cmTimestamp: For symlinks switch to timestamp of resolved path

ModifiedTime uses stat on UNIX which does resolve symlinks, however Windows implementation relies on GetFileAttributesExW which does not. Getting real file path before calling ModifiedTime will not change UNIX semantic and will fix Windows behavior.

Fixes: #17206

1 files changed, 4 insertions, 2 deletions

diff --git a/Source/cmTimestamp.cxx b/Source/cmTimestamp.cxx
index 9fb79d9..e747adb 100644
--- a/Source/cmTimestamp.cxx
+++ b/Source/cmTimestamp.cxx
@@ -33,11 +33,13 @@ std::string cmTimestamp::FileModificationTime(const char* path,
                                               const std::string& formatString,
                                               bool utcFlag)
 {
-  if (!cmsys::SystemTools::FileExists(path)) {
+  std::string real_path = cmSystemTools::GetRealPath(path);
+
+  if (!cmsys::SystemTools::FileExists(real_path)) {
     return std::string();
   }
 
-  time_t mtime = cmsys::SystemTools::ModifiedTime(path);
+  time_t mtime = cmsys::SystemTools::ModifiedTime(real_path);
   return CreateTimestampFromTimeT(mtime, formatString, utcFlag);
 }