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pytest-server-fixtures: Support large pids in xvfb #250

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pytest-server-fixtures: Support large pids in xvfb #250

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5 changes: 4 additions & 1 deletion pytest-server-fixtures/pytest_server_fixtures/xvfb.py
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,10 @@ class XvfbServer(object):

def __init__(self):
tmpdir = mkdtemp(prefix='XvfbServer.', dir=Workspace.get_base_tempdir())
for servernum in range(os.getpid(), 65536):
pid_max = 65536
with open('/proc/sys/kernel/pid_max') as pid_max_file:
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Is this guaranteed to exist on all Linux distributions? We should probably safely fall back to 65536 if the file doesn't exist.

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We do fall back, it's set before we open the /proc file. That /proc file was added sometime in 2.5, so it should exist, but it may throw an exception if /proc isn't mounted -- but we probably have bigger problems in that case.

pid_max = int(pid_max_file.read())
for servernum in range(os.getpid(), pid_max):
if os.path.exists('/tmp/.X{0}-lock'.format(servernum)):
continue
self.display = ':' + str(servernum)
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22 changes: 21 additions & 1 deletion pytest-server-fixtures/tests/integration/test_xvfb_server.py
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Expand Up @@ -5,7 +5,7 @@
from itertools import chain, repeat

try:
from unittest.mock import patch
from unittest.mock import mock_open, patch
except ImportError:
# python 2
from mock import patch
Expand Down Expand Up @@ -69,3 +69,23 @@ def test_handles_unexpected_failure_to_start():
with raises(RuntimeError) as ex:
XvfbServer()
assert 'Failed to start Xvfb' in str(ex)


def test_handles_64_bit_pids():
with patch('os.getpid') as mock_getpid:
# This just has to be larger than 65535
mock_getpid.return_value = 65537
with XvfbServer() as server:
assert server.display


def test_errors_64_bit_pids():
with patch('os.getpid') as mock_getpid:
target = 'pytest_server_fixtures.xvfb.open'
with patch(target, mock_open(read_data='4')) as m:
# This just has to be larger than the returned max PID
mock_getpid.return_value = 7
with raises(RuntimeError) as ex:
XvfbServer()
m.assert_called_once_with('/proc/sys/kernel/pid_max')
assert 'Unable to find a free server number to start Xvfb' in str(ex)