/usr/lib/python2.7/dist-packages/gnatpython/ex.py is in python-gnatpython 54-3+b1.
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# #
# EX.PY #
# #
# Copyright (C) 2008 - 2011 Ada Core Technologies, Inc. #
# #
# 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 3 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/> #
# #
############################################################################
"""Subprocesses management
This package provides a single class called run which ease spawn of processes
in blocking or non blocking mode and redirection of its stdout, stderr and
stdin"""
from subprocess import Popen, STDOUT, PIPE
import errno
import logging
import os
import sys
BUF_SIZE = 128
logger = logging.getLogger('gnatpython.ex')
class Run(object):
"""
ATTRIBUTES
cmds : The `cmds' argument passed to the __init__ method
(a command line passed in a list, of a list of command
lines passed as a list of list).
status : exit status (meaningfull only after the end of the process)
out : process standard output (if instanciated with output = PIPE)
err : same as out but for standard error
pid : PID
"""
def __init__(self, cmds, cwd=None, output=PIPE,
error=STDOUT, input=None, bg=False, timeout=None, env=None,
set_sigpipe=True, parse_shebang=False):
"""Spawn a process
PARAMETERS
cmds: two possibilities:
(1) a command line: a tool name and its arguments, passed
in a list. e.g. ['ls', '-a', '.']
(2) a list of command lines (as defined in (1)): the
different commands will be piped. This means that
[['ps', '-a'], ['grep', 'vxsim']] will be equivalent to
the system command line 'ps -a | grep vxsim'.
cwd : directory in which the process should be executed (string
or None). If None then current directory is used
output: can be PIPE (default), a filename string, a fd on an already
opened file, a python file object or None (for stdout).
error: same as output or STDOUT, which indicates that the stderr
data from the applications should be captured into the
same file handle as for stdout.
input: same as output
bg: if True then run in background
timeout: limit execution time (in seconds)
env: dictionary for environment variables (e.g. os.environ)
set_sigpipe: reset SIGPIPE handler to default value
parse_shebang: take the #! interpreter line into account
RETURN VALUE
Return an object of type run.
EXCEPTIONS
Raise OSError when trying to execute a non-existent file.
REMARKS
If you specify a filename for output or stderr then file content is
reseted (equiv. to > in shell). If you prepend the filename with '+'
then the file will be opened in append mode (equiv. to >> in shell)
If you prepend the input with '|', then the content of input string
will be used for process stdin.
"""
def subprocess_setup():
"""Reset SIGPIPE hander
Python installs a SIGPIPE handler by default. This is usually not
what non-Python subprocesses expect.
"""
if set_sigpipe:
# Set sigpipe only when set_sigpipe is True
# This should fix HC16-020 and could be activated by default
import signal
signal.signal(signal.SIGPIPE, signal.SIG_DFL)
def add_interpreter_command(cmd_line):
"""Add the interpreter defined in the #! line to cmd_line
If the #! line cannot be parsed, just return the cmd_line
unchanged
REMARKS
if the interpreter command line contains /usr/bin/env python
it will be replaced by the value of sys.executable
On windows, /usr/bin/env will be ignored to avoid a dependency on
cygwin
"""
if not parse_shebang:
# nothing to do
return cmd_line
# Import gnatpython.fileutils just now to avoid a circular
# dependency
from gnatpython.fileutils import which
prog = which(cmd_line[0])
if not os.path.exists(prog):
return cmd_line
with open(prog) as f:
header = f.read()[0:2]
if header != "#!":
# Unknown header
return cmd_line
# Header found, get the interpreter command in the first line
f.seek(0)
line = f.readline()
interpreter_cmds = [l.strip() for l in
line[line.find('!') + 1:].split()]
# Pass the program path to the interpreter
if len(cmd_line) > 1:
cmd_line = [prog] + cmd_line[1:]
else:
cmd_line = [prog]
# If the interpreter is '/usr/bin/env python', use
# sys.executable instead to keep the same python executable
if interpreter_cmds[0:1] == ['/usr/bin/env', 'python']:
if len(interpreter_cmds > 2):
return [sys.executable] + interpreter_cmds[2:] \
+ cmd_line
else:
return [sys.executable] + cmd_line
elif sys.platform == 'win32':
if interpreter_cmds[0] == '/usr/bin/env':
return interpreter_cmds[1:] + cmd_line
return interpreter_cmds + cmd_line
# First resolve output, error and input
self.input_file = File(input, 'r')
self.output_file = File(output, 'w')
self.error_file = File(error, 'w')
self.status = None
self.out = ''
self.err = ''
if env is None:
env = os.environ
rlimit_args = []
if timeout is not None:
# Import gnatpython.fileutils just now to avoid a circular
# dependency
from gnatpython.fileutils import get_rlimit
rlimit = get_rlimit()
assert rlimit, 'rlimit not found'
rlimit_args = [rlimit, '%d' % timeout]
try:
if not isinstance(cmds[0], list):
self.cmds = rlimit_args + add_interpreter_command(cmds)
logger.debug('Run: %s' % self.command_line_image())
popen_args = {
'stdin': self.input_file.fd,
'stdout': self.output_file.fd,
'stderr': self.error_file.fd,
'cwd': cwd,
'env': env,
'universal_newlines': True}
if sys.platform != 'win32':
# preexec_fn is no supported on windows
popen_args['preexec_fn'] = subprocess_setup
self.internal = Popen(self.cmds, **popen_args)
else:
self.cmds = [add_interpreter_command(c) for c in cmds]
self.cmds[0] = rlimit_args + self.cmds[0]
logger.debug('Run: %s ' %
" | ".join([" ".join(cmd) for cmd in self.cmds]))
runs = []
for index, cmd in enumerate(self.cmds):
if index == 0:
stdin = self.input_file.fd
else:
stdin = runs[index - 1].stdout
# When connecting two processes using a Pipe don't use
# universal_newlines mode. Indeed commands transmitting
# binary data between them will crash
# (ex: gzip -dc toto.txt | tar -xf -)
if index == len(self.cmds) - 1:
stdout = self.output_file.fd
txt_mode = True
else:
stdout = PIPE
txt_mode = False
popen_args = {
'stdin': stdin,
'stdout': stdout,
'stderr': self.error_file.fd,
'cwd': cwd,
'env': env,
'universal_newlines': txt_mode}
if sys.platform != 'win32':
# preexec_fn is no supported on windows
popen_args['preexec_fn'] = subprocess_setup
runs.append(Popen(cmd, **popen_args))
self.internal = runs[-1]
except Exception, e:
self.__error(e, self.cmds)
raise
self.pid = self.internal.pid
if not bg:
self.wait()
def command_line_image(self):
"""Return a string representation of the command(s) that
were run to create this object.
REMARKS
This method also handles quoting as defined for POSIX shells.
This means that arguments containing special characters
(such as a simple space, or a backslash, for instance),
are properly quoted. This makes it possible to execute
the same command by copy/pasting the image in a shell
prompt.
"""
def quote_arg(arg):
"""Return a human-friendly representation of the given
argument, but with all extra quoting done if necessary.
The intent is to produce an argument image that can be
copy/pasted on a POSIX shell command (at a shell prompt).
"""
need_quoting = ('|', '&', ';', '<', '>', '(', ')', '$',
'`', '\\', '"', "'", ' ', '\t', '\n',
# The POSIX spec says that the following
# characters might need some extra quoting
# depending on the circumstances. We just
# always quote them, to be safe (and to avoid
# things like file globbing which are sometimes
# performed by the shell). We do leave '%' and
# '=' alone, as I don't see how they could
# cause problems.
'*', '?', '[', '#', '~')
for char in need_quoting:
if char in arg:
# The way we do this is by simply enclosing the argument
# inside single quotes. However, we have to be careful
# of single-quotes inside the argument, as they need
# to be escaped (which we cannot do while still inside.
# a single-quote string).
arg = arg.replace("'", r"'\''")
# Also, it seems to be nicer to print new-line characters
# as '\n' rather than as a new-line...
arg = arg.replace('\n', r"'\n'")
return "'%s'" % arg
# No quoting needed. Return the argument as is.
return arg
cmds = self.cmds
if not isinstance(cmds[0], list):
# Turn the simple command into a special case of
# the multiple-commands case. This will allow us
# to treat both cases the same way.
cmds = [cmds]
return ' | '.join([' '.join([quote_arg(arg) for arg in cmd])
for cmd in cmds])
def _close_files(self):
"""Internal procedure"""
self.output_file.close()
self.error_file.close()
self.input_file.close()
def __error(self, error, cmds):
"""Set pid to -1 and status to 127 before closing files"""
self.pid = -1
self.status = 127
self._close_files()
# Try to send an helpful message if one of the executable has not
# been found.
not_found = None
# Import gnatpython.fileutils here to avoid a circular dependency
from gnatpython.fileutils import which
if not isinstance(cmds[0], list):
if not which(cmds[0]):
not_found = cmds[0]
else:
for cmd in cmds:
if not which(cmd[0]):
not_found = cmd[0]
break
if not_found is not None:
logger.error("%s, %s not found" % (error, not_found))
raise OSError(getattr(error, 'errno', errno.ENOENT),
getattr(error, 'strerror', 'No such file or directory') +
" %s not found" % not_found)
def wait(self):
"""Wait until process ends and return its status"""
if self.status == 127:
return self.status
self.status = None
# If there is no pipe in the loop then just do a wait. Otherwise
# in order to avoid blocked processes due to full pipes, use
# communicate.
if self.output_file.fd != PIPE and self.error_file.fd != PIPE and \
self.input_file.fd != PIPE:
self.status = self.internal.wait()
else:
tmp_input = None
if self.input_file.fd == PIPE:
tmp_input = self.input_file.get_command()
(self.out, self.err) = self.internal.communicate(tmp_input)
self.status = self.internal.returncode
self._close_files()
return self.status
def poll(self):
"""Test if the process is still alive. If yes then return None,
otherwise return process status"""
if self.status != 127:
result = self.internal.poll()
if result is not None:
self.status = result
else:
result = 127
return result
class File(object):
"""Can be a PIPE, a file object"""
def __init__(self, name, mode='r'):
"""Create a new File
PARAMETERS
name: can be PIPE, STDOUT, a filename string,
an opened fd, a python file object,
or a command to pipe (if starts with |)
mode: can be 'r' or 'w'
if name starts with + the mode will be a+
"""
assert mode in 'rw', 'Mode should be r or w'
self.name = name
self.to_close = False
if isinstance(name, str):
# can be a pipe or a filename
if mode == 'r' and name.startswith('|'):
self.fd = PIPE
else:
if mode == 'w':
if name.startswith('+'):
open_mode = 'a+'
name = name[1:]
else:
open_mode = 'w+'
else:
open_mode = 'r'
self.fd = open(name, open_mode)
if open_mode == 'a+':
self.fd.seek(0, 2)
self.to_close = True
else:
# this is a file descriptor
self.fd = name
def get_command(self):
"""Returns the command to run to create the pipe"""
if self.fd == PIPE:
return self.name[1:]
def close(self):
"""Close the file if needed"""
if self.to_close:
self.fd.close()
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