Really trust umask in file(WRITE) command (#10789, #10126)

Commit 8d0161c8 (Trust umask for file permissions, 2010-01-12) taught
these commands to set permissions to 0666 explicitly.  The intention was
to let the open() call inside ofstream handle permsisions so that umask
would be honored.  Now we set permissions only when we need to preserve
those on an existing file.  New files will be created with umask-based
permissions.

Source/cmFileCommand.cxx

@@ -183,24 +183,16 @@ bool cmFileCommand::HandleWriteCommand(std::vector<std::string> const& args,
   std::string dir = cmSystemTools::GetFilenamePath(fileName);
   cmSystemTools::MakeDirectory(dir.c_str());
 
-  mode_t mode =
-#if defined( _MSC_VER ) || defined( __MINGW32__ )
-    S_IREAD | S_IWRITE
-#elif defined( __BORLANDC__ )
-    S_IRUSR | S_IWUSR
-#else
-    0666
-#endif
-    ;
+  mode_t mode = 0;
 
   // Set permissions to writable
   if ( cmSystemTools::GetPermissions(fileName.c_str(), mode) )
     {
     cmSystemTools::SetPermissions(fileName.c_str(),
 #if defined( _MSC_VER ) || defined( __MINGW32__ )
-      S_IREAD | S_IWRITE
+      mode | S_IWRITE
 #else
-      0666
+      mode | S_IWUSR | S_IWGRP
 #endif
     );
     }
@@ -217,7 +209,10 @@ bool cmFileCommand::HandleWriteCommand(std::vector<std::string> const& args,
     }
   file << message;
   file.close();
-  cmSystemTools::SetPermissions(fileName.c_str(), mode);
+  if(mode)
+    {
+    cmSystemTools::SetPermissions(fileName.c_str(), mode);
+    }
   return true;
 }
 

Source/cmWriteFileCommand.cxx

@@ -54,24 +54,16 @@ bool cmWriteFileCommand
   std::string dir = cmSystemTools::GetFilenamePath(fileName);
   cmSystemTools::MakeDirectory(dir.c_str());
 
-  mode_t mode =
-#if defined( _MSC_VER ) || defined( __MINGW32__ )
-    S_IREAD | S_IWRITE
-#elif defined( __BORLANDC__ )
-    S_IRUSR | S_IWUSR
-#else
-    0666
-#endif
-    ;
+  mode_t mode = 0;
 
   // Set permissions to writable
   if ( cmSystemTools::GetPermissions(fileName.c_str(), mode) )
     {
     cmSystemTools::SetPermissions(fileName.c_str(),
 #if defined( _MSC_VER ) || defined( __MINGW32__ )
-      S_IREAD | S_IWRITE
+      mode | S_IWRITE
 #else
-      0666
+      mode | S_IWUSR | S_IWGRP
 #endif
     );
     }
@@ -89,7 +81,10 @@ bool cmWriteFileCommand
     }
   file << message << std::endl;
   file.close();
-  cmSystemTools::SetPermissions(fileName.c_str(), mode);
+  if(mode)
+    {
+    cmSystemTools::SetPermissions(fileName.c_str(), mode);
+    }
 
   return true;
 }