Hooks

- It is now an error for a failing hook script to fail to also generate some
  feedback.
- Updated NEWS file to mention stricter hook script controls.

NEWS

@@ -2,10 +2,11 @@
 New Features in taskwarrior 2.4.1
 
   - New German translation.
+  - Hook scripts are now under much stricter control.
 
 New commands in taskwarrior 2.4.1
 
-  -
+  - None
 
 New configuration options in taskwarrior 2.4.1
 
@@ -17,11 +18,11 @@ New configuration options in taskwarrior 2.4.1
 
 Newly deprecated features in taskwarrior 2.4.1
 
-  -
+  - None
 
 Removed features in 2.4.1
 
-  -
+  - None
 
 Known Issues
 

src/Hooks.cpp

@@ -144,6 +144,8 @@ void Hooks::onLaunch ()
       }
       else
       {
+        assertFeedback (outputFeedback);
+
         std::vector <std::string>::iterator message;
         for (message = outputFeedback.begin (); message != outputFeedback.end (); ++message)
           context.error (*message);
@@ -209,6 +211,8 @@ void Hooks::onExit ()
       }
       else
       {
+        assertFeedback (outputFeedback);
+
         std::vector <std::string>::iterator message;
         for (message = outputFeedback.begin (); message != outputFeedback.end (); ++message)
           context.error (*message);
@@ -273,6 +277,8 @@ void Hooks::onAdd (Task& task)
       }
       else
       {
+        assertFeedback (outputFeedback);
+
         std::vector <std::string>::iterator message;
         for (message = outputFeedback.begin (); message != outputFeedback.end (); ++message)
           context.error (*message);
@@ -342,6 +348,8 @@ void Hooks::onModify (const Task& before, Task& after)
       }
       else
       {
+        assertFeedback (outputFeedback);
+
         std::vector <std::string>::iterator message;
         for (message = outputFeedback.begin (); message != outputFeedback.end (); ++message)
           context.error (*message);
@@ -493,6 +501,22 @@ void Hooks::assertSameTask (const std::vector <std::string>& input, const Task&
   }
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void Hooks::assertFeedback (const std::vector <std::string>& input) const
+{
+  bool foundSomething = false;
+  std::vector <std::string>::const_iterator i;
+  for (i = input.begin (); i != input.end (); ++i)
+    if (nontrivial (*i))
+      foundSomething = true;
+
+  if (! foundSomething)
+  {
+    context.error ("Hook Error: Expected feedback from a failing hook script.");
+    throw 0;
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 int Hooks::callHookScript (
   const std::string& script,

src/Hooks.h

@@ -56,6 +56,7 @@ private:
   void assertValidJSON (const std::vector <std::string>&) const;
   void assertNTasks (const std::vector <std::string>&, int) const;
   void assertSameTask (const std::vector <std::string>&, const Task&) const;
+  void assertFeedback (const std::vector <std::string>&) const;
   int callHookScript (const std::string&, const std::vector <std::string>&, std::vector <std::string>&);
 
 private: