From d9ae6dbcc34669e3880a1a64f538fa222a1d1657 Mon Sep 17 00:00:00 2001
From: Eugene Burkov <e.burkov@adguard.com>
Date: Mon, 17 May 2021 15:24:05 +0300
Subject: [PATCH] Pull request: improve installation script

Merge in DNS/adguard-home from 2542-2462-imp-script to master

Closes #2462.
Updates #2542.
Updates #2613.

Squashed commit of the following:

commit 4a7472200f2ae07aeccc3511a75a94674b655cdb
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon May 17 15:11:08 2021 +0300

    scripts: imp naming, docs

commit acbb5864a34e81d8c80767dd7ef57dffb189dc64
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon May 17 15:05:57 2021 +0300

    scripts: imp fix

commit 64777015b6d50e7330fbe7546de1f436f4cb707f
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon May 17 14:54:05 2021 +0300

    scripts: fix bsd

commit 3308921f4c253c8670c4be70896c55f7a892ff3e
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon May 17 14:04:04 2021 +0300

    scripts: imp requirements checking

commit 453cf7a4ce676d2eb09d423304e4d5a8962ac4e5
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon May 17 13:54:38 2021 +0300

    scripts: fix docs

commit a2229052f6cf747247c8290cd0de27cc88c14977
Merge: 0852c87b 120ba967
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon May 17 13:50:45 2021 +0300

    Merge branch 'master' into 2542-2462-imp-script

commit 0852c87bf33b833095644e649bbcedbf89ad4f82
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon May 17 13:49:27 2021 +0300

    scripts: add os-specific requirements check

commit 6313d8fd19f70c41b7091511ca8d979859ddb10c
Merge: 1b4092d5 a031cae4
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri May 14 19:46:57 2021 +0300

    Merge branch 'master' into 2542-2462-imp-script

commit 1b4092d5ee1de5b56c6252bf9debe8b90cdf954e
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri May 14 19:46:09 2021 +0300

    scripts: imp install.sh a little

commit 0584b30b4648b88f542fff6f2879c4a7ae042af4
Merge: 22621c86 9d788a29
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri May 14 19:27:47 2021 +0300

    Merge branch 'master' into 2542-2462-imp-script

commit 22621c86a70e61f98850a10f0c5e450c8aeaa90f
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri May 14 19:25:47 2021 +0300

    all: imp code

commit a38f4adc4688995ca515f8d0d8d271427365623c
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri May 14 18:40:37 2021 +0300

    all: fix url variable

commit 238cb859184da4af025137d99216d51d3b481dc0
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri May 14 18:27:13 2021 +0300

    imp code quality

commit 0e36c125369d47612fd97c2841a2a688bed5841d
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri May 14 16:34:49 2021 +0300

    all: fix typos

commit b20f0b72141f5abb5e598324a3f2bd750164e612
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Apr 29 14:02:40 2021 +0300

    all: imp installation script
---
 CHANGELOG.md       |   5 +
 HACKING.md         |   7 +-
 README.md          |  10 +-
 scripts/install.sh | 724 ++++++++++++++++++++++++++++++---------------
 4 files changed, 510 insertions(+), 236 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8d14f836..c6c2106b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,16 +19,21 @@ and this project adheres to
 
 ### Added
 
+- Support for reinstall (`-r`) and uninstall (`-u`) flags in the installation
+  script ([#2462]).
 - Support for DHCP `DECLINE` and `RELEASE` message types ([#3053]).
 
 ### Fixed
 
+- Error when using installation script on some ARMv7 devices ([#2542]).
 - DHCP leases validation ([#3107], [#3127]).
 - Local PTR request recursion in Docker containers ([#3064]).
 - Ignoring client-specific filtering settings when filtering is disabled in
   general settings ([#2875]).
 - Disallowed domains are now case-insensitive ([#3115]).
 
+[#2462]: https://github.com/AdguardTeam/AdGuardHome/issues/2462
+[#2542]: https://github.com/AdguardTeam/AdGuardHome/issues/2542
 [#2875]: https://github.com/AdguardTeam/AdGuardHome/issues/2875
 [#3053]: https://github.com/AdguardTeam/AdGuardHome/issues/3053
 [#3064]: https://github.com/AdguardTeam/AdGuardHome/issues/3064
diff --git a/HACKING.md b/HACKING.md
index e1b3bebb..a979a885 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -313,6 +313,8 @@ on GitHub and most other Markdown renderers. -->
 
  *  Avoid bashisms and GNUisms, prefer POSIX features only.
 
+ *  Avoid spaces between patterns of the same `case` condition.
+
  *  Prefer `'raw strings'` to `"double quoted strings"` whenever possible.
 
  *  Put spaces within `$( cmd )`, `$(( expr ))`, and `{ cmd; }`.
@@ -328,10 +330,10 @@ on GitHub and most other Markdown renderers. -->
  *  UPPERCASE names for external exported variables, lowercase for local,
     unexported ones.
 
- *  Use `set -e -f -u` and also `set -x` in verbose mode.
-
  *  Use `readonly` liberally.
 
+ *  Use `set -e -f -u` and also `set -x` in verbose mode.
+
  *  Use the `"$var"` form instead of the `$var` form, unless word splitting is
     required.
 
@@ -356,6 +358,7 @@ on GitHub and most other Markdown renderers. -->
  *  When using `test` (aka `[`), spell compound conditions with `&&`, `||`, and
     `!` **outside** of `test` instead of `-a`, `-o`, and `!` inside of `test`
     correspondingly.  The latter ones are pretty much deprecated in POSIX.
+    Also, prefer `!= ''` form instead of `-n` to check if string is empty.
 
     See also: “[Problems With the `test` Builtin: What Does `-a` Mean?]”.
 
diff --git a/README.md b/README.md
index 5402a482..20de93f7 100644
--- a/README.md
+++ b/README.md
@@ -68,9 +68,17 @@ It operates as a DNS server that re-routes tracking domains to a "black hole", t
 ### Automated install (Linux and Mac)
 Run the following command in your terminal:
 ```
-curl -sSL https://raw.githubusercontent.com/AdguardTeam/AdGuardHome/master/scripts/install.sh | sh
+curl -s -S -L https://raw.githubusercontent.com/AdguardTeam/AdGuardHome/master/scripts/install.sh | sh -s -- -v
 ```
 
+The script also accepts some options:
+* `-c <channel>` to use specified channel.
+* `-r` to reinstall AdGuard Home;
+* `-u` to uninstall AdGuard Home;
+* `-v` for verbose output;
+
+Note that options `-r` and `-u` are mutually exclusive.
+
 ### Alternative methods
 
 #### Manual installation
diff --git a/scripts/install.sh b/scripts/install.sh
index 7a410cee..3d5403aa 100644
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -1,249 +1,507 @@
 #!/bin/sh
 
 # AdGuard Home Installation Script
-#
-# 1. Download the package
-# 2. Unpack it
-# 3. Install as a service
-#
-# Requirements:
-# . bash
-# . which
-# . printf
-# . uname
-# . id
-# . head, tail
-# . curl
-# . tar or unzip
-# . rm
 
-set -e
-
-log_info()
-{
-    printf "[info] %s\\n" "$1"
-}
-
-log_error()
-{
-    printf "[error] %s\\n" "$1"
-}
-
-# Get OS
-# Return: darwin, linux, freebsd
-detect_os()
-{
-	UNAME_S="$(uname -s)"
-	OS=
-	case "$UNAME_S" in
-		Linux)
-			OS=linux
-			;;
-
-		FreeBSD)
-			OS=freebsd
-			;;
-
-		Darwin)
-			OS=darwin
-			;;
-
-		*)
-			return 1
-			;;
-
-	esac
-
-	echo $OS
-}
-
-# Get CPU endianness
-# Return: le, ""
-cpu_little_endian()
-{
-	ENDIAN_FLAG="$(head -c 6 /bin/bash | tail -c 1)"
-	if [ "$ENDIAN_FLAG" = "$(printf '\001')" ]; then
-		echo 'le'
-		return 0
+# Function log is an echo wrapper that writes to stderr if the caller
+# requested verbosity level greater than 0.  Otherwise, it does nothing.
+log() {
+	if [ "$verbose" -gt '0' ]
+	then
+		echo "$1" 1>&2
 	fi
 }
 
-# Get CPU
-# Return: amd64, 386, armv5, armv6, armv7, arm64, mips_softfloat, mipsle_softfloat, mips64_softfloat, mips64le_softfloat
-detect_cpu()
-{
-	UNAME_M="$(uname -m)"
-	CPU=
+# Function error_exit is an echo wrapper that writes to stderr and stops the
+# script execution with code 1.
+error_exit() {
+	echo "$1" 1>&2
 
-	case "$UNAME_M" in
-
-		x86_64 | x86-64 | x64 | amd64)
-			CPU=amd64
-			;;
-
-		i386 | i486 | i686 | i786 | x86)
-			CPU=386
-			;;
-
-		armv5l)
-			CPU=armv5
-			;;
-
-		armv6l)
-			CPU=armv6
-			;;
-
-		armv7l | armv8l)
-			CPU=armv7
-			;;
-
-		aarch64 | arm64)
-			CPU=arm64
-			;;
-
-		mips)
-			LE=$(cpu_little_endian)
-			CPU=mips${LE}_softfloat
-			;;
-
-		mips64)
-			LE=$(cpu_little_endian)
-			CPU=mips64${LE}_softfloat
-			;;
-
-		*)
-			return 1
-
-	esac
-
-	echo "${CPU}"
-}
-
-# Get package file name extension
-# Return: tar.gz, zip
-package_extension()
-{
-	if [ "$OS" = "darwin" ]; then
-		echo "zip"
-		return 0
-	fi
-	echo "tar.gz"
-}
-
-# Download data to a file
-# Use: download URL OUTPUT
-download()
-{
-	log_info "Downloading package from $1 -> $2"
-	if is_command curl ; then
-		curl -s "$1" --output "$2" || error_exit "Failed to download $1"
-	else
-		error_exit "curl is necessary to install AdGuard Home"
-	fi
-}
-
-# Unpack package to a directory
-# Use: unpack INPUT OUTPUT_DIR PKG_EXT
-unpack()
-{
-	log_info "Unpacking package from $1 -> $2"
-	mkdir -p "$2"
-	if [ "$3" = "zip" ]; then
-		unzip -qq "$1" -d "$2" || return 1
-	elif [ "$3" = "tar.gz" ]; then
-		tar xzf "$1" -C "$2" || return 1
-	else
-		return 1
-	fi
-}
-
-# Print error message and exit
-# Use: error_exit MESSAGE
-error_exit()
-{
-	log_error "$1"
 	exit 1
 }
 
-# Check if command exists
-# Use: is_command COMMAND
+# Function usage prints the note about how to use the script.
+#
+# TODO(e.burkov): Document each option.
+usage() {
+	echo 'install.sh: usage: [-c channel] [-C cpu_type] [-h] [-O os] [-o output_dir]'\
+		'[-r|-R] [-u|-U] [-v|-V]' 1>&2
+
+	exit 2
+}
+
+# Function is_command checks if the command exists on the machine.
 is_command() {
-    check_command="$1"
-    command -v "${check_command}" >/dev/null 2>&1
+	command -v "$1" >/dev/null 2>&1
 }
 
-# Entry point
-main() {
-    log_info "Starting AdGuard Home installation script"
-
-    CHANNEL=${1}
-    if [ "${CHANNEL}" != "beta" ] && [ "${CHANNEL}" != "edge" ]; then
-        CHANNEL=release
-    fi
-    log_info "Channel ${CHANNEL}"
-
-    OS=$(detect_os) || error_exit "Cannot detect your OS"
-    CPU=$(detect_cpu) || error_exit "Cannot detect your CPU"
-
-    # TODO: Remove when Mac M1 native support is added
-    if [ "${OS}" = "darwin" ] && [ "${CPU}" = "arm64" ]; then
-        CPU="amd64"
-        log_info "Use ${CPU} build on Mac M1 until the native ARM support is added"
-    fi
-
-    PKG_EXT=$(package_extension)
-    PKG_NAME=AdGuardHome_${OS}_${CPU}.${PKG_EXT}
-
-    SCRIPT_URL="https://raw.githubusercontent.com/AdguardTeam/AdGuardHome/master/scripts/install.sh"
-    URL="https://static.adguard.com/adguardhome/${CHANNEL}/${PKG_NAME}"
-    OUT_DIR="/opt"
-    if [ "${OS}" = "darwin" ]; then
-        # It may be important to install AdGuard Home to /Applications on MacOS
-        # Otherwise, it may not grant enough privileges to it
-        OUT_DIR="/Applications"
-    fi
-
-    AGH_DIR="${OUT_DIR}/AdGuardHome"
-
-    # Root check
-    if [ "$(id -u)" -eq 0 ]; then
-        log_info "Script called with root privileges"
-    else
-        if is_command sudo ; then
-            log_info "Please note, that AdGuard Home requires root privileges to install using this script."
-            log_info "Restarting with root privileges"
-
-            exec curl -sSL ${SCRIPT_URL} | sudo sh -s "$@"
-            exit $?
-        else
-            log_info "Root privileges are required to install AdGuard Home using this installer."
-            log_info "Please, re-run this script as root."
-            exit 1
-        fi
-    fi
-
-    log_info "AdGuard Home will be installed to ${AGH_DIR}"
-
-    [ -d "${AGH_DIR}" ] && [ -n "$(ls -1 -A -q ${AGH_DIR})" ] && error_exit "Directory ${AGH_DIR} is not empty, abort installation"
-
-    download "${URL}" "${PKG_NAME}" || error_exit "Cannot download the package"
-
-    if [ "${OS}" = "darwin" ]; then
-      # TODO: remove this after v0.106.0 release
-      mkdir "${AGH_DIR}"
-      unpack "${PKG_NAME}" "${AGH_DIR}" "${PKG_EXT}" || error_exit "Cannot unpack the package"
-    else
-      unpack "${PKG_NAME}" "${OUT_DIR}" "${PKG_EXT}" || error_exit "Cannot unpack the package"
-    fi
-
-    # Install AdGuard Home service and run it.
-    ( cd "${AGH_DIR}" && ./AdGuardHome -s install || error_exit "Cannot install AdGuardHome as a service" )
-
-    rm "${PKG_NAME}"
-
-    log_info "AdGuard Home is now installed and running."
-    log_info "You can control the service status with the following commands:"
-    log_info "  sudo ${AGH_DIR}/AdGuardHome -s start|stop|restart|status|install|uninstall"
+# Function is_little_endian checks if the CPU is little-endian.
+is_little_endian() {
+	[ "$( head -c 6 /bin/sh | tail -c 1 )" = "$( printf '\001' )" ]
 }
 
-main "$@"
+# Function check_required checks if the required software is available on the
+# machine.  The required software:
+#
+#   curl
+#   unzip (macOS) / tar (other unices)
+#
+check_required() {
+	readonly required_darwin="unzip"
+	readonly required_unix="tar"
+
+	# Split with space.
+	required="curl"
+	if [ "$os" = 'linux' ] || [ "$os" = 'freebsd' ]
+	then
+		required="$required $required_unix"
+	elif [ "$os" = 'darwin' ]
+	then
+		required="$required $required_darwin"
+	fi
+
+	# Don't use quotes to get word splitting.
+	for cmd in ${required}
+	do
+		echo "checking $cmd"
+		if ! is_command "$cmd"
+		then
+			log "the full list of required software: [$required]"
+
+			error_exit "$cmd is required to install AdGuard Home via this script"
+		fi
+	done
+}
+
+# Function check_out_dir requires the output directory to be set and exist.
+check_out_dir() {
+	if [ "$out_dir" = '' ]
+	then
+		error_exit 'output directory should be presented'
+	fi
+
+	if ! [ -d "$out_dir" ]
+	then
+		log "$out_dir directory will be created"
+	fi
+}
+
+# Function parse_opts parses the options list and validates it's combinations.
+parse_opts() {
+	while getopts "C:c:hO:o:rRuUvV" opt $*
+	do
+		case "$opt"
+		in
+		(C)
+			cpu="$OPTARG"
+			;;
+		(c)
+			channel="$OPTARG"
+			;;
+		(h)
+			usage
+			;;
+		(O)
+			os="$OPTARG"
+			;;
+		(o)
+			out_dir="$OPTARG"
+			;;
+		(R)
+			reinstall='0'
+			;;
+		(U)
+			uninstall='0'
+			;;
+		(r)
+			reinstall='1'
+			;;
+		(u)
+			uninstall='1'
+			;;
+		(V)
+			verbose='0'
+			;;
+		(v)
+			verbose='1'
+			;;
+		(*)
+			log "bad option $OPTARG"
+
+			usage
+			;;
+		esac
+	done
+
+	if [ "$uninstall" = '1' ] && [ "$reinstall" = '1' ]
+	then
+		error_exit 'the -r and -u options are mutually exclusive'
+	fi
+}
+
+# Function set_channel sets the channel if needed and validates the value.
+set_channel() {
+	# Validate.
+	case "$channel"
+	in
+	('development'|'edge'|'beta'|'release')
+		# All is well, go on.
+		;;
+	(*)
+		error_exit \
+"invalid channel '$channel'
+supported values are 'development', 'edge', 'beta', and 'release'"
+		;;
+	esac
+
+	# Log.
+	log "channel: $channel"
+}
+
+# Function set_os sets the os if needed and validates the value.
+set_os() {
+	# Set if needed.
+	if [ "$os" = '' ]
+	then
+		os="$( uname -s )"
+		case "$os"
+		in
+		('Linux')
+			os='linux'
+			;;
+		('FreeBSD')
+			os='freebsd'
+			;;
+		('Darwin')
+			os='darwin'
+			;;
+		esac
+	fi
+
+	# Validate.
+	case "$os"
+	in
+	('linux'|'freebsd'|'darwin')
+		# All right, go on.
+		;;
+	(*)
+		error_exit "unsupported operating system: $os"
+		;;
+	esac
+
+	# Log.
+	log "operating system: $os"
+}
+
+# Function set_cpu sets the cpu if needed and validates the value.
+set_cpu() {
+	# Set if needed.
+	if [ "$cpu" = '' ]
+	then
+		cpu="$( uname -m )"
+		case "$cpu"
+		in
+		('x86_64'|'x86-64'|'x64'|'amd64')
+			cpu='amd64'
+			;;
+		('i386'|'i486'|'i686'|'i786'|'x86')
+			cpu='386'
+			;;
+		('armv5l')
+			cpu='armv5'
+			;;
+		('armv6l')
+			cpu='armv6'
+			;;
+		('armv7l' | 'armv8l')
+			cpu='armv7'
+			;;
+		('aarch64'|'arm64')
+			cpu='arm64'
+			;;
+		('mips'|'mips64')
+			if is_little_endian
+			then
+				cpu="${cpu}le"
+			fi
+			cpu="${cpu}_softfloat"
+			;;
+		esac
+	fi
+
+	# Validate.
+	case "$cpu"
+	in
+	('amd64'|'386'|'armv5'|'armv6'|'armv7'|'arm64')
+		# All right, go on.
+		;;
+	('mips64le_softfloat'|'mips64_softfloat'|'mipsle_softfloat'|'mips_softfloat')
+		# That's right too.
+		;;
+	(*)
+		error_exit "unsupported cpu type: $cpu"
+		;;
+	esac
+
+	# Log.
+	log "cpu type: $cpu"
+}
+
+# Function fix_darwin performs some configuration changes for macOS if
+# needed.
+fix_darwin() {
+	if ! [ "$os" = 'darwin' ]
+	then
+		return 0
+	fi
+
+	# TODO: Remove when Mac M1 native support is added.
+	if [ "$cpu" = 'arm64' ]
+	then
+		cpu='amd64'
+		log "use $cpu build on Mac M1 until the native ARM support is added."
+	fi
+
+	# Set the package extension.
+	pkg_ext='zip'
+
+	# It is important to install AdGuard Home into the /Applications
+	# directory on MacOS.  Otherwise, it may not grant enough privileges to
+	# the AdGuard Home.
+	out_dir='/Applications'
+}
+
+# Function fix_freebsd performs some fixes to make it work on FreeBSD.
+fix_freebsd() {
+	if ! [ "$os" = 'freebsd' ]
+	then
+		return 0
+	fi
+
+	readonly rcd='/usr/local/etc/rc.d'
+	if ! [ -d "$rcd" ]
+	then
+		mkdir "$rcd"
+	fi
+}
+
+# Function configure sets the script's configuration.
+configure() {
+	set_channel
+	set_os
+	set_cpu
+	fix_darwin
+	check_out_dir
+
+	readonly pkg_name="AdGuardHome_${os}_${cpu}.${pkg_ext}"
+	readonly url="https://static.adguard.com/adguardhome/${channel}/${pkg_name}"
+	readonly agh_dir="${out_dir}/AdGuardHome"
+
+	log "AdGuard Home will be installed into $agh_dir"
+}
+
+# Function is_root checks for root privileges to be granted.
+is_root() {
+	if [ "$( id -u )" = '0' ]
+	then
+		log 'script is executed with root privileges'
+
+		return 0
+	fi
+
+	if is_command sudo
+	then
+		log 'note that AdGuard Home requires root privileges to install using this script'
+
+		return 1
+	fi
+
+	error_exit \
+'root privileges are required to install AdGuard Home using this script
+please, restart it with root privileges'
+}
+
+# Function rerun_with_root downloads the script and tries to run it with root
+# privileges.  It also uses the configuration that already set.
+#
+# TODO(e.burkov): Try to avoid restarting.
+rerun_with_root() {
+	readonly script_url=\
+'https://raw.githubusercontent.com/AdguardTeam/AdGuardHome/master/scripts/install.sh'
+
+	flags=''
+	if [ "$reinstall" = '1' ]
+	then
+		flags="${flags} -r"
+	fi
+	if [ "$uninstall" = '1' ]
+	then
+		flags="${flags} -u"
+	fi
+	if [ "$verbose" = '1' ]
+	then
+		flags="${flags} -v"
+	fi
+
+	readonly opts="-c $channel -C $cpu -O $os -o $out_dir $flags"
+
+	log 'restarting with root privileges'
+	
+	curl  -L -S -s "$script_url" | sudo sh -s -- $opts
+	exit $?
+}
+
+# Function download downloads the file from the URL and saves it to the
+# specified filepath.
+download() {
+	log "downloading package from $url -> $pkg_name"
+
+	if ! curl -s "$url" --output "$pkg_name"
+	then
+		error_exit "cannot download the package from $url into $pkg_name"
+	fi
+}
+
+# Function unpack unpacks the passed archive depending on it's extension.
+unpack() {
+	log "unpacking package from $pkg_name into $out_dir"
+	if ! mkdir -p "$out_dir"
+	then
+		error_exit "cannot create directory at the $out_dir"
+	fi
+
+	case "$pkg_ext"
+	in
+	('zip')
+		unzip "$pkg_name" -d "$out_dir"
+		;;
+	('tar.gz')
+		tar -C "$out_dir" -f "$pkg_name" -x -z
+		;;
+	(*)
+		error_exit "unexpected package extension: '$pkg_ext'"
+		;;
+	esac
+
+	if [ "$?" != '0' ]
+	then
+		error_exit "cannot unpack the package into $out_dir"
+	fi
+
+	rm "$pkg_name"
+}
+
+# Function handle_existing detects the existing AGH installation and takes care
+# of removing it if needed.
+handle_existing() {
+	if ! [ -d "$agh_dir" ]
+	then
+		log 'no need to uninstall'
+
+		if [ "$uninstall" = '1' ]
+		then
+			exit 0
+		fi
+
+		return 0
+	fi
+
+	if [ "$( ls -1 -A -q $agh_dir )" != '' ]
+	then
+		log 'the existing AdGuard Home installation is detected'
+
+		if [ "$reinstall" != '1' ] && [ "$uninstall" != '1' ]
+		then
+			error_exit \
+"to reinstall/uninstall the AdGuard Home using\this script specify one of the '-r' or '-u' flags"
+		fi
+
+		if ( cd "$agh_dir" && ! ./AdGuardHome -s uninstall )
+		then
+			# It doesn't terminate the script since it is possible
+			# that AGH just not installed as service but appearing
+			# in the directory.
+			log "cannot uninstall AdGuard Home from $agh_dir"
+		fi
+
+		rm -r "$agh_dir"
+
+		log 'AdGuard Home was successfully uninstalled'
+	fi
+
+	if [ "$uninstall" = '1' ]
+	then
+		exit 0
+	fi
+}
+
+# Function install_service tries to install AGH as service.
+install_service() {
+	# TODO(e.burkov): Think about AGH's output suppressing with no verbose
+	# flag.
+	if ( cd "$agh_dir" && ./AdGuardHome -s install )
+	then
+		return 0
+	fi
+
+	rm -r "$agh_dir"
+
+	# Some devices detected to have armv7 CPU face the compatibility
+	# issues with actual armv7 builds.  We should try to install the
+	# armv5 binary instead.
+	#
+	# See https://github.com/AdguardTeam/AdGuardHome/issues/2542.
+	if [ "$cpu" = 'armv7' ]
+	then
+		cpu='armv5'
+		reinstall='1'
+
+		log "trying to use $cpu cpu"
+
+		rerun_with_root
+	fi
+
+	error_exit 'cannot install AdGuardHome as a service'
+}
+
+
+
+# Entrypoint
+
+# Exit the script if a pipeline fails (-e), prevent accidental filename
+# expansion (-f), and consider undefined variables as errors (-u).
+set -e -f -u
+
+# Set default values of configuration variables.
+channel='release'
+reinstall='0'
+uninstall='0'
+verbose='0'
+cpu=''
+os=''
+out_dir='/opt'
+pkg_ext='tar.gz'
+parse_opts $*
+
+echo 'starting AdGuard Home installation script'
+
+configure
+check_required
+
+if ! is_root
+then
+	rerun_with_root
+fi
+# Needs rights.
+fix_freebsd
+
+handle_existing
+
+download
+unpack
+
+install_service
+
+echo "\
+AdGuard Home is now installed and running
+you can control the service status with the following commands:
+sudo ${agh_dir}/AdGuardHome -s start|stop|restart|status|install|uninstall"