Fix: Open files read only if requested

src/validation.cpp

@@ -3464,7 +3464,7 @@ static FILE* OpenDiskFile(const CDiskBlockPos &pos, const char *prefix, bool fRe
         return nullptr;
     fs::path path = GetBlockPosFilename(pos, prefix);
     fs::create_directories(path.parent_path());
-    FILE* file = fsbridge::fopen(path, "rb+");
+    FILE* file = fsbridge::fopen(path, fReadOnly ? "rb": "rb+");
     if (!file && !fReadOnly)
         file = fsbridge::fopen(path, "wb+");
     if (!file) {