DRTVWR-558: Nail down LLDispatchListener exception handling

for exceptions other than those thrown by base-class LLEventDispatcher.

Explain in LLDispatchListener Doxygen comments that for a request lacking a
"reply" key, any exception is allowed to propagate because it's likely to
reach the post() call that triggered the exception in the first place.

For batch LLDispatchListener operations, catch not only LLEventDispatcher::
DispatchError exceptions but any std::exception, so we can collect them to
report to the invoker. "Gotta catch 'em all!"

Make LLLeap catch any std::exception thrown by processing a request from the
plugin child process, log it and send a reply to the plugin. No plugin should
be allowed to crash the viewer.

(cherry picked from commit 94e10fd039b79f71ed8d7e10807b6e4eebd1928c)

indra/llcommon/lleventdispatcher.cpp

@@ -848,10 +848,12 @@ void LLDispatchListener::call_map(const LLSD& reqmap, const LLSD& event) const
             // which request keys succeeded.
             result[name] = (*this)(name, args);
         }
-        catch (const DispatchError& err)
+        catch (const std::exception& err)
         {
-            // collect message in 'errors'
-            errors << delim << err.what();
+            // Catch not only DispatchError, but any C++ exception thrown by
+            // the target callable. Collect exception name and message in
+            // 'errors'.
+            errors << delim << LLError::Log::classname(err) << ": " << err.what();
             delim = "\n";
         }
     }
@@ -921,9 +923,12 @@ void LLDispatchListener::call_array(const LLSD& reqarray, const LLSD& event) con
             // With this form, capture return value even if undefined
             results.append((*this)(name, args));
         }
-        catch (const DispatchError& err)
+        catch (const std::exception& err)
         {
-            error = err.what();
+            // Catch not only DispatchError, but any C++ exception thrown by
+            // the target callable. Report the exception class as well as the
+            // error string.
+            error = stringize(LLError::Log::classname(err), ": ", err.what());
             break;
         }
     }

indra/llcommon/lleventdispatcher.h

@@ -747,7 +747,10 @@ LLEventDispatcher::make_invoker(Method f, const InstanceGetter& getter)
  * "reply" is present, LLDispatchListener will send a response map to the
  * specified LLEventPump containing an "error" key whose value is the relevant
  * error message. If "reply" is not present, the DispatchError exception will
- * propagate.
+ * propagate. Since LLDispatchListener bundles an LLEventStream, which
+ * attempts the call immediately on receiving the post() call, there's a
+ * reasonable chance that the exception will highlight the post() call that
+ * triggered the error.
  *
  * If LLDispatchListener successfully calls the target callable, but no
  * "reply" key is present, any value returned by that callable is discarded.

indra/llcommon/llleap.cpp

@@ -327,11 +327,28 @@ public:
             }
             else
             {
-                // The LLSD object we got from our stream contains the keys we
-                // need.
-                LLEventPumps::instance().obtain(data["pump"]).post(data["data"]);
-                // Block calls to this method; resetting mBlocker unblocks calls
-                // to the other method.
+                try
+                {
+                    // The LLSD object we got from our stream contains the
+                    // keys we need.
+                    LLEventPumps::instance().obtain(data["pump"]).post(data["data"]);
+                }
+                catch (const std::exception& err)
+                {
+                    // No plugin should be allowed to crash the viewer by
+                    // driving an exception -- intentionally or not.
+                    LOG_UNHANDLED_EXCEPTION(stringize("handling request ", data));
+                    // Whether or not the plugin added a "reply" key to the
+                    // request, send a reply. We happen to know who originated
+                    // this request, and the reply LLEventPump of interest.
+                    // Not our problem if the plugin ignores the reply event.
+                    data["reply"] = mReplyPump.getName();
+                    sendReply(llsd::map("error",
+                                        stringize(LLError::Log::classname(err), ": ", err.what())),
+                              data);
+                }
+                // Block calls to this method; resetting mBlocker unblocks
+                // calls to the other method.
                 mBlocker.reset(new LLEventPump::Blocker(mStdoutDataConnection));
                 // Go check for any more pending events in the buffer.
                 if (childout.size())