Don't allocate on the Dart heap during Bigint::ToCString().

runtime/vm/snapshot_test.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 
 #include "include/dart_tools_api.h"
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
 #include "vm/clustered_snapshot.h"
@@ skipping 359 matching lines @@
   ApiNativeScope scope;
   ApiMessageReader api_reader(buffer, buffer_len);
   Dart_CObject* root = api_reader.ReadMessage();
   EXPECT_NOTNULL(root);
   EXPECT_EQ(Dart_CObject_kBool, root->type);
   EXPECT_EQ(false, root->value.as_bool);
   CheckEncodeDecodeMessage(root);
 }
 
 
-static uword allocator(intptr_t size) {
-  return reinterpret_cast<uword>(malloc(size));
-}
-
-
 TEST_CASE(SerializeCapability) {
   // Write snapshot with object content.
   const Capability& capability = Capability::Handle(Capability::New(12345));
   uint8_t* buffer;
   MessageWriter writer(&buffer, &zone_allocator, true);
   writer.WriteMessage(capability);
   intptr_t buffer_len = writer.BytesWritten();
 
   // Read object back from the snapshot.
   MessageSnapshotReader reader(buffer, buffer_len, thread);
@@ skipping 23 matching lines @@
   uint8_t* buffer;
   MessageWriter writer(&buffer, &zone_allocator, true);
   writer.WriteMessage(bigint);
   intptr_t buffer_len = writer.BytesWritten();
 
   // Read object back from the snapshot.
   MessageSnapshotReader reader(buffer, buffer_len, thread);
   Bigint& obj = Bigint::Handle();
   obj ^= reader.ReadObject();
 
-  EXPECT_STREQ(bigint.ToHexCString(allocator), obj.ToHexCString(allocator));
+  Zone* zone = Thread::Current()->zone();
+  EXPECT_STREQ(bigint.ToHexCString(zone), obj.ToHexCString(zone));
 
   // Read object back from the snapshot into a C structure.
   ApiNativeScope scope;
   ApiMessageReader api_reader(buffer, buffer_len);
   Dart_CObject* root = api_reader.ReadMessage();
   EXPECT_NOTNULL(root);
   EXPECT_EQ(Dart_CObject_kBigint, root->type);
   char* hex_value = TestCase::BigintToHexValue(root);
   EXPECT_STREQ(cstr, hex_value);
   free(hex_value);
   CheckEncodeDecodeMessage(root);
 }
 
 
 Dart_CObject* SerializeAndDeserializeBigint(const Bigint& bigint) {
   // Write snapshot with object content.
   uint8_t* buffer;
   MessageWriter writer(&buffer, &zone_allocator, true);
   writer.WriteMessage(bigint);
   intptr_t buffer_len = writer.BytesWritten();
 
   {
     // Switch to a regular zone, where VM handle allocation is allowed.
     Thread* thread = Thread::Current();
     StackZone zone(thread);
     // Read object back from the snapshot.
     MessageSnapshotReader reader(buffer, buffer_len, thread);
     Bigint& serialized_bigint = Bigint::Handle();
     serialized_bigint ^= reader.ReadObject();
-    const char* str1 = bigint.ToHexCString(allocator);
-    const char* str2 = serialized_bigint.ToHexCString(allocator);
+    const char* str1 = bigint.ToHexCString(thread->zone());
+    const char* str2 = serialized_bigint.ToHexCString(thread->zone());
     EXPECT_STREQ(str1, str2);
-    free(const_cast<char*>(str1));
-    free(const_cast<char*>(str2));
   }
 
   // Read object back from the snapshot into a C structure.
   ApiMessageReader api_reader(buffer, buffer_len);
   Dart_CObject* root = api_reader.ReadMessage();
   // Bigint not supported.
   EXPECT_NOTNULL(root);
   CheckEncodeDecodeMessage(root);
   return root;
 }
@@ skipping 2545 matching lines @@
   StackZone zone(Thread::Current());
   uint8_t* buffer;
   MessageWriter writer(&buffer, &zone_allocator, true);
   writer.WriteInlinedObjectHeader(kOmittedObjectId);
   // For performance, we'd like single-byte headers when ids are omitted.
   // If this starts failing, consider renumbering the snapshot ids.
   EXPECT_EQ(1, writer.BytesWritten());
 }
 
 }  // namespace dart