Fixes #49, logs filling up hard drive.

6 files changed, 164 insertions, 26 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 78c81bd..14b710f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 > - **Fixed**: for any bug fixes.
 > - **Security**: in case of vulnerabilities.
 
+## [3.3.0] - 
+
+- Logs are now rotated. Settings are currently hard-coded at 4 files of 5MB
+  each, so logs shouldn't take up more than 20MB.  I'm going to see how many
+  complain about wanting to configure these settings before I add code to do
+  that.
+
 ## [3.2.0] - 2020-02-14
 
 Bug fixes & pull requests
diff --git a/cmd/gotop/main.go b/cmd/gotop/main.go
index d3384b0..eb2364f 100644
--- a/cmd/gotop/main.go
+++ b/cmd/gotop/main.go
@@ -79,7 +79,7 @@ Colorschemes:
 	conf = gotop.Config{
 		ConfigDir:            cd,
 		LogDir:               ld,
-		LogPath:              filepath.Join(ld, "errors.log"),
+		LogFile:              "errors.log",
 		GraphHorizontalScale: 7,
 		HelpVisible:          false,
 		Colorscheme:          colorschemes.Default,
@@ -90,6 +90,7 @@ Colorschemes:
 		Battery:              false,
 		Statusbar:            false,
 		NetInterface:         w.NET_INTERFACE_ALL,
+		MaxLogSize:           5000000,
 	}
 
 	args, err := docopt.ParseArgs(usage, os.Args[1:], version)
@@ -376,32 +377,13 @@ func eventLoop(c gotop.Config, grid *layout.MyGrid) {
 	}
 }
 
-func setupLogfile(c gotop.Config) (*os.File, 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)
-	}
-	// open the log file
-	logfile, err := os.OpenFile(c.LogPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0660)
-	if err != nil {
-		return nil, fmt.Errorf("failed to open log file: %v", err)
-	}
-
-	// log time, filename, and line number
-	log.SetFlags(log.Ltime | log.Lshortfile)
-	// log to file
-	log.SetOutput(logfile)
-
-	return logfile, nil
-}
-
 func main() {
 	conf, err := parseArgs()
 	if err != nil {
 		stderrLogger.Fatalf("failed to parse cli args: %v", err)
 	}
 
-	logfile, err := setupLogfile(conf)
+	logfile, err := logging.New(conf)
 	if err != nil {
 		stderrLogger.Fatalf("failed to setup log file: %v", err)
 	}
@@ -412,8 +394,6 @@ func main() {
 	}
 	defer ui.Close()
 
-	logging.StderrToLogfile(logfile)
-
 	setDefaultTermuiColors(conf) // done before initializing widgets to allow inheriting colors
 	help = w.NewHelpMenu()
 	if statusbar {
diff --git a/config.go b/config.go
index c2e4cc5..a400539 100644
--- a/config.go
+++ b/config.go
@@ -18,7 +18,7 @@ import (
 type Config struct {
 	ConfigDir string
 	LogDir    string
-	LogPath   string
+	LogFile   string
 
 	GraphHorizontalScale int
 	HelpVisible          bool
@@ -32,4 +32,5 @@ type Config struct {
 	Statusbar      bool
 	NetInterface   string
 	Layout         io.Reader
+	MaxLogSize     int64
 }
diff --git a/logging/logging_arm64.go b/logging/logging_arm64.go
index 2b7a25f..48ace31 100644
--- a/logging/logging_arm64.go
+++ b/logging/logging_arm64.go
@@ -5,6 +5,6 @@ import (
 	"syscall"
 )
 
-func StderrToLogfile(logfile *os.File) {
+func stderrToLogfile(logfile *os.File) {
 	syscall.Dup3(int(logfile.Fd()), 2, 0)
 }
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
+}
diff --git a/logging/logging_test.go b/logging/logging_test.go
new file mode 100644
index 0000000..3bff162
--- /dev/null
+++ b/logging/logging_test.go
@@ -0,0 +1,55 @@
+package logging
+
+import (
+	"io/ioutil"
+	//"log"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/xxxserxxx/gotop"
+)
+
+func TestLogging(t *testing.T) {
+	tdn := "testdir"
+	path, err := filepath.Abs(tdn)
+	defer os.RemoveAll(path)
+	c := gotop.Config{
+		MaxLogSize: 300,
+		LogDir:     path,
+		LogFile:    "errors.log",
+	}
+	wc, err := New(c)
+	assert.NoError(t, err)
+	if err != nil {
+		return
+	}
+	defer wc.Close()
+	ds := make([]byte, 100)
+	for i, _ := range ds {
+		ds[i] = 'x'
+	}
+
+	// Base case -- empty log file
+	td, err := ioutil.ReadDir(path)
+	assert.NoError(t, err)
+	if err != nil {
+		return
+	}
+	assert.Equal(t, 1, len(td))
+
+	for i := 1; i < 6; i++ {
+		wc.Write(ds)
+		wc.Write(ds)
+		wc.Write(ds)
+		wc.Write([]byte{'\n'}) // max... + 1
+		td, err = ioutil.ReadDir(path)
+		assert.NoError(t, err)
+		k := i
+		if k > 4 {
+			k = 4
+		}
+		assert.Equal(t, k, len(td))
+	}
+}