update download contents as more files become available

src/zip.rs

@@ -43,6 +43,17 @@ pub fn file_data_offset(files: &[UploadedFile], idx: usize) -> u64 {
         + files[idx].name.len() as u64
 }
 
+pub fn file_data_offsets(files: &[UploadedFile]) -> Vec<u64> {
+    let mut offsets = Vec::new();
+    let mut offset: u64 = 0;
+    for file in files.iter() {
+        offset += LOCAL_HEADER_SIZE_MINUS_FILENAME + file.name.len() as u64;
+        offsets.push(offset);
+        offset += file.size + DATA_DESCRIPTOR_SIZE;
+    }
+    offsets
+}
+
 fn central_directory_size(files: &[UploadedFile]) -> u64 {
     let mut total = 0;
     for file in files.iter() {