IsGCZBlob: try to leave the file position where it was before

callers that don't seek afterwards might be missing a few bytes that way.

1 files changed, 6 insertions, 1 deletions

diff --git a/Source/Core/DiscIO/CompressedBlob.cpp b/Source/Core/DiscIO/CompressedBlob.cpp
index 0cf8dbc5b3..447088de61 100644
--- a/Source/Core/DiscIO/CompressedBlob.cpp
+++ b/Source/Core/DiscIO/CompressedBlob.cpp
@@ -410,8 +410,13 @@ bool DecompressBlobToFile(const std::string& infile_path, const std::string& out
 
 bool IsGCZBlob(File::IOFile& file)
 {
+  const u64 position = file.Tell();
+  if (!file.Seek(0, SEEK_SET))
+    return false;
   CompressedBlobHeader header;
-  return file.Seek(0, SEEK_SET) && file.ReadArray(&header, 1) && header.magic_cookie == GCZ_MAGIC;
+  bool is_gcz = file.ReadArray(&header, 1) && header.magic_cookie == GCZ_MAGIC;
+  file.Seek(position, SEEK_SET);
+  return is_gcz;
 }
 
 }  // namespace