fix(termux-bootstrap-second-stage.sh): do not exit with the wrong "second stage has already been run before" error if ln process used to create lock file got killed instead of failing to create lock file if it already existed

Related termux/termux-app#4219

Author: agnostic-apollo

scripts/bootstrap/termux-bootstrap-second-stage.sh

@@ -92,16 +92,29 @@ run_bootstrap_second_stage() {
 
 	local return_value
 
-	if ! ln -s "termux-bootstrap-second-stage.sh" \
-		"@TERMUX_BOOTSTRAPS__BOOTSTRAP_CONFIG_DIR@/termux-bootstrap-second-stage.sh.lock" 2>/dev/null; then
-		log "The termux bootstrap second stage has already been run before and cannot be run again."
-		log "If you still want to force run it again (not recommended), \
+	local output
+
+	output="$(ln -s "termux-bootstrap-second-stage.sh" \
+		"@TERMUX_BOOTSTRAPS__BOOTSTRAP_CONFIG_DIR@/termux-bootstrap-second-stage.sh.lock" 2>&1)"
+	return_value=$?
+	if [ $return_value -ne 0 ]; then
+		if [ $return_value -eq 1 ] && [[ "$output" == *"File exists"* ]]; then
+			log "The termux bootstrap second stage has already been run before and cannot be run again."
+			log "If you still want to force run it again (not recommended), \
 like in case of previous failure and it must be re-run again for testing, \
 then delete the '@TERMUX_BOOTSTRAPS__BOOTSTRAP_CONFIG_DIR@/termux-bootstrap-second-stage.sh.lock' \
 file manually and run 'termux-bootstrap-second-stage.sh' again."
-		return 0
+			return 0
+		else
+			log_error "$output"
+			log_error "Failed to create lock file for termux bootstrap second stage at \
+'@TERMUX_BOOTSTRAPS__BOOTSTRAP_CONFIG_DIR@/termux-bootstrap-second-stage.sh.lock'"
+			warn_if_process_killed "$return_value" "ln"
+			return $return_value
+		fi
 	fi
 
+
 	log "Running termux bootstrap second stage"
 	run_bootstrap_second_stage_inner
 	return_value=$?
@@ -112,6 +125,7 @@ file manually and run 'termux-bootstrap-second-stage.sh' again."
 
 	log "The termux bootstrap second stage completed successfully"
 
+
 	return 0
 
 }
@@ -360,6 +374,30 @@ run_package_postinst_maintainer_scripts() {
 
 }
 
+
+
+
+
+warn_if_process_killed() {
+
+	local return_value="${1:-}"
+	local command="${2:-}"
+
+	if [[ "$return_value" == "137" ]]; then
+		log_error "The '$command' command was apparently killed with SIGKILL (signal 9). \
+This may have been due to the security policies of the Android OS installed on your device.
+Check https://github.com/termux/termux-app/issues/4219 for more info."
+		return 0
+	fi
+
+	return 1
+
+}
+
+
+
+
+
 # If running in bash, run script logic, otherwise exit with usage error
 if [ -n "${BASH_VERSION:-}" ]; then
 	# If script is sourced, return with error, otherwise call main function