tidy

Co-authored-by: Clyde Stubbs <2366188+clydebarrow@users.noreply.github.com>

esphome/components/cse7766/cse7766.cpp

@@ -2,6 +2,7 @@
 #include "esphome/core/application.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
+#include <cstdarg>
 
 namespace esphome {
 namespace cse7766 {
@@ -9,6 +10,32 @@ namespace cse7766 {
 static const char *const TAG = "cse7766";
 static constexpr size_t CSE7766_RAW_DATA_SIZE = 24;
 
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
+/// @brief Safely append formatted string to buffer.
+/// @param buf Destination buffer (must be non-null)
+/// @param size Total buffer size in bytes
+/// @param pos Current write position (0 to size-1 for valid positions, size means full)
+/// @param fmt printf-style format string
+/// @return New write position: pos + chars_written, capped at size when buffer is full.
+///         Returns size (not size-1) when full because vsnprintf already wrote the null
+///         terminator at buf[size-1]. Returning size signals "no room for more content".
+///         On encoding error, returns pos unchanged (no write occurred).
+__attribute__((format(printf, 4, 5))) static size_t buf_append(char *buf, size_t size, size_t pos, const char *fmt,
+                                                               ...) {
+  if (pos >= size) {
+    return size;
+  }
+  va_list args;
+  va_start(args, fmt);
+  int written = vsnprintf(buf + pos, size - pos, fmt, args);
+  va_end(args);
+  if (written < 0) {
+    return pos;  // encoding error
+  }
+  return std::min(pos + static_cast<size_t>(written), size);
+}
+#endif
+
 void CSE7766Component::loop() {
   const uint32_t now = App.get_loop_component_start_time();
   if (now - this->last_transmission_ >= 500) {
@@ -207,20 +234,23 @@ void CSE7766Component::parse_data_() {
 
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
   {
-    std::string buf = "Parsed:";
+    // Buffer: 7 + 15 + 33 + 15 + 25 = 95 chars max + null, rounded to 128 for safety margin.
+    // Float sizes with %.4f can be up to 11 chars for large values (e.g., 999999.9999).
+    char buf[128];
+    size_t pos = buf_append(buf, sizeof(buf), 0, "Parsed:");
     if (have_voltage) {
-      buf += str_sprintf(" V=%fV", voltage);
+      pos = buf_append(buf, sizeof(buf), pos, " V=%.4fV", voltage);
     }
     if (have_current) {
-      buf += str_sprintf(" I=%fmA (~%fmA)", current * 1000.0f, calculated_current * 1000.0f);
+      pos = buf_append(buf, sizeof(buf), pos, " I=%.4fmA (~%.4fmA)", current * 1000.0f, calculated_current * 1000.0f);
     }
     if (have_power) {
-      buf += str_sprintf(" P=%fW", power);
+      pos = buf_append(buf, sizeof(buf), pos, " P=%.4fW", power);
     }
     if (energy != 0.0f) {
-      buf += str_sprintf(" E=%fkWh (%u)", energy, cf_pulses);
+      buf_append(buf, sizeof(buf), pos, " E=%.4fkWh (%u)", energy, cf_pulses);
     }
-    ESP_LOGVV(TAG, "%s", buf.c_str());
+    ESP_LOGVV(TAG, "%s", buf);
   }
 #endif
 }

esphome/components/lvgl/lv_validation.py

@@ -413,6 +413,7 @@ class TextValidator(LValidator):
                 str_args = [str(x) for x in value[CONF_ARGS]]
                 arg_expr = cg.RawExpression(",".join(str_args))
                 format_str = cpp_string_escape(format_str)
+                # str_sprintf justified: user-defined format, can't optimize without permanent RAM cost
                 sprintf_str = f"str_sprintf({format_str}, {arg_expr}).c_str()"
                 if nanval := value.get(CONF_IF_NAN):
                     nanval = cpp_string_escape(nanval)

esphome/components/lvgl/lvgl_esphome.cpp

@@ -65,7 +65,10 @@ std::string lv_event_code_name_for(uint8_t event_code) {
   if (event_code < sizeof(EVENT_NAMES) / sizeof(EVENT_NAMES[0])) {
     return EVENT_NAMES[event_code];
   }
-  return str_sprintf("%2d", event_code);
+  // max 4 bytes: "%u" with uint8_t (max 255, 3 digits) + null
+  char buf[4];
+  snprintf(buf, sizeof(buf), "%u", event_code);
+  return buf;
 }
 
 static void rounder_cb(lv_disp_drv_t *disp_drv, lv_area_t *area) {

esphome/components/zephyr/preferences.cpp

@@ -5,8 +5,6 @@
 #include "esphome/core/preferences.h"
 #include "esphome/core/log.h"
 #include <zephyr/settings/settings.h>
-#include <cinttypes>
-#include <cstring>
 
 namespace esphome {
 namespace zephyr {
@@ -15,9 +13,6 @@ static const char *const TAG = "zephyr.preferences";
 
 #define ESPHOME_SETTINGS_KEY "esphome"
 
-// Buffer size for key: "esphome/" (8) + max hex uint32 (8) + null terminator (1) = 17; use 20 for safety margin
-static constexpr size_t KEY_BUFFER_SIZE = 20;
-
 class ZephyrPreferenceBackend : public ESPPreferenceBackend {
  public:
   ZephyrPreferenceBackend(uint32_t type) { this->type_ = type; }
@@ -32,9 +27,7 @@ class ZephyrPreferenceBackend : public ESPPreferenceBackend {
 
   bool load(uint8_t *data, size_t len) override {
     if (len != this->data.size()) {
-      char key_buf[KEY_BUFFER_SIZE];
-      this->format_key(key_buf, sizeof(key_buf));
-      ESP_LOGE(TAG, "size of setting key %s changed, from: %u, to: %u", key_buf, this->data.size(), len);
+      ESP_LOGE(TAG, "size of setting key %s changed, from: %u, to: %u", get_key().c_str(), this->data.size(), len);
       return false;
     }
     std::memcpy(data, this->data.data(), len);
@@ -43,7 +36,7 @@ class ZephyrPreferenceBackend : public ESPPreferenceBackend {
   }
 
   uint32_t get_type() const { return this->type_; }
-  void format_key(char *buf, size_t size) const { snprintf(buf, size, ESPHOME_SETTINGS_KEY "/%" PRIx32, this->type_); }
+  std::string get_key() const { return str_sprintf(ESPHOME_SETTINGS_KEY "/%" PRIx32, this->type_); }
 
   std::vector<uint8_t> data;
 
@@ -92,9 +85,7 @@ class ZephyrPreferences : public ESPPreferences {
     }
     printf("type %u size %u\n", type, this->backends_.size());
     auto *pref = new ZephyrPreferenceBackend(type);  // NOLINT(cppcoreguidelines-owning-memory)
-    char key_buf[KEY_BUFFER_SIZE];
-    pref->format_key(key_buf, sizeof(key_buf));
-    ESP_LOGD(TAG, "Add new setting %s.", key_buf);
+    ESP_LOGD(TAG, "Add new setting %s.", pref->get_key().c_str());
     this->backends_.push_back(pref);
     return ESPPreferenceObject(pref);
   }
@@ -143,10 +134,9 @@ class ZephyrPreferences : public ESPPreferences {
 
   static int export_settings(int (*cb)(const char *name, const void *value, size_t val_len)) {
     for (auto *backend : static_cast<ZephyrPreferences *>(global_preferences)->backends_) {
-      char name[KEY_BUFFER_SIZE];
-      backend->format_key(name, sizeof(name));
-      int err = cb(name, backend->data.data(), backend->data.size());
-      ESP_LOGD(TAG, "save in flash, name %s, len %u, err %d", name, backend->data.size(), err);
+      auto name = backend->get_key();
+      int err = cb(name.c_str(), backend->data.data(), backend->data.size());
+      ESP_LOGD(TAG, "save in flash, name %s, len %u, err %d", name.c_str(), backend->data.size(), err);
     }
     return 0;
   }