Clone file owner and mode on compressed log.

Clone the log file owner and the log file mode to the compressed
log file. Add tests to ensure that this is handled correctly.

linux_test.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"syscall"
 	"testing"
+	"time"
 )
 
 func TestMaintainMode(t *testing.T) {
@@ -83,6 +84,97 @@ func TestMaintainOwner(t *testing.T) {
 	equals(666, fakeFS.files[filename].gid, t)
 }
 
+func TestCompressMaintainMode(t *testing.T) {
+	currentTime = fakeTime
+
+	dir := makeTempDir("TestCompressMaintainMode", t)
+	defer os.RemoveAll(dir)
+
+	filename := logFile(dir)
+
+	mode := os.FileMode(0600)
+	f, err := os.OpenFile(filename, os.O_CREATE|os.O_RDWR, mode)
+	isNil(err, t)
+	f.Close()
+
+	l := &Logger{
+		Compress: true,
+		Filename:   filename,
+		MaxBackups: 1,
+		MaxSize:    100, // megabytes
+	}
+	defer l.Close()
+	b := []byte("boo!")
+	n, err := l.Write(b)
+	isNil(err, t)
+	equals(len(b), n, t)
+
+	newFakeTime()
+
+	err = l.Rotate()
+	isNil(err, t)
+
+	// we need to wait a little bit since the files get compressed on a different
+	// goroutine.
+	<-time.After(10 * time.Millisecond)
+
+	// a compressed version of the log file should now exist with the correct
+	// mode.
+	filename2 := backupFile(dir)
+	info, err := os.Stat(filename)
+	isNil(err, t)
+	info2, err := os.Stat(filename2+compressSuffix)
+	isNil(err, t)
+	equals(mode, info.Mode(), t)
+	equals(mode, info2.Mode(), t)
+}
+
+func TestCompressMaintainOwner(t *testing.T) {
+	fakeFS := newFakeFS()
+	os_Chown = fakeFS.Chown
+	os_Stat = fakeFS.Stat
+	defer func() {
+		os_Chown = os.Chown
+		os_Stat = os.Stat
+	}()
+	currentTime = fakeTime
+	dir := makeTempDir("TestCompressMaintainOwner", t)
+	defer os.RemoveAll(dir)
+
+	filename := logFile(dir)
+
+	f, err := os.OpenFile(filename, os.O_CREATE|os.O_RDWR, 0644)
+	isNil(err, t)
+	f.Close()
+
+	l := &Logger{
+		Compress:   true,
+		Filename:   filename,
+		MaxBackups: 1,
+		MaxSize:    100, // megabytes
+	}
+	defer l.Close()
+	b := []byte("boo!")
+	n, err := l.Write(b)
+	isNil(err, t)
+	equals(len(b), n, t)
+
+	newFakeTime()
+
+	err = l.Rotate()
+	isNil(err, t)
+
+	// we need to wait a little bit since the files get compressed on a different
+	// goroutine.
+	<-time.After(10 * time.Millisecond)
+
+	// a compressed version of the log file should now exist with the correct
+	// owner.
+	filename2 := backupFile(dir)
+	equals(555, fakeFS.files[filename2+compressSuffix].uid, t)
+	equals(666, fakeFS.files[filename2+compressSuffix].gid, t)
+}
+
 type fakeFile struct {
 	uid int
 	gid int

lumberjack.go

@@ -472,9 +472,18 @@ func compressLogFile(src, dst string) (err error) {
 	}
 	defer f.Close()
 
+	fi, err := os_Stat(src)
+	if err != nil {
+		return fmt.Errorf("failed to stat log file: %v", err)
+	}
+
+	if err := chown(dst, fi); err != nil {
+		return fmt.Errorf("failed to chown compressed log file: %v", err)
+	}
+
 	// If this file already exists, we presume it was created by
 	// a previous attempt to compress the log file.
-	gzf, err := os.OpenFile(dst, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
+	gzf, err := os.OpenFile(dst, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, fi.Mode())
 	if err != nil {
 		return fmt.Errorf("failed to open compressed log file: %v", err)
 	}