ENH: try to better handle control-c during make Makefiles

Source/cmGeneratedFileStream.h

@@ -63,7 +63,8 @@ public:
     m_Name(name),
     m_TempName(m_Name+".tmp"),
     m_Stream(m_TempName.c_str()),
-    m_Copied(false)
+    m_Copied(false),
+    m_AlwaysCopy(false)
     {}
   
   /**
@@ -87,7 +88,11 @@ public:
    * real file name to occur.
    */
   void close() { this->DoCopy(); }
-  
+  /**
+   * If always copy is true, then copy the file all the time without
+   *  checking for differences.  The default is false.
+   */
+  bool SetAlwaysCopy(bool v) { m_AlwaysCopy = v; return v;}
 private:
   /**
    * The name of the real file where output will be copied if it has changed.
@@ -110,14 +115,29 @@ private:
   bool m_Copied;
 
   /**
-   * Closes the temporary file and does the copy-if-different to the real file.
+   *  If always copy is true, then copy the file all the time without
+   *  checking for differences.  The default is false.
+   */
+  bool m_AlwaysCopy;
+  
+  /**
+   * Closes the temporary file and does the copy-if-different to the
+   * real file.
    */
   void DoCopy()
     {
     if(!m_Copied)
       {
       m_Stream.close();
-      cmSystemTools::CopyFileIfDifferent(m_TempName.c_str(), m_Name.c_str());
+      if(m_AlwaysCopy)
+        {
+        cmSystemTools::cmCopyFile(m_TempName.c_str(), m_Name.c_str());
+        }
+      else
+        {
+        cmSystemTools::CopyFileIfDifferent(m_TempName.c_str(),
+                                           m_Name.c_str());
+        }
       cmSystemTools::RemoveFile(m_TempName.c_str());
       m_Copied = true;
       }

Source/cmUnixMakefileGenerator.cxx

@@ -45,6 +45,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "cmSourceFile.h"
 #include "cmMakeDepend.h"
 #include "cmCacheManager.h"
+#include "cmGeneratedFileStream.h"
 
 cmUnixMakefileGenerator::cmUnixMakefileGenerator()
 {
@@ -93,7 +94,12 @@ void cmUnixMakefileGenerator::OutputMakefile(const char* file)
       cmSystemTools::MakeDirectory(i->c_str());
       }
     }
-  std::ofstream fout(file);
+  // Create a stream that writes to a temporary file
+  // then does a copy at the end.   This is to allow users
+  // to hit control-c during the make of the makefile
+  cmGeneratedFileStream tempFile(file);
+  tempFile.SetAlwaysCopy(true);
+  std::ostream&  fout = tempFile.GetStream();
   if(!fout)
     {
     cmSystemTools::Error("Error can not open for write: ", file);
@@ -950,6 +956,12 @@ void cmUnixMakefileGenerator::OutputMakeRules(std::ostream& fout)
                        "${CMAKE_COMMAND}",
                        0,
                        "echo \"cmake might be out of date\"");
+  this->OutputMakeRule(fout, 
+                       "Rule to keep make from removing Makefiles "
+                       "if control-C is hit during a run of cmake.",
+                       ".PRECIOUS",
+                       "Makefile cmake.depends",
+                       0);
   
 }