fixes linting errors

backend.go

@@ -1,12 +1,13 @@
 package logging
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"os"
 )
 
+// Backend is the interface that specifies the methods that a backend must
+// implement
 type Backend interface {
 	Write(*Record) error
 	SetFormatter(*Formatter)
@@ -19,6 +20,7 @@ type Backend interface {
 // Backend to write in file-like objects
 //
 
+// FileBackend is a backend that writes to a file.
 type FileBackend struct {
 	l         io.Writer
 	formatter *Formatter
@@ -26,7 +28,8 @@ type FileBackend struct {
 	filepath  string
 }
 
-// Creates a new backend to write the logs on the standard output
+// NewStdoutBackend creates a new backend to write the logs on the standard
+// output
 func NewStdoutBackend() (b *FileBackend) {
 	b = &FileBackend{
 		l:         os.Stdout,
@@ -35,7 +38,7 @@ func NewStdoutBackend() (b *FileBackend) {
 	return
 }
 
-// Creates a new backend to write the logs on the error output
+// NewStderrBackend creates a new backend to write the logs on the error output
 func NewStderrBackend() (b *FileBackend) {
 	b = &FileBackend{
 		l:         os.Stderr,
@@ -44,21 +47,23 @@ func NewStderrBackend() (b *FileBackend) {
 	return
 }
 
-// Creates a new backend to write the logs in a given file
-func NewFileBackend(filename string) (b *FileBackend, e error) {
-	filename_fd, err := os.OpenFile(filename, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
+// NewFileBackend creates a new backend to write the logs in a given file
+func NewFileBackend(filename string) (*FileBackend, error) {
+	fd, err := os.OpenFile(filename, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644) //nolint: gosec
 	if err != nil {
-		e = errors.New(fmt.Sprintf("Cannot open log file %s (%s)", filename, err.Error()))
+		return nil, fmt.Errorf("Cannot open log file %s: %w", filename, err)
 	}
-	b = &FileBackend{
-		l:         filename_fd,
+
+	b := &FileBackend{
+		l:         fd,
 		formatter: &defaultFormatter,
 		filepath:  filename,
 	}
-	return
+
+	return b, nil
 }
 
-// Creates a new backend to write the logs in a given io.Writer
+// NewIoBackend creates a new backend to write the logs in a given io.Writer
 func NewIoBackend(buf io.Writer) (b *FileBackend) {
 	return &FileBackend{
 		l:         buf,
@@ -72,18 +77,23 @@ func (b FileBackend) Write(r *Record) error {
 	return err
 }
 
+// SetLevel changes the log level of the backend
 func (b *FileBackend) SetLevel(l Level) {
 	b.level = l
 }
 
+// Level returns the log level set for this backend
 func (b *FileBackend) Level() Level {
 	return b.level
 }
 
+// SetFormatter defines the formatter for this backend
 func (b *FileBackend) SetFormatter(f *Formatter) {
 	b.formatter = f
 }
 
+// Reopen closes and reopens the file it writes to. It should be used after log
+// rotation
 func (b *FileBackend) Reopen() error {
 	if b.filepath == "" {
 		return nil
@@ -95,7 +105,7 @@ func (b *FileBackend) Reopen() error {
 		}
 	}
 
-	fd, err := os.OpenFile(b.filepath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
+	fd, err := os.OpenFile(b.filepath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644) //nolint: gosec
 	if err != nil {
 		return fmt.Errorf("Cannot open log file %s: %w", b.filepath, err)
 	}
@@ -109,24 +119,31 @@ func (b *FileBackend) Reopen() error {
 // Noop Backend
 //
 
+// NoopBackend does nothing and discards all log entries without writing them anywhere
 type NoopBackend struct{}
 
+// NewNoopBackend creates a noop backend
 func NewNoopBackend() (Backend, error) {
 	return &NoopBackend{}, nil
 }
 
+// Write is a noop
 func (nb *NoopBackend) Write(r *Record) error {
 	return nil
 }
 
+// SetFormatter is a noop
 func (nb *NoopBackend) SetFormatter(f *Formatter) {}
 
+// SetLevel is a noop
 func (nb *NoopBackend) SetLevel(level Level) {}
 
+// Level always returns DefeultLevel
 func (nb *NoopBackend) Level() Level {
 	return DefaultLevel
 }
 
+// Reopen is a noop
 func (nb *NoopBackend) Reopen() error {
 	return nil
 }

backend_syslog_linux.go

@@ -12,12 +12,16 @@ import (
 // Syslog Backend
 //
 
+// SyslogBackend writes the logs to a syslog system
 type SyslogBackend struct {
 	w         *syslog.Writer
 	formatter *Formatter
 	level     Level
 }
 
+// NewSyslogBackend initializes a new connection to a syslog server with the
+// given facility.
+// tag can contain an identifier for the log stream. It defaults to os.Arg[0].
 func NewSyslogBackend(facilityName string, tag string) (Backend, error) {
 	f, err := facility(facilityName)
 	if err != nil {
@@ -34,37 +38,42 @@ func NewSyslogBackend(facilityName string, tag string) (Backend, error) {
 	return sb, nil
 }
 
+// Write sends an entry to the syslog server
 func (sb *SyslogBackend) Write(r *Record) (err error) {
 	text := (*sb.formatter)(r)
 	switch r.Level {
-	case DEBUG:
+	case Debug:
 		err = sb.w.Debug(text)
-	case INFO:
+	case Info:
 		err = sb.w.Info(text)
-	case WARNING:
+	case Warning:
 		err = sb.w.Warning(text)
-	case ERROR:
+	case Error:
 		err = sb.w.Err(text)
-	case CRITICAL:
+	case Critical:
 		err = sb.w.Crit(text)
-	case FATAL:
+	case Fatal:
 		err = sb.w.Emerg(text)
 	}
 	return err
 }
 
+// SetFormatter defines the formatter for this backend
 func (sb *SyslogBackend) SetFormatter(f *Formatter) {
 	sb.formatter = f
 }
 
+// SetLevel changes the log level of the backend
 func (sb *SyslogBackend) SetLevel(level Level) {
 	sb.level = level
 }
 
+// Level returns the log level set for this backend
 func (sb *SyslogBackend) Level() Level {
 	return sb.level
 }
 
+// Reopen is a no-op
 func (sb *SyslogBackend) Reopen() error {
 	return nil
 }
@@ -93,9 +102,10 @@ var facilities = map[string]syslog.Priority{
 }
 
 func facility(name string) (syslog.Priority, error) {
-	if p, ok := facilities[strings.ToLower(name)]; !ok {
+	p, ok := facilities[strings.ToLower(name)]
+	if !ok {
 		return 0, fmt.Errorf("Facility '%s' does not exist", name)
-	} else {
-		return p, nil
 	}
+
+	return p, nil
 }

logger.go

@@ -7,35 +7,38 @@ import (
 	"sync"
 )
 
+// Logger is a facility that writes logs to one or more backands (files,
+// stdout/stderr, syslog, etc.) which can be configured independently
+//
+// Loggers are concurrent-safe.
 type Logger struct {
-	// added to avoid concurrent writes
 	sync.Mutex
 
 	name     string
-	level    Level
 	backends []Backend
 }
 
+// NewLogger initializes a new Logger with no backend and with the default log level.
 func NewLogger(name string) (l *Logger) {
 	l = &Logger{
 		name: name,
-		level: DEFAULT_LEVEL,
 	}
 	return
 }
 
-// Add a new Backend to the logger
+// AddBackend add a new Backend to the logger. All set backends are kept.
 func (l *Logger) AddBackend(b Backend) {
 	l.backends = append(l.backends, b)
 }
 
-// Sets the backend list to the logger. Any existing backend will be lost
+// SetBackend sets the backend list to the logger. Any existing backend will be lost.
+// FIXME must close file backends to avoid fd leaks
 func (l *Logger) SetBackend(b ...Backend) {
 	l.backends = b
 }
 
+// SetLevel changes the log level of all regisered backends to the given level.
 func (l *Logger) SetLevel(level Level) {
-	l.level = level
 	for _, backend := range l.backends {
 		backend.SetLevel(level)
 	}
@@ -51,12 +54,18 @@ func (b *buffer) Write(p []byte) (n int, err error) {
 	return len(p), nil
 }
 
+// AsStdLog encapsulate the logger in an instance of lof.Logger from the
+// standard library and returns it.
+//
+// It is there for interoperability reasons.
 func (l *Logger) AsStdLog(level Level) *log.Logger {
 	stdLogger := log.New(&buffer{logger: l, level: level}, "", 0)
 
 	return stdLogger
 }
 
+// Log sends a record containing the message `m` to the registered backends
+// whose level is at least `level`
 func (l *Logger) Log(level Level, m string) {
 	l.Lock()
 	defer l.Unlock()
@@ -64,56 +73,74 @@ func (l *Logger) Log(level Level, m string) {
 	r := NewRecord(l.name, level, m)
 	for _, backend := range l.backends {
 		if r.Level >= backend.Level() {
-			backend.Write(r)
+			_ = backend.Write(r)
 		}
 	}
 }
 
+// Debug logs a message with the Debug level
 func (l *Logger) Debug(text string) {
-	l.Log(DEBUG, text)
+	l.Log(Debug, text)
 }
 
+// Debugf formats the message with given args and logs the result with the
+// Debug level
 func (l *Logger) Debugf(text string, args ...interface{}) {
 	l.Debug(fmt.Sprintf(text, args...))
 }
 
+// Info logs a message with the Info level
 func (l *Logger) Info(text string) {
-	l.Log(INFO, text)
+	l.Log(Info, text)
 }
 
+// Infof formats the message with given args and logs the result with the
+// Info level
 func (l *Logger) Infof(text string, args ...interface{}) {
 	l.Info(fmt.Sprintf(text, args...))
 }
 
+// Warning logs a message with the Warning level
 func (l *Logger) Warning(text string) {
-	l.Log(WARNING, text)
+	l.Log(Warning, text)
 }
 
+// Warningf formats the message with given args and logs the result with the
+// Warning level
 func (l *Logger) Warningf(text string, args ...interface{}) {
 	l.Warning(fmt.Sprintf(text, args...))
 }
 
+// Error logs a message with the Error level
 func (l *Logger) Error(text string) {
-	l.Log(ERROR, text)
+	l.Log(Error, text)
 }
 
+// Errorf formats the message with given args and logs the result with the
+// Error level
 func (l *Logger) Errorf(text string, args ...interface{}) {
 	l.Error(fmt.Sprintf(text, args...))
 }
 
+// Critical logs a message with the Critical level
 func (l *Logger) Critical(text string) {
-	l.Log(CRITICAL, text)
+	l.Log(Critical, text)
 }
 
+// Criticalf formats the message with given args and logs the result with the
+// Critical level
 func (l *Logger) Criticalf(text string, args ...interface{}) {
 	l.Critical(fmt.Sprintf(text, args...))
 }
 
+// Fatal logs a message with the Fatal level
 func (l *Logger) Fatal(text string) {
-	l.Log(DEBUG, text)
+	l.Log(Debug, text)
 	os.Exit(100)
 }
 
+// Fatalf formats the message with given args and logs the result with the
+// Fatal level
 func (l *Logger) Fatalf(text string, args ...interface{}) {
 	l.Fatal(fmt.Sprintf(text, args...))
 }

logging.go

@@ -1,7 +1,6 @@
 package logging
 
 import (
-	"errors"
 	"fmt"
 	"strings"
 	"sync"
@@ -12,8 +11,10 @@ var (
 	lock    sync.Mutex
 )
 
+// Level is the type of log levels
 type Level byte
 
+//nolint: golint
 const (
 	Debug Level = iota
 	Info
@@ -26,21 +27,28 @@ const (
 
 var levelNames = [6]string{"DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL", "FATAL"}
 
+// Name returns the name of the log level
 func (l Level) Name() string {
 	return levelNames[l]
 }
 
+// LevelByName creates a log level given its name. It returns an error if the
+// name does not match any level.
 func LevelByName(l string) (Level, error) {
 	for pos, name := range levelNames {
 		if name == l {
 			return Level(pos), nil
 		}
 	}
-	return DEBUG, errors.New(fmt.Sprintf("Invalid log level %s", l))
+	return Debug, fmt.Errorf("Invalid log level %s", l)
 }
 
+// Formatter is the types of the functions that can be used to format a log
+// entry. They take a pointer to a record and return a formatted string.
 type Formatter func(*Record) string
 
+// GetLogger returns a logger given its name. if the logger does not exist, it
+// initializes one with the defaults (it logs to stdout with level debug)
 func GetLogger(name string) (l *Logger) {
 	lock.Lock()
 	defer lock.Unlock()

record.go

@@ -4,6 +4,8 @@ import (
 	"time"
 )
 
+// Record contains the data to be logged. It is passed to a formatter to
+// generate the logged message
 type Record struct {
 	Logger    string
 	Timestamp time.Time
@@ -11,6 +13,7 @@ type Record struct {
 	Message   string
 }
 
+// NewRecord creates a new record, setting its timestamp to time.Now()
 func NewRecord(name string, l Level, m string) (r *Record) {
 	r = &Record{
 		Logger:    name,