[tor-commits] [stem/master] Support process renaming
atagar at torproject.org
atagar at torproject.org
Sun Jan 13 07:43:32 UTC 2013
commit 427fce8bd6777542f234e1738b35ee553853a366
Author: Damian Johnson <atagar at torproject.org>
Date: Sat Jan 12 23:42:11 2013 -0800
Support process renaming
Renaming our python process from "python our_script.py" to something more
sensible is a very handy capability to have. Thanks to Jake arm has had this
for years, which makes it easier to identify in top and ps listings.
We'll want this capability for other controllers so snagging arm's utility and
cleaning it up.
---
stem/util/system.py | 164 +++++++++++++++++++++++++++++++++++++++++++++
test/integ/util/system.py | 16 ++++-
2 files changed, 179 insertions(+), 1 deletions(-)
diff --git a/stem/util/system.py b/stem/util/system.py
index a8cecd1..2b46dad 100644
--- a/stem/util/system.py
+++ b/stem/util/system.py
@@ -10,6 +10,7 @@ best-effort, providing **None** if the lookup fails.
is_windows - checks if we're running on windows
is_mac - checks if we're running on a mac
is_bsd - checks if we're running on the bsd family of operating systems
+
is_available - determines if a command is available on this system
is_running - determines if a given process is running
get_pid_by_name - gets the pid for a process by the given name
@@ -19,8 +20,13 @@ best-effort, providing **None** if the lookup fails.
get_bsd_jail_id - provides the BSD jail id a given process is running within
expand_path - expands relative paths and ~ entries
call - runs the given system command and provides back the results
+
+ get_process_name - provides our process' name
+ set_process_name - changes our process' name
"""
+import ctypes
+import ctypes.util
import os
import platform
import subprocess
@@ -59,6 +65,34 @@ GET_CWD_PWDX = "pwdx %s"
GET_CWD_LSOF = "lsof -a -p %s -d cwd -Fn"
GET_BSD_JAIL_ID_PS = "ps -p %s -o jid"
+# flag for setting the process name, found in '/usr/include/linux/prctl.h'
+
+PR_SET_NAME = 15
+
+argc_t = ctypes.POINTER(ctypes.c_char_p)
+
+Py_GetArgcArgv = ctypes.pythonapi.Py_GetArgcArgv
+Py_GetArgcArgv.restype = None
+Py_GetArgcArgv.argtypes = [
+ ctypes.POINTER(ctypes.c_int),
+ ctypes.POINTER(argc_t),
+]
+
+# This is both a cache for get_process_name() and tracks what we've changed our
+# process name to.
+
+_PROCESS_NAME = None
+
+# Length of our original process name.
+#
+# The original author our process renaming is based on did a memset for 256,
+# while Jake did it for the original process name length (capped at 1608). I'm
+# not sure of the reasons for either of these limits, but setting it to
+# anything higher than our original name length should be pointless, so opting
+# for Jake's limit.
+
+_MAX_NAME_LENGTH = -1
+
def is_windows():
"""
@@ -648,3 +682,133 @@ def call(command, default = UNDEFINED):
return default
else:
raise exc
+
+
+def get_process_name():
+ """
+ Provides the present name of our process.
+
+ :returns: **str** with the present name of our process
+ """
+
+ global _PROCESS_NAME, _MAX_NAME_LENGTH
+
+ if _PROCESS_NAME is None:
+ # Example output...
+ #
+ # COMMAND
+ # python run_tests.py --unit
+
+ ps_output = call("ps -p %i -o args" % os.getpid(), [])
+
+ if len(ps_output) == 2 and ps_output[0] == "COMMAND":
+ _PROCESS_NAME = ps_output[1]
+ else:
+ # Falling back on using ctypes to get our argv. Unfortunately the simple
+ # method for getting this...
+ #
+ # " ".join(["python"] + sys.argv)
+ #
+ # ... doesn't do the trick since this will miss interpretor arguments.
+ #
+ # python -W ignore::DeprecationWarning my_script.py
+
+ args, argc = [], argc_t()
+
+ for i in xrange(100):
+ if argc[i] is None:
+ break
+
+ args.append(str(argc[i]))
+
+ _PROCESS_NAME = " ".join(args)
+
+ _MAX_NAME_LENGTH = len(_PROCESS_NAME)
+
+ return _PROCESS_NAME
+
+
+def set_process_name(process_name):
+ """
+ Renames our current process from "python <args>" to a custom name. This is
+ best-effort, not necessarily working on all platforms.
+
+ :param str process_name: new name for our process
+ """
+
+ # This is mostly based on...
+ #
+ # http://www.rhinocerus.net/forum/lang-python/569677-setting-program-name-like-0-perl.html#post2272369
+ #
+ # ... and an adaptation by Jake...
+ #
+ # https://github.com/ioerror/chameleon
+ #
+ # A cleaner implementation is available at...
+ #
+ # https://github.com/cream/libs/blob/b38970e2a6f6d2620724c828808235be0445b799/cream/util/procname.py
+ #
+ # but I'm not quite clear on their implementation, and it only does targeted
+ # argument replacement (ie, replace argv[0], argv[1], etc but with a string
+ # the same size).
+
+ _set_argv(process_name)
+
+ if platform.system() == "Linux":
+ _set_prctl_name(process_name)
+ elif platform.system() in ("Darwin", "FreeBSD", "OpenBSD"):
+ _set_proc_title(process_name)
+
+
+def _set_argv(process_name):
+ """
+ Overwrites our argv in a similar fashion to how it's done in C with:
+ strcpy(argv[0], "new_name");
+ """
+
+ global _PROCESS_NAME
+
+ # both gets the current process name and initializes _MAX_NAME_LENGTH
+
+ current_name = get_process_name()
+
+ argv, argc = ctypes.c_int(0), argc_t()
+ Py_GetArgcArgv(argv, ctypes.pointer(argc))
+
+ if len(process_name) > _MAX_NAME_LENGTH:
+ raise IOError("Can't rename process to something longer than our initial name (this would overwrite memory used for the env)")
+
+ # space we need to clear
+ zero_size = max(len(current_name), len(process_name))
+
+ ctypes.memset(argc.contents, 0, zero_size + 1) # null terminate the string's end
+ ctypes.memmove(argc.contents, process_name, len(process_name))
+ _PROCESS_NAME = process_name
+
+
+def _set_prctl_name(process_name):
+ """
+ Sets the prctl name, which is used by top and killall. This appears to be
+ Linux specific and has the max of 15 characters.
+
+ This is from...
+ http://stackoverflow.com/questions/564695/is-there-a-way-to-change-effective-process-name-in-python/923034#923034
+ """
+
+ libc = ctypes.CDLL(ctypes.util.find_library("c"))
+ name_buffer = ctypes.create_string_buffer(len(process_name) + 1)
+ name_buffer.value = process_name
+ libc.prctl(PR_SET_NAME, ctypes.byref(name_buffer), 0, 0, 0)
+
+
+def _set_proc_title(process_name):
+ """
+ BSD specific calls (should be compataible with both FreeBSD and OpenBSD:
+ http://fxr.watson.org/fxr/source/gen/setproctitle.c?v=FREEBSD-LIBC
+ http://www.rootr.net/man/man/setproctitle/3
+ """
+
+ libc = ctypes.CDLL(ctypes.util.find_library("c"))
+ name_buffer = ctypes.create_string_buffer(len(process_name) + 1)
+ name_buffer.value = process_name
+ libc.setproctitle(ctypes.byref(name_buffer))
diff --git a/test/integ/util/system.py b/test/integ/util/system.py
index f7592af..1528d05 100644
--- a/test/integ/util/system.py
+++ b/test/integ/util/system.py
@@ -384,7 +384,7 @@ class TestSystem(unittest.TestCase):
def test_expand_path(self):
"""
- Exercises the stem.expand_path method with actual runtime data.
+ Exercises the expand_path() method with actual runtime data.
"""
self.assertEquals(os.getcwd(), stem.util.system.expand_path("."))
@@ -396,3 +396,17 @@ class TestSystem(unittest.TestCase):
self.assertEquals(home_dir, stem.util.system.expand_path("~/"))
self.assertEquals(home_dir, stem.util.system.expand_path("~%s" % username))
self.assertEquals(os.path.join(home_dir, "foo"), stem.util.system.expand_path("~%s/foo" % username))
+
+ def test_set_process_name(self):
+ """
+ Exercises the get_process_name() and set_process_name() methods.
+ """
+
+ initial_name = stem.util.system.get_process_name()
+ self.assertTrue("run_tests.py" in initial_name)
+
+ try:
+ stem.util.system.set_process_name("stem_integ")
+ self.assertEqual("stem_integ", stem.util.system.get_process_name())
+ finally:
+ stem.util.system.set_process_name(initial_name)
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