Move logtarget to its own package.

pkg/logtarget/Makefile

@@ -0,0 +1,7 @@
+include $(GOROOT)/src/Make.inc
+
+TARG = grumble/logtarget
+GOFILES = \
+	logtarget.go
+
+include $(GOROOT)/src/Make.pkg

pkg/logtarget/logtarget.go

@@ -0,0 +1,66 @@
+// Copyright (c) 2011 The Grumble Authors
+// The use of this source code is goverened by a BSD-style
+// license that can be found in the LICENSE-file.
+
+// Package logtarget implements a multiplexing logging target
+package logtarget
+
+import (
+	"bytes"
+	"os"
+	"sync"
+)
+
+// LogTarget implements the io.Writer interface, allowing
+// LogTarget to be registered with the regular Go log package.
+// LogTarget multiplexes its incoming writes to multiple optional
+// output writers, and one main output writer (the log file). 
+type LogTarget struct {
+	mu       sync.Mutex
+	logfn    string
+	file     *os.File
+	memLog   *bytes.Buffer
+}
+
+var Target LogTarget
+
+// Write writes a log message to all registered io.Writers
+func (target *LogTarget) Write(in []byte) (int, error) {
+	target.mu.Lock()
+	defer target.mu.Unlock()
+
+	return target.file.Write(in)
+}
+
+// OpenFile opens the main 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
+}
+
+// Rotate rotates the current log file.
+// This method holds a lock while rotating the log file,
+// and all log writes will be held back until the rotation
+// is complete.
+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
+}