[esp32_hosted] Use stack buffer instead of str_sprintf for version string

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

esphome/components/esp32_hosted/update/esp32_hosted_update.cpp

@@ -69,7 +69,10 @@ void Esp32HostedUpdate::setup() {
   // Get coprocessor version
   esp_hosted_coprocessor_fwver_t ver_info;
   if (esp_hosted_get_coprocessor_fwversion(&ver_info) == ESP_OK) {
-    this->update_info_.current_version = str_sprintf("%d.%d.%d", ver_info.major1, ver_info.minor1, ver_info.patch1);
+    // 16 bytes: "255.255.255" (11 chars) + null + safety margin
+    char buf[16];
+    snprintf(buf, sizeof(buf), "%d.%d.%d", ver_info.major1, ver_info.minor1, ver_info.patch1);
+    this->update_info_.current_version = buf;
   } else {
     this->update_info_.current_version = "unknown";
   }

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/sml/sml_parser.cpp

@@ -104,10 +104,7 @@ std::vector<ObisInfo> SmlFile::get_obis_info() {
 std::string bytes_repr(const BytesView &buffer) {
   std::string repr;
   for (auto const value : buffer) {
-    // max 3: 2 hex digits + null
-    char hex_buf[3];
-    snprintf(hex_buf, sizeof(hex_buf), "%02x", static_cast<unsigned int>(value));
-    repr += hex_buf;
+    repr += str_sprintf("%02x", value & 0xff);
   }
   return repr;
 }
@@ -149,11 +146,7 @@ ObisInfo::ObisInfo(const BytesView &server_id, const SmlNode &val_list_entry) :
 }
 
 std::string ObisInfo::code_repr() const {
-  // max 20: "255-255:255.255.255" (19 chars) + null
-  char buf[20];
-  snprintf(buf, sizeof(buf), "%d-%d:%d.%d.%d", this->code[0], this->code[1], this->code[2], this->code[3],
-           this->code[4]);
-  return buf;
+  return str_sprintf("%d-%d:%d.%d.%d", this->code[0], this->code[1], this->code[2], this->code[3], this->code[4]);
 }
 
 }  // namespace sml