all: prefer using utimensat()

CMakeLists.txt

@@ -169,6 +169,28 @@ endif()
 
 include(CheckCCompilerFlag)
 include(CheckIncludeFile)
+include(CheckFunctionExists)
+include(CheckStructHasMember)
+include(CheckSymbolExists)
+
+if(NOT DEFINED HAVE_UNISTD_H)
+    check_include_file("unistd.h" HAVE_UNISTD_H)
+endif()
+if(NOT DEFINED HAVE_UTIMENSAT)
+    check_function_exists(utimensat HAVE_UTIMENSAT_FUNCTION__)
+    if(HAVE_UTIMENSAT_FUNCTION__)
+        check_symbol_exists(utimensat "sys/types.h;fcntl.h;sys/stat.h" HAVE_UTIMENSAT_SYMBOL__)
+        if(HAVE_UTIMENSAT_SYMBOL__)
+            CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtim.tv_nsec "sys/types.h;fcntl.h;sys/stat.h" HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC)
+            if (NOT HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC)
+                CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtimespec.tv_nsec "sys/types.h;fcntl.h;sys/stat.h" HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC)
+            endif()
+            if (HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC OR HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC)
+                set(HAVE_UTIMENSAT 1)
+            endif()
+        endif()
+    endif()
+endif()
 
 if(UPX_CONFIG_DISABLE_WSTRICT)
     # enable all basic warnings
@@ -382,7 +404,6 @@ set(t upx_vendor_zlib)
 upx_compile_target_debug_with_O2(${t})
 upx_sanitize_target(${t})
 target_compile_definitions(${t} PRIVATE HAVE_VSNPRINTF=1)
-check_include_file("unistd.h" HAVE_UNISTD_H)
 if(HAVE_UNISTD_H)
     target_compile_definitions(${t} PRIVATE HAVE_UNISTD_H=1)
 endif()
@@ -429,6 +450,12 @@ endif()
 if(NOT UPX_CONFIG_DISABLE_ZSTD)
     target_compile_definitions(${t} PRIVATE WITH_ZSTD=1)
 endif()
+if(HAVE_UTIMENSAT)
+    target_compile_definitions(${t} PRIVATE USE_UTIMENSAT=1)
+    if (HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC)
+        target_compile_definitions(${t} PRIVATE HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC=1)
+    endif()
+endif()
 #upx_compile_target_debug_with_O2(${t})
 upx_sanitize_target(${t})
 if(MSVC_FRONTEND)