_desc->elem_type,

[viettrungluu, 2016/08/02 20:15:06]

Presumably, this could fail too. But that would pose a bigger problem, since you
can't cleanly bail here if you're modifying in_array (e.g., to "move" handles).

+                               in_type_desc->elem_descriptor, in_elem_data,
+                               out_elem_data);
+  }
+
+  return out_array;
+}