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Commit 1f950e84 authored by Martín Ferrari's avatar Martín Ferrari
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Backticks and system() support; improved docs, tests.

parent 792cc930
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Showing with 119 additions and 41 deletions
src/netns/subprocess.py
View file @ 1f950e84
......@@ -3,19 +3,47 @@
import fcntl, grp, os, pickle, pwd, signal, select, sys, traceback
__all__ = [ 'PIPE', 'STDOUT', 'Popen', 'Subprocess', 'spawn', 'wait', 'poll' ]
__all__ = [ 'PIPE', 'STDOUT', 'Popen', 'Subprocess', 'spawn', 'wait', 'poll',
'system', 'backticks', 'backticks_raise' ]
# User-facing interfaces
class Subprocess(object):
# FIXME: this is the visible interface; documentation should move here.
"""OO-style interface to spawn(), but invoked through the controlling
process."""
"""Class that allows the execution of programs inside a netns Node. This is
the base class for all process operations, Popen provides a more high level
interface."""
# FIXME
default_user = None
def __init__(self, node, executable, argv = None, cwd = None, env = None,
stdin = None, stdout = None, stderr = None, user = None):
self._slave = node._slave
"""Forks and execs a program, with stdio redirection and user
switching.
A netns Node to run the program is is specified as the first parameter.
The program is specified by `executable', if it does not contain any
slash, the PATH environment variable is used to search for the file.
The `user` parameter, if not None, specifies a user name to run the
command as, after setting its primary and secondary groups. If a
numerical UID is given, a reverse lookup is performed to find the user
name and then set correctly the groups.
To run the program in a different directory than the current one, it
should be set in `cwd'.
If specified, `env' replaces the caller's environment with the
dictionary provided.
The standard input, output, and error of the created process will be
redirected to the file descriptors specified by `stdin`, `stdout`, and
`stderr`, respectively. These parameters must be open file objects,
integers, or None (for no redirection). Note that the descriptors will
not be closed by this class.
Exceptions occurred while trying to set up the environment or executing
the program are propagated to the parent."""
if user == None:
user = Subprocess.default_user
......@@ -32,9 +60,12 @@ class Subprocess(object):
@property
def pid(self):
"""The real process ID of this subprocess."""
return self._pid
def poll(self):
"""Checks status of program, returns exitcode or None if still running.
See Popen.poll."""
r = self._slave.poll(self._pid)
if r != None:
del self._pid
......@@ -42,15 +73,22 @@ class Subprocess(object):
return self.returncode
def wait(self):
"""Waits for program to complete and returns the exitcode.
See Popen.wait"""
self._returncode = self._slave.wait(self._pid)
del self._pid
return self.returncode
def signal(self, sig = signal.SIGTERM):
"""Sends a signal to the process."""
return self._slave.signal(self._pid, sig)
@property
def returncode(self):
"""When the program has finished (and has been waited for with
communicate, wait, or poll), returns the signal that killed the
program, if negative; otherwise, it is the exit code of the program.
"""
if self._returncode == None:
return None
if os.WIFSIGNALED(self._returncode):
......@@ -67,9 +105,20 @@ class Subprocess(object):
PIPE = -1
STDOUT = -2
class Popen(Subprocess):
"""Higher-level interface for executing processes, that tries to emulate
the stdlib's subprocess.Popen as much as possible."""
def __init__(self, node, executable, argv = None, cwd = None, env = None,
stdin = None, stdout = None, stderr = None, user = None,
bufsize = 0):
"""As in Subprocess, `node' specifies the netns Node to run in.
The `stdin', `stdout', and `stderr' parameters also accept the special
values subprocess.PIPE or subprocess.STDOUT. Check the stdlib's
subprocess module for more details. `bufsize' specifies the buffer size
for the buffered IO provided for PIPE'd descriptors.
"""
self.stdin = self.stdout = self.stderr = None
fdmap = { "stdin": stdin, "stdout": stdout, "stderr": stderr }
# if PIPE: all should be closed at the end
......@@ -107,6 +156,7 @@ class Popen(Subprocess):
#communicate = subprocess.communicate
#_communicate = subprocess._communicate
def communicate(self, input = None):
"""See Popen.communicate."""
# FIXME: almost verbatim from stdlib version, need to be removed or
# something
wset = []
......@@ -130,9 +180,10 @@ class Popen(Subprocess):
while rset or wset:
r, w, x = select.select(rset, wset, [])
if self.stdin in w:
offset += os.write(self.stdin.fileno(),
wrote = os.write(self.stdin.fileno(),
#buffer(input, offset, select.PIPE_BUF))
buffer(input, offset, 512)) # XXX: py2.7
offset += wrote
if offset >= len(input):
self.stdin.close()
wset = []
......@@ -155,41 +206,57 @@ class Popen(Subprocess):
self.wait()
return (out, err)
def system(node, args):
"""Emulates system() function, if `args' is an string, it uses `/bin/sh' to
exexecute it, otherwise is interpreted as the argv array to call execve."""
if isinstance(args, str):
args = [ '/bin/sh', '/bin/sh', '-c', args ]
return Popen(node, args[0], args[1:]).wait()
def backticks(node, args):
"""Emulates shell backticks, if `args' is an string, it uses `/bin/sh' to
exexecute it, otherwise is interpreted as the argv array to call execve."""
if isinstance(args, str):
args = [ '/bin/sh', '/bin/sh', '-c', args ]
return Popen(node, args[0], args[1:], stdout = PIPE).communicate()[0]
def backticks_raise(node, args):
"""Emulates shell backticks, if `args' is an string, it uses `/bin/sh' to
exexecute it, otherwise is interpreted as the argv array to call execve.
Raises an RuntimeError if the return value is not 0."""
if isinstance(args, str):
args = [ '/bin/sh', '/bin/sh', '-c', args ]
p = Popen(node, args[0], args[1:], stdout = PIPE)
out = p.communicate()[0]
if p.returncode > 0:
raise RuntimeError("Command failed with return code %d." %
p.returncode)
if p.returncode < 0:
raise RuntimeError("Command killed by signal %d." % -p.returncode)
return out
# =======================================================================
#
# Server-side code, called from netns.protocol.Server
def spawn(executable, argv = None, cwd = None, env = None, stdin = None,
stdout = None, stderr = None, close_fds = False, user = None):
"""Forks and execs a program, with stdio redirection and user switching.
The program is specified by `executable', if it does not contain any slash,
the PATH environment variable is used to search for the file.
The `user` parameter, if not None, specifies a user name to run the
command as, after setting its primary and secondary groups. If a numerical
UID is given, a reverse lookup is performed to find the user name and
then set correctly the groups.
To run the program in a different directory than the current one, it should
be set in `cwd'.
If specified, `env' replaces the caller's environment with the dictionary
provided.
The standard input, output, and error of the created process will be
redirected to the file descriptors specified by `stdin`, `stdout`, and
`stderr`, respectively. These parameters must be open file objects,
integers or None, in which case, no redirection will occur.
"""Internal function that performs all the dirty work for Subprocess, Popen
and friends. This is executed in the slave process, directly from the
protocol.Server class.
Note that the original descriptors are not closed, and that piping should
be handled externally.
Parameters have the same meaning as the stdlib's subprocess.Popen class,
with one addition: the `user` parameter, if not None, specifies a user name
to run the command as, after setting its primary and secondary groups. If a
numerical UID is given, a reverse lookup is performed to find the user name
and then set correctly the groups.
When close_fds is True, it closes all file descriptors bigger than 2. It
When close_fds is True, it closes all file descriptors bigger than 2. It
can also be an iterable of file descriptors to close after fork.
Exceptions occurred while trying to set up the environment or executing the
program are propagated to the parent."""
Note that 'std{in,out,err}' must be None, integers, or file objects, PIPE
is not supported here. Also, the original descriptors are not closed.
"""
userfd = [stdin, stdout, stderr]
filtered_userfd = filter(lambda x: x != None and x >= 0, userfd)
for i in range(3):
......
t/test_subprocess.py
View file @ 1f950e84
......@@ -4,7 +4,7 @@
import netns, netns.subprocess, test_util
import grp, os, pwd, signal, sys, unittest
from netns.subprocess import PIPE, STDOUT, spawn, Subprocess, Popen, wait
from netns.subprocess import *
def _stat(path):
try:
......@@ -38,6 +38,7 @@ def _readall(fd):
break
s += s1
return s
_longstring = "Long string is long!\n" * 1000
class TestSubprocess(unittest.TestCase):
def _check_ownership(self, user, pid):
......@@ -167,8 +168,7 @@ class TestSubprocess(unittest.TestCase):
self.assertEquals(p.wait(), 0)
p = Popen(node, '/bin/cat', stdin = PIPE, stdout = PIPE)
self.assertEquals(p.communicate("hello world\n"),
("hello world\n", None))
self.assertEquals(p.communicate(_longstring), (_longstring, None))
#
p = Popen(node, '/bin/sh', ['sh', '-c', 'cat >&2'],
......@@ -181,8 +181,7 @@ class TestSubprocess(unittest.TestCase):
p = Popen(node, '/bin/sh', ['sh', '-c', 'cat >&2'],
stdin = PIPE, stderr = PIPE)
self.assertEquals(p.communicate("hello world\n"),
(None, "hello world\n"))
self.assertEquals(p.communicate(_longstring), (None, _longstring))
#
p = Popen(node, '/bin/sh', ['sh', '-c', 'cat >&2'],
......@@ -195,8 +194,7 @@ class TestSubprocess(unittest.TestCase):
p = Popen(node, '/bin/sh', ['sh', '-c', 'cat >&2'],
stdin = PIPE, stdout = PIPE, stderr = STDOUT)
self.assertEquals(p.communicate("hello world\n"),
("hello world\n", None))
self.assertEquals(p.communicate(_longstring), (_longstring, None))
#
p = Popen(node, 'tee', ['tee', '/dev/stderr'],
......@@ -209,8 +207,8 @@ class TestSubprocess(unittest.TestCase):
p = Popen(node, 'tee', ['tee', '/dev/stderr'],
stdin = PIPE, stdout = PIPE, stderr = STDOUT)
self.assertEquals(p.communicate("hello world\n"),
("hello world\n" * 2, None))
self.assertEquals(p.communicate(_longstring[0:512]),
(_longstring[0:512] * 2, None))
#
p = Popen(node, 'tee', ['tee', '/dev/stderr'],
......@@ -223,9 +221,22 @@ class TestSubprocess(unittest.TestCase):
p = Popen(node, 'tee', ['tee', '/dev/stderr'],
stdin = PIPE, stdout = PIPE, stderr = PIPE)
self.assertEquals(p.communicate("hello world\n"),
("hello world\n",) * 2)
self.assertEquals(p.communicate(_longstring), (_longstring, ) * 2)
def test_backticks(self):
node = netns.Node(nonetns = True, debug=0)
self.assertEquals(backticks(node, "echo hello world"), "hello world\n")
self.assertEquals(backticks(node, r"echo hello\ \ world"),
"hello world\n")
self.assertEquals(backticks(node, ["echo", "echo", "hello", "world"]),
"hello world\n")
self.assertEquals(backticks(node, "echo hello world > /dev/null"), "")
self.assertRaises(RuntimeError, backticks_raise, node, "false")
def test_system(self):
node = netns.Node(nonetns = True, debug=0)
self.assertEquals(system(node, "true"), 0)
self.assertEquals(system(node, "false"), 1)
# FIXME: tests for Popen!
if __name__ == '__main__':
......
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