From b9a688a946d118e8bd97346fef3da6ceffae18ed Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 16 Mar 2026 12:35:08 -1000
Subject: [PATCH] Clean up write_raw_: collapse error checks, remove redundant
 comments

---
 esphome/components/api/api_frame_helper.cpp | 32 +++++++++------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/esphome/components/api/api_frame_helper.cpp b/esphome/components/api/api_frame_helper.cpp
index b19556f034e..35c0fc8a08b 100644
--- a/esphome/components/api/api_frame_helper.cpp
+++ b/esphome/components/api/api_frame_helper.cpp
@@ -100,11 +100,10 @@ const LogString *api_error_to_logstr(APIError err) {
   return LOG_STR("UNKNOWN");
 }
 
-// This method writes data to socket or buffers it
+// Write data to socket, overflow to backlog buffer if LWIP TCP send buffer is full.
+// Returns OK if all data was sent or successfully queued.
+// Returns SOCKET_WRITE_FAILED on hard error (sets state to FAILED).
 APIError APIFrameHelper::write_raw_(const struct iovec *iov, int iovcnt, uint16_t total_write_len) {
-  // Returns APIError::OK if all data was sent or successfully queued.
-  // Returns APIError::SOCKET_WRITE_FAILED if socket write failed, and sets state to FAILED.
-
 #ifdef HELPER_LOG_PACKETS
   for (int i = 0; i < iovcnt; i++) {
     LOG_PACKET_SENDING(reinterpret_cast<uint8_t *>(iov[i].iov_base), iov[i].iov_len);
@@ -113,34 +112,29 @@ APIError APIFrameHelper::write_raw_(const struct iovec *iov, int iovcnt, uint16_
 
   uint16_t skip = 0;
 
-  // If there is already backlogged data, try to drain it first
+  // Drain any existing backlog first
   if (!this->overflow_buf_.empty()) [[unlikely]] {
-    if (this->overflow_buf_.try_drain(this->socket_.get()) == -1) {
-      HELPER_LOG("Socket write failed with errno %d", errno);
-      if (this->check_socket_write_err_(errno) != APIError::WOULD_BLOCK)
-        return APIError::SOCKET_WRITE_FAILED;
-    }
-    // If drain didn't fully clear, skip direct send and queue behind backlog
+    if (this->overflow_buf_.try_drain(this->socket_.get()) == -1 &&
+        this->check_socket_write_err_(errno) != APIError::WOULD_BLOCK)
+      return APIError::SOCKET_WRITE_FAILED;
   }
 
+  // If backlog is clear, try direct send
   if (this->overflow_buf_.empty()) {
-    // No backlog — try to send directly
-    // Optimize for single iovec case (common for plaintext API)
     ssize_t sent =
         (iovcnt == 1) ? this->socket_->write(iov[0].iov_base, iov[0].iov_len) : this->socket_->writev(iov, iovcnt);
 
-    if (sent == -1) [[unlikely]] {  // Socket write failed
-      HELPER_LOG("Socket write failed with errno %d", errno);
+    if (sent == -1) [[unlikely]] {
       if (this->check_socket_write_err_(errno) != APIError::WOULD_BLOCK)
         return APIError::SOCKET_WRITE_FAILED;
-    } else if (static_cast<uint16_t>(sent) >= total_write_len) [[likely]] {  // All data sent successfully
-      return APIError::OK;                                                   // All data sent successfully
+    } else if (static_cast<uint16_t>(sent) >= total_write_len) [[likely]] {
+      return APIError::OK;
     } else {
-      skip = static_cast<uint16_t>(sent);  // Partially sent — queue the remainder
+      skip = static_cast<uint16_t>(sent);
     }
   }
 
-  // Queue data into overflow buffer, or fail the connection if full
+  // Queue unsent data into overflow buffer
   if (!this->overflow_buf_.enqueue_iov(iov, iovcnt, total_write_len, skip)) {
     this->state_ = State::FAILED;
     return APIError::SOCKET_WRITE_FAILED;