Pull request: hup-reload

Merge in DNS/adguard-home from hup-reload to master

Squashed commit of the following:

commit 5cd4ab85bdc7544a4eded2a61f5a5571175daa44
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Oct 7 19:58:17 2022 +0300

    next: imp signal hdlr

commit 8fd18e749fec46982d26fc408e661bd802586c37
Merge: a8780455 f1dd3334
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Oct 7 19:46:48 2022 +0300

    Merge branch 'master' into hup-reload

commit a87804550e15d7fe3d9ded2e5a736c395f96febd
Merge: 349dbe54 960a7a75
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Oct 7 15:49:23 2022 +0300

    Merge branch 'master' into hup-reload

commit 349dbe54fe27eeaf56776c73c3cc5649018d4c60
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Oct 7 15:43:52 2022 +0300

    next: imp docs, names

commit 7287a86d283489127453009267911003cea5227e
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Oct 7 13:39:44 2022 +0300

    WIP all: impl dynamic reconfiguration

internal/aghos/filewalker_internal_test.go

@@ -15,11 +15,11 @@ import (
 // errFSOpen.
 type errFS struct{}
 
-// errFSOpen is returned from errGlobFS.Open.
+// errFSOpen is returned from errFS.Open.
 const errFSOpen errors.Error = "test open error"
 
-// Open implements the fs.FS interface for *errGlobFS.  fsys is always nil and
-// err is always errFSOpen.
+// Open implements the fs.FS interface for *errFS.  fsys is always nil and err
+// is always errFSOpen.
 func (efs *errFS) Open(name string) (fsys fs.File, err error) {
 	return nil, errFSOpen
 }

internal/aghos/os.go

@@ -175,11 +175,21 @@ func RootDirFS() (fsys fs.FS) {
 	return os.DirFS("")
 }
 
+// NotifyReconfigureSignal notifies c on receiving reconfigure signals.
+func NotifyReconfigureSignal(c chan<- os.Signal) {
+	notifyReconfigureSignal(c)
+}
+
 // NotifyShutdownSignal notifies c on receiving shutdown signals.
 func NotifyShutdownSignal(c chan<- os.Signal) {
 	notifyShutdownSignal(c)
 }
 
+// IsReconfigureSignal returns true if sig is a reconfigure signal.
+func IsReconfigureSignal(sig os.Signal) (ok bool) {
+	return isReconfigureSignal(sig)
+}
+
 // IsShutdownSignal returns true if sig is a shutdown signal.
 func IsShutdownSignal(sig os.Signal) (ok bool) {
 	return isShutdownSignal(sig)

internal/aghos/os_unix.go

@@ -9,10 +9,18 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+func notifyReconfigureSignal(c chan<- os.Signal) {
+	signal.Notify(c, unix.SIGHUP)
+}
+
 func notifyShutdownSignal(c chan<- os.Signal) {
 	signal.Notify(c, unix.SIGINT, unix.SIGQUIT, unix.SIGTERM)
 }
 
+func isReconfigureSignal(sig os.Signal) (ok bool) {
+	return sig == unix.SIGHUP
+}
+
 func isShutdownSignal(sig os.Signal) (ok bool) {
 	switch sig {
 	case

internal/aghos/os_windows.go

@@ -39,12 +39,20 @@ func isOpenWrt() (ok bool) {
 	return false
 }
 
+func notifyReconfigureSignal(c chan<- os.Signal) {
+	signal.Notify(c, windows.SIGHUP)
+}
+
 func notifyShutdownSignal(c chan<- os.Signal) {
 	// syscall.SIGTERM is processed automatically.  See go doc os/signal,
 	// section Windows.
 	signal.Notify(c, os.Interrupt)
 }
 
+func isReconfigureSignal(sig os.Signal) (ok bool) {
+	return sig == windows.SIGHUP
+}
+
 func isShutdownSignal(sig os.Signal) (ok bool) {
 	switch sig {
 	case