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package common
import (
"fmt"
"io/ioutil"
"os"
"os/signal"
"sync"
"time"
)
func TrapSignal(cb func()) {
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
signal.Notify(c, os.Kill)
go func() {
for sig := range c {
fmt.Printf("captured %v, exiting...\n", sig)
if cb != nil {
cb()
}
os.Exit(1)
}
}()
select {}
}
func Exit(s string) {
fmt.Printf(s + "\n")
os.Exit(1)
}
func EnsureDir(dir string) error {
if _, err := os.Stat(dir); os.IsNotExist(err) {
err := os.MkdirAll(dir, 0700)
if err != nil {
return fmt.Errorf("Could not create directory %v. %v", dir, err)
}
}
return nil
}
func FileExists(filePath string) bool {
_, err := os.Stat(filePath)
return !os.IsNotExist(err)
}
func ReadFile(filePath string) ([]byte, error) {
return ioutil.ReadFile(filePath)
}
func MustReadFile(filePath string) []byte {
fileBytes, err := ioutil.ReadFile(filePath)
if err != nil {
Exit(Fmt("MustReadFile failed: %v", err))
return nil
}
return fileBytes
}
func WriteFile(filePath string, contents []byte) error {
err := ioutil.WriteFile(filePath, contents, 0600)
if err != nil {
return err
}
fmt.Printf("File written to %v.\n", filePath)
return nil
}
func MustWriteFile(filePath string, contents []byte) {
err := WriteFile(filePath, contents)
if err != nil {
Exit(Fmt("MustWriteFile failed: %v", err))
}
}
// Writes to newBytes to filePath.
// Guaranteed not to lose *both* oldBytes and newBytes,
// (assuming that the OS is perfect)
func WriteFileAtomic(filePath string, newBytes []byte) error {
// If a file already exists there, copy to filePath+".bak" (overwrite anything)
if _, err := os.Stat(filePath); !os.IsNotExist(err) {
fileBytes, err := ioutil.ReadFile(filePath)
if err != nil {
return fmt.Errorf("Could not read file %v. %v", filePath, err)
}
err = ioutil.WriteFile(filePath+".bak", fileBytes, 0600)
if err != nil {
return fmt.Errorf("Could not write file %v. %v", filePath+".bak", err)
}
}
// Write newBytes to filePath.new
err := ioutil.WriteFile(filePath+".new", newBytes, 0600)
if err != nil {
return fmt.Errorf("Could not write file %v. %v", filePath+".new", err)
}
// Move filePath.new to filePath
err = os.Rename(filePath+".new", filePath)
return err
}
//--------------------------------------------------------------------------------
/* AutoFile usage
// Create/Append to ./autofile_test
af, err := OpenAutoFile("autofile_test")
if err != nil {
panic(err)
}
// Stream of writes.
// During this time, the file may be moved e.g. by logRotate.
for i := 0; i < 60; i++ {
af.Write([]byte(Fmt("LOOP(%v)", i)))
time.Sleep(time.Second)
}
// Close the AutoFile
err = af.Close()
if err != nil {
panic(err)
}
*/
const autoFileOpenDuration = 1000 * time.Millisecond
// Automatically closes and re-opens file for writing.
// This is useful for using a log file with the logrotate tool.
type AutoFile struct {
Path string
ticker *time.Ticker
mtx sync.Mutex
file *os.File
}
func OpenAutoFile(path string) (af *AutoFile, err error) {
af = &AutoFile{
Path: path,
ticker: time.NewTicker(autoFileOpenDuration),
}
if err = af.openFile(); err != nil {
return
}
go af.processTicks()
return
}
func (af *AutoFile) Close() error {
af.ticker.Stop()
af.mtx.Lock()
err := af.closeFile()
af.mtx.Unlock()
return err
}
func (af *AutoFile) processTicks() {
for {
_, ok := <-af.ticker.C
if !ok {
return // Done.
}
af.mtx.Lock()
af.closeFile()
af.mtx.Unlock()
}
}
func (af *AutoFile) closeFile() (err error) {
file := af.file
if file == nil {
return nil
}
af.file = nil
return file.Close()
}
func (af *AutoFile) Write(b []byte) (n int, err error) {
af.mtx.Lock()
defer af.mtx.Unlock()
if af.file == nil {
if err = af.openFile(); err != nil {
return
}
}
return af.file.Write(b)
}
func (af *AutoFile) openFile() error {
file, err := os.OpenFile(af.Path, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0600)
if err != nil {
return err
}
af.file = file
return nil
}