Guard the replay, warn on dropped lines, cap captured text, and register the action as an apply action

esphome/components/logger/__init__.py

@@ -402,8 +402,9 @@ async def to_code(config: ConfigType) -> None:
     if (boot_log_buffer_size := config[CONF_BOOT_LOG_BUFFER_SIZE]) > 0:
         cg.add_define("USE_LOGGER_BOOT_LOG_BUFFER")
         cg.add_define("ESPHOME_LOGGER_BOOT_LOG_BUFFER_SIZE", boot_log_buffer_size)
-        cg.add_build_flag(
-            f"-DESPHOME_LOGGER_BOOT_LOG_LEVEL={LOG_LEVELS[config[CONF_BOOT_LOG_LEVEL]]}"
+        cg.add_define(
+            "ESPHOME_LOGGER_BOOT_LOG_LEVEL",
+            cg.RawExpression(str(LOG_LEVELS[config[CONF_BOOT_LOG_LEVEL]])),
         )
         if boot_logs_config := config[CONF_BOOT_LOGS]:
             cg.add_define("USE_LOGGER_BOOT_LOG_PER_TAG_LEVELS")
@@ -663,30 +664,17 @@ async def logger_set_level_to_code(
     )
 
 
-@automation.register_action(
+automation.register_apply_action(
     "logger.replay_boot_logs",
-    LambdaAction,
     automation.maybe_conf(
         CONF_LOGGER_ID,
         {
             cv.GenerateID(CONF_LOGGER_ID): cv.use_id(Logger),
         },
     ),
-    synchronous=True,
+    automation.ApplyCall("replay_boot_logs()"),
+    id_key=CONF_LOGGER_ID,
 )
-async def logger_replay_boot_logs_to_code(
-    config: ConfigType,
-    action_id: ID,
-    template_arg: cg.TemplateArguments,
-    args: TemplateArgsType,
-) -> MockObj:
-    logger = await cg.get_variable(config[CONF_LOGGER_ID])
-    text = str(cg.statement(logger.replay_boot_logs()))
-
-    lambda_ = await cg.process_lambda(Lambda(text), args, return_type=cg.void)
-    return automation.new_lambda_pvariable(
-        action_id, lambda_, StatelessLambdaAction, template_arg
-    )
 
 
 FILTER_SOURCE_FILES = filter_source_files_from_platform(

esphome/components/logger/logger.cpp

@@ -218,6 +218,9 @@ void Logger::process_messages_() {
 #ifdef USE_LOGGER_BOOT_LOG_BUFFER
 // Record layout in boot_log_buffer_: u16 text_len | u8 level | u32 millis | const char *tag | text
 static constexpr uint16_t BOOT_LOG_RECORD_HEADER_SIZE = 2 + 1 + 4 + sizeof(const char *);
+// Replay writes "\033[0;3Xm@4294967295ms " (22 bytes) and "\033[0m" (4 bytes) around the stored text
+static constexpr uint16_t BOOT_LOG_REPLAY_PREFIX_SIZE = 22;
+static constexpr uint16_t BOOT_LOG_MAX_TEXT = ESPHOME_LOGGER_TX_BUFFER_SIZE - BOOT_LOG_REPLAY_PREFIX_SIZE - 4;
 
 void Logger::boot_log_capture_(uint8_t level, const char *tag, const LogBuffer &buf) {
   if (this->boot_log_done_ || level > boot_level_for(tag) || level == ESPHOME_LOG_LEVEL_NONE)
@@ -235,6 +238,9 @@ void Logger::boot_log_capture_(uint8_t level, const char *tag, const LogBuffer &
   }
   if (len >= 4 && memcmp(text + len - 4, "\033[0m", 4) == 0)
     len -= 4;
+  // Leave room in the transmit buffer for the replay prefix and reset so no stored text is cut on replay
+  if (len > BOOT_LOG_MAX_TEXT)
+    len = BOOT_LOG_MAX_TEXT;
   if (this->boot_log_pos_ + BOOT_LOG_RECORD_HEADER_SIZE + len > ESPHOME_LOGGER_BOOT_LOG_BUFFER_SIZE) {
     this->boot_log_dropped_++;
     return;
@@ -252,7 +258,20 @@ void Logger::boot_log_capture_(uint8_t level, const char *tag, const LogBuffer &
 void Logger::replay_boot_logs() {
   // Stop capturing first so the replay output is not buffered again.
   this->boot_log_done_ = true;
-  ESP_LOGI(TAG, "Replaying boot logs (%u bytes used, %u lines dropped)", this->boot_log_pos_, this->boot_log_dropped_);
+  // Dropped lines are reported at WARN so a device at level WARN still learns the buffer was too small
+  esp_log_printf_(this->boot_log_dropped_ > 0 ? ESPHOME_LOG_LEVEL_WARN : ESPHOME_LOG_LEVEL_INFO, TAG, __LINE__,
+                  ESPHOME_LOG_FORMAT("Replaying boot logs (%u bytes used, %u lines dropped)"), this->boot_log_pos_,
+                  this->boot_log_dropped_);
+  // The replay shares tx_buffer_ with normal logging, so a listener that logs during
+  // the replay is dropped like any other re-entrant log; see process_messages_()
+#if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
+  bool &recursion_guard = this->main_task_recursion_guard_;
+#else
+  bool &recursion_guard = this->global_recursion_guard_;
+#endif
+  if (recursion_guard)
+    return;
+  RecursionGuard guard(recursion_guard);
   uint16_t pos = 0;
   while (pos + BOOT_LOG_RECORD_HEADER_SIZE <= this->boot_log_pos_) {
     const char *p = this->boot_log_buffer_ + pos;

tests/components/logger/__init__.py

@@ -17,6 +17,9 @@ def override_manifest(manifest: ComponentManifestOverride) -> None:
         # read the replay through a log listener, which nothing else registers here.
         cg.add_define("USE_LOGGER_BOOT_LOG_BUFFER")
         cg.add_define("ESPHOME_LOGGER_BOOT_LOG_BUFFER_SIZE", 512)
+        cg.add_define(
+            "ESPHOME_LOGGER_BOOT_LOG_LEVEL", cg.RawExpression("ESPHOME_LOG_LEVEL_WARN")
+        )
         request_log_listener()
 
     manifest.to_code = to_code

tests/components/logger/boot_log_buffer_test.cpp

@@ -99,4 +99,19 @@ TEST_F(BootLogBufferTest, LinesThatDoNotFitAreCounted) {
   EXPECT_TRUE(summary);
 }
 
+TEST_F(BootLogBufferTest, LongestLineIsReplayedWithoutLosingItsTail) {
+  // A line that fills the transmit buffer must still fit once the replay adds its stamp
+  std::string text(ESPHOME_LOGGER_TX_BUFFER_SIZE, 'x');
+  ESP_LOGW(BOOT_TAG, "%s", text.c_str());
+  this->listen();
+  this->logger_->replay_boot_logs();
+
+  const auto lines = this->replayed();
+  ASSERT_EQ(lines.size(), 1u);
+  EXPECT_LE(lines[0].message.size(), static_cast<size_t>(ESPHOME_LOGGER_TX_BUFFER_SIZE));
+  // The reset code at the end shows the stored text was not cut short by the prefix
+  EXPECT_EQ(lines[0].message.substr(lines[0].message.size() - 4), "\033[0m") << lines[0].message.size();
+  EXPECT_NE(lines[0].message.find("xxxxxxxxxx\033[0m"), std::string::npos);
+}
+
 }  // namespace esphome::logger::testing

tests/components/logger/test-boot_log_buffer.esp32-idf.yaml

@@ -9,3 +9,6 @@ esphome:
 logger:
   id: logger_id
   boot_log_buffer_size: 2kB
+  boot_log_level: INFO
+  boot_logs:
+    wifi: DEBUG