| # -*- coding:utf-8 -*- |
| # 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.""" |
| |
| from __future__ import print_function |
| |
| 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 |
| from rh.sixish import string_types |
| |
| |
| class CommandResult(object): |
| """An object to store various attributes of a child process.""" |
| |
| def __init__(self, cmd=None, error=None, output=None, returncode=None): |
| self.cmd = cmd |
| self.error = error |
| self.output = output |
| self.returncode = returncode |
| |
| @property |
| def cmdstr(self): |
| """Return self.cmd as a nicely formatted string (useful for logs).""" |
| return rh.shell.cmd_to_str(self.cmd) |
| |
| |
| class RunCommandError(Exception): |
| """Error caught in RunCommand() method.""" |
| |
| def __init__(self, msg, result, exception=None): |
| self.msg, self.result, self.exception = msg, result, exception |
| if exception is not None and not isinstance(exception, Exception): |
| raise ValueError('exception must be an exception instance; got %r' |
| % (exception,)) |
| Exception.__init__(self, msg) |
| self.args = (msg, result, exception) |
| |
| def stringify(self, error=True, output=True): |
| """Custom method for controlling what is included in stringifying this. |
| |
| Each individual argument is the literal name of an attribute |
| on the result object; if False, that value is ignored for adding |
| to this string content. If true, it'll be incorporated. |
| |
| Args: |
| error: See comment about individual arguments above. |
| output: See comment about individual arguments above. |
| """ |
| items = [ |
| 'return code: %s; command: %s' % ( |
| self.result.returncode, self.result.cmdstr), |
| ] |
| if error and self.result.error: |
| items.append(self.result.error) |
| if output and self.result.output: |
| items.append(self.result.output) |
| if self.msg: |
| items.append(self.msg) |
| return '\n'.join(items) |
| |
| def __str__(self): |
| return self.stringify() |
| |
| def __eq__(self, other): |
| return (isinstance(other, type(self)) and |
| self.args == other.args) |
| |
| def __ne__(self, other): |
| return not self.__eq__(other) |
| |
| |
| class TerminateRunCommandError(RunCommandError): |
| """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 sudo_run_command(cmd, user='root', **kwargs): |
| """Run a command via sudo. |
| |
| Client code must use this rather than coming up with their own RunCommand |
| invocation that jams sudo in- this function is used to enforce certain |
| rules in our code about sudo usage, and as a potential auditing point. |
| |
| Args: |
| cmd: The command to run. See RunCommand for rules of this argument- |
| SudoRunCommand purely prefixes it with sudo. |
| user: The user to run the command as. |
| kwargs: See RunCommand options, it's a direct pass thru to it. |
| Note that this supports a 'strict' keyword that defaults to True. |
| If set to False, it'll suppress strict sudo behavior. |
| |
| Returns: |
| See RunCommand documentation. |
| |
| Raises: |
| This function may immediately raise RunCommandError if we're operating |
| in a strict sudo context and the API is being misused. |
| Barring that, see RunCommand's documentation- it can raise the same things |
| RunCommand does. |
| """ |
| # We don't use this anywhere, so it's easier to not bother supporting it. |
| assert not isinstance(cmd, string_types), 'shell commands not supported' |
| assert 'shell' not in kwargs, 'shell=True is not supported' |
| |
| sudo_cmd = ['sudo'] |
| |
| if user == 'root' and os.geteuid() == 0: |
| return run_command(cmd, **kwargs) |
| |
| if user != 'root': |
| sudo_cmd += ['-u', user] |
| |
| # Pass these values down into the sudo environment, since sudo will |
| # just strip them normally. |
| extra_env = kwargs.pop('extra_env', None) |
| extra_env = {} if extra_env is None else extra_env.copy() |
| |
| sudo_cmd.extend('%s=%s' % (k, v) for k, v in extra_env.items()) |
| |
| # Finally, block people from passing options to sudo. |
| sudo_cmd.append('--') |
| |
| sudo_cmd.extend(cmd) |
| |
| return run_command(sudo_cmd, **kwargs) |
| |
| |
| 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() is None and int_timeout >= 0: |
| time.sleep(0.1) |
| int_timeout -= 0.1 |
| |
| proc.terminate() |
| while proc.poll() is None and kill_timeout >= 0: |
| time.sleep(0.1) |
| kill_timeout -= 0.1 |
| |
| if proc.poll() is None: |
| # Still doesn't want to die. Too bad, so sad, time to die. |
| proc.kill() |
| except EnvironmentError as e: |
| print('Ignoring unhandled exception in _kill_child_process: %s' % e, |
| file=sys.stderr) |
| |
| # Ensure our child process has been reaped. |
| proc.wait() |
| |
| if not rh.signals.relay_signal(original_handler, signum, frame): |
| # Mock up our own, matching exit code for signaling. |
| cmd_result = CommandResult(cmd=cmd, returncode=signum << 8) |
| raise TerminateRunCommandError('Received signal %i' % signum, |
| cmd_result) |
| |
| |
| 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 |
| 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.EPERM: |
| # Kill returns either 0 (signal delivered), or 1 (signal wasn't |
| # delivered). This isn't particularly informative, but we still |
| # need that info to decide what to do, thus error_code_ok=True. |
| ret = sudo_run_command(['kill', '-%i' % signum, str(self.pid)], |
| redirect_stdout=True, |
| redirect_stderr=True, error_code_ok=True) |
| if ret.returncode == 1: |
| # The kill binary doesn't distinguish between permission |
| # denied and the pid is missing. Denied can only occur |
| # under weird grsec/selinux policies. We ignore that |
| # potential and just assume the pid was already dead and |
| # try to reap it. |
| self.poll() |
| elif 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 |
| |
| |
| # We use the keyword arg |input| which trips up pylint checks. |
| # pylint: disable=redefined-builtin,input-builtin |
| def run_command(cmd, error_message=None, redirect_stdout=False, |
| redirect_stderr=False, cwd=None, input=None, |
| shell=False, env=None, extra_env=None, ignore_sigint=False, |
| combine_stdout_stderr=False, log_stdout_to_file=None, |
| error_code_ok=False, int_timeout=1, kill_timeout=1, |
| stdout_to_pipe=False, capture_output=False, |
| quiet=False, close_fds=True): |
| """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. |
| error_message: Prints out this message when an error occurs. |
| 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. |
| ignore_sigint: If True, we'll ignore signal.SIGINT before calling the |
| child. This is the desired behavior if we know our child will handle |
| Ctrl-C. If we don't do this, I think we and the child will both get |
| Ctrl-C at the same time, which means we'll forcefully kill the child. |
| combine_stdout_stderr: Combines stdout and stderr streams into stdout. |
| log_stdout_to_file: If set, redirects stdout to file specified by this |
| path. If |combine_stdout_stderr| is set to True, then stderr will |
| also be logged to the specified file. |
| error_code_ok: Does not raise an exception when command returns a non-zero |
| exit code. Instead, returns the CommandResult object containing the |
| exit code. |
| 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. |
| stdout_to_pipe: Redirect stdout to pipe. |
| capture_output: Set |redirect_stdout| and |redirect_stderr| to True. |
| quiet: Set |stdout_to_pipe| and |combine_stdout_stderr| to True. |
| close_fds: Whether to close all fds before running |cmd|. |
| |
| Returns: |
| A CommandResult object. |
| |
| Raises: |
| RunCommandError: Raises exception on error with optional error_message. |
| """ |
| if capture_output: |
| redirect_stdout, redirect_stderr = True, True |
| |
| if quiet: |
| stdout_to_pipe, combine_stdout_stderr = True, True |
| |
| # Set default for variables. |
| stdout = None |
| stderr = None |
| stdin = None |
| cmd_result = CommandResult() |
| |
| # 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(): |
| kwargs = {} |
| if sys.version_info.major < 3: |
| kwargs['bufsize'] = 0 |
| else: |
| kwargs['buffering'] = 0 |
| try: |
| return tempfile.TemporaryFile(**kwargs) |
| 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', **kwargs) |
| |
| # 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 log_stdout_to_file: |
| stdout = open(log_stdout_to_file, 'w+') |
| elif stdout_to_pipe: |
| stdout = subprocess.PIPE |
| elif redirect_stdout: |
| stdout = _get_tempfile() |
| |
| if combine_stdout_stderr: |
| stderr = subprocess.STDOUT |
| elif redirect_stderr: |
| 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 stdout is None or 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, string_types): |
| stdin = subprocess.PIPE |
| input = input.encode('utf-8') |
| elif input is not None: |
| stdin = input |
| input = None |
| |
| if isinstance(cmd, string_types): |
| 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 {}) |
| |
| cmd_result.cmd = cmd |
| |
| proc = None |
| try: |
| proc = _Popen(cmd, cwd=cwd, stdin=stdin, stdout=stdout, |
| stderr=stderr, shell=False, env=env, |
| close_fds=close_fds) |
| |
| old_sigint = signal.getsignal(signal.SIGINT) |
| if ignore_sigint: |
| handler = signal.SIG_IGN |
| else: |
| handler = functools.partial( |
| _kill_child_process, proc, int_timeout, kill_timeout, cmd, |
| old_sigint) |
| signal.signal(signal.SIGINT, handler) |
| |
| old_sigterm = signal.getsignal(signal.SIGTERM) |
| handler = functools.partial(_kill_child_process, proc, int_timeout, |
| kill_timeout, cmd, old_sigterm) |
| signal.signal(signal.SIGTERM, handler) |
| |
| try: |
| (cmd_result.output, cmd_result.error) = proc.communicate(input) |
| finally: |
| signal.signal(signal.SIGINT, old_sigint) |
| signal.signal(signal.SIGTERM, old_sigterm) |
| |
| if stdout and not log_stdout_to_file and not stdout_to_pipe: |
| # The linter is confused by how stdout is a file & an int. |
| # pylint: disable=maybe-no-member,no-member |
| stdout.seek(0) |
| cmd_result.output = stdout.read() |
| stdout.close() |
| |
| if stderr and stderr != subprocess.STDOUT: |
| # The linter is confused by how stderr is a file & an int. |
| # pylint: disable=maybe-no-member,no-member |
| stderr.seek(0) |
| cmd_result.error = stderr.read() |
| stderr.close() |
| |
| cmd_result.returncode = proc.returncode |
| |
| if not error_code_ok and proc.returncode: |
| msg = 'cwd=%s' % cwd |
| if extra_env: |
| msg += ', extra env=%s' % extra_env |
| if error_message: |
| msg += '\n%s' % error_message |
| raise RunCommandError(msg, cmd_result) |
| except OSError as e: |
| estr = str(e) |
| if e.errno == errno.EACCES: |
| estr += '; does the program need `chmod a+x`?' |
| if error_code_ok: |
| cmd_result = CommandResult(cmd=cmd, error=estr, returncode=255) |
| else: |
| raise RunCommandError(estr, CommandResult(cmd=cmd), exception=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. |
| if cmd_result.output is not None: |
| cmd_result.output = cmd_result.output.decode('utf-8', 'replace') |
| if cmd_result.error is not None: |
| cmd_result.error = cmd_result.error.decode('utf-8', 'replace') |
| |
| return cmd_result |
| # pylint: enable=redefined-builtin,input-builtin |
