middleclick-autoscroll 1.0.0

Middle-click autoscroll for every Chromium-based application on the system:
Electron and CEF applications, Chromium-based browsers, Flatpaks, Spotify and
Steam, plus anything installed later.

The flag goes into an Arch wrapper's <name>-flags.conf where one exists, and
into a shadowing desktop entry where it does not. Steam gets its web helper
script patched and -noverifyfiles on its launcher, because it restores its own
files otherwise. Every change is recorded so it can be taken back exactly.

src/lib/config.sh

@@ -0,0 +1,162 @@
+# shellcheck shell=bash
+#
+# Reading and writing ~/.config/middleclick-autoscroll/config.
+#
+# The file exists so the tool has somewhere to remember what it was told; it is
+# not meant to be edited. Every option it holds is reachable from the interface,
+# which is why there is no commented template shipped anywhere and no reference
+# to the path in the interface itself.
+#
+# It is parsed rather than sourced. One "Key=Value" per line, '#' comments.
+
+MCA_CONFIG_CACHE=''
+MCA_CONFIG_CACHED=0
+
+_mca_config_slurp() {
+	(( MCA_CONFIG_CACHED )) && return 0
+	MCA_CONFIG_CACHE=''
+	[[ -r $MCA_CONFIG ]] && MCA_CONFIG_CACHE="$(< "$MCA_CONFIG")"
+	MCA_CONFIG_CACHED=1
+	return 0
+}
+
+# _mca_config_lookup <Key> [default]
+# Result in MCA_CONFIG_VALUE. Assigning rather than printing matters on the
+# settings screen, which reads every key on every frame: a command substitution
+# there is a fork, and forks are the whole cost of a redraw.
+MCA_CONFIG_VALUE=''
+
+_mca_config_lookup() {
+	local key="$1" default="${2:-}" val='' line
+
+	MCA_CONFIG_VALUE="$default"
+	[[ -r $MCA_CONFIG ]] || return 0
+	_mca_config_slurp
+
+	while IFS= read -r line; do
+		[[ $line == *"$key"* ]] || continue
+		[[ $line =~ ^[[:space:]]*"$key"[[:space:]]*=(.*)$ ]] || continue
+		val="${BASH_REMATCH[1]}"
+	done <<< "$MCA_CONFIG_CACHE"
+
+	val="${val%%#*}"
+	val="${val#"${val%%[![:space:]]*}"}"
+	val="${val%"${val##*[![:space:]]}"}"
+	val="${val%\"}"
+	val="${val#\"}"
+
+	[[ -n $val ]] && MCA_CONFIG_VALUE="$val"
+	return 0
+}
+
+# mca_config_get <Key> [default]
+mca_config_get() {
+	_mca_config_lookup "$@"
+	printf '%s\n' "$MCA_CONFIG_VALUE"
+}
+
+# mca_config_bool <Key> <default: yes|no>
+mca_config_bool() {
+	local val
+	val="$(mca_config_get "$1" "$2")"
+	case "${val,,}" in
+		yes|y|true|1|on|enabled) return 0 ;;
+		*) return 1 ;;
+	esac
+}
+
+# mca_config_set <Key> <Value>
+mca_config_set() {
+	local key="$1" value="$2" tmp
+
+	if [[ ! -e $MCA_CONFIG ]]; then
+		mkdir -p "$(dirname "$MCA_CONFIG")" || return 1
+		{
+			printf '# %s\n' "$MCA_PRETTY"
+			printf '#\n'
+			printf '# Written by `%s`. Nothing here needs editing by hand -\n' "$MCA_NAME"
+			printf '# every option is reachable from `%s` itself.\n' "$MCA_NAME"
+		} > "$MCA_CONFIG" || return 1
+	fi
+	[[ -w $MCA_CONFIG ]] || return 1
+
+	tmp="$(mktemp "${MCA_CONFIG}.XXXXXX")" || return 1
+	chmod --reference="$MCA_CONFIG" "$tmp" 2>/dev/null || chmod 0644 "$tmp"
+
+	if grep -qE "^[[:space:]]*#?[[:space:]]*${key}[[:space:]]*=" "$MCA_CONFIG"; then
+		awk -v key="$key" -v value="$value" '
+			!done && $0 ~ "^[[:space:]]*#?[[:space:]]*" key "[[:space:]]*=" {
+				print key "=" value; done = 1; next
+			}
+			# drop any further occurrences so the file cannot grow duplicates
+			$0 ~ "^[[:space:]]*" key "[[:space:]]*=" { next }
+			{ print }
+		' "$MCA_CONFIG" > "$tmp" || { rm -f "$tmp"; return 1; }
+	else
+		cat "$MCA_CONFIG" > "$tmp" || { rm -f "$tmp"; return 1; }
+		printf '%s=%s\n' "$key" "$value" >> "$tmp"
+	fi
+
+	mv -f "$tmp" "$MCA_CONFIG"
+	MCA_CONFIG_CACHED=0
+}
+
+# mca_config_list_has <Key> <item>
+# The per-application overrides are stored as space separated lists.
+mca_config_list_has() {
+	local list item="$2" entry
+	list="$(mca_config_get "$1" '')"
+	for entry in $list; do
+		[[ $entry == "$item" ]] && return 0
+	done
+	return 1
+}
+
+# mca_config_list_add <Key> <item> / mca_config_list_del <Key> <item>
+mca_config_list_add() {
+	local key="$1" item="$2" list
+	mca_config_list_has "$key" "$item" && return 0
+	list="$(mca_config_get "$key" '')"
+	mca_config_set "$key" "${list:+$list }$item"
+}
+
+mca_config_list_del() {
+	local key="$1" item="$2" list entry out=''
+	list="$(mca_config_get "$key" '')"
+	for entry in $list; do
+		[[ $entry == "$item" ]] && continue
+		out="${out:+$out }$entry"
+	done
+	mca_config_set "$key" "$out"
+}
+
+# ---------------------------------------------------------------------------
+# Resolved settings
+# ---------------------------------------------------------------------------
+
+mca_config_load() {
+	CFG_ENABLED=no;    mca_config_bool Enabled          no  && CFG_ENABLED=yes
+	CFG_APPS=no;       mca_config_bool PatchApps        yes && CFG_APPS=yes
+	CFG_BROWSERS=no;   mca_config_bool PatchBrowsers    yes && CFG_BROWSERS=yes
+	CFG_FLATPAK=no;    mca_config_bool PatchFlatpak     yes && CFG_FLATPAK=yes
+	CFG_AUTOSTART=no;  mca_config_bool PatchAutostart   yes && CFG_AUTOSTART=yes
+	CFG_STEAM=no;      mca_config_bool PatchSteam       yes && CFG_STEAM=yes
+	CFG_SPOTIFY=no;    mca_config_bool PatchSpotify     yes && CFG_SPOTIFY=yes
+	CFG_WATCH=no;      mca_config_bool WatchNewApps     yes && CFG_WATCH=yes
+
+	CFG_EXTRA_FLAGS="$(mca_config_get ExtraFlags '')"
+
+	# Applications the user turned on or off by hand on the applications
+	# screen, by desktop file id. Include wins over detection, Skip wins over
+	# everything.
+	CFG_INCLUDE="$(mca_config_get Include '')"
+	CFG_SKIP="$(mca_config_get Skip '')"
+}
+
+# The full argument string that gets injected. Kept in one place so the flag
+# file writer and the desktop entry writer cannot drift apart.
+mca_flags() {
+	printf '%s' "$MCA_FLAG"
+	[[ -n ${CFG_EXTRA_FLAGS:-} ]] && printf ' %s' "$CFG_EXTRA_FLAGS"
+	printf '\n'
+}