Double check that read_buf is properly implemented.

[kixelated]

and some nix stuff

[coderabbitai]

Walkthrough

This pull request adds rust-overlay to the Nix flake configuration and consolidates Rust tooling into a single rust-toolchain derivation with rust-src and rust-analyzer extensions targeting wasm32-unknown-unknown. Across multiple web-transport modules (quiche, trait, wasm, ws, quinn), pattern matching in RecvStream read operations was refined to treat zero-byte or empty reads as end-of-stream (None) instead of returning empty data chunks.

Pre-merge checks and finishing touches

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Description check	❓ Inconclusive	The description is vague and generic, using non-descriptive terms ('nix stuff') that don't convey meaningful information about the changeset.	Expand the description to explain the purpose of the read_buf changes and how the nix modifications support them.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main focus of the changeset: adding safety checks to read_buf implementations across multiple files to handle zero-byte reads properly.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing touches

• 📝 Generate docstrings

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📜 Recent review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between a2db253 and c21da4f.

⛔ Files ignored due to path filters (1)

• flake.lock is excluded by !**/*.lock

📒 Files selected for processing (6)

• flake.nix
• web-transport-quiche/src/ez/recv.rs
• web-transport-trait/src/lib.rs
• web-transport-wasm/src/recv.rs
• web-transport-ws/src/session.rs
• web-transport/src/quinn.rs

🧰 Additional context used

🧬 Code graph analysis (3)

web-transport/src/quinn.rs (2)

web-transport-ws/src/varint.ts (1)

• size (17-24)

web-transport-proto/src/varint.rs (1)

• size (53-66)

web-transport-ws/src/session.rs (2)

web-transport-ws/src/varint.ts (1)

• size (17-24)

web-transport-proto/src/varint.rs (1)

• size (53-66)

web-transport-trait/src/lib.rs (2)

web-transport-ws/src/varint.ts (1)

• size (17-24)

web-transport-proto/src/varint.rs (1)

• size (53-66)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

• GitHub Check: build

🔇 Additional comments (10)

flake.nix (4)

7-10: LGTM!

The rust-overlay input is correctly configured with nixpkgs.follows to ensure consistent nixpkgs usage and avoid duplicate derivations.

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18-27: LGTM!

The overlay application follows the standard rust-overlay pattern. Importing nixpkgs with the overlay correctly makes pkgs.rust-bin available.

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29-35: LGTM!

The rust-toolchain configuration is well-structured with appropriate extensions for IDE support and the wasm32-unknown-unknown target. The default profile includes rustc, cargo, rustfmt, and clippy, consolidating what were previously separate entries.

Note: Using stable.latest means the Rust version may change when nixpkgs updates. If reproducibility is critical, consider pinning to a specific version (e.g., pkgs.rust-bin.stable."1.83.0".default).

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37-59: LGTM!

The consolidation from individual Rust tools to a single rust-toolchain entry is cleaner and ensures all components (rustc, cargo, rustfmt, clippy) come from the same toolchain version. The shellHook reformatting improves readability.

web-transport-ws/src/session.rs (1)

703-710: LGTM: Zero-byte reads now correctly treated as end-of-stream.

The refined pattern matching ensures Some(size) is only returned when actual data (!data.is_empty()) is read. Empty chunks and None from read_chunk are both mapped to Ok(None), which correctly signals end-of-stream or no progress. This aligns with Rust async I/O semantics and prevents ambiguity when read_buf returns Some(0).

web-transport-wasm/src/recv.rs (1)

57-60: LGTM: Consistent zero-byte read handling.

The tightened match guard (!chunk.is_empty()) ensures that only non-empty chunks are treated as valid data. This change aligns the WASM implementation with the pattern applied across other modules, where zero-length reads signal end-of-stream rather than a successful read of zero bytes.

web-transport/src/quinn.rs (1)

261-264: LGTM: Zero-size reads properly handled.

The guard condition size > 0 ensures that only positive-sized reads are treated as data. Zero-size reads and None from the underlying self.inner.read() are both routed to Ok(None), correctly signaling end-of-stream. This matches the pattern applied in other transport implementations.

web-transport-quiche/src/ez/recv.rs (1)

285-290: LGTM: Zero-byte reads no longer advance buffers.

The condition n > 0 ensures that Some(n) is only returned when data is actually read. Zero-byte reads fall through to the catch-all arm returning Ok(None), preventing the buffer from being advanced without reading data. This aligns with the behavior in other transport layers.

web-transport-trait/src/lib.rs (2)

197-200: LGTM: Trait contract tightened for zero-byte reads.

The size > 0 guard ensures that read_buf implementations consistently return Some(n) only when n > 0. Zero-size and None reads both yield Ok(None), establishing a clear contract: Some(n) means data was read, None means end-of-stream or no progress. This trait-level change ensures all implementations follow the same semantics.

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256-258: LGTM: Consistent treatment in read loop.

The n > 0 check in read_all_buf ensures the loop only continues when actual data is read. Zero-byte reads trigger the break, treating them as end-of-stream. This prevents infinite loops when the underlying stream returns Some(0) and aligns with the updated read_buf contract.

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