Merge remote-tracking branch 'upstream/dev' into modbus_string

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

esphome/components/modbus_controller/modbus_controller.h

@@ -271,24 +271,31 @@ class ServerRegister {
 
   // Formats a raw value into a string representation based on the value type for debugging
   std::string format_value(int64_t value) const {
+    // max 48: float with %.1f can be up to 42 chars (3.4e38 → 38 integer digits + decimal + 1 digit + sign + null)
+    // int64_t max is 20 chars + sign + null = 22, so 48 covers both
+    char buf[48];
     switch (this->value_type) {
       case SensorValueType::U_WORD:
       case SensorValueType::U_DWORD:
       case SensorValueType::U_DWORD_R:
       case SensorValueType::U_QWORD:
       case SensorValueType::U_QWORD_R:
-        return std::to_string(static_cast<uint64_t>(value));
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRIu64, static_cast<uint64_t>(value));
+        return buf;
       case SensorValueType::S_WORD:
       case SensorValueType::S_DWORD:
       case SensorValueType::S_DWORD_R:
       case SensorValueType::S_QWORD:
       case SensorValueType::S_QWORD_R:
-        return std::to_string(value);
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, value);
+        return buf;
       case SensorValueType::FP32_R:
       case SensorValueType::FP32:
-        return str_sprintf("%.1f", bit_cast<float>(static_cast<uint32_t>(value)));
+        buf_append_printf(buf, sizeof(buf), 0, "%.1f", bit_cast<float>(static_cast<uint32_t>(value)));
+        return buf;
       default:
-        return std::to_string(value);
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, value);
+        return buf;
     }
   }
 

esphome/components/modbus_controller/text_sensor/modbus_textsensor.cpp

@@ -16,12 +16,20 @@ 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:
-        output_str += str_snprintf("%02x", 2, b);
+      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;
         break;
-      case RawEncoding::COMMA:
-        output_str += str_sprintf(index != this->offset ? ",%d" : "%d", b);
+      }
+      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;
         break;
+      }
       case RawEncoding::ANSI:
         if (b < 0x20)
           break;

esphome/components/opentherm/opentherm.cpp

@@ -561,8 +561,9 @@ const char *OpenTherm::message_id_to_str(MessageId id) {
 }
 
 void OpenTherm::debug_data(OpenthermData &data) {
-  ESP_LOGD(TAG, "%s %s %s %s", format_bin(data.type).c_str(), format_bin(data.id).c_str(),
-           format_bin(data.valueHB).c_str(), format_bin(data.valueLB).c_str());
+  char type_buf[9], id_buf[9], hb_buf[9], lb_buf[9];
+  ESP_LOGD(TAG, "%s %s %s %s", format_bin_to(type_buf, data.type), format_bin_to(id_buf, data.id),
+           format_bin_to(hb_buf, data.valueHB), format_bin_to(lb_buf, data.valueLB));
   ESP_LOGD(TAG, "type: %s; id: %u; HB: %u; LB: %u; uint_16: %u; float: %f",
            this->message_type_to_str((MessageType) data.type), data.id, data.valueHB, data.valueLB, data.u16(),
            data.f88());

esphome/core/helpers.cpp

@@ -404,15 +404,31 @@ std::string format_hex_pretty(const std::string &data, char separator, bool show
   return format_hex_pretty_uint8(reinterpret_cast<const uint8_t *>(data.data()), data.length(), separator, show_length);
 }
 
+char *format_bin_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length) {
+  if (buffer_size == 0) {
+    return buffer;
+  }
+  // Calculate max bytes we can format: each byte needs 8 chars
+  size_t max_bytes = (buffer_size - 1) / 8;
+  if (max_bytes == 0 || length == 0) {
+    buffer[0] = '\0';
+    return buffer;
+  }
+  size_t bytes_to_format = std::min(length, max_bytes);
+
+  for (size_t byte_idx = 0; byte_idx < bytes_to_format; byte_idx++) {
+    for (size_t bit_idx = 0; bit_idx < 8; bit_idx++) {
+      buffer[byte_idx * 8 + bit_idx] = ((data[byte_idx] >> (7 - bit_idx)) & 1) + '0';
+    }
+  }
+  buffer[bytes_to_format * 8] = '\0';
+  return buffer;
+}
+
 std::string format_bin(const uint8_t *data, size_t length) {
   std::string result;
   result.resize(length * 8);
-  for (size_t byte_idx = 0; byte_idx < length; byte_idx++) {
-    for (size_t bit_idx = 0; bit_idx < 8; bit_idx++) {
-      result[byte_idx * 8 + bit_idx] = ((data[byte_idx] >> (7 - bit_idx)) & 1) + '0';
-    }
-  }
-
+  format_bin_to(&result[0], length * 8 + 1, data, length);
   return result;
 }
 

esphome/core/helpers.h

@@ -1096,9 +1096,66 @@ std::string format_hex_pretty(T val, char separator = '.', bool show_length = tr
   return format_hex_pretty(reinterpret_cast<uint8_t *>(&val), sizeof(T), separator, show_length);
 }
 
+/// Calculate buffer size needed for format_bin_to: "01234567...\0" = bytes * 8 + 1
+constexpr size_t format_bin_size(size_t byte_count) { return byte_count * 8 + 1; }
+
+/** Format byte array as binary string to buffer.
+ *
+ * Each byte is formatted as 8 binary digits (MSB first).
+ * Truncates output if data exceeds buffer capacity.
+ *
+ * @param buffer Output buffer to write to.
+ * @param buffer_size Size of the output buffer.
+ * @param data Pointer to the byte array to format.
+ * @param length Number of bytes in the array.
+ * @return Pointer to buffer.
+ *
+ * Buffer size needed: length * 8 + 1 (use format_bin_size()).
+ *
+ * Example:
+ * @code
+ * char buf[9];  // format_bin_size(1)
+ * format_bin_to(buf, sizeof(buf), data, 1);  // "10101011"
+ * @endcode
+ */
+char *format_bin_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length);
+
+/// Format byte array as binary to buffer. Automatically deduces buffer size.
+template<size_t N> inline char *format_bin_to(char (&buffer)[N], const uint8_t *data, size_t length) {
+  static_assert(N >= 9, "Buffer must hold at least one binary byte (9 chars)");
+  return format_bin_to(buffer, N, data, length);
+}
+
+/** Format an unsigned integer in binary to buffer, MSB first.
+ *
+ * @tparam N Buffer size (must be >= sizeof(T) * 8 + 1).
+ * @tparam T Unsigned integer type.
+ * @param buffer Output buffer to write to.
+ * @param val The unsigned integer value to format.
+ * @return Pointer to buffer.
+ *
+ * Example:
+ * @code
+ * char buf[9];  // format_bin_size(sizeof(uint8_t))
+ * format_bin_to(buf, uint8_t{0xAA});  // "10101010"
+ * char buf16[17];  // format_bin_size(sizeof(uint16_t))
+ * format_bin_to(buf16, uint16_t{0x1234});  // "0001001000110100"
+ * @endcode
+ */
+template<size_t N, typename T, enable_if_t<std::is_unsigned<T>::value, int> = 0>
+inline char *format_bin_to(char (&buffer)[N], T val) {
+  static_assert(N >= sizeof(T) * 8 + 1, "Buffer too small for type");
+  val = convert_big_endian(val);
+  return format_bin_to(buffer, reinterpret_cast<const uint8_t *>(&val), sizeof(T));
+}
+
 /// Format the byte array \p data of length \p len in binary.
+/// @warning Allocates heap memory. Use format_bin_to() with a stack buffer instead.
+/// Causes heap fragmentation on long-running devices.
 std::string format_bin(const uint8_t *data, size_t length);
 /// Format an unsigned integer in binary, starting with the most significant byte.
+/// @warning Allocates heap memory. Use format_bin_to() with a stack buffer instead.
+/// Causes heap fragmentation on long-running devices.
 template<typename T, enable_if_t<std::is_unsigned<T>::value, int> = 0> std::string format_bin(T val) {
   val = convert_big_endian(val);
   return format_bin(reinterpret_cast<uint8_t *>(&val), sizeof(T));

script/ci-custom.py

@@ -682,6 +682,7 @@ def lint_trailing_whitespace(fname, match):
 # Heap-allocating helpers that cause fragmentation on long-running embedded devices.
 # These return std::string and should be replaced with stack-based alternatives.
 HEAP_ALLOCATING_HELPERS = {
+    "format_bin": "format_bin_to() with a stack buffer",
     "format_hex": "format_hex_to() with a stack buffer",
     "format_hex_pretty": "format_hex_pretty_to() with a stack buffer",
     "format_mac_address_pretty": "format_mac_addr_upper() with a stack buffer",
@@ -699,6 +700,7 @@ HEAP_ALLOCATING_HELPERS = {
     # get_mac_address(?!_) ensures we don't match get_mac_address_into_buffer, etc.
     # CPP_RE_EOL captures rest of line so NOLINT comments are detected
     r"[^\w]("
+    r"format_bin(?!_)|"
     r"format_hex(?!_)|"
     r"format_hex_pretty(?!_)|"
     r"format_mac_address_pretty|"