Merge topic 'vs-atomic-generated-stamp'

2dc17f8 VS: Replace generation timestamp file atomically

1 files changed, 12 insertions, 3 deletions

diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index 036440a..d44a36b 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -4033,10 +4033,18 @@ static bool cmakeCheckStampFile(const char* stampName)
     }
 
   // The build system is up to date.  The stamp file has been removed
-  // by the VS IDE due to a "rebuild" request.  Just restore it.
-  std::ofstream stamp(stampName);
+  // by the VS IDE due to a "rebuild" request.  Restore it atomically.
+  cmOStringStream stampTempStream;
+  stampTempStream << stampName << ".tmp" << cmSystemTools::RandomSeed();
+  std::string stampTempString = stampTempStream.str();
+  const char* stampTemp = stampTempString.c_str();
+  {
+  // TODO: Teach cmGeneratedFileStream to use a random temp file (with
+  // multiple tries in unlikely case of conflict) and use that here.
+  std::ofstream stamp(stampTemp);
   stamp << "# CMake generation timestamp file this directory.\n";
-  if(stamp)
+  }
+  if(cmSystemTools::RenameFile(stampTemp, stampName))
     {
     // Notify the user why CMake is not re-running.  It is safe to
     // just print to stdout here because this code is only reachable
@@ -4047,6 +4055,7 @@ static bool cmakeCheckStampFile(const char* stampName)
     }
   else
     {
+    cmSystemTools::RemoveFile(stampTemp);
     cmSystemTools::Error("Cannot restore timestamp ", stampName);
     return false;
     }