xref: /linux/tools/testing/selftests/net/packetdrill/set_sysctls.py (revision 836265d31631e28000fc8917ce697fc687a58724)
1#!/usr/bin/env python3
2# SPDX-License-Identifier: GPL-2.0
3
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 creates
8a shell script named "/tmp/sysctl_restore_${PACKETDRILL_PID}.sh" which
9restores the values when executed. It then sets the new values.
10
11PACKETDRILL_PID is set by packetdrill to the pid of itself, so a .pkt
12file could restore sysctls by running `/tmp/sysctl_restore_${PPID}.sh`
13at the end.
14"""
15
16import os
17import subprocess
18import sys
19
20filename = '/tmp/sysctl_restore_%s.sh' % os.environ['PACKETDRILL_PID']
21
22# Open file for restoring sysctl values
23restore_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 value
29
30  # read current value and add restore command to file
31  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 value
35  cmd = 'echo "%s" > %s' % (sysctl[1], sysctl[0])
36  os.system(cmd)
37
38os.system('chmod u+x %s' % filename)
39