diff --git a/src/util/system.h b/src/util/system.h
--- a/src/util/system.h
+++ b/src/util/system.h
@@ -63,6 +63,17 @@
 bool DirIsWritable(const fs::path &directory);
 bool CheckDiskSpace(const fs::path &dir, uint64_t additional_bytes = 0);
 
+/**
+ * Get the size of a file by scanning it.
+ *
+ * @param[in] path The file path
+ * @param[in] max Stop seeking beyond this limit
+ * @return The file size or max
+ */
+std::streampos
+GetFileSize(const char *path,
+            std::streamsize max = std::numeric_limits<std::streamsize>::max());
+
 /**
  * Release all directory locks. This is used for unit testing only, at runtime
  * the global destructor will take care of the locks.
diff --git a/src/util/system.cpp b/src/util/system.cpp
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -143,6 +143,12 @@
     return free_bytes_available >= min_disk_space + additional_bytes;
 }
 
+std::streampos GetFileSize(const char *path, std::streamsize max) {
+    std::ifstream file(path, std::ios::binary);
+    file.ignore(max);
+    return file.gcount();
+}
+
 /**
  * Interpret a string argument as a boolean.
  *