cmake: Teach "-E tar" command a "--mtime=" option

Add an option to set the mtime of entries in a tarball so that one can
create a tarball with a consistent content hash (e.g. MD5) for a given
set of files regardless of their current timestamps on disk.  This will
be useful for submission of tarballs to CDash, which tracks content
hashes to avoid duplication.

Inspired-by: Bill Hoffman <bill.hoffman@kitware.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/Source/cmArchiveWrite.cxx b/Source/cmArchiveWrite.cxx
index 16f67f4..c24c68e 100644
--- a/Source/cmArchiveWrite.cxx
+++ b/Source/cmArchiveWrite.cxx
@@ -16,6 +16,7 @@
 #include <cmsys/Directory.hxx>
 #include <cmsys/FStream.hxx>
 #include <cm_libarchive.h>
+#include "cm_get_date.h"
 
 //----------------------------------------------------------------------------
 static std::string cm_archive_error_string(struct archive* a)
@@ -277,6 +278,20 @@ bool cmArchiveWrite::AddFile(const char* file,
     this->Error += cm_archive_error_string(this->Disk);
     return false;
     }
+  if (!this->MTime.empty())
+    {
+    time_t now;
+    time(&now);
+    time_t t = cm_get_date(now, this->MTime.c_str());
+    if (t == -1)
+      {
+      this->Error = "unable to parse mtime '";
+      this->Error += this->MTime;
+      this->Error += "'";
+      return false;
+      }
+    archive_entry_set_mtime(e, t, 0);
+    }
   // Clear acl and xattr fields not useful for distribution.
   archive_entry_acl_clear(e);
   archive_entry_xattr_clear(e);