| // 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" |
| "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 // File descriptor (as returned by the inotify_init() syscall) |
| watches map[string]*watch // Map of inotify watches (key: path) |
| paths map[int]string // Map of watched paths (key: watch descriptor) |
| done chan bool // Channel for sending a "quit message" to the reader goroutine |
| isClosed bool // Set to true when Close() is first called |
| } |
| |
| // NewWatcher establishes a new watcher with the underlying OS and begins waiting for events. |
| func NewWatcher() (*Watcher, error) { |
| fd, errno := syscall.InotifyInit() |
| if fd == -1 { |
| return nil, os.NewSyscallError("inotify_init", errno) |
| } |
| w := &Watcher{ |
| fd: fd, |
| watches: make(map[string]*watch), |
| paths: make(map[int]string), |
| Events: make(chan Event), |
| Errors: make(chan error), |
| done: make(chan bool, 1), |
| } |
| |
| go w.readEvents() |
| return w, nil |
| } |
| |
| // Close removes all watches and closes the events channel. |
| func (w *Watcher) Close() error { |
| if w.isClosed { |
| return nil |
| } |
| w.isClosed = true |
| |
| // Remove all watches |
| for name := range w.watches { |
| w.Remove(name) |
| } |
| |
| // Send "quit" message to the reader goroutine |
| w.done <- true |
| |
| 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 os.NewSyscallError("inotify_add_watch", 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 the named file or directory (non-recursively). |
| func (w *Watcher) Remove(name string) error { |
| name = filepath.Clean(name) |
| w.mu.Lock() |
| defer w.mu.Unlock() |
| watch, ok := w.watches[name] |
| if !ok { |
| return fmt.Errorf("can't remove non-existent inotify watch for: %s", name) |
| } |
| success, errno := syscall.InotifyRmWatch(w.fd, watch.wd) |
| if success == -1 { |
| return os.NewSyscallError("inotify_rm_watch", errno) |
| } |
| delete(w.watches, name) |
| 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 |
| ) |
| |
| for { |
| // See if there is a message on the "done" channel |
| select { |
| case <-w.done: |
| syscall.Close(w.fd) |
| close(w.Events) |
| close(w.Errors) |
| return |
| default: |
| } |
| |
| n, errno = syscall.Read(w.fd, buf[:]) |
| |
| // If EOF is received |
| if n == 0 { |
| syscall.Close(w.fd) |
| close(w.Events) |
| close(w.Errors) |
| return |
| } |
| |
| if n < 0 { |
| w.Errors <- os.NewSyscallError("read", errno) |
| continue |
| } |
| if n < syscall.SizeofInotifyEvent { |
| w.Errors <- errors.New("inotify: short read in readEvents()") |
| 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) { |
| w.Events <- event |
| } |
| |
| // 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 |
| } |