Ensure that SkMemoryStream does not crash dereferencing fData.

SkMemoryStream attempts to dereference fData in multiple places.
Instead of allowing it to be NULL, resulting in a crash, set it
to SkData::NewEmpty().

Add a test for SkStream that will crash when its SkData is set to NULL.

Review URL: https://codereview.appspot.com/7061059

git-svn-id: http://skia.googlecode.com/svn/trunk@7111 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/StreamTest.cpp b/tests/StreamTest.cpp
index b5e3cd98b8..ed51aa7baf 100644
--- a/tests/StreamTest.cpp
+++ b/tests/StreamTest.cpp
@@ -130,10 +130,29 @@ static void TestPackedUInt(skiatest::Reporter* reporter) {
     }
 }
 
+// Test that setting an SkMemoryStream to a NULL data does not result in a crash when calling
+// methods that access fData.
+static void TestDereferencingData(SkMemoryStream* memStream) {
+    memStream->read(NULL, 0);
+    memStream->getMemoryBase();
+    SkAutoDataUnref data(memStream->copyToData());
+}
+
+static void TestNullData() {
+    SkData* nullData = NULL;
+    SkMemoryStream memStream(nullData);
+    TestDereferencingData(&memStream);
+
+    memStream.setData(nullData);
+    TestDereferencingData(&memStream);
+
+}
+
 static void TestStreams(skiatest::Reporter* reporter) {
     TestRStream(reporter);
     TestWStream(reporter);
     TestPackedUInt(reporter);
+    TestNullData();
 }
 
 #include "TestClassDef.h"