github.com/checksum/notify@v0.0.0-20190119234841-59aa2d88664f/watcher_kqueue.go (about) 1 // Copyright (c) 2014-2015 The Notify Authors. All rights reserved. 2 // Use of this source code is governed by the MIT license that can be 3 // found in the LICENSE file. 4 5 // +build darwin,kqueue dragonfly freebsd netbsd openbsd 6 7 package notify 8 9 import ( 10 "fmt" 11 "os" 12 "syscall" 13 ) 14 15 // newTrigger returns implementation of trigger. 16 func newTrigger(pthLkp map[string]*watched) trigger { 17 return &kq{ 18 pthLkp: pthLkp, 19 idLkp: make(map[int]*watched), 20 } 21 } 22 23 // kq is a structure implementing trigger for kqueue. 24 type kq struct { 25 // fd is a kqueue file descriptor 26 fd int 27 // pipefds are file descriptors used to stop `Kevent` call. 28 pipefds [2]int 29 // idLkp is a data structure mapping file descriptors with data about watching 30 // represented by them files/directories. 31 idLkp map[int]*watched 32 // pthLkp is a structure mapping monitored files/dir with data about them, 33 // shared with parent trg structure 34 pthLkp map[string]*watched 35 } 36 37 // watched is a data structure representing watched file/directory. 38 type watched struct { 39 trgWatched 40 // fd is a file descriptor for watched file/directory. 41 fd int 42 } 43 44 // Stop implements trigger. 45 func (k *kq) Stop() (err error) { 46 // trigger event used to interrupt Kevent call. 47 _, err = syscall.Write(k.pipefds[1], []byte{0x00}) 48 return 49 } 50 51 // Close implements trigger. 52 func (k *kq) Close() error { 53 return syscall.Close(k.fd) 54 } 55 56 // NewWatched implements trigger. 57 func (*kq) NewWatched(p string, fi os.FileInfo) (*watched, error) { 58 fd, err := syscall.Open(p, syscall.O_NONBLOCK|syscall.O_RDONLY, 0) 59 if err != nil { 60 return nil, err 61 } 62 return &watched{ 63 trgWatched: trgWatched{p: p, fi: fi}, 64 fd: fd, 65 }, nil 66 } 67 68 // Record implements trigger. 69 func (k *kq) Record(w *watched) { 70 k.idLkp[w.fd], k.pthLkp[w.p] = w, w 71 } 72 73 // Del implements trigger. 74 func (k *kq) Del(w *watched) { 75 syscall.Close(w.fd) 76 delete(k.idLkp, w.fd) 77 delete(k.pthLkp, w.p) 78 } 79 80 func inter2kq(n interface{}) syscall.Kevent_t { 81 kq, ok := n.(syscall.Kevent_t) 82 if !ok { 83 panic(fmt.Sprintf("kqueue: type should be Kevent_t, %T instead", n)) 84 } 85 return kq 86 } 87 88 // Init implements trigger. 89 func (k *kq) Init() (err error) { 90 if k.fd, err = syscall.Kqueue(); err != nil { 91 return 92 } 93 // Creates pipe used to stop `Kevent` call by registering it, 94 // watching read end and writing to other end of it. 95 if err = syscall.Pipe(k.pipefds[:]); err != nil { 96 return nonil(err, k.Close()) 97 } 98 var kevn [1]syscall.Kevent_t 99 syscall.SetKevent(&kevn[0], k.pipefds[0], syscall.EVFILT_READ, syscall.EV_ADD) 100 if _, err = syscall.Kevent(k.fd, kevn[:], nil, nil); err != nil { 101 return nonil(err, k.Close()) 102 } 103 return 104 } 105 106 // Unwatch implements trigger. 107 func (k *kq) Unwatch(w *watched) (err error) { 108 var kevn [1]syscall.Kevent_t 109 syscall.SetKevent(&kevn[0], w.fd, syscall.EVFILT_VNODE, syscall.EV_DELETE) 110 111 _, err = syscall.Kevent(k.fd, kevn[:], nil, nil) 112 return 113 } 114 115 // Watch implements trigger. 116 func (k *kq) Watch(fi os.FileInfo, w *watched, e int64) (err error) { 117 var kevn [1]syscall.Kevent_t 118 syscall.SetKevent(&kevn[0], w.fd, syscall.EVFILT_VNODE, 119 syscall.EV_ADD|syscall.EV_CLEAR) 120 kevn[0].Fflags = uint32(e) 121 122 _, err = syscall.Kevent(k.fd, kevn[:], nil, nil) 123 return 124 } 125 126 // Wait implements trigger. 127 func (k *kq) Wait() (interface{}, error) { 128 var ( 129 kevn [1]syscall.Kevent_t 130 err error 131 ) 132 kevn[0] = syscall.Kevent_t{} 133 _, err = syscall.Kevent(k.fd, nil, kevn[:], nil) 134 135 return kevn[0], err 136 } 137 138 // Watched implements trigger. 139 func (k *kq) Watched(n interface{}) (*watched, int64, error) { 140 kevn, ok := n.(syscall.Kevent_t) 141 if !ok { 142 panic(fmt.Sprintf("kq: type should be syscall.Kevent_t, %T instead", kevn)) 143 } 144 if _, ok = k.idLkp[int(kevn.Ident)]; !ok { 145 return nil, 0, errNotWatched 146 } 147 return k.idLkp[int(kevn.Ident)], int64(kevn.Fflags), nil 148 } 149 150 // IsStop implements trigger. 151 func (k *kq) IsStop(n interface{}, err error) bool { 152 return int(inter2kq(n).Ident) == k.pipefds[0] 153 } 154 155 func init() { 156 encode = func(e Event, dir bool) (o int64) { 157 // Create event is not supported by kqueue. Instead NoteWrite event will 158 // be registered for a directory. If this event will be reported on dir 159 // which is to be monitored for Create, dir will be rescanned 160 // and Create events will be generated and returned for new files. 161 // In case of files, if not requested NoteRename event is reported, 162 // it will be ignored. 163 o = int64(e &^ Create) 164 if (e&Create != 0 && dir) || e&Write != 0 { 165 o = (o &^ int64(Write)) | int64(NoteWrite) 166 } 167 if e&Rename != 0 { 168 o = (o &^ int64(Rename)) | int64(NoteRename) 169 } 170 if e&Remove != 0 { 171 o = (o &^ int64(Remove)) | int64(NoteDelete) 172 } 173 return 174 } 175 nat2not = map[Event]Event{ 176 NoteWrite: Write, 177 NoteRename: Rename, 178 NoteDelete: Remove, 179 NoteExtend: Event(0), 180 NoteAttrib: Event(0), 181 NoteRevoke: Event(0), 182 NoteLink: Event(0), 183 } 184 not2nat = map[Event]Event{ 185 Write: NoteWrite, 186 Rename: NoteRename, 187 Remove: NoteDelete, 188 } 189 }