forked from snapcore/snapd
/
logger.go
176 lines (144 loc) · 4.03 KB
/
logger.go
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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2014,2015,2017 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package logger
import (
"bytes"
"fmt"
"io"
"log"
"os"
"sync"
"github.com/snapcore/snapd/osutil"
)
// A Logger is a fairly minimal logging tool.
type Logger interface {
// Notice is for messages that the user should see
Notice(msg string)
// Debug is for messages that the user should be able to find if they're debugging something
Debug(msg string)
}
const (
// DefaultFlags are passed to the default console log.Logger
DefaultFlags = log.Ldate | log.Ltime | log.Lmicroseconds | log.Lshortfile
)
type nullLogger struct{}
func (nullLogger) Notice(string) {}
func (nullLogger) Debug(string) {}
// NullLogger is a logger that does nothing
var NullLogger = nullLogger{}
var (
logger Logger = NullLogger
lock sync.Mutex
)
// Panicf notifies the user and then panics
func Panicf(format string, v ...interface{}) {
msg := fmt.Sprintf(format, v...)
lock.Lock()
defer lock.Unlock()
logger.Notice("PANIC " + msg)
panic(msg)
}
// Noticef notifies the user of something
func Noticef(format string, v ...interface{}) {
msg := fmt.Sprintf(format, v...)
lock.Lock()
defer lock.Unlock()
logger.Notice(msg)
}
// Debugf records something in the debug log
func Debugf(format string, v ...interface{}) {
msg := fmt.Sprintf(format, v...)
lock.Lock()
defer lock.Unlock()
logger.Debug(msg)
}
// MockLogger replaces the exiting logger with a buffer and returns
// the log buffer and a restore function.
func MockLogger() (buf *bytes.Buffer, restore func()) {
buf = &bytes.Buffer{}
oldLogger := logger
l, err := New(buf, DefaultFlags)
if err != nil {
panic(err)
}
SetLogger(l)
return buf, func() {
SetLogger(oldLogger)
}
}
// WithLoggerLock invokes f with the global logger lock, useful for
// tests involving goroutines with MockLogger.
func WithLoggerLock(f func()) {
lock.Lock()
defer lock.Unlock()
f()
}
// SetLogger sets the global logger to the given one
func SetLogger(l Logger) {
lock.Lock()
defer lock.Unlock()
logger = l
}
type Log struct {
log *log.Logger
debug bool
}
// Debug only prints if SNAPD_DEBUG is set
func (l *Log) Debug(msg string) {
if l.debug || osutil.GetenvBool("SNAPD_DEBUG") {
l.log.Output(3, "DEBUG: "+msg)
}
}
// Notice alerts the user about something, as well as putting it syslog
func (l *Log) Notice(msg string) {
l.log.Output(3, msg)
}
// New creates a log.Logger using the given io.Writer and flag.
func New(w io.Writer, flag int) (Logger, error) {
logger := &Log{
log: log.New(w, "", flag),
debug: debugEnabledOnKernelCmdline(),
}
return logger, nil
}
// SimpleSetup creates the default (console) logger
func SimpleSetup() error {
flags := log.Lshortfile
if term := os.Getenv("TERM"); term != "" {
// snapd is probably not running under systemd
flags = DefaultFlags
}
l, err := New(os.Stderr, flags)
if err == nil {
SetLogger(l)
}
return err
}
// used to force testing of the kernel command line parsing
var procCmdlineUseDefaultMockInTests = true
// TODO: consider generalizing this to snapdenv and having it used by
// other places that consider SNAPD_DEBUG
func debugEnabledOnKernelCmdline() bool {
// if this is called during tests, always ignore it so we don't have to mock
// the /proc/cmdline for every test that ends up using a logger
if osutil.IsTestBinary() && procCmdlineUseDefaultMockInTests {
return false
}
m, _ := osutil.KernelCommandLineKeyValues("snapd.debug")
return m["snapd.debug"] == "1"
}