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fsnotify.go
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fsnotify.go
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// Package fsnotify provides a cross-platform interface for file system
// notifications.
//
// Currently supported systems:
//
// Linux 2.6.32+ via inotify
// BSD, macOS via kqueue
// Windows via ReadDirectoryChangesW
// illumos via FEN
package fsnotify
import (
"errors"
"fmt"
"path/filepath"
"strings"
)
// Event represents a file system notification.
type Event struct {
// Path to the file or directory.
//
// Paths are relative to the input; for example with Add("dir") the Name
// will be set to "dir/file" if you create that file, but if you use
// Add("/path/to/dir") it will be "/path/to/dir/file".
Name string
// File operation that triggered the event.
//
// This is a bitmask and some systems may send multiple operations at once.
// Use the Event.Has() method instead of comparing with ==.
Op Op
}
// Op describes a set of file operations.
type Op uint32
// The operations fsnotify can trigger; see the documentation on [Watcher] for a
// full description, and check them with [Event.Has].
const (
// A new pathname was created.
Create Op = 1 << iota
// The pathname was written to; this does *not* mean the write has finished,
// and a write can be followed by more writes.
Write
// The path was removed; any watches on it will be removed. Some "remove"
// operations may trigger a Rename if the file is actually moved (for
// example "remove to trash" is often a rename).
Remove
// The path was renamed to something else; any watched on it will be
// removed.
Rename
// File attributes were changed.
//
// It's generally not recommended to take action on this event, as it may
// get triggered very frequently by some software. For example, Spotlight
// indexing on macOS, anti-virus software, backup software, etc.
Chmod
)
// Common errors that can be reported.
var (
ErrNonExistentWatch = errors.New("fsnotify: can't remove non-existent watch")
ErrEventOverflow = errors.New("fsnotify: queue or buffer overflow")
ErrClosed = errors.New("fsnotify: watcher already closed")
)
func (o Op) String() string {
var b strings.Builder
if o.Has(Create) {
b.WriteString("|CREATE")
}
if o.Has(Remove) {
b.WriteString("|REMOVE")
}
if o.Has(Write) {
b.WriteString("|WRITE")
}
if o.Has(Rename) {
b.WriteString("|RENAME")
}
if o.Has(Chmod) {
b.WriteString("|CHMOD")
}
if b.Len() == 0 {
return "[no events]"
}
return b.String()[1:]
}
// Has reports if this operation has the given operation.
func (o Op) Has(h Op) bool { return o&h == h }
// Has reports if this event has the given operation.
func (e Event) Has(op Op) bool { return e.Op.Has(op) }
// String returns a string representation of the event with their path.
func (e Event) String() string {
return fmt.Sprintf("%-13s %q", e.Op.String(), e.Name)
}
type (
addOpt func(opt *withOpts)
withOpts struct {
bufsize int
}
)
var defaultOpts = withOpts{
bufsize: 65536, // 64K
}
func getOptions(opts ...addOpt) withOpts {
with := defaultOpts
for _, o := range opts {
o(&with)
}
return with
}
// WithBufferSize sets the buffer size for the Windows backend. This is a no-op
// for other backends.
//
// The default value is 64K (65536 bytes) which is the highest value that works
// on all filesystems and should be enough for most applications, but if you
// have a large burst of events it may not be enough. You can increase it if
// you're hitting "queue or buffer overflow" errors ([ErrEventOverflow]).
func WithBufferSize(bytes int) addOpt {
return func(opt *withOpts) { opt.bufsize = bytes }
}
// Check if this path is recursive (ends with "/..." or "\..."), and return the
// path with the /... stripped.
func recursivePath(path string) (string, bool) {
if filepath.Base(path) == "..." {
return filepath.Dir(path), true
}
return path, false
}