Refactor: Extract new fn central_header_to_zip_file_inner

that does not require `reader` to implement `io::Seek`.

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

src/read.rs

@@ -650,6 +650,16 @@ pub(crate) fn central_header_to_zip_file<R: Read + io::Seek>(
     archive_offset: u64,
 ) -> ZipResult<ZipFileData> {
     let central_header_start = reader.stream_position()?;
+
+    central_header_to_zip_file_inner(reader, archive_offset, central_header_start)
+}
+
+/// Parse a central directory entry to collect the information for the file.
+fn central_header_to_zip_file_inner<R: Read>(
+    reader: &mut R,
+    central_header_start: u64,
+    archive_offset: u64,
+) -> ZipResult<ZipFileData> {
     // Parse central header
     let signature = reader.read_u32::<LittleEndian>()?;
     if signature != spec::CENTRAL_DIRECTORY_HEADER_SIGNATURE {