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"""Utilities for running subprocesses"""
import os
import signal
import subprocess
import sys
from cram._encoding import fsdecode
__all__ = ['PIPE', 'STDOUT', 'execute']
PIPE = subprocess.PIPE
STDOUT = subprocess.STDOUT
def _makeresetsigpipe():
"""Make a function to reset SIGPIPE to SIG_DFL (for use in subprocesses).
Doing subprocess.Popen(..., preexec_fn=makeresetsigpipe()) will prevent
Python's SIGPIPE handler (SIG_IGN) from being inherited by the
child process.
"""
if (sys.platform == 'win32' or
getattr(signal, 'SIGPIPE', None) is None): # pragma: nocover
return None
return lambda: signal.signal(signal.SIGPIPE, signal.SIG_DFL)
def execute(args, stdin=None, stdout=None, stderr=None, cwd=None, env=None):
"""Run a process and return its output and return code.
stdin may either be None or a string to send to the process.
stdout may either be None or PIPE. If set to PIPE, the process's output
is returned as a string.
stderr may either be None or STDOUT. If stdout is set to PIPE and stderr
is set to STDOUT, the process's stderr output will be interleaved with
stdout and returned as a string.
cwd sets the process's current working directory.
env can be set to a dictionary to override the process's environment
variables.
This function returns a 2-tuple of (output, returncode).
"""
if sys.platform == 'win32': # pragma: nocover
args = [fsdecode(arg) for arg in args]
p = subprocess.Popen(args, stdin=PIPE, stdout=stdout, stderr=stderr,
cwd=cwd, env=env, bufsize=-1,
preexec_fn=_makeresetsigpipe(),
close_fds=os.name == 'posix')
out, err = p.communicate(stdin)
return out, p.returncode