1# SPDX-License-Identifier: GPL-2.0 2 3import json as _json 4import os 5import re 6import select 7import socket 8import subprocess 9import time 10 11 12class CmdExitFailure(Exception): 13 def __init__(self, msg, cmd_obj): 14 super().__init__(msg) 15 self.cmd = cmd_obj 16 17 18def fd_read_timeout(fd, timeout): 19 rlist, _, _ = select.select([fd], [], [], timeout) 20 if rlist: 21 return os.read(fd, 1024) 22 raise TimeoutError("Timeout waiting for fd read") 23 24 25class cmd: 26 """ 27 Execute a command on local or remote host. 28 29 @shell defaults to false, and class will try to split @comm into a list 30 if it's a string with spaces. 31 32 Use bkg() instead to run a command in the background. 33 """ 34 def __init__(self, comm, shell=None, fail=True, ns=None, background=False, 35 host=None, timeout=5, ksft_wait=None): 36 if ns: 37 comm = f'ip netns exec {ns} ' + comm 38 39 self.stdout = None 40 self.stderr = None 41 self.ret = None 42 self.ksft_term_fd = None 43 44 self.comm = comm 45 if host: 46 self.proc = host.cmd(comm) 47 else: 48 # If user doesn't explicitly request shell try to avoid it. 49 if shell is None and isinstance(comm, str) and ' ' in comm: 50 comm = comm.split() 51 52 # ksft_wait lets us wait for the background process to fully start, 53 # we pass an FD to the child process, and wait for it to write back. 54 # Similarly term_fd tells child it's time to exit. 55 pass_fds = () 56 env = os.environ.copy() 57 if ksft_wait is not None: 58 rfd, ready_fd = os.pipe() 59 wait_fd, self.ksft_term_fd = os.pipe() 60 pass_fds = (ready_fd, wait_fd, ) 61 env["KSFT_READY_FD"] = str(ready_fd) 62 env["KSFT_WAIT_FD"] = str(wait_fd) 63 64 self.proc = subprocess.Popen(comm, shell=shell, stdout=subprocess.PIPE, 65 stderr=subprocess.PIPE, pass_fds=pass_fds, 66 env=env) 67 if ksft_wait is not None: 68 os.close(ready_fd) 69 os.close(wait_fd) 70 msg = fd_read_timeout(rfd, ksft_wait) 71 os.close(rfd) 72 if not msg: 73 raise Exception("Did not receive ready message") 74 if not background: 75 self.process(terminate=False, fail=fail, timeout=timeout) 76 77 def process(self, terminate=True, fail=None, timeout=5): 78 if fail is None: 79 fail = not terminate 80 81 if self.ksft_term_fd: 82 os.write(self.ksft_term_fd, b"1") 83 if terminate: 84 self.proc.terminate() 85 stdout, stderr = self.proc.communicate(timeout) 86 self.stdout = stdout.decode("utf-8") 87 self.stderr = stderr.decode("utf-8") 88 self.proc.stdout.close() 89 self.proc.stderr.close() 90 self.ret = self.proc.returncode 91 92 if self.proc.returncode != 0 and fail: 93 if len(stderr) > 0 and stderr[-1] == "\n": 94 stderr = stderr[:-1] 95 raise CmdExitFailure("Command failed: %s\nSTDOUT: %s\nSTDERR: %s" % 96 (self.proc.args, stdout, stderr), self) 97 98 99class bkg(cmd): 100 """ 101 Run a command in the background. 102 103 Examples usage: 104 105 Run a command on remote host, and wait for it to finish. 106 This is usually paired with wait_port_listen() to make sure 107 the command has initialized: 108 109 with bkg("socat ...", exit_wait=True, host=cfg.remote) as nc: 110 ... 111 112 Run a command and expect it to let us know that it's ready 113 by writing to a special file descriptor passed via KSFT_READY_FD. 114 Command will be terminated when we exit the context manager: 115 116 with bkg("my_binary", ksft_wait=5): 117 """ 118 def __init__(self, comm, shell=None, fail=None, ns=None, host=None, 119 exit_wait=False, ksft_wait=None): 120 super().__init__(comm, background=True, 121 shell=shell, fail=fail, ns=ns, host=host, 122 ksft_wait=ksft_wait) 123 self.terminate = not exit_wait and not ksft_wait 124 self._exit_wait = exit_wait 125 self.check_fail = fail 126 127 if shell and self.terminate: 128 print("# Warning: combining shell and terminate is risky!") 129 print("# SIGTERM may not reach the child on zsh/ksh!") 130 131 def __enter__(self): 132 return self 133 134 def __exit__(self, ex_type, ex_value, ex_tb): 135 # Force termination on exception 136 terminate = self.terminate or (self._exit_wait and ex_type) 137 return self.process(terminate=terminate, fail=self.check_fail) 138 139 140global_defer_queue = [] 141 142 143class defer: 144 def __init__(self, func, *args, **kwargs): 145 if not callable(func): 146 raise Exception("defer created with un-callable object, did you call the function instead of passing its name?") 147 148 self.func = func 149 self.args = args 150 self.kwargs = kwargs 151 152 self._queue = global_defer_queue 153 self._queue.append(self) 154 155 def __enter__(self): 156 return self 157 158 def __exit__(self, ex_type, ex_value, ex_tb): 159 return self.exec() 160 161 def exec_only(self): 162 self.func(*self.args, **self.kwargs) 163 164 def cancel(self): 165 self._queue.remove(self) 166 167 def exec(self): 168 self.cancel() 169 self.exec_only() 170 171 172def tool(name, args, json=None, ns=None, host=None): 173 cmd_str = name + ' ' 174 if json: 175 cmd_str += '--json ' 176 cmd_str += args 177 cmd_obj = cmd(cmd_str, ns=ns, host=host) 178 if json: 179 return _json.loads(cmd_obj.stdout) 180 return cmd_obj 181 182 183def bpftool(args, json=None, ns=None, host=None): 184 return tool('bpftool', args, json=json, ns=ns, host=host) 185 186 187def ip(args, json=None, ns=None, host=None): 188 if ns: 189 args = f'-netns {ns} ' + args 190 return tool('ip', args, json=json, host=host) 191 192 193def ethtool(args, json=None, ns=None, host=None): 194 return tool('ethtool', args, json=json, ns=ns, host=host) 195 196 197def bpftrace(expr, json=None, ns=None, host=None, timeout=None): 198 """ 199 Run bpftrace and return map data (if json=True). 200 The output of bpftrace is inconvenient, so the helper converts 201 to a dict indexed by map name, e.g.: 202 { 203 "@": { ... }, 204 "@map2": { ... }, 205 } 206 """ 207 cmd_arr = ['bpftrace'] 208 # Throw in --quiet if json, otherwise the output has two objects 209 if json: 210 cmd_arr += ['-f', 'json', '-q'] 211 if timeout: 212 expr += ' interval:s:' + str(timeout) + ' { exit(); }' 213 cmd_arr += ['-e', expr] 214 cmd_obj = cmd(cmd_arr, ns=ns, host=host, shell=False) 215 if json: 216 # bpftrace prints objects as lines 217 ret = {} 218 for l in cmd_obj.stdout.split('\n'): 219 if not l.strip(): 220 continue 221 one = _json.loads(l) 222 if one.get('type') != 'map': 223 continue 224 for k, v in one["data"].items(): 225 if k.startswith('@'): 226 k = k.lstrip('@') 227 ret[k] = v 228 return ret 229 return cmd_obj 230 231 232def rand_port(stype=socket.SOCK_STREAM): 233 """ 234 Get a random unprivileged port. 235 """ 236 with socket.socket(socket.AF_INET6, stype) as s: 237 s.bind(("", 0)) 238 return s.getsockname()[1] 239 240 241def wait_port_listen(port, proto="tcp", ns=None, host=None, sleep=0.005, deadline=5): 242 end = time.monotonic() + deadline 243 244 pattern = f":{port:04X} .* " 245 if proto == "tcp": # for tcp protocol additionally check the socket state 246 pattern += "0A" 247 pattern = re.compile(pattern) 248 249 while True: 250 data = cmd(f'cat /proc/net/{proto}*', ns=ns, host=host, shell=True).stdout 251 for row in data.split("\n"): 252 if pattern.search(row): 253 return 254 if time.monotonic() > end: 255 raise Exception("Waiting for port listen timed out") 256 time.sleep(sleep) 257 258 259def wait_file(fname, test_fn, sleep=0.005, deadline=5, encoding='utf-8'): 260 """ 261 Wait for file contents on the local system to satisfy a condition. 262 test_fn() should take one argument (file contents) and return whether 263 condition is met. 264 """ 265 end = time.monotonic() + deadline 266 267 with open(fname, "r", encoding=encoding) as fp: 268 while True: 269 if test_fn(fp.read()): 270 break 271 fp.seek(0) 272 if time.monotonic() > end: 273 raise TimeoutError("Wait for file contents failed", fname) 274 time.sleep(sleep) 275