Sarthak-Pandey commented on PR #20702:
URL: https://github.com/apache/nuttx/pull/20702#issuecomment-6502524330
Hi @casaroli,
Thank you so much for the detailed and constructive review! I have addressed
all of your feedback and squashed the changes into a clean commit:
1. **Default CAN send path (`can_sendmsg.c`)**:
- Added multi-`iovec` support to the unbuffered CAN send path by
calculating `total_len` across all `iov` segments, validating against
CAN/CAN-FD MTU, and gathering multiple buffers into a stack buffer (`uint8_t
buf[CANFD_MTU]`) without heap overhead before sending.
- For single-iov sends, zero-copy pointer passthrough is preserved.
2. **TCP send (`inet_sockif.c`)**:
- Gated the sequential zero-allocation loop with `#if
defined(CONFIG_NET_TCP) && defined(CONFIG_NET_TCP_WRITE_BUFFERS)`.
- When write buffers are disabled (`CONFIG_NET_TCP_WRITE_BUFFERS=n`,
default), it preserves the gather-into-one-buffer fallback, preventing
multi-RTT latency from delayed ACKs and eliminating thread-interleaving race
conditions.
3. **`MSG_WAITALL` handling (`local_recvmsg.c`)**:
- Added an inner loop in `local_recvmsg()` to repeatedly read into the
current `iov[i]` buffer until it is completely filled before advancing to
`iov[i + 1]`.
- This ensures contiguous stream data without leaving uninitialized gaps
in previous `iovec` elements when `MSG_WAITALL` is set.
4. **`PIPEIOC_PEEK` (`local_recvmsg.c`)**:
- Reverted the `*readlen = ret;` assignment in `psock_fifo_read` to keep
this PR strictly focused on scatter-gather `msg_iov` transfers and prevent
false EOF returns on empty blocking streams or affecting datagram peek logic.
5. **POSIX Error Codes**:
- Updated all `msg_iovlen == 0` validation checks across the network
stack (`inet_sockif.c`, `can_recvmsg.c`, `can_sendmsg.c`,
`can_sendmsg_buffered.c`, `udp_recvfrom.c`, and `local_recvmsg.c`) to return
standard `-EMSGSIZE` per POSIX.1-2017 specification.
6. **Merge Conflicts Resolved**:
- Resolved conflicts with `master` in `can_recvmsg.c` (preserving the new
`MSG_CONFIRM` check alongside `iob_copyout_iov`) and in
`can_sendmsg_buffered.c` (incorporating the `while (!IOB_QEMPTY(...))` queue
wait loop using `total_len`).
All modified files pass `nxstyle` cleanly with 0 errors and 0 warnings.
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