Open Session - check fileType for native file formats while identifying the file format from filename; also find size of metadata and use it when parsing just the metadata instead of the whole file

client/mainwindow.cpp

@@ -276,8 +276,10 @@ bool MainWindow::openSession(QString fileName, QString &error)
     OstProto::SessionContent session;
     SessionFileFormat *fmt = SessionFileFormat::fileFormatFromFile(fileName);
 
-    if (fmt == NULL)
+    if (fmt == NULL) {
+        error = tr("Unknown session file format");
         goto _fail;
+    }
 
     if ((optDialog = fmt->openOptionsDialog()))
     {

client/port.cpp

@@ -551,8 +551,10 @@ bool Port::openStreams(QString fileName, bool append, QString &error)
     OstProto::StreamConfigList streams;
     AbstractFileFormat *fmt = AbstractFileFormat::fileFormatFromFile(fileName);
 
-    if (fmt == NULL)
+    if (fmt == NULL) {
+        error = tr("Unknown streams file format");
         goto _fail;
+    }
 
     if ((optDialog = fmt->openOptionsDialog()))
     {

common/nativefileformat.cpp

@@ -140,11 +140,9 @@ bool NativeFileFormat::open(
         goto _cksum_verify_fail;
 
     // Parse the metadata first before we parse the full contents
-    // FIXME: metadata size is not known beforehand, so we end up
-    // parsing till EOF
     if (!meta.ParseFromArray(
                 (void*)(buf.constData() + kFileMetaDataOffset),
-                size - kFileMetaDataOffset))
+                fileMetaSize((quint8*)buf.constData(), size)))
     {
         goto _metadata_parse_fail;
     }
@@ -420,15 +418,21 @@ bool NativeFileFormat::isNativeFileFormat(
     if (!file.open(QIODevice::ReadOnly))
         goto _exit;
 
-    buf = file.peek(kFileMagicOffset + kFileMagicSize);
+    // Assume tag/length for MetaData will fit in 8 bytes
+    buf = file.peek(kFileMagicOffset + kFileMagicSize + 8);
     if (!magic.ParseFromArray((void*)(buf.constData() + kFileMagicOffset),
                 kFileMagicSize))
         goto _close_exit;
 
-    if (magic.value() == kFileMagicValue)
-        ret = true;
-
-    // TODO: check fileType
+    if (magic.value() == kFileMagicValue) {
+        OstProto::FileMetaData meta;
+        if (!meta.ParseFromArray(
+                (void*)(buf.constData() + kFileMetaDataOffset),
+                fileMetaSize((quint8*)buf.constData(), buf.size())))
+            goto _close_exit;
+        if (meta.file_type() == fileType)
+            ret = true;
+    }
 
 _close_exit:
     file.close();
@@ -451,6 +455,50 @@ void NativeFileFormat::initFileMetaData(OstProto::FileMetaData &metaData)
         qApp->property("revision").toString().toUtf8().constData());
 }
 
+int NativeFileFormat::fileMetaSize(const quint8* file, int size)
+{
+    int i = kFileMetaDataOffset;
+    uint result, shift;
+    const int kWireTypeLengthDelimited = 2;
+
+    // An embedded Message field is encoded as
+    // <Key> <Length> <Serialized-Value>
+    // See Protobuf Encoding for more details
+
+    // Decode 'Key' varint
+    result = 0;
+    shift = 0;
+    while (i < size) {
+      quint8 byte = file[i++];
+      result |= (byte & 0x7f) << shift;
+      if (!(byte & 0x80)) // MSB == 0?
+        break;
+      shift += 7;
+    }
+
+    if (i >= size)
+        return 0;
+
+    Q_ASSERT(result == ((OstProto::File::kMetaDataFieldNumber << 3)
+                            | kWireTypeLengthDelimited));
+
+    // Decode 'Length' varint
+    result = 0;
+    shift = 0;
+    while (i < size) {
+      quint8 byte = file[i++];
+      result |= (byte & 0x7f) << shift;
+      if (!(byte & 0x80)) // MSB == 0?
+        break;
+      shift += 7;
+    }
+
+    if (i >= size)
+        return 0;
+
+    return int(result+(i-kFileMetaDataOffset));
+}
+
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 /*! Fixup content to what is expected in the native version */
 void NativeFileFormat::postParseFixup(OstProto::FileMetaData metaData,

common/nativefileformat.h

@@ -57,6 +57,7 @@ public:
 
 private:
     void initFileMetaData(OstProto::FileMetaData &metaData);
+    int fileMetaSize(const quint8* file, int size);
 
     static const int kFileMagicSize = 12;
     static const int kFileChecksumSize = 5;