avoid touching packfiles on startup (#1793)

ArchiveFile::start_up() truncates packfiles unconditionally,
causing unneeded filesystem writes (mtime) and complicating
auditing on file level.

Co-authored-by: mkiesel <[email protected]>

Author: mkiesel

validator/db/package.cpp

@@ -48,8 +48,16 @@ Package::Package(td::FileFd fd) : fd_(std::move(fd)) {
 }
 
 td::Status Package::truncate(td::uint64 size) {
-  TRY_STATUS(fd_.seek(size + header_size()));
-  return fd_.truncate_to_current_position(size + header_size());
+  auto target_size = size + header_size();
+  TRY_RESULT(current_size, fd_.get_size());
+
+  // Only truncate if the size actually differs to avoid updating mtime unnecessarily
+  if (current_size != target_size) {
+    TRY_STATUS(fd_.seek(target_size));
+    return fd_.truncate_to_current_position(target_size);
+  }
+
+  return td::Status::OK();
 }
 
 td::uint64 Package::append(std::string filename, td::Slice data, bool sync) {