From ac9d05efa27d07a65511b6e55ebe2f50203cb1f5 Mon Sep 17 00:00:00 2001
From: Alex Bramley <a.bramley@gmail.com>
Date: Sun, 10 Mar 2013 13:30:00 +0000
Subject: [PATCH] Port sp0rkle's panic recovery back into goirc.

---
 client/connection.go    |  4 ++++
 client/dispatch.go      | 11 ++++++++++-
 client/dispatch_test.go | 35 ++++++++++++++++++++++++++++++-----
 3 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/client/connection.go b/client/connection.go
index 02d1b4b..88f992e 100644
--- a/client/connection.go
+++ b/client/connection.go
@@ -68,6 +68,9 @@ type Config struct {
 
 	// Sent as the QUIT message.
 	QuitMessage string
+
+	// Configurable panic recovery for all handlers.
+	Recover func(*Conn, *Line)
 }
 
 func NewConfig(nick string, args ...string) *Config {
@@ -75,6 +78,7 @@ func NewConfig(nick string, args ...string) *Config {
 		Me:       state.NewNick(nick),
 		PingFreq: 3 * time.Minute,
 		NewNick:  func(s string) string { return s + "_" },
+		Recover:  (*Conn).LogPanic,  // in dispatch.go
 	}
 	cfg.Me.Ident = "goirc"
 	if len(args) > 0 && args[0] != "" {
diff --git a/client/dispatch.go b/client/dispatch.go
index e0645a4..0c7ae89 100644
--- a/client/dispatch.go
+++ b/client/dispatch.go
@@ -2,6 +2,7 @@ package client
 
 import (
 	"github.com/fluffle/golog/logging"
+	"runtime"
 	"strings"
 	"sync"
 )
@@ -45,8 +46,9 @@ type hNode struct {
 	handler    Handler
 }
 
-// A hNode implements both Handler...
+// A hNode implements both Handler (with configurable panic recovery)...
 func (hn *hNode) Handle(conn *Conn, line *Line) {
+	defer conn.cfg.Recover(conn, line)
 	hn.handler.Handle(conn, line)
 }
 
@@ -141,3 +143,10 @@ func (conn *Conn) HandleFunc(name string, hf HandlerFunc) Remover {
 func (conn *Conn) dispatch(line *Line) {
 	conn.handlers.dispatch(conn, line)
 }
+
+func (conn *Conn) LogPanic(line *Line) {
+	if err := recover(); err != nil {
+		_, f, l, _ := runtime.Caller(2)
+		logging.Error("%s:%d: panic: %v", f, l, err)
+    }
+}
diff --git a/client/dispatch_test.go b/client/dispatch_test.go
index 965528c..026dea9 100644
--- a/client/dispatch_test.go
+++ b/client/dispatch_test.go
@@ -6,6 +6,11 @@ import (
 )
 
 func TestHandlerSet(t *testing.T) {
+	// A Conn is needed here because the previous behaviour of passing nil to
+	// hset.dispatch causes a nil pointer dereference with panic recovery.
+	c, s := setUp(t)
+	defer s.tearDown()
+
 	hs := handlerSet()
 	if len(hs.set) != 0 {
 		t.Errorf("New set contains things!")
@@ -83,7 +88,7 @@ func TestHandlerSet(t *testing.T) {
 	if callcount != 0 {
 		t.Errorf("Something incremented call count before we were expecting it.")
 	}
-	hs.dispatch(nil, &Line{Cmd: "One"})
+	hs.dispatch(c, &Line{Cmd: "One"})
 	<-time.After(time.Millisecond)
 	if callcount != 4 {
 		t.Errorf("Our handler wasn't called four times :-(")
@@ -107,7 +112,7 @@ func TestHandlerSet(t *testing.T) {
 	}
 
 	// Dispatch should result in 3 additions.
-	hs.dispatch(nil, &Line{Cmd: "One"})
+	hs.dispatch(c, &Line{Cmd: "One"})
 	<-time.After(time.Millisecond)
 	if callcount != 7 {
 		t.Errorf("Our handler wasn't called three times :-(")
@@ -129,7 +134,7 @@ func TestHandlerSet(t *testing.T) {
 	}
 
 	// Dispatch should result in 2 additions.
-	hs.dispatch(nil, &Line{Cmd: "One"})
+	hs.dispatch(c, &Line{Cmd: "One"})
 	<-time.After(time.Millisecond)
 	if callcount != 9 {
 		t.Errorf("Our handler wasn't called two times :-(")
@@ -151,7 +156,7 @@ func TestHandlerSet(t *testing.T) {
 	}
 
 	// Dispatch should result in 1 addition.
-	hs.dispatch(nil, &Line{Cmd: "One"})
+	hs.dispatch(c, &Line{Cmd: "One"})
 	<-time.After(time.Millisecond)
 	if callcount != 10 {
 		t.Errorf("Our handler wasn't called once :-(")
@@ -170,9 +175,29 @@ func TestHandlerSet(t *testing.T) {
 	}
 
 	// Dispatch should result in NO additions.
-	hs.dispatch(nil, &Line{Cmd: "One"})
+	hs.dispatch(c, &Line{Cmd: "One"})
 	<-time.After(time.Millisecond)
 	if callcount != 10 {
 		t.Errorf("Our handler was called?")
 	}
 }
+
+func TestPanicRecovery(t *testing.T) {
+	c, s := setUp(t)
+	defer s.tearDown()
+
+	recovered := false
+	c.cfg.Recover = func(conn *Conn, line *Line) {
+		if err, ok := recover().(string); ok && err == "panic!" {
+			recovered = true
+		}
+	}
+	c.HandleFunc(PRIVMSG, func(conn *Conn, line *Line) {
+		panic("panic!")
+	})
+	c.in <- parseLine(":nick!user@host.com PRIVMSG #channel :OH NO PIGEONS")
+	<-time.After(time.Millisecond)
+	if recovered != true {
+		t.Errorf("Failed to recover panic!")
+	}
+}