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Code Issues Releases Wiki Activity

Allow to set watcher to follow symlinks

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Signed-off-by: Knut Ahlers <knut@ahlers.me>
This commit is contained in:
Knut Ahlers 2023-03-19 01:42:30 +01:00
parent 98aacbd5ad
commit d67686d26f
Signed by: luzifer
GPG key ID: D91C3E91E4CAD6F5
3 changed files with 61 additions and 24 deletions
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69
file/watcher.go
View file

@ -2,6 +2,7 @@ package file
import (
"crypto/sha256"
"os"
"sync"
"time"
@ -18,10 +19,11 @@ type (
Err error
FilePath string
c chan WatcherEvent
checks []WatcherCheck
lock sync.RWMutex
stateCache map[string]any
c chan WatcherEvent
checks []WatcherCheck
followSymlinks bool
lock sync.RWMutex
stateCache map[string]any
}
// WatcherCheck is an interface to implement own checks
@ -30,6 +32,14 @@ type (
// WatcherEvent is the detected change to be signeld through the
// channel within the Watcher
WatcherEvent uint
// WatcherOpts holds configuration for newly created watcher
WatcherOpts struct {
// FollowSymlinks switches watchers based on file metadata into
// a mode where they follow a symlink and check the real target
// file instead of the symlink
FollowSymlinks bool
}
)
const (
@ -40,6 +50,12 @@ const (
WatcherEventFileVanished
)
// DefaultWatcherOpts is used when creating the Watcher without
// giving options
var DefaultWatcherOpts = WatcherOpts{
FollowSymlinks: false,
}
// NewCryptographicWatcher is a wrapper around NewWatcher to configure
// the Watcher with presence and sha256 hash checks.
func NewCryptographicWatcher(filePath string, interval time.Duration) (*Watcher, error) {
@ -53,15 +69,27 @@ func NewSimpleWatcher(filePath string, interval time.Duration) (*Watcher, error)
}
// NewWatcher creates a new Watcher configured with the given filePath,
// interval and checks given. The checks are executed once during
// initialization and will not cause an event to be sent. The created
// Watcher will automatically start its periodic check and the C
// channel should immediately be watched for changes. If the channel
// is not listened on the check loop will be paused until events are
// retrieved. If during the initial checks an error is detected the
// loop is NOT started and the watcher needs to be initialized again.
// default options, interval and checks given. The checks are executed
// once during initialization and will not cause an event to be sent. The
// created Watcher will automatically start its periodic check and the C
// channel should immediately be watched for changes. If the channel is
// not listened on the check loop will be paused until events are
// retrieved. If during the initial checks an error is detected the loop
// is NOT started and the watcher needs to be initialized again.
func NewWatcher(filePath string, interval time.Duration, checks ...WatcherCheck) (*Watcher, error) {
w, err := newWatcher(filePath, interval, checks...)
return NewWatcherWithOpts(filePath, DefaultWatcherOpts, interval, checks...)
}
// NewWatcherWithOpts creates a new Watcher configured with the given
// filePath, options, interval and checks given. The checks are executed
// once during initialization and will not cause an event to be sent. The
// created Watcher will automatically start its periodic check and the C
// channel should immediately be watched for changes. If the channel is
// not listened on the check loop will be paused until events are
// retrieved. If during the initial checks an error is detected the loop
// is NOT started and the watcher needs to be initialized again.
func NewWatcherWithOpts(filePath string, opts WatcherOpts, interval time.Duration, checks ...WatcherCheck) (*Watcher, error) {
w, err := newWatcher(filePath, opts, interval, checks...)
if err == nil {
go w.loop()
@ -70,7 +98,7 @@ func NewWatcher(filePath string, interval time.Duration, checks ...WatcherCheck)
return w, err
}
func newWatcher(filePath string, interval time.Duration, checks ...WatcherCheck) (*Watcher, error) {
func newWatcher(filePath string, opts WatcherOpts, interval time.Duration, checks ...WatcherCheck) (*Watcher, error) {
notify := make(chan WatcherEvent, 1)
w := &Watcher{
@ -78,9 +106,10 @@ func newWatcher(filePath string, interval time.Duration, checks ...WatcherCheck)
CheckInterval: interval,
FilePath: filePath,
c: notify,
checks: checks,
stateCache: make(map[string]any),
c: notify,
checks: checks,
followSymlinks: opts.FollowSymlinks,
stateCache: make(map[string]any),
}
// Initially run checks once
_, err := w.runStateChecks()
@ -141,3 +170,11 @@ func (w *Watcher) runStateChecks() (WatcherEvent, error) {
return WatcherEventNoChange, nil
}
func (w *Watcher) stat(filePath string) (os.FileInfo, error) {
if w.followSymlinks {
return os.Stat(filePath)
}
return os.Lstat(filePath)
}

8
file/watcher_checks.go
View file

@ -29,7 +29,7 @@ func WatcherCheckHash(hcf func() hash.Hash) WatcherCheck {
lastHash = v
}
if _, err := os.Lstat(w.FilePath); errors.Is(err, fs.ErrNotExist) {
if _, err := w.stat(w.FilePath); errors.Is(err, fs.ErrNotExist) {
return WatcherEventInvalid, nil
}
@ -65,7 +65,7 @@ func WatcherCheckMtime(w *Watcher) (WatcherEvent, error) {
lastChange = v
}
s, err := os.Lstat(w.FilePath)
s, err := w.stat(w.FilePath)
switch {
case err == nil:
// handle size change
@ -94,7 +94,7 @@ func WatcherCheckPresence(w *Watcher) (WatcherEvent, error) {
wasPresent = v
}
_, err := os.Lstat(w.FilePath)
_, err := w.stat(w.FilePath)
if err != nil && !errors.Is(err, fs.ErrNotExist) {
// Some weird error occurred
return WatcherEventInvalid, errors.Wrap(err, "getting file stat")
@ -124,7 +124,7 @@ func WatcherCheckSize(w *Watcher) (WatcherEvent, error) {
knownSize = v
}
s, err := os.Lstat(w.FilePath)
s, err := w.stat(w.FilePath)
switch {
case err == nil:
// handle size change

8
file/watcher_test.go
View file

@ -22,7 +22,7 @@ func TestWatcherCheckHash(t *testing.T) {
testFile := path.Join(testDir, "test.txt")
w, err := newWatcher(testFile, time.Second, WatcherCheckHash(sha256.New))
w, err := newWatcher(testFile, DefaultWatcherOpts, time.Second, WatcherCheckHash(sha256.New))
require.NoError(t, err, "initial check should not error on non existing file")
evt, err := w.runStateChecks()
@ -73,7 +73,7 @@ func TestWatcherCheckMtime(t *testing.T) {
testFile := path.Join(testDir, "test.txt")
w, err := newWatcher(testFile, time.Second, WatcherCheckMtime)
w, err := newWatcher(testFile, DefaultWatcherOpts, time.Second, WatcherCheckMtime)
require.NoError(t, err, "initial check should not error on non existing file")
evt, err := w.runStateChecks()
@ -128,7 +128,7 @@ func TestWatcherCheckPresence(t *testing.T) {
testFile := path.Join(testDir, "test.txt")
w, err := newWatcher(testFile, time.Second, WatcherCheckPresence)
w, err := newWatcher(testFile, DefaultWatcherOpts, time.Second, WatcherCheckPresence)
require.NoError(t, err, "initial check should not error on non existing file")
evt, err := w.runStateChecks()
@ -165,7 +165,7 @@ func TestWatcherCheckSize(t *testing.T) {
testFile := path.Join(testDir, "test.txt")
w, err := newWatcher(testFile, time.Second, WatcherCheckSize)
w, err := newWatcher(testFile, DefaultWatcherOpts, time.Second, WatcherCheckSize)
require.NoError(t, err, "initial check should not error on non existing file")
evt, err := w.runStateChecks()