refactor: Add AutoFile::size

src/streams.cpp

@@ -57,6 +57,20 @@ int64_t AutoFile::tell()
     return *m_position;
 }
 
+int64_t AutoFile::size()
+{
+    if (IsNull()) {
+        throw std::ios_base::failure("AutoFile::size: file handle is nullptr");
+    }
+    // Temporarily save the current position
+    int64_t current_pos = tell();
+    seek(0, SEEK_END);
+    int64_t file_size = tell();
+    // Restore the original position
+    seek(current_pos, SEEK_SET);
+    return file_size;
+}
+
 void AutoFile::read(std::span<std::byte> dst)
 {
     if (detail_fread(dst) != dst.size()) {