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// 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 implements a wrapper for the Linux inotify system.
 
Example:
    watcher, err := inotify.NewWatcher()
    if err != nil {
        log.Fatal(err)
    }
    err = watcher.Watch("/tmp")
    if err != nil {
        log.Fatal(err)
    }
    for {
        select {
        case ev := <-watcher.Event:
            log.Println("event:", ev)
        case err := <-watcher.Error:
            log.Println("error:", err)
        }
    }
 
*/
package inotify
 
import (
        "errors"
        "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 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, 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 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() 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) error {
        if w.isClosed {
                return errors.New("inotify instance already closed")
        }
 
        watchEntry, found := w.watches[path]
        if found {
                watchEntry.flags |= flags
                flags |= syscall.IN_MASK_ADD
        }
        wd, err := syscall.InotifyAddWatch(w.fd, path, flags)
        if err != nil {
                return &os.PathError{
                        Op:   "inotify_add_watch",
                        Path: path,
                        Err:  err,
                }
        }
 
        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) error {
        return w.AddWatch(path, IN_ALL_EVENTS)
}
 
// RemoveWatch removes path from the watched file set.
func (w *Watcher) RemoveWatch(path string) error {
        watch, ok := w.watches[path]
        if !ok {
                return errors.New(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)
        }
        delete(w.watches, path)
        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
 
        for {
                n, err := syscall.Read(w.fd, buf[0:])
                // See if there is a message on the "done" channel
                var done bool
                select {
                case done = <-w.done:
                default:
                }
 
                // If EOF or a "done" message is received
                if n == 0 || done {
                        err := syscall.Close(w.fd)
                        if err != nil {
                                w.Error <- os.NewSyscallError("close", err)
                        }
                        close(w.Event)
                        close(w.Error)
                        return
                }
                if n < 0 {
                        w.Error <- os.NewSyscallError("read", err)
                        continue
                }
                if n < syscall.SizeofInotifyEvent {
                        w.Error <- errors.New("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"},
}

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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [exp/] [inotify/] [inotify_linux.go] - Blame information for rev 775

Line No.	Rev	Author	Line
1	747	jeremybenn	`// Copyright 2010 The Go Authors. All rights reserved.`
2			`// Use of this source code is governed by a BSD-style`
3			`// license that can be found in the LICENSE file.`
4
5			`/*`
6			`Package inotify implements a wrapper for the Linux inotify system.`
7
8			`Example:`
9			`watcher, err := inotify.NewWatcher()`
10			`if err != nil {`
11			`log.Fatal(err)`
12			`}`
13			`err = watcher.Watch("/tmp")`
14			`if err != nil {`
15			`log.Fatal(err)`
16			`}`
17			`for {`
18			`select {`
19			`case ev := <-watcher.Event:`
20			`log.Println("event:", ev)`
21			`case err := <-watcher.Error:`
22			`log.Println("error:", err)`
23			`}`
24			`}`
25
26			`*/`
27			`package inotify`
28
29			`import (`
30			`"errors"`
31			`"fmt"`
32			`"os"`
33			`"strings"`
34			`"syscall"`
35			`"unsafe"`
36			`)`
37
38			`type Event struct {`
39			`Mask uint32 // Mask of events`
40			`Cookie uint32 // Unique cookie associating related events (for rename(2))`
41			`Name string // File name (optional)`
42			`}`
43
44			`type watch struct {`
45			`wd uint32 // Watch descriptor (as returned by the inotify_add_watch() syscall)`
46			`flags uint32 // inotify flags of this watch (see inotify(7) for the list of valid flags)`
47			`}`
48
49			`type Watcher struct {`
50			`fd int // File descriptor (as returned by the inotify_init() syscall)`
51			`watches map[string]*watch // Map of inotify watches (key: path)`
52			`paths map[int]string // Map of watched paths (key: watch descriptor)`
53			`Error chan error // Errors are sent on this channel`
54			`Event chan *Event // Events are returned on this channel`
55			`done chan bool // Channel for sending a "quit message" to the reader goroutine`
56			`isClosed bool // Set to true when Close() is first called`
57			`}`
58
59			`// NewWatcher creates and returns a new inotify instance using inotify_init(2)`
60			`func NewWatcher() (*Watcher, error) {`
61			`fd, errno := syscall.InotifyInit()`
62			`if fd == -1 {`
63			`return nil, os.NewSyscallError("inotify_init", errno)`
64			`}`
65			`w := &Watcher{`
66			`fd: fd,`
67			`watches: make(map[string]*watch),`
68			`paths: make(map[int]string),`
69			`Event: make(chan *Event),`
70			`Error: make(chan error),`
71			`done: make(chan bool, 1),`
72			`}`
73
74			`go w.readEvents()`
75			`return w, nil`
76			`}`
77
78			`// Close closes an inotify watcher instance`
79			`// It sends a message to the reader goroutine to quit and removes all watches`
80			`// associated with the inotify instance`
81			`func (w *Watcher) Close() error {`
82			`if w.isClosed {`
83			`return nil`
84			`}`
85			`w.isClosed = true`
86
87			`// Send "quit" message to the reader goroutine`
88			`w.done <- true`
89			`for path := range w.watches {`
90			`w.RemoveWatch(path)`
91			`}`
92
93			`return nil`
94			`}`
95
96			`// AddWatch adds path to the watched file set.`
97			`// The flags are interpreted as described in inotify_add_watch(2).`
98			`func (w *Watcher) AddWatch(path string, flags uint32) error {`
99			`if w.isClosed {`
100			`return errors.New("inotify instance already closed")`
101			`}`
102
103			`watchEntry, found := w.watches[path]`
104			`if found {`
105			`watchEntry.flags \|= flags`
106			`flags \|= syscall.IN_MASK_ADD`
107			`}`
108			`wd, err := syscall.InotifyAddWatch(w.fd, path, flags)`
109			`if err != nil {`
110			`return &os.PathError{`
111			`Op: "inotify_add_watch",`
112			`Path: path,`
113			`Err: err,`
114			`}`
115			`}`
116
117			`if !found {`
118			`w.watches[path] = &watch{wd: uint32(wd), flags: flags}`
119			`w.paths[wd] = path`
120			`}`
121			`return nil`
122			`}`
123
124			`// Watch adds path to the watched file set, watching all events.`
125			`func (w *Watcher) Watch(path string) error {`
126			`return w.AddWatch(path, IN_ALL_EVENTS)`
127			`}`
128
129			`// RemoveWatch removes path from the watched file set.`
130			`func (w *Watcher) RemoveWatch(path string) error {`
131			`watch, ok := w.watches[path]`
132			`if !ok {`
133			`return errors.New(fmt.Sprintf("can't remove non-existent inotify watch for: %s", path))`
134			`}`
135			`success, errno := syscall.InotifyRmWatch(w.fd, watch.wd)`
136			`if success == -1 {`
137			`return os.NewSyscallError("inotify_rm_watch", errno)`
138			`}`
139			`delete(w.watches, path)`
140			`return nil`
141			`}`
142
143			`// readEvents reads from the inotify file descriptor, converts the`
144			`// received events into Event objects and sends them via the Event channel`
145			`func (w *Watcher) readEvents() {`
146			`var buf [syscall.SizeofInotifyEvent * 4096]byte`
147
148			`for {`
149			`n, err := syscall.Read(w.fd, buf[0:])`
150			`// See if there is a message on the "done" channel`
151			`var done bool`
152			`select {`
153			`case done = <-w.done:`
154			`default:`
155			`}`
156
157			`// If EOF or a "done" message is received`
158			`if n == 0 \|\| done {`
159			`err := syscall.Close(w.fd)`
160			`if err != nil {`
161			`w.Error <- os.NewSyscallError("close", err)`
162			`}`
163			`close(w.Event)`
164			`close(w.Error)`
165			`return`
166			`}`
167			`if n < 0 {`
168			`w.Error <- os.NewSyscallError("read", err)`
169			`continue`
170			`}`
171			`if n < syscall.SizeofInotifyEvent {`
172			`w.Error <- errors.New("inotify: short read in readEvents()")`
173			`continue`
174			`}`
175
176			`var offset uint32 = 0`
177			`// We don't know how many events we just read into the buffer`
178			`// While the offset points to at least one whole event...`
179			`for offset <= uint32(n-syscall.SizeofInotifyEvent) {`
180			`// Point "raw" to the event in the buffer`
181			`raw := (*syscall.InotifyEvent)(unsafe.Pointer(&buf[offset]))`
182			`event := new(Event)`
183			`event.Mask = uint32(raw.Mask)`
184			`event.Cookie = uint32(raw.Cookie)`
185			`nameLen := uint32(raw.Len)`
186			`// If the event happened to the watched directory or the watched file, the kernel`
187			`// doesn't append the filename to the event, but we would like to always fill the`
188			`// the "Name" field with a valid filename. We retrieve the path of the watch from`
189			`// the "paths" map.`
190			`event.Name = w.paths[int(raw.Wd)]`
191			`if nameLen > 0 {`
192			`// Point "bytes" at the first byte of the filename`
193			`bytes := (*[syscall.PathMax]byte)(unsafe.Pointer(&buf[offset+syscall.SizeofInotifyEvent]))`
194			`// The filename is padded with NUL bytes. TrimRight() gets rid of those.`
195			`event.Name += "/" + strings.TrimRight(string(bytes[0:nameLen]), "\000")`
196			`}`
197			`// Send the event on the events channel`
198			`w.Event <- event`
199
200			`// Move to the next event in the buffer`
201			`offset += syscall.SizeofInotifyEvent + nameLen`
202			`}`
203			`}`
204			`}`
205
206			`// String formats the event e in the form`
207			`// "filename: 0xEventMask = IN_ACCESS\|IN_ATTRIB_\|..."`
208			`func (e *Event) String() string {`
209			`var events string = ""`
210
211			`m := e.Mask`
212			`for _, b := range eventBits {`
213			`if m&b.Value != 0 {`
214			`m &^= b.Value`
215			`events += "\|" + b.Name`
216			`}`
217			`}`
218
219			`if m != 0 {`
220			`events += fmt.Sprintf("\|%#x", m)`
221			`}`
222			`if len(events) > 0 {`
223			`events = " == " + events[1:]`
224			`}`
225
226			`return fmt.Sprintf("%q: %#x%s", e.Name, e.Mask, events)`
227			`}`
228
229			`const (`
230			`// Options for inotify_init() are not exported`
231			`// IN_CLOEXEC uint32 = syscall.IN_CLOEXEC`
232			`// IN_NONBLOCK uint32 = syscall.IN_NONBLOCK`
233
234			`// Options for AddWatch`
235			`IN_DONT_FOLLOW uint32 = syscall.IN_DONT_FOLLOW`
236			`IN_ONESHOT uint32 = syscall.IN_ONESHOT`
237			`IN_ONLYDIR uint32 = syscall.IN_ONLYDIR`
238
239			`// The "IN_MASK_ADD" option is not exported, as AddWatch`
240			`// adds it automatically, if there is already a watch for the given path`
241			`// IN_MASK_ADD uint32 = syscall.IN_MASK_ADD`
242
243			`// Events`
244			`IN_ACCESS uint32 = syscall.IN_ACCESS`
245			`IN_ALL_EVENTS uint32 = syscall.IN_ALL_EVENTS`
246			`IN_ATTRIB uint32 = syscall.IN_ATTRIB`
247			`IN_CLOSE uint32 = syscall.IN_CLOSE`
248			`IN_CLOSE_NOWRITE uint32 = syscall.IN_CLOSE_NOWRITE`
249			`IN_CLOSE_WRITE uint32 = syscall.IN_CLOSE_WRITE`
250			`IN_CREATE uint32 = syscall.IN_CREATE`
251			`IN_DELETE uint32 = syscall.IN_DELETE`
252			`IN_DELETE_SELF uint32 = syscall.IN_DELETE_SELF`
253			`IN_MODIFY uint32 = syscall.IN_MODIFY`
254			`IN_MOVE uint32 = syscall.IN_MOVE`
255			`IN_MOVED_FROM uint32 = syscall.IN_MOVED_FROM`
256			`IN_MOVED_TO uint32 = syscall.IN_MOVED_TO`
257			`IN_MOVE_SELF uint32 = syscall.IN_MOVE_SELF`
258			`IN_OPEN uint32 = syscall.IN_OPEN`
259
260			`// Special events`
261			`IN_ISDIR uint32 = syscall.IN_ISDIR`
262			`IN_IGNORED uint32 = syscall.IN_IGNORED`
263			`IN_Q_OVERFLOW uint32 = syscall.IN_Q_OVERFLOW`
264			`IN_UNMOUNT uint32 = syscall.IN_UNMOUNT`
265			`)`
266
267			`var eventBits = []struct {`
268			`Value uint32`
269			`Name string`
270			`}{`
271			`{IN_ACCESS, "IN_ACCESS"},`
272			`{IN_ATTRIB, "IN_ATTRIB"},`
273			`{IN_CLOSE, "IN_CLOSE"},`
274			`{IN_CLOSE_NOWRITE, "IN_CLOSE_NOWRITE"},`
275			`{IN_CLOSE_WRITE, "IN_CLOSE_WRITE"},`
276			`{IN_CREATE, "IN_CREATE"},`
277			`{IN_DELETE, "IN_DELETE"},`
278			`{IN_DELETE_SELF, "IN_DELETE_SELF"},`
279			`{IN_MODIFY, "IN_MODIFY"},`
280			`{IN_MOVE, "IN_MOVE"},`
281			`{IN_MOVED_FROM, "IN_MOVED_FROM"},`
282			`{IN_MOVED_TO, "IN_MOVED_TO"},`
283			`{IN_MOVE_SELF, "IN_MOVE_SELF"},`
284			`{IN_OPEN, "IN_OPEN"},`
285			`{IN_ISDIR, "IN_ISDIR"},`
286			`{IN_IGNORED, "IN_IGNORED"},`
287			`{IN_Q_OVERFLOW, "IN_Q_OVERFLOW"},`
288			`{IN_UNMOUNT, "IN_UNMOUNT"},`
289			`}`