# SPDX-License-Identifier: GPL-2.0
import json as _json
import os
import re
import select
import socket
import subprocess
import time
class CmdInitFailure(Exception):
""" Command failed to start. Only raised by bkg(). """
def __init__(self, msg, cmd_obj):
super().__init__(msg + "\n" + repr(cmd_obj))
self.cmd = cmd_obj
class CmdExitFailure(Exception):
""" Command failed (returned non-zero exit code). """
def __init__(self, msg, cmd_obj):
super().__init__(msg + "\n" + repr(cmd_obj))
self.cmd = cmd_obj
class CmdExitZeroFailure(CmdExitFailure):
""" Command succeeded (returned zero exit code), but expected failure. """
def fd_read_timeout(fd, timeout):
rlist, _, _ = select.select([fd], [], [], timeout)
if rlist:
return os.read(fd, 1024)
raise TimeoutError("Timeout waiting for fd read")
class cmd:
"""
Execute a command on local or remote host.
@shell defaults to false, and class will try to split @comm into a list
if it's a string with spaces.
Use bkg() instead to run a command in the background.
"""
def __init__(self, comm, shell=None, fail=True, expect_fail=False, ns=None,
background=False, host=None, timeout=20, ksft_ready=None,
ksft_wait=None):
if ns:
if hasattr(ns, 'user_ns_path'):
comm = (f'nsenter --user={ns.user_ns_path} '
f'--net={ns.net_ns_path} --setuid=0 --setgid=0 -- '
+ comm)
else:
comm = f'ip netns exec {ns} ' + comm
self.stdout = None
self.stderr = None
self.ret = None
self.ksft_term_fd = None
self.host = host
self.comm = comm
if host:
self.proc = host.cmd(comm)
else:
# If user doesn't explicitly request shell try to avoid it.
if shell is None and isinstance(comm, str) and ' ' in comm:
comm = comm.split()
# ksft_wait lets us wait for the background process to fully start,
# we pass an FD to the child process, and wait for it to write back.
# Similarly term_fd tells child it's time to exit.
pass_fds = []
env = os.environ.copy()
if ksft_wait is not None:
wait_fd, self.ksft_term_fd = os.pipe()
pass_fds.append(wait_fd)
env["KSFT_WAIT_FD"] = str(wait_fd)
ksft_ready = True # ksft_wait implies ready
if ksft_ready is not None:
rfd, ready_fd = os.pipe()
pass_fds.append(ready_fd)
env["KSFT_READY_FD"] = str(ready_fd)
self.proc = subprocess.Popen(comm, shell=shell, stdout=subprocess.PIPE,
stderr=subprocess.PIPE, pass_fds=pass_fds,
env=env)
if ksft_wait is not None:
os.close(wait_fd)
if ksft_ready is not None:
os.close(ready_fd)
msg = fd_read_timeout(rfd, ksft_wait)
os.close(rfd)
if not msg:
terminate = self.proc.poll() is None
self._process_terminate(terminate=terminate, timeout=1)
raise CmdInitFailure("Did not receive ready message", self)
if not background:
self.process(terminate=False, fail=fail, expect_fail=expect_fail,
timeout=timeout)
def _process_terminate(self, terminate, timeout):
if terminate:
self.proc.terminate()
stdout, stderr = self.proc.communicate(timeout=timeout)
self.stdout = stdout.decode("utf-8")
self.stderr = stderr.decode("utf-8")
self.proc.stdout.close()
self.proc.stderr.close()
self.ret = self.proc.returncode
return stdout, stderr
def process(self, terminate=True, fail=None, expect_fail=False, timeout=20):
if fail is None:
fail = not terminate
if self.ksft_term_fd:
os.write(self.ksft_term_fd, b"1")
stdout, stderr = self._process_terminate(terminate=terminate,
timeout=timeout)
# Fail on unexpected test failure if fail.
# Fail on unexpected test success if expect_fail.
# Fail on negative returncode if either:
# Set by subprocess on crash or signal, this is never expected failure.
if (self.proc.returncode != 0 and fail or
(self.proc.returncode < 0 and expect_fail)):
if len(stderr) > 0 and stderr[-1] == "\n":
stderr = stderr[:-1]
raise CmdExitFailure("Command failed", self)
elif self.proc.returncode == 0 and expect_fail:
raise CmdExitZeroFailure("Command succeeded (expected fail)", self)
def __repr__(self):
def str_fmt(name, s):
name += ': '
return (name + s.strip().replace('\n', '\n' + ' ' * len(name)))
ret = "CMD"
if self.host:
ret += "[remote]"
if self.ret is None:
ret += f" (unterminated): {self.comm}\n"
elif self.ret == 0:
ret += f" (success): {self.comm}\n"
else:
ret += f": {self.comm}\n"
ret += f" EXIT: {self.ret}\n"
if self.stdout:
ret += str_fmt(" STDOUT", self.stdout) + "\n"
if self.stderr:
ret += str_fmt(" STDERR", self.stderr) + "\n"
return ret.strip()
class bkg(cmd):
"""
Run a command in the background.
Examples usage:
Run a command on remote host, and wait for it to finish.
This is usually paired with wait_port_listen() to make sure
the command has initialized:
with bkg("socat ...", exit_wait=True, host=cfg.remote) as nc:
...
Run a command and expect it to let us know that it's ready
by writing to a special file descriptor passed via KSFT_READY_FD.
Command will be terminated when we exit the context manager:
with bkg("my_binary", ksft_wait=5):
"""
def __init__(self, comm, shell=None, fail=None, expect_fail=None,
ns=None, host=None, exit_wait=False, ksft_ready=None,
ksft_wait=None):
super().__init__(comm, background=True,
shell=shell, fail=fail, expect_fail=expect_fail,
ns=ns, host=host, ksft_ready=ksft_ready,
ksft_wait=ksft_wait)
self.terminate = not exit_wait and not ksft_wait
self._exit_wait = exit_wait
self.check_fail = fail
self.expect_fail = expect_fail
if shell and self.terminate:
print("# Warning: combining shell and terminate is risky!")
print("# SIGTERM may not reach the child on zsh/ksh!")
def __enter__(self):
return self
def __exit__(self, ex_type, ex_value, ex_tb):
terminate = self.terminate
# Force termination on exception, but only if bkg() didn't already exit
# since forcing termination silences failures with fail=None
if self.proc.poll() is None:
terminate = terminate or (self._exit_wait and ex_type is not None)
return self.process(terminate=terminate, fail=self.check_fail,
expect_fail=self.expect_fail)
GLOBAL_DEFER_QUEUE = []
GLOBAL_DEFER_ARMED = False
class defer:
def __init__(self, func, *args, **kwargs):
if not callable(func):
raise Exception("defer created with un-callable object, did you call the function instead of passing its name?")
self.func = func
self.args = args
self.kwargs = kwargs
if not GLOBAL_DEFER_ARMED:
raise Exception("defer queue not armed, did you use defer() outside of a test case?")
self._queue = GLOBAL_DEFER_QUEUE
self._queue.append(self)
def __enter__(self):
return self
def __exit__(self, ex_type, ex_value, ex_tb):
return self.exec()
def exec_only(self):
self.func(*self.args, **self.kwargs)
def cancel(self):
self._queue.remove(self)
def exec(self):
self.cancel()
self.exec_only()
def tool(name, args, json=None, ns=None, host=None):
cmd_str = name + ' '
if json:
if name == 'tc':
cmd_str += '-json '
else:
cmd_str += '--json '
cmd_str += args
cmd_obj = cmd(cmd_str, ns=ns, host=host)
if json:
return _json.loads(cmd_obj.stdout)
return cmd_obj
def bpftool(args, json=None, ns=None, host=None):
return tool('bpftool', args, json=json, ns=ns, host=host)
def ip(args, json=None, ns=None, host=None):
if ns:
args = f'-netns {ns} ' + args
return tool('ip', args, json=json, host=host)
def tc(args, json=None, ns=None, host=None):
""" Helper to call tc with standard set of optional args. """
if ns:
args = f'-netns {ns} ' + args
return tool('tc', args, json=json, host=host)
def ethtool(args, json=None, ns=None, host=None):
return tool('ethtool', args, json=json, ns=ns, host=host)
def bpftrace(expr, json=None, ns=None, host=None, timeout=None):
"""
Run bpftrace and return map data (if json=True).
The output of bpftrace is inconvenient, so the helper converts
to a dict indexed by map name, e.g.:
{
"@": { ... },
"@map2": { ... },
}
"""
cmd_arr = ['bpftrace']
# Throw in --quiet if json, otherwise the output has two objects
if json:
cmd_arr += ['-f', 'json', '-q']
if timeout:
expr += ' interval:s:' + str(timeout) + ' { exit(); }'
timeout += 20
cmd_arr += ['-e', expr]
cmd_obj = cmd(cmd_arr, ns=ns, host=host, shell=False, timeout=timeout)
if json:
# bpftrace prints objects as lines
ret = {}
for l in cmd_obj.stdout.split('\n'):
if not l.strip():
continue
one = _json.loads(l)
if one.get('type') != 'map':
continue
for k, v in one["data"].items():
if k.startswith('@'):
k = k.lstrip('@')
ret[k] = v
return ret
return cmd_obj
def rand_port(stype=socket.SOCK_STREAM):
"""
Get a random unprivileged port.
"""
return rand_ports(1, stype)[0]
def rand_ports(count, stype=socket.SOCK_STREAM):
"""
Get a unique set of random unprivileged ports.
"""
sockets = []
ports = []
try:
for _ in range(count):
s = socket.socket(socket.AF_INET6, stype)
sockets.append(s)
s.bind(("", 0))
ports.append(s.getsockname()[1])
finally:
for s in sockets:
s.close()
return ports
def wait_port_listen(port, proto="tcp", ns=None, host=None, sleep=0.005, deadline=5):
end = time.monotonic() + deadline
pattern = f":{port:04X} .* "
if proto == "tcp": # for tcp protocol additionally check the socket state
pattern += "0A"
pattern = re.compile(pattern)
while True:
data = cmd(f'cat /proc/net/{proto}*', ns=ns, host=host, shell=True).stdout
for row in data.split("\n"):
if pattern.search(row):
return
if time.monotonic() > end:
raise Exception("Waiting for port listen timed out")
time.sleep(sleep)
def wait_file(fname, test_fn, sleep=0.005, deadline=5, encoding='utf-8'):
"""
Wait for file contents on the local system to satisfy a condition.
test_fn() should take one argument (file contents) and return whether
condition is met.
"""
end = time.monotonic() + deadline
with open(fname, "r", encoding=encoding) as fp:
while True:
if test_fn(fp.read()):
break
fp.seek(0)
if time.monotonic() > end:
raise TimeoutError("Wait for file contents failed", fname)
time.sleep(sleep)
