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import os
import subprocess
import errno
import fcntl
BUFSIZ = 1024
def _set_nonblocking(fd):
flags = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK)
"""A non-blocking version of subprocess.check_output on the tornado ioloop."""
def check_output(call, callback, ioloop):
out_r, out_w = os.pipe()
nul_f = open(os.devnull, 'w')
p = subprocess.Popen(call, stdout=out_w, stderr=nul_f)
nul_f.close()
os.close(out_w)
_set_nonblocking(out_r)
data = []
def _poll():
if p.returncode is None:
p.poll()
if p.returncode is not None:
ioloop.remove_handler(out_r)
try:
buf = os.read(out_r, BUFSIZ)
except (IOError, OSError) as e:
pass
os.close(out_r)
if buf:
data.append(buf)
callback("".join(data), p.returncode)
def _handle_read(fd, events):
if events & ioloop.READ:
try:
buf = os.read(out_r, BUFSIZ)
except (IOError, OSError) as e:
if e.args[0] == errno.EBADF:
_poll()
elif e.args[0] not in (errno.EWOULDBLOCK, errno.EAGAIN):
raise
if not buf:
_poll()
else:
data.append(buf)
if events & ioloop.ERROR:
_poll()
ioloop.add_handler(out_r, _handle_read,
ioloop.ERROR | ioloop.READ)
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