1 files changed, 96 insertions, 1 deletions
diff --git a/logging/logging_other.go b/logging/logging_other.go
index 382baca..b102e29 100644
--- a/logging/logging_other.go
+++ b/logging/logging_other.go
@@ -3,10 +3,105 @@
 package logging
 
 import (
+	"fmt"
+	"io"
+	"log"
 	"os"
+	"path/filepath"
+	"sync"
 	"syscall"
+
+	"github.com/xxxserxxx/gotop"
 )
 
-func StderrToLogfile(logfile *os.File) {
+func stderrToLogfile(logfile *os.File) {
 	syscall.Dup2(int(logfile.Fd()), 2)
 }
+
+func New(c gotop.Config) (io.WriteCloser, error) {
+	// create the log directory
+	if err := os.MkdirAll(c.LogDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to make the log directory: %v", err)
+	}
+	w := &RotateWriter{
+		filename:   filepath.Join(c.LogDir, c.LogFile),
+		maxLogSize: c.MaxLogSize,
+	}
+	err := w.rotate()
+	if err != nil {
+		return nil, err
+	}
+	// log time, filename, and line number
+	log.SetFlags(log.Ltime | log.Lshortfile)
+	// log to file
+	log.SetOutput(w)
+
+	stderrToLogfile(w.fp)
+	return w, nil
+}
+
+type RotateWriter struct {
+	lock       sync.Mutex
+	filename   string // should be set to the actual filename
+	fp         *os.File
+	maxLogSize int64
+}
+
+func (w *RotateWriter) Close() error {
+	return w.fp.Close()
+}
+
+// Write satisfies the io.Writer interface.
+func (w *RotateWriter) Write(output []byte) (int, error) {
+	w.lock.Lock()
+	defer w.lock.Unlock()
+	// Rotate if the log hits the size limit
+	s, err := os.Stat(w.filename)
+	if err == nil {
+		if s.Size() > w.maxLogSize {
+			w.rotate()
+		}
+	}
+	return w.fp.Write(output)
+}
+
+// Perform the actual act of rotating and reopening file.
+func (w *RotateWriter) rotate() (err error) {
+	// Close existing file if open
+	if w.fp != nil {
+		err = w.fp.Close()
+		w.fp = nil
+		if err != nil {
+			return
+		}
+	}
+	// This will keep three logs
+	for i := 1; i > -1; i-- {
+		from := fmt.Sprintf("%s.%d", w.filename, i)
+		to := fmt.Sprintf("%s.%d", w.filename, i+1)
+		// Rename dest file if it already exists
+		_, err = os.Stat(from)
+		if err == nil {
+			err = os.Rename(from, to)
+			if err != nil {
+				return
+			}
+		}
+	}
+	// Rename dest file if it already exists
+	_, err = os.Stat(w.filename)
+	if err == nil {
+		err = os.Rename(w.filename, fmt.Sprintf("%s.%d", w.filename, 0))
+		if err != nil {
+			return
+		}
+	}
+
+	// open the log file
+	w.fp, err = os.OpenFile(w.filename, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0660)
+	if err != nil {
+		return fmt.Errorf("failed to open log file %s: %v", w.filename, err)
+	}
+
+	return nil
+}