| # Copyright 2016 The Android Open Source Project |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """Various utility functions.""" |
| |
| import errno |
| import functools |
| import os |
| import signal |
| import subprocess |
| import sys |
| import tempfile |
| import time |
| |
| _path = os.path.realpath(__file__ + '/../..') |
| if sys.path[0] != _path: |
| sys.path.insert(0, _path) |
| del _path |
| |
| # pylint: disable=wrong-import-position |
| import rh.shell |
| import rh.signals |
| |
| |
| def timedelta_str(delta): |
| """A less noisy timedelta.__str__. |
| |
| The default timedelta stringification contains a lot of leading zeros and |
| uses microsecond resolution. This makes for noisy output. |
| """ |
| total = delta.total_seconds() |
| hours, rem = divmod(total, 3600) |
| mins, secs = divmod(rem, 60) |
| ret = f'{int(secs)}.{delta.microseconds // 1000:03}s' |
| if mins: |
| ret = f'{int(mins)}m{ret}' |
| if hours: |
| ret = f'{int(hours)}h{ret}' |
| return ret |
| |
| |
| class CompletedProcess(subprocess.CompletedProcess): |
| """An object to store various attributes of a child process. |
| |
| This is akin to subprocess.CompletedProcess. |
| """ |
| |
| def __init__(self, args=None, returncode=None, stdout=None, stderr=None): |
| super().__init__( |
| args=args, returncode=returncode, stdout=stdout, stderr=stderr) |
| |
| @property |
| def cmd(self): |
| """Alias to self.args to better match other subprocess APIs.""" |
| return self.args |
| |
| @property |
| def cmdstr(self): |
| """Return self.cmd as a nicely formatted string (useful for logs).""" |
| return rh.shell.cmd_to_str(self.cmd) |
| |
| |
| class CalledProcessError(subprocess.CalledProcessError): |
| """Error caught in run() function. |
| |
| This is akin to subprocess.CalledProcessError. We do not support |output|, |
| only |stdout|. |
| |
| Attributes: |
| returncode: The exit code of the process. |
| cmd: The command that triggered this exception. |
| msg: Short explanation of the error. |
| """ |
| |
| def __init__(self, returncode, cmd, stdout=None, stderr=None, msg=None): |
| super().__init__(returncode, cmd, stdout, stderr=stderr) |
| |
| # The parent class will set |output|, so delete it. If Python ever drops |
| # this output/stdout compat logic, we can drop this to match. |
| del self.output |
| self._stdout = stdout |
| |
| self.msg = msg |
| |
| @property |
| def stdout(self): |
| """Override parent's usage of .output""" |
| return self._stdout |
| |
| @stdout.setter |
| def stdout(self, value): |
| """Override parent's usage of .output""" |
| self._stdout = value |
| |
| @property |
| def cmdstr(self): |
| """Return self.cmd as a well shell-quoted string for debugging.""" |
| return '' if self.cmd is None else rh.shell.cmd_to_str(self.cmd) |
| |
| def stringify(self, stdout=True, stderr=True): |
| """Custom method for controlling what is included in stringifying this. |
| |
| Args: |
| stdout: Whether to include captured stdout in the return value. |
| stderr: Whether to include captured stderr in the return value. |
| |
| Returns: |
| A summary string for this result. |
| """ |
| items = [ |
| f'return code: {self.returncode}; command: {self.cmdstr}', |
| ] |
| if stderr and self.stderr: |
| items.append(self.stderr) |
| if stdout and self.stdout: |
| items.append(self.stdout) |
| if self.msg: |
| items.append(self.msg) |
| return '\n'.join(items) |
| |
| def __str__(self): |
| return self.stringify() |
| |
| |
| class TerminateCalledProcessError(CalledProcessError): |
| """We were signaled to shutdown while running a command. |
| |
| Client code shouldn't generally know, nor care about this class. It's |
| used internally to suppress retry attempts when we're signaled to die. |
| """ |
| |
| |
| def _kill_child_process(proc, int_timeout, kill_timeout, cmd, original_handler, |
| signum, frame): |
| """Used as a signal handler by RunCommand. |
| |
| This is internal to Runcommand. No other code should use this. |
| """ |
| if signum: |
| # If we've been invoked because of a signal, ignore delivery of that |
| # signal from this point forward. The invoking context of this func |
| # restores signal delivery to what it was prior; we suppress future |
| # delivery till then since this code handles SIGINT/SIGTERM fully |
| # including delivering the signal to the original handler on the way |
| # out. |
| signal.signal(signum, signal.SIG_IGN) |
| |
| # Do not trust Popen's returncode alone; we can be invoked from contexts |
| # where the Popen instance was created, but no process was generated. |
| if proc.returncode is None and proc.pid is not None: |
| try: |
| while proc.poll_lock_breaker() is None and int_timeout >= 0: |
| time.sleep(0.1) |
| int_timeout -= 0.1 |
| |
| proc.terminate() |
| while proc.poll_lock_breaker() is None and kill_timeout >= 0: |
| time.sleep(0.1) |
| kill_timeout -= 0.1 |
| |
| if proc.poll_lock_breaker() is None: |
| # Still doesn't want to die. Too bad, so sad, time to die. |
| proc.kill() |
| except EnvironmentError as e: |
| print(f'Ignoring unhandled exception in _kill_child_process: {e}', |
| file=sys.stderr) |
| |
| # Ensure our child process has been reaped, but don't wait forever. |
| proc.wait_lock_breaker(timeout=60) |
| |
| if not rh.signals.relay_signal(original_handler, signum, frame): |
| # Mock up our own, matching exit code for signaling. |
| raise TerminateCalledProcessError( |
| signum << 8, cmd, msg=f'Received signal {signum}') |
| |
| |
| class _Popen(subprocess.Popen): |
| """subprocess.Popen derivative customized for our usage. |
| |
| Specifically, we fix terminate/send_signal/kill to work if the child process |
| was a setuid binary; on vanilla kernels, the parent can wax the child |
| regardless, on goobuntu this apparently isn't allowed, thus we fall back |
| to the sudo machinery we have. |
| |
| While we're overriding send_signal, we also suppress ESRCH being raised |
| if the process has exited, and suppress signaling all together if the |
| process has knowingly been waitpid'd already. |
| """ |
| |
| # pylint: disable=arguments-differ,arguments-renamed |
| def send_signal(self, signum): |
| if self.returncode is not None: |
| # The original implementation in Popen allows signaling whatever |
| # process now occupies this pid, even if the Popen object had |
| # waitpid'd. Since we can escalate to sudo kill, we do not want |
| # to allow that. Fixing this addresses that angle, and makes the |
| # API less sucky in the process. |
| return |
| |
| try: |
| os.kill(self.pid, signum) |
| except EnvironmentError as e: |
| if e.errno == errno.ESRCH: |
| # Since we know the process is dead, reap it now. |
| # Normally Popen would throw this error- we suppress it since |
| # frankly that's a misfeature and we're already overriding |
| # this method. |
| self.poll() |
| else: |
| raise |
| |
| def _lock_breaker(self, func, *args, **kwargs): |
| """Helper to manage the waitpid lock. |
| |
| Workaround https://bugs.python.org/issue25960. |
| """ |
| # If the lock doesn't exist, or is not locked, call the func directly. |
| lock = getattr(self, '_waitpid_lock', None) |
| if lock is not None and lock.locked(): |
| try: |
| lock.release() |
| return func(*args, **kwargs) |
| finally: |
| if not lock.locked(): |
| lock.acquire() |
| else: |
| return func(*args, **kwargs) |
| |
| def poll_lock_breaker(self, *args, **kwargs): |
| """Wrapper around poll() to break locks if needed.""" |
| return self._lock_breaker(self.poll, *args, **kwargs) |
| |
| def wait_lock_breaker(self, *args, **kwargs): |
| """Wrapper around wait() to break locks if needed.""" |
| return self._lock_breaker(self.wait, *args, **kwargs) |
| |
| |
| # We use the keyword arg |input| which trips up pylint checks. |
| # pylint: disable=redefined-builtin |
| def run(cmd, redirect_stdout=False, redirect_stderr=False, cwd=None, input=None, |
| shell=False, env=None, extra_env=None, combine_stdout_stderr=False, |
| check=True, int_timeout=1, kill_timeout=1, capture_output=False): |
| """Runs a command. |
| |
| Args: |
| cmd: cmd to run. Should be input to subprocess.Popen. If a string, shell |
| must be true. Otherwise the command must be an array of arguments, |
| and shell must be false. |
| redirect_stdout: Returns the stdout. |
| redirect_stderr: Holds stderr output until input is communicated. |
| cwd: The working directory to run this cmd. |
| input: The data to pipe into this command through stdin. If a file object |
| or file descriptor, stdin will be connected directly to that. |
| shell: Controls whether we add a shell as a command interpreter. See cmd |
| since it has to agree as to the type. |
| env: If non-None, this is the environment for the new process. |
| extra_env: If set, this is added to the environment for the new process. |
| This dictionary is not used to clear any entries though. |
| combine_stdout_stderr: Combines stdout and stderr streams into stdout. |
| check: Whether to raise an exception when command returns a non-zero exit |
| code, or return the CompletedProcess object containing the exit code. |
| Note: will still raise an exception if the cmd file does not exist. |
| int_timeout: If we're interrupted, how long (in seconds) should we give |
| the invoked process to clean up before we send a SIGTERM. |
| kill_timeout: If we're interrupted, how long (in seconds) should we give |
| the invoked process to shutdown from a SIGTERM before we SIGKILL it. |
| capture_output: Set |redirect_stdout| and |redirect_stderr| to True. |
| |
| Returns: |
| A CompletedProcess object. |
| |
| Raises: |
| CalledProcessError: Raises exception on error. |
| """ |
| if capture_output: |
| redirect_stdout, redirect_stderr = True, True |
| |
| # Set default for variables. |
| popen_stdout = None |
| popen_stderr = None |
| stdin = None |
| result = CompletedProcess() |
| |
| # Force the timeout to float; in the process, if it's not convertible, |
| # a self-explanatory exception will be thrown. |
| kill_timeout = float(kill_timeout) |
| |
| def _get_tempfile(): |
| try: |
| return tempfile.TemporaryFile(buffering=0) |
| except EnvironmentError as e: |
| if e.errno != errno.ENOENT: |
| raise |
| # This can occur if we were pointed at a specific location for our |
| # TMP, but that location has since been deleted. Suppress that |
| # issue in this particular case since our usage gurantees deletion, |
| # and since this is primarily triggered during hard cgroups |
| # shutdown. |
| return tempfile.TemporaryFile(dir='/tmp', buffering=0) |
| |
| # Modify defaults based on parameters. |
| # Note that tempfiles must be unbuffered else attempts to read |
| # what a separate process did to that file can result in a bad |
| # view of the file. |
| # The Popen API accepts either an int or a file handle for stdout/stderr. |
| # pylint: disable=redefined-variable-type |
| if redirect_stdout: |
| popen_stdout = _get_tempfile() |
| |
| if combine_stdout_stderr: |
| popen_stderr = subprocess.STDOUT |
| elif redirect_stderr: |
| popen_stderr = _get_tempfile() |
| # pylint: enable=redefined-variable-type |
| |
| # If subprocesses have direct access to stdout or stderr, they can bypass |
| # our buffers, so we need to flush to ensure that output is not interleaved. |
| if popen_stdout is None or popen_stderr is None: |
| sys.stdout.flush() |
| sys.stderr.flush() |
| |
| # If input is a string, we'll create a pipe and send it through that. |
| # Otherwise we assume it's a file object that can be read from directly. |
| if isinstance(input, str): |
| stdin = subprocess.PIPE |
| input = input.encode('utf-8') |
| elif input is not None: |
| stdin = input |
| input = None |
| |
| if isinstance(cmd, str): |
| if not shell: |
| raise Exception('Cannot run a string command without a shell') |
| cmd = ['/bin/bash', '-c', cmd] |
| shell = False |
| elif shell: |
| raise Exception('Cannot run an array command with a shell') |
| |
| # If we are using enter_chroot we need to use enterchroot pass env through |
| # to the final command. |
| env = env.copy() if env is not None else os.environ.copy() |
| env.update(extra_env if extra_env else {}) |
| |
| def ensure_text(s): |
| """Make sure |s| is a string if it's bytes.""" |
| if isinstance(s, bytes): |
| s = s.decode('utf-8', 'replace') |
| return s |
| |
| result.args = cmd |
| |
| proc = None |
| try: |
| proc = _Popen(cmd, cwd=cwd, stdin=stdin, stdout=popen_stdout, |
| stderr=popen_stderr, shell=False, env=env, |
| close_fds=True) |
| |
| old_sigint = signal.getsignal(signal.SIGINT) |
| handler = functools.partial(_kill_child_process, proc, int_timeout, |
| kill_timeout, cmd, old_sigint) |
| # We have to ignore ValueError in case we're run from a thread. |
| try: |
| signal.signal(signal.SIGINT, handler) |
| except ValueError: |
| old_sigint = None |
| |
| old_sigterm = signal.getsignal(signal.SIGTERM) |
| handler = functools.partial(_kill_child_process, proc, int_timeout, |
| kill_timeout, cmd, old_sigterm) |
| try: |
| signal.signal(signal.SIGTERM, handler) |
| except ValueError: |
| old_sigterm = None |
| |
| try: |
| (result.stdout, result.stderr) = proc.communicate(input) |
| finally: |
| if old_sigint is not None: |
| signal.signal(signal.SIGINT, old_sigint) |
| if old_sigterm is not None: |
| signal.signal(signal.SIGTERM, old_sigterm) |
| |
| if popen_stdout: |
| # The linter is confused by how stdout is a file & an int. |
| # pylint: disable=maybe-no-member,no-member |
| popen_stdout.seek(0) |
| result.stdout = popen_stdout.read() |
| popen_stdout.close() |
| |
| if popen_stderr and popen_stderr != subprocess.STDOUT: |
| # The linter is confused by how stderr is a file & an int. |
| # pylint: disable=maybe-no-member,no-member |
| popen_stderr.seek(0) |
| result.stderr = popen_stderr.read() |
| popen_stderr.close() |
| |
| result.returncode = proc.returncode |
| |
| if check and proc.returncode: |
| msg = f'cwd={cwd}' |
| if extra_env: |
| msg += f', extra env={extra_env}' |
| raise CalledProcessError( |
| result.returncode, result.cmd, msg=msg, |
| stdout=ensure_text(result.stdout), |
| stderr=ensure_text(result.stderr)) |
| except OSError as e: |
| # Avoid leaking tempfiles. |
| if popen_stdout is not None and not isinstance(popen_stdout, int): |
| popen_stdout.close() |
| if popen_stderr is not None and not isinstance(popen_stderr, int): |
| popen_stderr.close() |
| |
| estr = str(e) |
| if e.errno == errno.EACCES: |
| estr += '; does the program need `chmod a+x`?' |
| if not check: |
| result = CompletedProcess(args=cmd, returncode=255) |
| if combine_stdout_stderr: |
| result.stdout = estr |
| else: |
| result.stderr = estr |
| else: |
| raise CalledProcessError( |
| result.returncode, result.cmd, msg=estr, |
| stdout=ensure_text(result.stdout), |
| stderr=ensure_text(result.stderr)) from e |
| finally: |
| if proc is not None: |
| # Ensure the process is dead. |
| # Some pylint3 versions are confused here. |
| # pylint: disable=too-many-function-args |
| _kill_child_process(proc, int_timeout, kill_timeout, cmd, None, |
| None, None) |
| |
| # Make sure output is returned as a string rather than bytes. |
| result.stdout = ensure_text(result.stdout) |
| result.stderr = ensure_text(result.stderr) |
| |
| return result |
| # pylint: enable=redefined-builtin |
