Fixup build for Alpine (#1890) (#1894)

Co-authored-by: DownerCase <[email protected]>

README.md

@@ -63,7 +63,7 @@ sudo apt-get install ecal
 ```
 This PPA will always upgrade you to the latest eCAL Release (-> Rolling Release PPA). If you intend to stay on an specific release, check out other PPAs [here](https://eclipse-ecal.github.io/ecal/getting_started/setup.html#fa-ubuntu-automatically-install-ecal-from-a-ppa).
 
-*Ubuntu 16.04, 18.04, 20.04, 20.10, 21.04 for CPU architectures i386, x64, armhf, arm64 are supported at the time of writing.*
+*Ubuntu 18.04, 20.04, 20.10, 21.04 for CPU architectures i386, x64, armhf, arm64 are supported at the time of writing.*
 
 ## Example
 

ecal/core/src/ecal_process_stub.cpp

@@ -1,6 +1,6 @@
 /* ========================= eCAL LICENSE =================================
  *
- * Copyright (C) 2016 - 2019 Continental Corporation
+ * Copyright (C) 2016 - 2025 Continental Corporation
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,10 +17,12 @@
  * ========================= eCAL LICENSE =================================
 */
 
+#include <errno.h>
+#include <fcntl.h>
+#include <string>
 #include <sys/file.h>
 #include <sys/stat.h>
 #include <unistd.h>
-#include <errno.h>
 
 #include <string.h>
 #include <iostream>

lib/ecal_utils/CMakeLists.txt

@@ -1,6 +1,6 @@
 # ========================= eCAL LICENSE =================================
 #
-# Copyright (C) 2016 - 2019 Continental Corporation
+# Copyright (C) 2016 - 2025 Continental Corporation
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -51,6 +51,15 @@ target_include_directories(${PROJECT_NAME} PUBLIC
 
 target_compile_features(${PROJECT_NAME} PUBLIC cxx_std_14)
 
+# filesystem.cpp uses fts on Linux, some distibutions (i.e: Alpine) have fts as a
+# separate library
+if(LINUX)
+  find_library(libfts NAMES fts)
+  if(NOT "${libfts}" STREQUAL "libfts-NOTFOUND")
+    target_link_libraries(${PROJECT_NAME} PRIVATE "${libfts}")
+  endif()
+endif()
+
 # Create a source tree that mirrors the filesystem
 source_group(TREE "${CMAKE_CURRENT_LIST_DIR}"
     FILES