39 lines
1.2 KiB
Python
Executable File
39 lines
1.2 KiB
Python
Executable File
#!/usr/bin/env python3
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# SPDX-License-Identifier: GPL-2.0
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"""Sets sysctl values and writes a file that restores them.
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The arguments are of the form "<proc-file>=<val>" separated by spaces.
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The program first reads the current value of the proc-file and creates
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a shell script named "/tmp/sysctl_restore_${PACKETDRILL_PID}.sh" which
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restores the values when executed. It then sets the new values.
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PACKETDRILL_PID is set by packetdrill to the pid of itself, so a .pkt
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file could restore sysctls by running `/tmp/sysctl_restore_${PPID}.sh`
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at the end.
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"""
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import os
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import subprocess
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import sys
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filename = '/tmp/sysctl_restore_%s.sh' % os.environ['PACKETDRILL_PID']
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# Open file for restoring sysctl values
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restore_file = open(filename, 'w')
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print('#!/bin/bash', file=restore_file)
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for a in sys.argv[1:]:
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sysctl = a.split('=')
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# sysctl[0] contains the proc-file name, sysctl[1] the new value
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# read current value and add restore command to file
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cur_val = subprocess.check_output(['cat', sysctl[0]], universal_newlines=True)
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print('echo "%s" > %s' % (cur_val.strip(), sysctl[0]), file=restore_file)
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# set new value
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cmd = 'echo "%s" > %s' % (sysctl[1], sysctl[0])
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os.system(cmd)
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os.system('chmod u+x %s' % filename)
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