#
# executil.py - subprocess execution utility functions
#
# Copyright (C) 1999-2015
# Red Hat, Inc. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
import os
import subprocess
import signal
from time import sleep
import logging
log = logging.getLogger("pylorax")
program_log = logging.getLogger("program")
from threading import Lock
program_log_lock = Lock()
_child_env = {}
[docs]def setenv(name, value):
""" Set an environment variable to be used by child processes.
This method does not modify os.environ for the running process, which
is not thread-safe. If setenv has already been called for a particular
variable name, the old value is overwritten.
:param str name: The name of the environment variable
:param str value: The value of the environment variable
"""
_child_env[name] = value
[docs]def augmentEnv():
env = os.environ.copy()
env.update(_child_env)
return env
[docs]class ExecProduct(object):
def __init__(self, rc, stdout, stderr):
self.rc = rc
self.stdout = stdout
self.stderr = stderr
[docs]def startProgram(argv, root='/', stdin=None, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
env_prune=None, env_add=None, reset_handlers=True, reset_lang=True, **kwargs):
""" Start an external program and return the Popen object.
The root and reset_handlers arguments are handled by passing a
preexec_fn argument to subprocess.Popen, but an additional preexec_fn
can still be specified and will be run. The user preexec_fn will be run
last.
:param argv: The command to run and argument
:param root: The directory to chroot to before running command.
:param stdin: The file object to read stdin from.
:param stdout: The file object to write stdout to.
:param stderr: The file object to write stderr to.
:param env_prune: environment variables to remove before execution
:param env_add: environment variables to add before execution
:param reset_handlers: whether to reset to SIG_DFL any signal handlers set to SIG_IGN
:param reset_lang: whether to set the locale of the child process to C
:param kwargs: Additional parameters to pass to subprocess.Popen
:return: A Popen object for the running command.
"""
if env_prune is None:
env_prune = []
# Check for and save a preexec_fn argument
preexec_fn = kwargs.pop("preexec_fn", None)
def preexec():
# If a target root was specificed, chroot into it
if root and root != '/':
os.chroot(root)
os.chdir("/")
# Signal handlers set to SIG_IGN persist across exec. Reset
# these to SIG_DFL if requested. In particular this will include the
# SIGPIPE handler set by python.
if reset_handlers:
for signum in range(1, signal.NSIG):
if signal.getsignal(signum) == signal.SIG_IGN:
signal.signal(signum, signal.SIG_DFL)
# If the user specified an additional preexec_fn argument, run it
if preexec_fn is not None:
preexec_fn()
with program_log_lock:
program_log.info("Running... %s", " ".join(argv))
env = augmentEnv()
for var in env_prune:
env.pop(var, None)
if reset_lang:
env.update({"LC_ALL": "C"})
if env_add:
env.update(env_add)
return subprocess.Popen(argv,
stdin=stdin,
stdout=stdout,
stderr=stderr,
close_fds=True,
preexec_fn=preexec, cwd=root, env=env, **kwargs)
def _run_program(argv, root='/', stdin=None, stdout=None, env_prune=None, log_output=True,
binary_output=False, filter_stderr=False, raise_err=False, callback=None):
""" Run an external program, log the output and return it to the caller
:param argv: The command to run and argument
:param root: The directory to chroot to before running command.
:param stdin: The file object to read stdin from.
:param stdout: Optional file object to write the output to.
:param env_prune: environment variable to remove before execution
:param log_output: whether to log the output of command
:param binary_output: whether to treat the output of command as binary data
:param filter_stderr: whether to exclude the contents of stderr from the returned output
:param raise_err: whether to raise a CalledProcessError if the returncode is non-zero
:param callback: method to call while waiting for process to finish, passed Popen object
:return: The return code of the command and the output
:raises: OSError or CalledProcessError
"""
try:
if filter_stderr:
stderr = subprocess.PIPE
else:
stderr = subprocess.STDOUT
proc = startProgram(argv, root=root, stdin=stdin, stdout=subprocess.PIPE, stderr=stderr,
env_prune=env_prune, universal_newlines=not binary_output)
if callback:
while callback(proc) and proc.poll() is None:
sleep(1)
(output_string, err_string) = proc.communicate()
if output_string:
if binary_output:
output_lines = [output_string]
else:
if output_string[-1] != "\n":
output_string = output_string + "\n"
output_lines = output_string.splitlines(True)
if log_output:
with program_log_lock:
for line in output_lines:
program_log.info(line.strip())
if stdout:
stdout.write(output_string)
# If stderr was filtered, log it separately
if filter_stderr and err_string and log_output:
err_lines = err_string.splitlines(True)
with program_log_lock:
for line in err_lines:
program_log.info(line.strip())
except OSError as e:
with program_log_lock:
program_log.error("Error running %s: %s", argv[0], e.strerror)
raise
with program_log_lock:
program_log.debug("Return code: %d", proc.returncode)
if proc.returncode and raise_err:
raise subprocess.CalledProcessError(proc.returncode, argv)
return (proc.returncode, output_string)
[docs]def execWithRedirect(command, argv, stdin=None, stdout=None, root='/', env_prune=None,
log_output=True, binary_output=False, raise_err=False, callback=None):
""" Run an external program and redirect the output to a file.
:param command: The command to run
:param argv: The argument list
:param stdin: The file object to read stdin from.
:param stdout: Optional file object to redirect stdout and stderr to.
:param root: The directory to chroot to before running command.
:param env_prune: environment variable to remove before execution
:param log_output: whether to log the output of command
:param binary_output: whether to treat the output of command as binary data
:param raise_err: whether to raise a CalledProcessError if the returncode is non-zero
:param callback: method to call while waiting for process to finish, passed Popen object
:return: The return code of the command
"""
argv = [command] + list(argv)
return _run_program(argv, stdin=stdin, stdout=stdout, root=root, env_prune=env_prune,
log_output=log_output, binary_output=binary_output, raise_err=raise_err, callback=callback)[0]
[docs]def execWithCapture(command, argv, stdin=None, root='/', log_output=True, filter_stderr=False,
raise_err=False, callback=None):
""" Run an external program and capture standard out and err.
:param command: The command to run
:param argv: The argument list
:param stdin: The file object to read stdin from.
:param root: The directory to chroot to before running command.
:param log_output: Whether to log the output of command
:param filter_stderr: Whether stderr should be excluded from the returned output
:param raise_err: whether to raise a CalledProcessError if the returncode is non-zero
:return: The output of the command
"""
argv = [command] + list(argv)
return _run_program(argv, stdin=stdin, root=root, log_output=log_output, filter_stderr=filter_stderr,
raise_err=raise_err, callback=callback)[1]
[docs]def runcmd(cmd, **kwargs):
""" run execWithRedirect with raise_err=True
"""
kwargs["raise_err"] = True
return execWithRedirect(cmd[0], cmd[1:], **kwargs)
[docs]def runcmd_output(cmd, **kwargs):
""" run execWithCapture with raise_err=True
"""
kwargs["raise_err"] = True
return execWithCapture(cmd[0], cmd[1:], **kwargs)