From c77907694d48c785b4b958616c04c42449faf302 Mon Sep 17 00:00:00 2001
From: Simon Zolin <s.zolin@adguard.com>
Date: Tue, 18 Feb 2020 16:01:32 +0300
Subject: [PATCH] + service: support "-s reload" command

---
 home/home.go       |  2 +-
 home/service.go    | 49 ++++++++++++++++++++++++++++++++++++++++++++++
 util/os_freebsd.go |  5 +++++
 util/os_unix.go    |  5 +++++
 util/os_windows.go | 11 ++++++++++-
 5 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/home/home.go b/home/home.go
index 299653c4..ba01562e 100644
--- a/home/home.go
+++ b/home/home.go
@@ -528,7 +528,7 @@ func loadOptions() options {
 			}
 			o.bindPort = v
 		}, nil},
-		{"service", "s", "Service control action: status, install, uninstall, start, stop, restart", func(value string) {
+		{"service", "s", "Service control action: status, install, uninstall, start, stop, restart, reload (configuration)", func(value string) {
 			o.serviceControlAction = value
 		}, nil},
 		{"logfile", "l", "Path to log file. If empty: write to stdout; if 'syslog': write to system log", func(value string) {
diff --git a/home/service.go b/home/service.go
index d066e118..2cb31ecb 100644
--- a/home/service.go
+++ b/home/service.go
@@ -1,9 +1,11 @@
 package home
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"runtime"
+	"strconv"
 	"strings"
 	"syscall"
 
@@ -71,6 +73,48 @@ func svcAction(s service.Service, action string) error {
 	return err
 }
 
+// Send SIGHUP to a process with ID taken from our pid-file
+// If pid-file doesn't exist, find our PID using 'ps' command
+func sendSigReload() {
+	if runtime.GOOS == "windows" {
+		log.Error("Not implemented on Windows")
+		return
+	}
+
+	pidfile := fmt.Sprintf("/var/run/%s.pid", serviceName)
+	data, err := ioutil.ReadFile(pidfile)
+	if os.IsNotExist(err) {
+		code, psdata, err := util.RunCommand("ps", "-C", serviceName, "-o", "pid=")
+		if err != nil || code != 0 {
+			log.Error("Can't find AdGuardHome process: %s  code:%d", err, code)
+			return
+		}
+		data = []byte(psdata)
+
+	} else if err != nil {
+		log.Error("Can't read PID file %s: %s", pidfile, err)
+		return
+	}
+
+	parts := strings.SplitN(string(data), "\n", 2)
+	if len(parts) == 0 {
+		log.Error("Can't read PID file %s: bad value", pidfile)
+		return
+	}
+
+	pid, err := strconv.Atoi(parts[0])
+	if err != nil {
+		log.Error("Can't read PID file %s: %s", pidfile, err)
+		return
+	}
+	err = util.SendProcessSignal(pid, syscall.SIGHUP)
+	if err != nil {
+		log.Error("Can't send signal to PID %d: %s", pid, err)
+		return
+	}
+	log.Debug("Sent signal to PID %d", pid)
+}
+
 // handleServiceControlAction one of the possible control actions:
 // install -- installs a service/daemon
 // uninstall -- uninstalls it
@@ -84,6 +128,11 @@ func svcAction(s service.Service, action string) error {
 func handleServiceControlAction(action string) {
 	log.Printf("Service control action: %s", action)
 
+	if action == "reload" {
+		sendSigReload()
+		return
+	}
+
 	pwd, err := os.Getwd()
 	if err != nil {
 		log.Fatal("Unable to find the path to the current directory")
diff --git a/util/os_freebsd.go b/util/os_freebsd.go
index 33311e16..8254d897 100644
--- a/util/os_freebsd.go
+++ b/util/os_freebsd.go
@@ -25,3 +25,8 @@ func SetRlimit(val uint) {
 func HaveAdminRights() (bool, error) {
 	return os.Getuid() == 0, nil
 }
+
+// SendProcessSignal - send signal to a process
+func SendProcessSignal(pid int, sig syscall.Signal) error {
+	return syscall.Kill(pid, sig)
+}
diff --git a/util/os_unix.go b/util/os_unix.go
index 338edfa8..9826a68c 100644
--- a/util/os_unix.go
+++ b/util/os_unix.go
@@ -25,3 +25,8 @@ func SetRlimit(val uint) {
 func HaveAdminRights() (bool, error) {
 	return os.Getuid() == 0, nil
 }
+
+// SendProcessSignal - send signal to a process
+func SendProcessSignal(pid int, sig syscall.Signal) error {
+	return syscall.Kill(pid, sig)
+}
diff --git a/util/os_windows.go b/util/os_windows.go
index e081f758..1c09e588 100644
--- a/util/os_windows.go
+++ b/util/os_windows.go
@@ -1,6 +1,11 @@
 package util
 
-import "golang.org/x/sys/windows"
+import (
+	"fmt"
+	"syscall"
+
+	"golang.org/x/sys/windows"
+)
 
 // Set user-specified limit of how many fd's we can use
 func SetRlimit(val uint) {
@@ -26,3 +31,7 @@ func HaveAdminRights() (bool, error) {
 	}
 	return true, nil
 }
+
+func SendProcessSignal(pid int, sig syscall.Signal) error {
+	return fmt.Errorf("not supported on Windows")
+}