Improved logging.

Makefile

@@ -55,6 +55,7 @@ GOFILES = \
 	gencert.go \
 	register.go \
 	ssh.go \
+	log.go \
 	args.go \
 
 ifeq ($(SQLITE),1)

args.go

@@ -11,6 +11,7 @@ import (
 type args struct {
 	ShowHelp  bool
 	DataDir   string
+	LogPath   string
 	SshAddr   string
 	RegenKeys bool
 	SQLiteDB  string
@@ -25,6 +26,10 @@ func defaultDataDir() string {
 	return filepath.Join(os.Getenv("HOME"), dirname)
 }
 
+func defaultLogPath() string {
+	return filepath.Join(defaultDataDir(), "grumble.log")
+}
+
 func Usage() {
 	fmt.Fprintf(os.Stderr, "usage: grumble [options]\n")
 	fmt.Fprintf(os.Stderr, "remote control: grumble [options] ctl [ctlopts]\n")
@@ -36,6 +41,7 @@ var Args args
 func init() {
 	flag.BoolVar(&Args.ShowHelp, "help", false, "Show this help")
 	flag.StringVar(&Args.DataDir, "datadir", defaultDataDir(), "Directory to use for server storage")
+	flag.StringVar(&Args.LogPath, "log", defaultLogPath(), "Log file path")
 	flag.StringVar(&Args.SshAddr, "ssh", "localhost:46545", "Address to use for SSH admin prompt")
 	flag.BoolVar(&Args.RegenKeys, "regenkeys", false, "Force Grumble to regenerate its global RSA keypair and certificate")
 

grumble.go

@@ -25,8 +25,16 @@ func main() {
 		return
 	}
 
+	err = LogTarget.OpenFile(Args.LogPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Unable to open log file: %v", err)
+		return
+	}
+
 	log.SetPrefix("[G] ")
 	log.SetFlags(log.LstdFlags | log.Lmicroseconds)
+	log.SetOutput(&LogTarget)
+
 	log.Printf("Grumble")
 
 	log.Printf("Using data directory: %s", Args.DataDir)

log.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"bytes"
+	"os"
+	"sync"
+)
+
+type logTarget struct {
+	mu       sync.Mutex
+	logfn    string
+	file     *os.File
+	memLog   *bytes.Buffer
+}
+
+var LogTarget logTarget
+
+func (target *logTarget) Write(in []byte) (int, error) {
+	target.mu.Lock()
+	defer target.mu.Unlock()
+
+	return target.file.Write(in)
+}
+
+// Open a log file for writing.
+// This method will open the file in append-only mode.
+func (target *logTarget) OpenFile(fn string) (err error) {
+	target.logfn = fn
+	target.file, err = os.OpenFile(target.logfn, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0650)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// Perform a log rotation
+func (target *logTarget) Rotate() error {
+	target.mu.Lock()
+	defer target.mu.Unlock()
+
+	// Close the existing log file
+	err := target.file.Close()
+	if err != nil {
+		return err
+	}
+
+	target.file, err = os.OpenFile(target.logfn, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0650)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

server.go

@@ -26,7 +26,6 @@ import (
 	"hash"
 	"log"
 	"net"
-	"os"
 	"path/filepath"
 	"strings"
 	"sync"
@@ -122,7 +121,7 @@ type clientLogForwarder struct {
 }
 
 func (lf clientLogForwarder) Write(incoming []byte) (int, error) {
-	buf := bytes.NewBuffer(nil)
+	buf := new(bytes.Buffer)
 	buf.WriteString(fmt.Sprintf("<%v:%v(%v)> ", lf.client.Session, lf.client.ShownName(), lf.client.UserId()))
 	buf.Write(incoming)
 	lf.logger.Output(3, buf.String())
@@ -166,7 +165,7 @@ func NewServer(id int64, addr string, port int) (s *Server, err error) {
 	s.Channels[0] = NewChannel(0, "Root")
 	s.nextChanId = 1
 
-	s.Logger = log.New(os.Stdout, fmt.Sprintf("[%v] ", s.Id), log.LstdFlags|log.Lmicroseconds)
+	s.Logger = log.New(&LogTarget, fmt.Sprintf("[%v] ", s.Id), log.LstdFlags|log.Lmicroseconds)
 
 	return
 }

signal_unix.go

@@ -5,6 +5,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 	"os/signal"
 )
@@ -12,9 +13,17 @@ import (
 func SignalHandler() {
 	for {
 		sig := <-signal.Incoming
-		if sig != os.SIGINT && sig != os.SIGTERM {
+
+		if sig == os.SIGUSR2 {
+			err := LogTarget.Rotate()
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "Unable to rotate log file: %v", err)
+			}
 			continue
 		}
+	
+		if sig == os.SIGINT || sig == os.SIGTERM {
 			os.Exit(0)
 		}
+	}
 }