Fix ImageMetadataDatabase::calculateImageSize calling Image::readPngMetadata on non-PNG images.

1 files changed, 6 insertions, 0 deletions

diff --git a/source/core/StarImage.cpp b/source/core/StarImage.cpp
index 82e3b05..52c2370 100644
--- a/source/core/StarImage.cpp
+++ b/source/core/StarImage.cpp
@@ -17,6 +17,12 @@ void readPngData(png_structp pngPtr, png_bytep data, png_size_t length) {
   ((IODevice*)png_get_io_ptr(pngPtr))->readFull((char*)data, length);
 };
 
+bool Image::isPng(IODevicePtr device) {
+  png_byte header[8];
+  device->readAbsolute(0, (char*)header, sizeof(header));
+  return !png_sig_cmp(header, 0, sizeof(header));
+}
+
 Image Image::readPng(IODevicePtr device) {
   png_byte header[8];
   device->readFull((char*)header, sizeof(header));