tweak comment

esphome/components/modbus_controller/modbus_controller.h

@@ -285,13 +285,8 @@ class ServerRegister {
       case SensorValueType::S_QWORD_R:
         return std::to_string(value);
       case SensorValueType::FP32_R:
-      case SensorValueType::FP32: {
-        // max 48: float with %.1f can be up to 42 chars incl. null (3.4e38 → 38 integer digits + decimal point + 1
-        // decimal digit + optional sign)
-        char buf[48];
-        snprintf(buf, sizeof(buf), "%.1f", bit_cast<float>(static_cast<uint32_t>(value)));
-        return buf;
-      }
+      case SensorValueType::FP32:
+        return str_sprintf("%.1f", bit_cast<float>(static_cast<uint32_t>(value)));
       default:
         return std::to_string(value);
     }

esphome/components/modbus_controller/text_sensor/modbus_textsensor.cpp

@@ -16,20 +16,12 @@ void ModbusTextSensor::parse_and_publish(const std::vector<uint8_t> &data) {
   while ((items_left > 0) && index < data.size()) {
     uint8_t b = data[index];
     switch (this->encode_) {
-      case RawEncoding::HEXBYTES: {
-        // max 3: 2 hex digits + null
-        char hex_buf[3];
-        snprintf(hex_buf, sizeof(hex_buf), "%02x", b);
-        output_str += hex_buf;
+      case RawEncoding::HEXBYTES:
+        output_str += str_snprintf("%02x", 2, b);
         break;
-      }
-      case RawEncoding::COMMA: {
-        // max 5: optional ','(1) + uint8(3) + null, for both ",%d" and "%d"
-        char dec_buf[5];
-        snprintf(dec_buf, sizeof(dec_buf), index != this->offset ? ",%d" : "%d", b);
-        output_str += dec_buf;
+      case RawEncoding::COMMA:
+        output_str += str_sprintf(index != this->offset ? ",%d" : "%d", b);
         break;
-      }
       case RawEncoding::ANSI:
         if (b < 0x20)
           break;

esphome/components/zephyr/preferences.cpp

@@ -5,6 +5,8 @@
 #include "esphome/core/preferences.h"
 #include "esphome/core/log.h"
 #include <zephyr/settings/settings.h>
+#include <cinttypes>
+#include <cstring>
 
 namespace esphome {
 namespace zephyr {
@@ -13,6 +15,9 @@ 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; }
@@ -27,7 +32,9 @@ class ZephyrPreferenceBackend : public ESPPreferenceBackend {
 
   bool load(uint8_t *data, size_t len) override {
     if (len != this->data.size()) {
-      ESP_LOGE(TAG, "size of setting key %s changed, from: %u, to: %u", get_key().c_str(), this->data.size(), len);
+      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);
       return false;
     }
     std::memcpy(data, this->data.data(), len);
@@ -36,7 +43,7 @@ class ZephyrPreferenceBackend : public ESPPreferenceBackend {
   }
 
   uint32_t get_type() const { return this->type_; }
-  std::string get_key() const { return str_sprintf(ESPHOME_SETTINGS_KEY "/%" PRIx32, this->type_); }
+  void format_key(char *buf, size_t size) const { snprintf(buf, size, ESPHOME_SETTINGS_KEY "/%" PRIx32, this->type_); }
 
   std::vector<uint8_t> data;
 
@@ -85,7 +92,9 @@ class ZephyrPreferences : public ESPPreferences {
     }
     printf("type %u size %u\n", type, this->backends_.size());
     auto *pref = new ZephyrPreferenceBackend(type);  // NOLINT(cppcoreguidelines-owning-memory)
-    ESP_LOGD(TAG, "Add new setting %s.", pref->get_key().c_str());
+    char key_buf[KEY_BUFFER_SIZE];
+    pref->format_key(key_buf, sizeof(key_buf));
+    ESP_LOGD(TAG, "Add new setting %s.", key_buf);
     this->backends_.push_back(pref);
     return ESPPreferenceObject(pref);
   }
@@ -134,9 +143,10 @@ 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_) {
-      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);
+      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);
     }
     return 0;
   }