From 680e92a226b7c643157ed2eb7d5d679a95879adc Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 18 Jan 2026 08:36:56 -1000
Subject: [PATCH] [core] Add str_endswith_ignore_case to avoid heap allocation
 in audio file type detection (#13313)

---
 esphome/components/audio/audio_reader.cpp | 8 +++-----
 esphome/core/helpers.cpp                  | 7 +++++++
 esphome/core/helpers.h                    | 9 +++++++++
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/esphome/components/audio/audio_reader.cpp b/esphome/components/audio/audio_reader.cpp
index 7794187a69..4e4bd31f9b 100644
--- a/esphome/components/audio/audio_reader.cpp
+++ b/esphome/components/audio/audio_reader.cpp
@@ -185,18 +185,16 @@ esp_err_t AudioReader::start(const std::string &uri, AudioFileType &file_type) {
       return err;
     }
 
-    std::string url_string = str_lower_case(url);
-
-    if (str_endswith(url_string, ".wav")) {
+    if (str_endswith_ignore_case(url, ".wav")) {
       file_type = AudioFileType::WAV;
     }
 #ifdef USE_AUDIO_MP3_SUPPORT
-    else if (str_endswith(url_string, ".mp3")) {
+    else if (str_endswith_ignore_case(url, ".mp3")) {
       file_type = AudioFileType::MP3;
     }
 #endif
 #ifdef USE_AUDIO_FLAC_SUPPORT
-    else if (str_endswith(url_string, ".flac")) {
+    else if (str_endswith_ignore_case(url, ".flac")) {
       file_type = AudioFileType::FLAC;
     }
 #endif
diff --git a/esphome/core/helpers.cpp b/esphome/core/helpers.cpp
index 4e3761675d..44c20845e8 100644
--- a/esphome/core/helpers.cpp
+++ b/esphome/core/helpers.cpp
@@ -174,6 +174,13 @@ bool str_endswith(const std::string &str, const std::string &end) {
   return str.rfind(end) == (str.size() - end.size());
 }
 #endif
+
+bool str_endswith_ignore_case(const char *str, size_t str_len, const char *suffix, size_t suffix_len) {
+  if (suffix_len > str_len)
+    return false;
+  return strncasecmp(str + str_len - suffix_len, suffix, suffix_len) == 0;
+}
+
 std::string str_truncate(const std::string &str, size_t length) {
   return str.length() > length ? str.substr(0, length) : str;
 }
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index cdc051fc90..8b581eb97a 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -545,6 +545,15 @@ bool str_startswith(const std::string &str, const std::string &start);
 /// Check whether a string ends with a value.
 bool str_endswith(const std::string &str, const std::string &end);
 
+/// Case-insensitive check if string ends with suffix (no heap allocation).
+bool str_endswith_ignore_case(const char *str, size_t str_len, const char *suffix, size_t suffix_len);
+inline bool str_endswith_ignore_case(const char *str, const char *suffix) {
+  return str_endswith_ignore_case(str, strlen(str), suffix, strlen(suffix));
+}
+inline bool str_endswith_ignore_case(const std::string &str, const char *suffix) {
+  return str_endswith_ignore_case(str.c_str(), str.size(), suffix, strlen(suffix));
+}
+
 /// Truncate a string to a specific length.
 /// @warning Allocates heap memory. Avoid in new code - causes heap fragmentation on long-running devices.
 std::string str_truncate(const std::string &str, size_t length);