39 lines · python
1#!/usr/bin/env python32# SPDX-License-Identifier: GPL-2.03 4"""Sets sysctl values and writes a file that restores them.5 6The arguments are of the form "<proc-file>=<val>" separated by spaces.7The program first reads the current value of the proc-file and creates8a shell script named "/tmp/sysctl_restore_${PACKETDRILL_PID}.sh" which9restores the values when executed. It then sets the new values.10 11PACKETDRILL_PID is set by packetdrill to the pid of itself, so a .pkt12file could restore sysctls by running `/tmp/sysctl_restore_${PPID}.sh`13at the end.14"""15 16import os17import subprocess18import sys19 20filename = '/tmp/sysctl_restore_%s.sh' % os.environ['PACKETDRILL_PID']21 22# Open file for restoring sysctl values23restore_file = open(filename, 'w')24print('#!/bin/bash', file=restore_file)25 26for a in sys.argv[1:]:27 sysctl = a.split('=')28 # sysctl[0] contains the proc-file name, sysctl[1] the new value29 30 # read current value and add restore command to file31 cur_val = subprocess.check_output(['cat', sysctl[0]], universal_newlines=True)32 print('echo "%s" > %s' % (cur_val.strip(), sysctl[0]), file=restore_file)33 34 # set new value35 cmd = 'echo "%s" > %s' % (sysctl[1], sysctl[0])36 os.system(cmd)37 38os.system('chmod u+x %s' % filename)39