#!/bin/bash

if [[ "$1" == '-h' || $# -ne 2 ]]
then
	echo 'Usage: kill-wpull-connections (-p PID | -j JOBID | -h)'
	echo
	echo ' -h: Display this message and exit'
	echo ' -j JOBID: Kill connections of the wpull process for ArchiveBot job JOBID'
	echo ' -p PID: Kill connections of wpull process PID'
	[[ "$1" == '-h' && $# -eq 1 ]] && exit 0 || exit 1
fi

if [[ "$1" == '-p' ]]
then
	wpullPid=$2
	if [[ "${wpullPid}" == *[^0-9]* ]]
	then
		echo "Error: '${wpullPid}' is not a valid PID"
		exit 1
	fi
elif [[ "$1" == '-j' ]]
then
	pids=($(pgrep --full "wpull.*/$2/"))
	if [[ ${#pids[@]} -ne 1 ]]
	then
		echo "Error: not exactly one process found for '$2'"
		exit 1
	fi
	wpullPid=${pids[0]}
fi

if ! command -v lsof >/dev/null 2>&1
then
	echo "Error: could not find lsof"
	exit 1
fi

if ! command -v gdb >/dev/null 2>&1
then
	echo "Error: could not find gdb"
	exit 1
fi

if ! ps -p ${wpullPid} >/dev/null 2>&1
then
	echo "Error: no process with PID ${wpullPid}"
	exit 1
fi

if [[ -e /proc/sys/kernel/yama/ptrace_scope && "$(< /proc/sys/kernel/yama/ptrace_scope)" != "0" && $EUID -ne 0 ]]
then
	echo "Warning: /proc/sys/kernel/yama/ptrace_scope is not zero. You likely need to run this script as root."
fi

gdb -batch -batch-silent \
	-ex "attach ${wpullPid}" \
	-ex 'python import subprocess' \
	-ex 'python def call(s): return subprocess.call(s, shell = True) == 0' \
	-ex 'python call("echo '\''FDs before forced shutdown:'\''") and call("lsof -an -p '${wpullPid}' -i TCP | grep -v 127\.0\.0\.1") and ([gdb.execute("p shutdown(" + fd + ", 2)") for fd in subprocess.check_output("lsof -an -p '${wpullPid}' -i TCP -F pfn | awk '\''NR%2==0{fd=substr($0,2)}NR%2==1&&NR>1&&!/127\.0\.0\.1/{print fd}'\''", shell = True).decode("ascii").strip().split("\n")] or True) and call("echo '\''FDs after forced shutdown:'\''") and call("lsof -an -p '${wpullPid}' -i TCP | grep -v 127\.0\.0\.1")' \
	-ex detach \
	-ex quit