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