[BlobStorage] Enforcing renderer constraints to prevent broken blobs

third_party/WebKit/Source/core/fileapi/File.cpp

Index: third_party/WebKit/Source/core/fileapi/File.cpp
diff --git a/third_party/WebKit/Source/core/fileapi/File.cpp b/third_party/WebKit/Source/core/fileapi/File.cpp
index 5ca1b94385feb6f04a5fa68a49858400638e3bb6..716b3a3d2613c38b2540d7fd0462e7e1f20a2dd6 100644
--- a/third_party/WebKit/Source/core/fileapi/File.cpp
+++ b/third_party/WebKit/Source/core/fileapi/File.cpp
@@ -84,22 +84,34 @@ static std::unique_ptr<BlobData> createBlobDataForFileWithName(
 static std::unique_ptr<BlobData> createBlobDataForFileWithMetadata(
     const String& fileSystemName,
     const FileMetadata& metadata) {
-  std::unique_ptr<BlobData> blobData = BlobData::create();
+  std::unique_ptr<BlobData> blobData;
+  if (metadata.length == BlobDataItem::toEndOfFile) {

[pwnall, 2017/03/06 21:13:45]

Tests?

[dmurph, 2017/03/06 23:43:29]

Tested by one or more of:
FileTest.fileSystemFileWithNativeSnapshot
V8ScriptValueSerializerTest.RoundTripFileNativeSnapshot
FileListTest.pathsForUserVisibleFiles
WebDragDataTest.items

[pwnall, 2017/03/06 23:45:12]

Do we know for sure that we have coverage of both branches?

[dmurph, 2017/03/29 23:19:24]

Checked. Added one test for case where we have the file length in metadata.

+    blobData = BlobData::createForFileWithUnknownSize(
+        metadata.platformPath, metadata.modificationTime / msPerSecond);
+  } else {
+    blobData = BlobData::create();
+    blobData->appendFile(metadata.platformPath, 0, metadata.length,
+                         metadata.modificationTime / msPerSecond);
+  }
   blobData->setContentType(
       getContentTypeFromFileName(fileSystemName, File::WellKnownContentTypes));
-  blobData->appendFile(metadata.platformPath, 0, metadata.length,
-                       metadata.modificationTime / msPerSecond);
   return blobData;
 }
 
 static std::unique_ptr<BlobData> createBlobDataForFileSystemURL(
     const KURL& fileSystemURL,
     const FileMetadata& metadata) {
-  std::unique_ptr<BlobData> blobData = BlobData::create();
+  std::unique_ptr<BlobData> blobData;
+  if (metadata.length == BlobDataItem::toEndOfFile) {
+    blobData = BlobData::createForFileSystemURLWithUnknownSize(
+        fileSystemURL, metadata.modificationTime / msPerSecond);
+  } else {
+    blobData = BlobData::create();
+    blobData->appendFileSystemURL(fileSystemURL, 0, metadata.length,
+                                  metadata.modificationTime / msPerSecond);
+  }
   blobData->setContentType(getContentTypeFromFileName(
       fileSystemURL.path(), File::WellKnownContentTypes));
-  blobData->appendFileSystemURL(fileSystemURL, 0, metadata.length,
-                                metadata.modificationTime / msPerSecond);
   return blobData;
 }