307 lines
8.3 KiB
Go
307 lines
8.3 KiB
Go
|
// Copyright 2010 The Go Authors. All rights reserved.
|
||
|
|
// Use of this source code is governed by a BSD-style
|
||
|
|
// license that can be found in the LICENSE file.
|
||
|
|
|
||
|
|
// +build linux
|
||
|
|
|
||
|
|
package fsnotify
|
||
|
|
|
||
|
|
import (
|
||
|
|
"errors"
|
||
|
|
"fmt"
|
||
|
|
"io"
|
||
|
|
"os"
|
||
|
|
"path/filepath"
|
||
|
|
"strings"
|
||
|
|
"sync"
|
||
|
|
"syscall"
|
||
|
|
"unsafe"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Watcher watches a set of files, delivering events to a channel.
|
||
|
|
type Watcher struct {
|
||
|
|
Events chan Event
|
||
|
|
Errors chan error
|
||
|
|
mu sync.Mutex // Map access
|
||
|
|
fd int
|
||
|
|
poller *fdPoller
|
||
|
|
watches map[string]*watch // Map of inotify watches (key: path)
|
||
|
|
paths map[int]string // Map of watched paths (key: watch descriptor)
|
||
|
|
done chan struct{} // Channel for sending a "quit message" to the reader goroutine
|
||
|
|
doneResp chan struct{} // Channel to respond to Close
|
||
|
|
}
|
||
|
|
|
||
|
|
// NewWatcher establishes a new watcher with the underlying OS and begins waiting for events.
|
||
|
|
func NewWatcher() (*Watcher, error) {
|
||
|
|
// Create inotify fd
|
||
|
|
fd, errno := syscall.InotifyInit()
|
||
|
|
if fd == -1 {
|
||
|
|
return nil, errno
|
||
|
|
}
|
||
|
|
// Create epoll
|
||
|
|
poller, err := newFdPoller(fd)
|
||
|
|
if err != nil {
|
||
|
|
syscall.Close(fd)
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
w := &Watcher{
|
||
|
|
fd: fd,
|
||
|
|
poller: poller,
|
||
|
|
watches: make(map[string]*watch),
|
||
|
|
paths: make(map[int]string),
|
||
|
|
Events: make(chan Event),
|
||
|
|
Errors: make(chan error),
|
||
|
|
done: make(chan struct{}),
|
||
|
|
doneResp: make(chan struct{}),
|
||
|
|
}
|
||
|
|
|
||
|
|
go w.readEvents()
|
||
|
|
return w, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func (w *Watcher) isClosed() bool {
|
||
|
|
select {
|
||
|
|
case <-w.done:
|
||
|
|
return true
|
||
|
|
default:
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Close removes all watches and closes the events channel.
|
||
|
|
func (w *Watcher) Close() error {
|
||
|
|
if w.isClosed() {
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Send 'close' signal to goroutine, and set the Watcher to closed.
|
||
|
|
close(w.done)
|
||
|
|
|
||
|
|
// Wake up goroutine
|
||
|
|
w.poller.wake()
|
||
|
|
|
||
|
|
// Wait for goroutine to close
|
||
|
|
<-w.doneResp
|
||
|
|
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Add starts watching the named file or directory (non-recursively).
|
||
|
|
func (w *Watcher) Add(name string) error {
|
||
|
|
name = filepath.Clean(name)
|
||
|
|
if w.isClosed() {
|
||
|
|
return errors.New("inotify instance already closed")
|
||
|
|
}
|
||
|
|
|
||
|
|
const agnosticEvents = syscall.IN_MOVED_TO | syscall.IN_MOVED_FROM |
|
||
|
|
syscall.IN_CREATE | syscall.IN_ATTRIB | syscall.IN_MODIFY |
|
||
|
|
syscall.IN_MOVE_SELF | syscall.IN_DELETE | syscall.IN_DELETE_SELF
|
||
|
|
|
||
|
|
var flags uint32 = agnosticEvents
|
||
|
|
|
||
|
|
w.mu.Lock()
|
||
|
|
watchEntry, found := w.watches[name]
|
||
|
|
w.mu.Unlock()
|
||
|
|
if found {
|
||
|
|
watchEntry.flags |= flags
|
||
|
|
flags |= syscall.IN_MASK_ADD
|
||
|
|
}
|
||
|
|
wd, errno := syscall.InotifyAddWatch(w.fd, name, flags)
|
||
|
|
if wd == -1 {
|
||
|
|
return errno
|
||
|
|
}
|
||
|
|
|
||
|
|
w.mu.Lock()
|
||
|
|
w.watches[name] = &watch{wd: uint32(wd), flags: flags}
|
||
|
|
w.paths[wd] = name
|
||
|
|
w.mu.Unlock()
|
||
|
|
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Remove stops watching the named file or directory (non-recursively).
|
||
|
|
func (w *Watcher) Remove(name string) error {
|
||
|
|
name = filepath.Clean(name)
|
||
|
|
|
||
|
|
// Fetch the watch.
|
||
|
|
w.mu.Lock()
|
||
|
|
defer w.mu.Unlock()
|
||
|
|
watch, ok := w.watches[name]
|
||
|
|
|
||
|
|
// Remove it from inotify.
|
||
|
|
if !ok {
|
||
|
|
return fmt.Errorf("can't remove non-existent inotify watch for: %s", name)
|
||
|
|
}
|
||
|
|
// inotify_rm_watch will return EINVAL if the file has been deleted;
|
||
|
|
// the inotify will already have been removed.
|
||
|
|
// That means we can safely delete it from our watches, whatever inotify_rm_watch does.
|
||
|
|
delete(w.watches, name)
|
||
|
|
success, errno := syscall.InotifyRmWatch(w.fd, watch.wd)
|
||
|
|
if success == -1 {
|
||
|
|
// TODO: Perhaps it's not helpful to return an error here in every case.
|
||
|
|
// the only two possible errors are:
|
||
|
|
// EBADF, which happens when w.fd is not a valid file descriptor of any kind.
|
||
|
|
// EINVAL, which is when fd is not an inotify descriptor or wd is not a valid watch descriptor.
|
||
|
|
// Watch descriptors are invalidated when they are removed explicitly or implicitly;
|
||
|
|
// explicitly by inotify_rm_watch, implicitly when the file they are watching is deleted.
|
||
|
|
return errno
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
type watch struct {
|
||
|
|
wd uint32 // Watch descriptor (as returned by the inotify_add_watch() syscall)
|
||
|
|
flags uint32 // inotify flags of this watch (see inotify(7) for the list of valid flags)
|
||
|
|
}
|
||
|
|
|
||
|
|
// readEvents reads from the inotify file descriptor, converts the
|
||
|
|
// received events into Event objects and sends them via the Events channel
|
||
|
|
func (w *Watcher) readEvents() {
|
||
|
|
var (
|
||
|
|
buf [syscall.SizeofInotifyEvent * 4096]byte // Buffer for a maximum of 4096 raw events
|
||
|
|
n int // Number of bytes read with read()
|
||
|
|
errno error // Syscall errno
|
||
|
|
ok bool // For poller.wait
|
||
|
|
)
|
||
|
|
|
||
|
|
defer close(w.doneResp)
|
||
|
|
defer close(w.Errors)
|
||
|
|
defer close(w.Events)
|
||
|
|
defer syscall.Close(w.fd)
|
||
|
|
defer w.poller.close()
|
||
|
|
|
||
|
|
for {
|
||
|
|
// See if we have been closed.
|
||
|
|
if w.isClosed() {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
ok, errno = w.poller.wait()
|
||
|
|
if errno != nil {
|
||
|
|
select {
|
||
|
|
case w.Errors <- errno:
|
||
|
|
case <-w.done:
|
||
|
|
return
|
||
|
|
}
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
|
||
|
|
if !ok {
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
|
||
|
|
n, errno = syscall.Read(w.fd, buf[:])
|
||
|
|
// If a signal interrupted execution, see if we've been asked to close, and try again.
|
||
|
|
// http://man7.org/linux/man-pages/man7/signal.7.html :
|
||
|
|
// "Before Linux 3.8, reads from an inotify(7) file descriptor were not restartable"
|
||
|
|
if errno == syscall.EINTR {
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
|
||
|
|
// syscall.Read might have been woken up by Close. If so, we're done.
|
||
|
|
if w.isClosed() {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
if n < syscall.SizeofInotifyEvent {
|
||
|
|
var err error
|
||
|
|
if n == 0 {
|
||
|
|
// If EOF is received. This should really never happen.
|
||
|
|
err = io.EOF
|
||
|
|
} else if n < 0 {
|
||
|
|
// If an error occured while reading.
|
||
|
|
err = errno
|
||
|
|
} else {
|
||
|
|
// Read was too short.
|
||
|
|
err = errors.New("notify: short read in readEvents()")
|
||
|
|
}
|
||
|
|
select {
|
||
|
|
case w.Errors <- err:
|
||
|
|
case <-w.done:
|
||
|
|
return
|
||
|
|
}
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
|
||
|
|
var offset uint32
|
||
|
|
// We don't know how many events we just read into the buffer
|
||
|
|
// While the offset points to at least one whole event...
|
||
|
|
for offset <= uint32(n-syscall.SizeofInotifyEvent) {
|
||
|
|
// Point "raw" to the event in the buffer
|
||
|
|
raw := (*syscall.InotifyEvent)(unsafe.Pointer(&buf[offset]))
|
||
|
|
|
||
|
|
mask := uint32(raw.Mask)
|
||
|
|
nameLen := uint32(raw.Len)
|
||
|
|
// If the event happened to the watched directory or the watched file, the kernel
|
||
|
|
// doesn't append the filename to the event, but we would like to always fill the
|
||
|
|
// the "Name" field with a valid filename. We retrieve the path of the watch from
|
||
|
|
// the "paths" map.
|
||
|
|
w.mu.Lock()
|
||
|
|
name := w.paths[int(raw.Wd)]
|
||
|
|
w.mu.Unlock()
|
||
|
|
if nameLen > 0 {
|
||
|
|
// Point "bytes" at the first byte of the filename
|
||
|
|
bytes := (*[syscall.PathMax]byte)(unsafe.Pointer(&buf[offset+syscall.SizeofInotifyEvent]))
|
||
|
|
// The filename is padded with NULL bytes. TrimRight() gets rid of those.
|
||
|
|
name += "/" + strings.TrimRight(string(bytes[0:nameLen]), "\000")
|
||
|
|
}
|
||
|
|
|
||
|
|
event := newEvent(name, mask)
|
||
|
|
|
||
|
|
// Send the events that are not ignored on the events channel
|
||
|
|
if !event.ignoreLinux(mask) {
|
||
|
|
select {
|
||
|
|
case w.Events <- event:
|
||
|
|
case <-w.done:
|
||
|
|
return
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Move to the next event in the buffer
|
||
|
|
offset += syscall.SizeofInotifyEvent + nameLen
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Certain types of events can be "ignored" and not sent over the Events
|
||
|
|
// channel. Such as events marked ignore by the kernel, or MODIFY events
|
||
|
|
// against files that do not exist.
|
||
|
|
func (e *Event) ignoreLinux(mask uint32) bool {
|
||
|
|
// Ignore anything the inotify API says to ignore
|
||
|
|
if mask&syscall.IN_IGNORED == syscall.IN_IGNORED {
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
|
||
|
|
// If the event is not a DELETE or RENAME, the file must exist.
|
||
|
|
// Otherwise the event is ignored.
|
||
|
|
// *Note*: this was put in place because it was seen that a MODIFY
|
||
|
|
// event was sent after the DELETE. This ignores that MODIFY and
|
||
|
|
// assumes a DELETE will come or has come if the file doesn't exist.
|
||
|
|
if !(e.Op&Remove == Remove || e.Op&Rename == Rename) {
|
||
|
|
_, statErr := os.Lstat(e.Name)
|
||
|
|
return os.IsNotExist(statErr)
|
||
|
|
}
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
|
||
|
|
// newEvent returns an platform-independent Event based on an inotify mask.
|
||
|
|
func newEvent(name string, mask uint32) Event {
|
||
|
|
e := Event{Name: name}
|
||
|
|
if mask&syscall.IN_CREATE == syscall.IN_CREATE || mask&syscall.IN_MOVED_TO == syscall.IN_MOVED_TO {
|
||
|
|
e.Op |= Create
|
||
|
|
}
|
||
|
|
if mask&syscall.IN_DELETE_SELF == syscall.IN_DELETE_SELF || mask&syscall.IN_DELETE == syscall.IN_DELETE {
|
||
|
|
e.Op |= Remove
|
||
|
|
}
|
||
|
|
if mask&syscall.IN_MODIFY == syscall.IN_MODIFY {
|
||
|
|
e.Op |= Write
|
||
|
|
}
|
||
|
|
if mask&syscall.IN_MOVE_SELF == syscall.IN_MOVE_SELF || mask&syscall.IN_MOVED_FROM == syscall.IN_MOVED_FROM {
|
||
|
|
e.Op |= Rename
|
||
|
|
}
|
||
|
|
if mask&syscall.IN_ATTRIB == syscall.IN_ATTRIB {
|
||
|
|
e.Op |= Chmod
|
||
|
|
}
|
||
|
|
return e
|
||
|
|
}
|