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# Copyright (C) 2011 Lars Wirzenius
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
import fcntl
import logging
import os
import select
import subprocess
import cliapp
def runcmd(argv, *args, **kwargs):
'''Run external command or pipeline.
Example: ``runcmd(['grep', 'foo'], ['wc', '-l'],
feed_stdin='foo\nbar\n')``
Return the standard output of the command.
Raise ``cliapp.AppException`` if external command returns
non-zero exit code. ``*args`` and ``**kwargs`` are passed
onto ``subprocess.Popen``.
'''
if 'ignore_fail' in kwargs:
ignore_fail = kwargs['ignore_fail']
del kwargs['ignore_fail']
else:
ignore_fail = False
exit, out, err = runcmd_unchecked(argv, *args, **kwargs)
if exit != 0:
msg = 'Command failed: %s\n%s' % (' '.join(argv), err)
if ignore_fail:
logging.info(msg)
else:
logging.error(msg)
raise cliapp.AppException(msg)
return out
def runcmd_unchecked(argv, *argvs, **kwargs):
'''Run external command or pipeline.
Return the exit code, and contents of standard output and error
of the command.
See also ``runcmd``.
'''
argvs = [argv] + list(argvs)
logging.debug('run external command: %s' % repr(argvs))
def pop_kwarg(name, default):
if name in kwargs:
value = kwargs[name]
del kwargs[name]
return value
else:
return default
feed_stdin = pop_kwarg('feed_stdin', '')
pipe_stdin = pop_kwarg('stdin', subprocess.PIPE)
pipe_stdout = pop_kwarg('stdout', subprocess.PIPE)
pipe_stderr = pop_kwarg('stderr', subprocess.PIPE)
try:
pipeline = _build_pipeline(argvs,
pipe_stdin,
pipe_stdout,
pipe_stderr,
kwargs)
return _run_pipeline(pipeline, feed_stdin, pipe_stdin,
pipe_stdout, pipe_stderr)
except OSError, e: # pragma: no cover
if e.errno == errno.ENOENT and e.filename is None:
e.filename = argv[0]
raise e
else:
raise
def _build_pipeline(argvs, pipe_stdin, pipe_stdout, pipe_stderr, kwargs):
procs = []
for i, argv in enumerate(argvs):
if i == 0 and i == len(argvs) - 1:
stdin = pipe_stdin
stdout = pipe_stdout
stderr = pipe_stderr
elif i == 0:
stdin = pipe_stdin
stdout = subprocess.PIPE
stderr = pipe_stderr
elif i == len(argv) - 1:
stdin = procs[-1].stdout
stdout = pipe_stdout
stderr = pipe_stderr
else:
stdin = procs[-1].stdout
stdout = subprocess.PIPE
stderr = pipe_stderr
p = subprocess.Popen(argv, stdin=stdin, stdout=stdout,
stderr=stderr, close_fds=True, **kwargs)
procs.append(p)
return procs
def _run_pipeline(procs, feed_stdin, pipe_stdin, pipe_stdout, pipe_stderr):
stdout_eof = False
stderr_eof = False
out = []
err = []
pos = 0
io_size = 1024
def set_nonblocking(fd):
flags = fcntl.fcntl(fd, fcntl.F_GETFL, 0)
flags = flags | os.O_NONBLOCK
fcntl.fcntl(fd, fcntl.F_SETFL, flags)
if feed_stdin and pipe_stdin == subprocess.PIPE:
set_nonblocking(procs[0].stdin.fileno())
if pipe_stdout == subprocess.PIPE:
set_nonblocking(procs[-1].stdout.fileno())
if pipe_stderr == subprocess.PIPE:
set_nonblocking(procs[-1].stderr.fileno())
def still_running():
for p in procs:
p.poll()
for p in procs:
if p.returncode is None:
return True
if pipe_stdout == subprocess.PIPE and not stdout_eof:
return True
if pipe_stderr == subprocess.PIPE and not stderr_eof:
return True # pragma: no cover
return False
while still_running():
rlist = []
if not stdout_eof and pipe_stdout == subprocess.PIPE:
rlist.append(procs[-1].stdout)
if not stderr_eof and pipe_stderr == subprocess.PIPE:
rlist.append(procs[-1].stderr)
wlist = []
if pipe_stdin == subprocess.PIPE and pos < len(feed_stdin):
wlist.append(procs[0].stdin)
if rlist or wlist:
r, w, x = select.select(rlist, wlist, [])
else:
r = w = [] # pragma: no cover
if procs[0].stdin in w and pos < len(feed_stdin):
data = feed_stdin[pos : pos+io_size]
procs[0].stdin.write(data)
pos += len(data)
if pos >= len(feed_stdin):
procs[0].stdin.close()
if procs[-1].stdout in r:
data = procs[-1].stdout.read(io_size)
if data:
out.append(data)
else:
stdout_eof = True
if procs[-1].stderr in r:
data = procs[-1].stderr.read(io_size)
if data:
err.append(data)
else:
stderr_eof = True
return procs[-1].returncode, ''.join(out), ''.join(err)
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