--- /dev/null
+// 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.
+
+/*
+This package implements a wrapper for the Linux inotify system.
+
+Example:
+ watcher, err := inotify.NewWatcher()
+ if err != nil {
+ log.Exit(err)
+ }
+ err = watcher.Watch("/tmp")
+ if err != nil {
+ log.Exit(err)
+ }
+ for {
+ select {
+ case ev := <-watcher.Event:
+ log.Println("event:", ev)
+ case err := <-watcher.Error:
+ log.Println("error:", err)
+ }
+ }
+
+*/
+package inotify
+
+import (
+ "fmt"
+ "os"
+ "strings"
+ "syscall"
+ "unsafe"
+)
+
+
+type Event struct {
+ Mask uint32 // Mask of events
+ Cookie uint32 // Unique cookie associating related events (for rename(2))
+ Name string // File name (optional)
+}
+
+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)
+}
+
+type Watcher struct {
+ 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)
+ Error chan os.Error // Errors are sent on this channel
+ Event chan *Event // Events are returned on this channel
+ done chan bool // Channel for sending a "quit message" to the reader goroutine
+ isClosed bool // Set to true when Close() is first called
+}
+
+
+// NewWatcher creates and returns a new inotify instance using inotify_init(2)
+func NewWatcher() (*Watcher, os.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),
+ Event: make(chan *Event),
+ Error: make(chan os.Error),
+ done: make(chan bool, 1),
+ }
+
+ go w.readEvents()
+ return w, nil
+}
+
+
+// Close closes an inotify watcher instance
+// It sends a message to the reader goroutine to quit and removes all watches
+// associated with the inotify instance
+func (w *Watcher) Close() os.Error {
+ if w.isClosed {
+ return nil
+ }
+ w.isClosed = true
+
+ // Send "quit" message to the reader goroutine
+ w.done <- true
+ for path, _ := range w.watches {
+ w.RemoveWatch(path)
+ }
+
+ return nil
+}
+
+// AddWatch adds path to the watched file set.
+// The flags are interpreted as described in inotify_add_watch(2).
+func (w *Watcher) AddWatch(path string, flags uint32) os.Error {
+ if w.isClosed {
+ return os.NewError("inotify instance already closed")
+ }
+
+ watchEntry, found := w.watches[path]
+ if found {
+ watchEntry.flags |= flags
+ flags |= syscall.IN_MASK_ADD
+ }
+ wd, errno := syscall.InotifyAddWatch(w.fd, path, flags)
+ if wd == -1 {
+ return os.NewSyscallError("inotify_add_watch", errno)
+ }
+
+ if !found {
+ w.watches[path] = &watch{wd: uint32(wd), flags: flags}
+ w.paths[wd] = path
+ }
+ return nil
+}
+
+
+// Watch adds path to the watched file set, watching all events.
+func (w *Watcher) Watch(path string) os.Error {
+ return w.AddWatch(path, IN_ALL_EVENTS)
+}
+
+
+// RemoveWatch removes path from the watched file set.
+func (w *Watcher) RemoveWatch(path string) os.Error {
+ watch, ok := w.watches[path]
+ if !ok {
+ return os.NewError(fmt.Sprintf("can't remove non-existent inotify watch for: %s", path))
+ }
+ success, errno := syscall.InotifyRmWatch(w.fd, watch.wd)
+ if success == -1 {
+ return os.NewSyscallError("inotify_rm_watch", errno)
+ }
+ w.watches[path] = nil, false
+ return nil
+}
+
+
+// readEvents reads from the inotify file descriptor, converts the
+// received events into Event objects and sends them via the Event 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 int // Syscall errno
+ )
+
+ for {
+ n, errno = syscall.Read(w.fd, buf[0:])
+ // See if there is a message on the "done" channel
+ _, done := <-w.done
+
+ // If EOF or a "done" message is received
+ if n == 0 || done {
+ errno := syscall.Close(w.fd)
+ if errno == -1 {
+ w.Error <- os.NewSyscallError("close", errno)
+ }
+ close(w.Event)
+ close(w.Error)
+ return
+ }
+ if n < 0 {
+ w.Error <- os.NewSyscallError("read", errno)
+ continue
+ }
+ if n < syscall.SizeofInotifyEvent {
+ w.Error <- os.NewError("inotify: short read in readEvents()")
+ continue
+ }
+
+ var offset uint32 = 0
+ // 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]))
+ event := new(Event)
+ event.Mask = uint32(raw.Mask)
+ event.Cookie = uint32(raw.Cookie)
+ 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.
+ event.Name = w.paths[int(raw.Wd)]
+ 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 NUL bytes. TrimRight() gets rid of those.
+ event.Name += "/" + strings.TrimRight(string(bytes[0:nameLen]), "\000")
+ }
+ // Send the event on the events channel
+ w.Event <- event
+
+ // Move to the next event in the buffer
+ offset += syscall.SizeofInotifyEvent + nameLen
+ }
+ }
+}
+
+
+// String formats the event e in the form
+// "filename: 0xEventMask = IN_ACCESS|IN_ATTRIB_|..."
+func (e *Event) String() string {
+ var events string = ""
+
+ m := e.Mask
+ for _, b := range eventBits {
+ if m&b.Value != 0 {
+ m &^= b.Value
+ events += "|" + b.Name
+ }
+ }
+
+ if m != 0 {
+ events += fmt.Sprintf("|%#x", m)
+ }
+ if len(events) > 0 {
+ events = " == " + events[1:]
+ }
+
+ return fmt.Sprintf("%q: %#x%s", e.Name, e.Mask, events)
+}
+
+const (
+ // Options for inotify_init() are not exported
+ // IN_CLOEXEC uint32 = syscall.IN_CLOEXEC
+ // IN_NONBLOCK uint32 = syscall.IN_NONBLOCK
+
+ // Options for AddWatch
+ IN_DONT_FOLLOW uint32 = syscall.IN_DONT_FOLLOW
+ IN_ONESHOT uint32 = syscall.IN_ONESHOT
+ IN_ONLYDIR uint32 = syscall.IN_ONLYDIR
+
+ // The "IN_MASK_ADD" option is not exported, as AddWatch
+ // adds it automatically, if there is already a watch for the given path
+ // IN_MASK_ADD uint32 = syscall.IN_MASK_ADD
+
+ // Events
+ IN_ACCESS uint32 = syscall.IN_ACCESS
+ IN_ALL_EVENTS uint32 = syscall.IN_ALL_EVENTS
+ IN_ATTRIB uint32 = syscall.IN_ATTRIB
+ IN_CLOSE uint32 = syscall.IN_CLOSE
+ IN_CLOSE_NOWRITE uint32 = syscall.IN_CLOSE_NOWRITE
+ IN_CLOSE_WRITE uint32 = syscall.IN_CLOSE_WRITE
+ IN_CREATE uint32 = syscall.IN_CREATE
+ IN_DELETE uint32 = syscall.IN_DELETE
+ IN_DELETE_SELF uint32 = syscall.IN_DELETE_SELF
+ IN_MODIFY uint32 = syscall.IN_MODIFY
+ IN_MOVE uint32 = syscall.IN_MOVE
+ IN_MOVED_FROM uint32 = syscall.IN_MOVED_FROM
+ IN_MOVED_TO uint32 = syscall.IN_MOVED_TO
+ IN_MOVE_SELF uint32 = syscall.IN_MOVE_SELF
+ IN_OPEN uint32 = syscall.IN_OPEN
+
+ // Special events
+ IN_ISDIR uint32 = syscall.IN_ISDIR
+ IN_IGNORED uint32 = syscall.IN_IGNORED
+ IN_Q_OVERFLOW uint32 = syscall.IN_Q_OVERFLOW
+ IN_UNMOUNT uint32 = syscall.IN_UNMOUNT
+)
+
+var eventBits = []struct {
+ Value uint32
+ Name string
+}{
+ {IN_ACCESS, "IN_ACCESS"},
+ {IN_ATTRIB, "IN_ATTRIB"},
+ {IN_CLOSE, "IN_CLOSE"},
+ {IN_CLOSE_NOWRITE, "IN_CLOSE_NOWRITE"},
+ {IN_CLOSE_WRITE, "IN_CLOSE_WRITE"},
+ {IN_CREATE, "IN_CREATE"},
+ {IN_DELETE, "IN_DELETE"},
+ {IN_DELETE_SELF, "IN_DELETE_SELF"},
+ {IN_MODIFY, "IN_MODIFY"},
+ {IN_MOVE, "IN_MOVE"},
+ {IN_MOVED_FROM, "IN_MOVED_FROM"},
+ {IN_MOVED_TO, "IN_MOVED_TO"},
+ {IN_MOVE_SELF, "IN_MOVE_SELF"},
+ {IN_OPEN, "IN_OPEN"},
+ {IN_ISDIR, "IN_ISDIR"},
+ {IN_IGNORED, "IN_IGNORED"},
+ {IN_Q_OVERFLOW, "IN_Q_OVERFLOW"},
+ {IN_UNMOUNT, "IN_UNMOUNT"},
+}
--- /dev/null
+// 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.
+
+package inotify
+
+import (
+ "os"
+ "time"
+ "testing"
+)
+
+func TestInotifyEvents(t *testing.T) {
+ // Create an inotify watcher instance and initialize it
+ watcher, err := NewWatcher()
+ if err != nil {
+ t.Fatalf("NewWatcher() failed: %s", err)
+ }
+
+ // Add a watch for "_obj"
+ err = watcher.Watch("_obj")
+ if err != nil {
+ t.Fatalf("Watcher.Watch() failed: %s", err)
+ }
+
+ // Receive errors on the error channel on a separate goroutine
+ go func() {
+ for err := range watcher.Error {
+ t.Fatalf("error received: %s", err)
+ }
+ }()
+
+ const testFile string = "_obj/TestInotifyEvents.testfile"
+
+ // Receive events on the event channel on a separate goroutine
+ eventstream := watcher.Event
+ var eventsReceived = 0
+ go func() {
+ for event := range eventstream {
+ // Only count relevant events
+ if event.Name == testFile {
+ eventsReceived++
+ t.Logf("event received: %s", event)
+ } else {
+ t.Logf("unexpected event received: %s", event)
+ }
+ }
+ }()
+
+ // Create a file
+ // This should add at least one event to the inotify event queue
+ _, err = os.Open(testFile, os.O_WRONLY|os.O_CREAT, 0666)
+ if err != nil {
+ t.Fatalf("creating test file failed: %s", err)
+ }
+
+ // We expect this event to be received almost immediately, but let's wait 1 s to be sure
+ time.Sleep(1000e6) // 1000 ms
+ if eventsReceived == 0 {
+ t.Fatal("inotify event hasn't been received after 1 second")
+ }
+
+ // Try closing the inotify instance
+ t.Log("calling Close()")
+ watcher.Close()
+ t.Log("waiting for the event channel to become closed...")
+ var i = 0
+ for !closed(eventstream) {
+ if i >= 20 {
+ t.Fatal("event stream was not closed after 1 second, as expected")
+ }
+ t.Log("waiting for 50 ms...")
+ time.Sleep(50e6) // 50 ms
+ i++
+ }
+ t.Log("event channel closed")
+}
+
+
+func TestInotifyClose(t *testing.T) {
+ watcher, _ := NewWatcher()
+ watcher.Close()
+
+ done := false
+ go func() {
+ watcher.Close()
+ done = true
+ }()
+
+ time.Sleep(50e6) // 50 ms
+ if !done {
+ t.Fatal("double Close() test failed: second Close() call didn't return")
+ }
+
+ err := watcher.Watch("_obj")
+ if err == nil {
+ t.Fatal("expected error on Watch() after Close(), got nil")
+ }
+}