From a031b83a09a8628435317a03f199cdc18b78262f Mon Sep 17 00:00:00 2001 From: Matthew Heon Date: Wed, 1 Nov 2017 11:24:59 -0400 Subject: Initial checkin from CRI-O repo Signed-off-by: Matthew Heon --- vendor/gopkg.in/fsnotify.v1/inotify.go | 325 +++++++++++++++++++++++++++++++++ 1 file changed, 325 insertions(+) create mode 100644 vendor/gopkg.in/fsnotify.v1/inotify.go (limited to 'vendor/gopkg.in/fsnotify.v1/inotify.go') diff --git a/vendor/gopkg.in/fsnotify.v1/inotify.go b/vendor/gopkg.in/fsnotify.v1/inotify.go new file mode 100644 index 000000000..f3b74c51f --- /dev/null +++ b/vendor/gopkg.in/fsnotify.v1/inotify.go @@ -0,0 +1,325 @@ +// 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" + "unsafe" + + "golang.org/x/sys/unix" +) + +// 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 + cv *sync.Cond // sync removing on rm_watch with IN_IGNORE + 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 := unix.InotifyInit1(unix.IN_CLOEXEC) + if fd == -1 { + return nil, errno + } + // Create epoll + poller, err := newFdPoller(fd) + if err != nil { + unix.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{}), + } + w.cv = sync.NewCond(&w.mu) + + 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 = unix.IN_MOVED_TO | unix.IN_MOVED_FROM | + unix.IN_CREATE | unix.IN_ATTRIB | unix.IN_MODIFY | + unix.IN_MOVE_SELF | unix.IN_DELETE | unix.IN_DELETE_SELF + + var flags uint32 = agnosticEvents + + w.mu.Lock() + watchEntry, found := w.watches[name] + w.mu.Unlock() + if found { + watchEntry.flags |= flags + flags |= unix.IN_MASK_ADD + } + wd, errno := unix.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. + // watches and pathes are deleted in ignoreLinux() implicitly and asynchronously + // by calling inotify_rm_watch() below. e.g. readEvents() goroutine receives IN_IGNORE + // so that EINVAL means that the wd is being rm_watch()ed or its file removed + // by another thread and we have not received IN_IGNORE event. + success, errno := unix.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 + } + + // wait until ignoreLinux() deleting maps + exists := true + for exists { + w.cv.Wait() + _, exists = 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 [unix.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 unix.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 = unix.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 == unix.EINTR { + continue + } + + // unix.Read might have been woken up by Close. If so, we're done. + if w.isClosed() { + return + } + + if n < unix.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 occurred 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-unix.SizeofInotifyEvent) { + // Point "raw" to the event in the buffer + raw := (*unix.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 := (*[unix.PathMax]byte)(unsafe.Pointer(&buf[offset+unix.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(w, raw.Wd, mask) { + select { + case w.Events <- event: + case <-w.done: + return + } + } + + // Move to the next event in the buffer + offset += unix.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(w *Watcher, wd int32, mask uint32) bool { + // Ignore anything the inotify API says to ignore + if mask&unix.IN_IGNORED == unix.IN_IGNORED { + w.mu.Lock() + defer w.mu.Unlock() + name := w.paths[int(wd)] + delete(w.paths, int(wd)) + delete(w.watches, name) + w.cv.Broadcast() + 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&unix.IN_CREATE == unix.IN_CREATE || mask&unix.IN_MOVED_TO == unix.IN_MOVED_TO { + e.Op |= Create + } + if mask&unix.IN_DELETE_SELF == unix.IN_DELETE_SELF || mask&unix.IN_DELETE == unix.IN_DELETE { + e.Op |= Remove + } + if mask&unix.IN_MODIFY == unix.IN_MODIFY { + e.Op |= Write + } + if mask&unix.IN_MOVE_SELF == unix.IN_MOVE_SELF || mask&unix.IN_MOVED_FROM == unix.IN_MOVED_FROM { + e.Op |= Rename + } + if mask&unix.IN_ATTRIB == unix.IN_ATTRIB { + e.Op |= Chmod + } + return e +} -- cgit v1.2.3-54-g00ecf