Fix arc_summary.py -d crash with Python3

Prevents arc_summary.py crashing when called with parameter -d or
long form --description with Python3.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Scot W. Stevenson <scot.stevenson@gmail.com>
Closes #6849 
Closes #6850
This commit is contained in:
Scot W. Stevenson 2017-11-12 05:27:43 +01:00 committed by Brian Behlendorf
parent 7c351e31d5
commit 5277f208f2

View File

@ -39,12 +39,12 @@ in-source documentation and code at
https://github.com/zfsonlinux/zfs/blob/master/module/zfs/arc.c for details.
"""
import getopt
import os
import re
import sys
import time
import getopt
import re
from os import listdir
from subprocess import Popen, PIPE
from decimal import Decimal as D
@ -858,12 +858,12 @@ def _vdev_summary(Kstat):
def _tunable_summary(Kstat):
"""Print information on tunables"""
"""Print information on tunables, including descriptions if requested"""
global show_tunable_descriptions
global alternate_tunable_layout
names = listdir("/sys/module/zfs/parameters/")
names = os.listdir("/sys/module/zfs/parameters/")
values = {}
for name in names:
@ -874,13 +874,21 @@ def _tunable_summary(Kstat):
descriptions = {}
if show_tunable_descriptions:
command = ["/sbin/modinfo", "zfs", "-0"]
try:
command = ["/sbin/modinfo", "zfs", "-0"]
p = Popen(command, stdin=PIPE, stdout=PIPE,
stderr=PIPE, shell=False, close_fds=True)
p.wait()
description_list = p.communicate()[0].strip().split('\0')
# By default, Python 2 returns a string as the first element of the
# tuple from p.communicate(), while Python 3 returns bytes which
# must be decoded first. The better way to do this would be with
# subprocess.run() or at least .check_output(), but this fails on
# CentOS 6 because of its old version of Python 2
desc = bytes.decode(p.communicate()[0])
description_list = desc.strip().split('\0')
if p.returncode == 0:
for tunable in description_list:
@ -899,7 +907,7 @@ def _tunable_summary(Kstat):
(sys.argv[0], command[0], e.strerror))
sys.stderr.write("Tunable descriptions will be disabled.\n")
sys.stdout.write("ZFS Tunable:\n")
sys.stdout.write("ZFS Tunables:\n")
names.sort()
if alternate_tunable_layout: