Bug 1237595 - FormData ctor and form submission should create empty Blob/File when a input type=file is not set, r=smaug

dom/base/File.cpp

@@ -957,6 +957,32 @@ BlobImplFile::LookupAndCacheIsDirectory()
   mDirState = isDir ? BlobDirState::eIsDir : BlobDirState::eIsNotDir;
 }
 
+////////////////////////////////////////////////////////////////////////////
+// BlobImplEmptyFile implementation
+
+NS_IMPL_ISUPPORTS_INHERITED0(BlobImplEmptyFile, BlobImpl)
+
+already_AddRefed<BlobImpl>
+BlobImplEmptyFile::CreateSlice(uint64_t aStart, uint64_t aLength,
+                               const nsAString& aContentType,
+                               ErrorResult& aRv)
+{
+  MOZ_ASSERT(!aStart && !aLength);
+  RefPtr<BlobImpl> impl = new BlobImplEmptyFile(aContentType);
+  return impl.forget();
+}
+
+void
+BlobImplEmptyFile::GetInternalStream(nsIInputStream** aStream,
+                                     ErrorResult& aRv)
+{
+  nsresult rv = NS_NewCStringInputStream(aStream, EmptyCString());
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    aRv.Throw(rv);
+    return;
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////
 // BlobImplMemory implementation
 

dom/base/File.h

@@ -833,6 +833,31 @@ private:
   bool mIsTemporary;
 };
 
+class BlobImplEmptyFile final : public BlobImplBase
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  explicit BlobImplEmptyFile(const nsAString& aContentType)
+    : BlobImplBase(EmptyString(), aContentType, 0 /* aLength */)
+  {}
+
+  virtual void GetInternalStream(nsIInputStream** aStream,
+                                 ErrorResult& aRv) override;
+
+  virtual already_AddRefed<BlobImpl>
+  CreateSlice(uint64_t aStart, uint64_t aLength,
+              const nsAString& aContentType, ErrorResult& aRv) override;
+
+  virtual bool IsMemoryFile() const override
+  {
+    return true;
+  }
+
+private:
+  ~BlobImplEmptyFile() {}
+};
+
 } // namespace dom
 } // namespace mozilla
 

dom/base/FormData.cpp

@@ -179,6 +179,8 @@ FormData::Has(const nsAString& aName)
 nsresult
 FormData::AddNameFilePair(const nsAString& aName, File* aFile)
 {
+  MOZ_ASSERT(aFile);
+
   FormDataTuple* data = mFormData.AppendElement();
   SetNameFilePair(data, aName, aFile);
   return NS_OK;
@@ -272,12 +274,10 @@ FormData::SetNameFilePair(FormDataTuple* aData,
                           File* aFile)
 {
   MOZ_ASSERT(aData);
+  MOZ_ASSERT(aFile);
+
   aData->name = aName;
-  if (aFile) {
   aData->value.SetAsFile() = aFile;
-  } else {
-    aData->value.SetAsUSVString() = EmptyString();
-  }
 }
 
 // -------------------------------------------------------------------------
@@ -364,7 +364,7 @@ FormData::GetSendInfo(nsIInputStream** aBody, uint64_t* aContentLength,
       fs.AddNameValuePair(mFormData[i].name,
                           mFormData[i].value.GetAsUSVString());
     } else {
-      fs.AddNameFilePair(mFormData[i].name, nullptr);
+      MOZ_CRASH("This should no be possible.");
     }
   }
 

dom/base/test/test_bug1187157.html

@@ -14,7 +14,16 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=789315
 <form id="a"><input name="b" type="file"/></form>
 
 <script type="text/javascript">
-  is(new FormData(document.getElementById('a')).get('b'), "", "This should return an empty string.");
+  var obj = new FormData(document.getElementById('a')).get('b');
+
+  ok(obj instanceof File, "This should return an empty File");
+  is(obj.size, 0, "Size should be 0");
+  is(obj.name, "", "Name should be an empty string");
+  is(obj.type, "application/octet-stream", "Type should be application/octet-stream");
+
+  var o = obj.slice(10, 100, "foo/bar");
+  is(o.size, 0, "The new blob has size 0");
+  is(o.type, "foo/bar", "The new blob has type foo/bar");
 </script>
 
 </body>

dom/html/HTMLInputElement.cpp

@@ -5593,9 +5593,10 @@ HTMLInputElement::SubmitNamesValues(nsFormSubmission* aFormSubmission)
     }
 
     if (files.IsEmpty()) {
-      // If no file was selected, pretend we had an empty file with an
+      RefPtr<BlobImpl> blobImpl =
-      // empty filename.
+        new BlobImplEmptyFile(NS_LITERAL_STRING("application/octet-stream"));
-      aFormSubmission->AddNameFilePair(name, nullptr);
+      RefPtr<File> file = File::Create(OwnerDoc()->GetInnerWindow(), blobImpl);
+      aFormSubmission->AddNameFilePair(name, file);
     }
 
     return NS_OK;

dom/html/nsFormSubmission.cpp

@@ -167,15 +167,15 @@ nsresult
 nsFSURLEncoded::AddNameFilePair(const nsAString& aName,
                                 File* aFile)
 {
+  MOZ_ASSERT(aFile);
+
   if (!mWarnedFileControl) {
     SendJSWarning(mDocument, "ForgotFileEnctypeWarning", nullptr, 0);
     mWarnedFileControl = true;
   }
 
   nsAutoString filename;
-  if (aFile) {
   aFile->GetName(filename);
-  }
 
   return AddNameValuePair(aName, filename);
 }
@@ -441,14 +441,13 @@ nsresult
 nsFSMultipartFormData::AddNameFilePair(const nsAString& aName,
                                        File* aFile)
 {
+  MOZ_ASSERT(aFile);
+
   // Encode the control name
   nsAutoCString nameStr;
   nsresult rv = EncodeVal(aName, nameStr, true);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsCString filename, contentType;
-  nsCOMPtr<nsIInputStream> fileStream;
-  if (aFile) {
   nsAutoString filename16;
   aFile->GetName(filename16);
 
@@ -464,6 +463,7 @@ nsFSMultipartFormData::AddNameFilePair(const nsAString& aName,
     filename16 = filepath16 + filename16;
   }
 
+  nsAutoCString filename;
   rv = EncodeVal(filename16, filename, true);
   NS_ENSURE_SUCCESS(rv, rv);
 
@@ -473,12 +473,15 @@ nsFSMultipartFormData::AddNameFilePair(const nsAString& aName,
   if (contentType16.IsEmpty()) {
     contentType16.AssignLiteral("application/octet-stream");
   }
+
+  nsAutoCString contentType;
   contentType.Adopt(nsLinebreakConverter::
                     ConvertLineBreaks(NS_ConvertUTF16toUTF8(contentType16).get(),
                                       nsLinebreakConverter::eLinebreakAny,
                                       nsLinebreakConverter::eLinebreakSpace));
 
   // Get input stream
+  nsCOMPtr<nsIInputStream> fileStream;
   aFile->GetInternalStream(getter_AddRefs(fileStream), error);
   if (NS_WARN_IF(error.Failed())) {
     return error.StealNSResult();
@@ -493,10 +496,6 @@ nsFSMultipartFormData::AddNameFilePair(const nsAString& aName,
 
     fileStream = bufferedStream;
   }
-  }
-  else {
-    contentType.AssignLiteral("application/octet-stream");
-  }
 
   //
   // Make MIME block for name/value pair
@@ -619,9 +618,7 @@ nsFSTextPlain::AddNameFilePair(const nsAString& aName,
                                File* aFile)
 {
   nsAutoString filename;
-  if (aFile) {
   aFile->GetName(filename);
-  }
 
   AddNameValuePair(aName, filename);
   return NS_OK;

dom/html/test/test_formSubmission.html

@@ -258,7 +258,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=523771
   <p>
     File input:
     <input type=file name="file_1" class="setfile">
-    <input type=file name="file_2" class="setfile empty">
+    <input type=file name="file_2">
     <input type=file name="" class="setfile">
     <input type=file name="">
     <input type=file class="setfile">
@@ -268,7 +268,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=523771
     Multifile input:
     <input multiple type=file name="file_3" class="setfile">
     <input multiple type=file name="file_4" class="setfile multi">
-    <input multiple type=file name="file_5" class="setfile empty">
+    <input multiple type=file name="file_5">
     <input multiple type=file name="" class="setfile">
     <input multiple type=file name="" class="setfile multi">
     <input multiple type=file name="">
@@ -426,7 +426,6 @@ function onFilesOpened(files) {
 
   let singleFile = textFile;
   let multiFile = [textFile, imageFile];
-  emptyFile = new File([], "", { type: "application/octet-stream" });
 
   var addList = document.getElementsByClassName("setfile");
   let i = 0;
@@ -434,8 +433,6 @@ function onFilesOpened(files) {
   while (input = addList[i++]) {
     if (input.classList.contains("multi")) {
       SpecialPowers.wrap(input).mozSetFileArray(multiFile);
-    } else if (input.classList.contains("empty")) {
-      SpecialPowers.wrap(input).mozSetFileArray([emptyFile]);
     } else {
       SpecialPowers.wrap(input).mozSetFileArray([singleFile]);
     }
@@ -449,6 +446,7 @@ function onFilesOpened(files) {
   myFile2 = input.files[1];
   is(myFile1.size, 20, "File1 size");
   is(myFile2.size, 2711, "File2 size");
+  emptyFile = { name: "", type: "application/octet-stream" };
 
   // Now, actually run the tests; see below.
   onFilesSet();