ccmake: Fix crash with cache entries almost the size of the window

The previous code:

if (curFieldLen < width) {
  ...
  strncpy(bar + curFieldLen + 2, help, width - curFieldLen - 2);

was not correctly guarded against cache entries whose size were exactly
1 or 2 characters short of the window size.
"if (curFieldLen - 2 < width)" would have prevented a copy of
negative/max_int characters and a subsequent crash.

The whole method was modernized with std::string instead of char*

1 files changed, 4 insertions, 2 deletions

diff --git a/Source/CursesDialog/cmCursesMainForm.h b/Source/CursesDialog/cmCursesMainForm.h
index 598fbdfba3..b7c204d64e 100644
--- a/Source/CursesDialog/cmCursesMainForm.h
+++ b/Source/CursesDialog/cmCursesMainForm.h
@@ -10,6 +10,8 @@
 #include <string>
 #include <vector>
 
+#include <cm/optional>
+
 #include "cmCursesCacheEntryComposite.h"
 #include "cmCursesForm.h"
 #include "cmCursesStandardIncludes.h"
@@ -67,8 +69,8 @@ public:
    * exception is during a resize. The optional argument specifies the
    * string to be displayed in the status bar.
    */
-  void UpdateStatusBar() override { this->UpdateStatusBar(nullptr); }
-  virtual void UpdateStatusBar(const char* message);
+  void UpdateStatusBar() override { this->UpdateStatusBar(cm::nullopt); }
+  void UpdateStatusBar(cm::optional<std::string> message);
 
   /**
    * Display current commands and their keys on the toolbar.  This