Fix issue 420: accept truncated log files.

test/mjsunit/tools/logreader.js

Index: test/mjsunit/tools/logreader.js
diff --git a/test/mjsunit/tools/logreader.js b/test/mjsunit/tools/logreader.js
index dfd7f9f54eb003646ea91c182b6cc73efdb80a69..8ed5ffd2670b68e3ec7e320d3f031c906f7c7edd 100644
--- a/test/mjsunit/tools/logreader.js
+++ b/test/mjsunit/tools/logreader.js
@@ -80,3 +80,19 @@
   assertEquals('bbbbaaaa', reader.expandBackRef_('bbbb#2:4'));
   assertEquals('"#1:1"', reader.expandBackRef_('"#1:1"'));
 })();
+
+
+// See http://code.google.com/p/v8/issues/detail?id=420
+(function testReadingTruncatedLog() {
+  // Having an incorrect event in the middle of a log should throw an exception.
+  var reader1 = new devtools.profiler.LogReader({});
+  assertThrows(function() {
+    reader1.processLogChunk('alias,a,b\nxxxx\nalias,c,d\n');
+  });
+
+  // But having it as the last record should not.
+  var reader2 = new devtools.profiler.LogReader({});
+  assertDoesNotThrow(function() {
+    reader2.processLogChunk('alias,a,b\nalias,c,d\nxxxx');
+  });
+})();