1 files changed, 26 insertions, 3 deletions
diff --git a/Source/cmExportFileGenerator.cxx b/Source/cmExportFileGenerator.cxx
index 2c916e5..dd0c33a 100644
--- a/Source/cmExportFileGenerator.cxx
+++ b/Source/cmExportFileGenerator.cxx
@@ -21,6 +21,14 @@
 #include "cmSystemTools.h"
 #include "cmTarget.h"
 
+#include <cmsys/auto_ptr.hxx>
+
+//----------------------------------------------------------------------------
+cmExportFileGenerator::cmExportFileGenerator()
+{
+  this->AppendMode = false;
+}
+
 //----------------------------------------------------------------------------
 void cmExportFileGenerator::AddConfiguration(const char* config)
 {
@@ -43,8 +51,23 @@ void cmExportFileGenerator::SetExportFile(const char* mainFile)
 bool cmExportFileGenerator::GenerateImportFile()
 {
   // Open the output file to generate it.
-  cmGeneratedFileStream exportFileStream(this->MainImportFile.c_str(), true);
-  if(!exportFileStream)
+  cmsys::auto_ptr<std::ofstream> foutPtr;
+  if(this->AppendMode)
+    {
+    // Open for append.
+    cmsys::auto_ptr<std::ofstream>
+      ap(new std::ofstream(this->MainImportFile.c_str(), std::ios::app));
+    foutPtr = ap;
+    }
+  else
+    {
+    // Generate atomically and with copy-if-different.
+    cmsys::auto_ptr<cmGeneratedFileStream>
+      ap(new cmGeneratedFileStream(this->MainImportFile.c_str(), true));
+    ap->SetCopyIfDifferent(true);
+    foutPtr = ap;
+    }
+  if(!foutPtr.get() || !*foutPtr)
     {
     std::string se = cmSystemTools::GetLastSystemError();
     cmOStringStream e;
@@ -53,7 +76,7 @@ bool cmExportFileGenerator::GenerateImportFile()
     cmSystemTools::Error(e.str().c_str());
     return false;
     }
-  std::ostream& os = exportFileStream;
+  std::ostream& os = *foutPtr;
 
   // Start with the import file header.
   this->GenerateImportHeaderCode(os);