Fix archive backend crash (#475)

* Fix archive backend

* Fix overflow bug + add workflow

* Potential fix for pull request finding 'CodeQL / Workflow does not contain permissions'

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

* Fix lint

---------

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

libraries/droplet/src/lib.rs

@@ -1,4 +1,6 @@
 #![deny(clippy::all)]
+// `#[async_trait]` emits `#[must_use]` on futures that are already `#[must_use]`, tripping `double_must_use`.
+#![allow(clippy::double_must_use)]
 #![feature(impl_trait_in_bindings)]
 pub mod file_utils;
 pub mod manifest;

libraries/droplet/src/versions/archive_backend.rs

@@ -41,8 +41,8 @@ impl AsyncRead for ArchiveReader {
     ) -> std::task::Poll<std::io::Result<()>> {
         if let Some(block) = &mut self.prev_block {
             let to_read = buf.remaining().min(block.len());
-            let result = block.split_off(to_read);
-            buf.put_slice(&result);
+            buf.put_slice(&block[..to_read]);
+            block.drain(..to_read);
 
             // If the block is empty, we can read more
             if block.is_empty() {