commit 8ec467eb5caeb4972e12a988a805d93f511bd192 Author: Damian Johnson atagar@torproject.org Date: Mon May 2 19:59:39 2011 -0700

Renaming our process to "arm <input args>"

Our process was called "python ./src/starter.py <input args>" which made it a pita to identify, use killall on, etc. Using some ctypes hacks to overwrite it with an intuitive name. --- src/starter.py | 8 +++ src/util/procname.py | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 130 insertions(+), 0 deletions(-)

diff --git a/src/starter.py b/src/starter.py index c0a0270..365676c 100644 --- a/src/starter.py +++ b/src/starter.py @@ -387,5 +387,13 @@ if __name__ == '__main__': util.log.log(CONFIG["log.savingDebugLog"], "Saving a debug log to '%s' (please check it for sensitive information before sharing)" % LOG_DUMP_PATH) _dumpConfig()

+ # Attempts to rename our process from "python setup.py <input args>" to + # "arm <input args>" + + try: + from util import procname + procname.renameProcess("arm %s" % " ".join(sys.argv[1:])) + except: pass + cli.controller.startTorMonitor(time.time() - initTime, expandedEvents, param["startup.blindModeEnabled"])

diff --git a/src/util/procname.py b/src/util/procname.py new file mode 100644 index 0000000..7641c5a --- /dev/null +++ b/src/util/procname.py @@ -0,0 +1,122 @@ +# Module to allow for arbitrary renaming of our python process. This is mostly +# based on: +# http://www.rhinocerus.net/forum/lang-python/569677-setting-program-name-like... +# and an adaptation by Jake: https://github.com/ioerror/chameleon +# +# A cleaner implementation is available at: +# https://github.com/cream/libs/blob/b38970e2a6f6d2620724c828808235be0445b799/... +# 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). + +import os +import sys +import ctypes +import ctypes.util + +from util import sysTools + +# flag for setting the process name, found in '/usr/include/linux/prctl.h' +PR_SET_NAME = 15 + +# Maximum number of characters we'll set the process name to. Evidently this +# cap was simply chosen since it didn't cause a segfault for its author. +MAX_CHAR = 1608 + +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)] + +# tracks the last name we've changed the process to +currentProcessName = None + +def renameProcess(processName): + """ + Renames our current process from "python <args>" to a custom name. + + Arguments: + processName - new name for our process + """ + + _setArgv(processName) + if sys.platform == "linux2": + _setPrctlName(processName) + elif sys.platform == "freebsd7": + _setProcTitle(processName) + +def _setArgv(processName): + """ + Overwrites our argv in a similar fashion to how it's done in C with: + strcpy(argv[0], "new_name"); + """ + + global currentProcessName + + argv = ctypes.c_int(0) + argc = argc_t() + Py_GetArgcArgv(argv, ctypes.pointer(argc)) + + # The original author did the memset for 256, while Jake did it for the + # processName length (capped at 1608). I'm not sure of the reasons for + # either of these limits, but setting it to anything higher than than the + # length of the null terminated process name should be pointless, so opting + # for Jake's implementation on this. + + if currentProcessName == None: + # Using argv via... + # currentProcessName = " ".join(["python"] + sys.argv) + # + # doesn't do the trick since this will miss interpretor arguments like... + # python -W ignore::DeprecationWarning myScript.py + # + # hence simply getting an outside opinion of our command. + + psResults = sysTools.call("ps -p %i -o args" % os.getpid()) + + if len(psResults) == 2: + # output looks like: + # COMMAND + # python ./src/starter.py + + currentProcessName = psResults[1] + + if not currentProcessName: + raise IOError("unable to determine our process name") + + # we need to fill extra space with null characters, otherwise the process + # will end with a '?' when you run ps against it + if len(currentProcessName) > len(processName): + processName += "\0" * (len(currentProcessName) - len(processName)) + + size = min(len(processName), MAX_CHAR) + ctypes.memset(argc.contents, 0, size + 1) # null terminate the string's end + ctypes.memmove(argc.contents, processName, size) + currentProcessName = processName[:MAX_CHAR] + +def _setPrctlName(processName): + """ + Sets the prctl name, which is used by top and killall. This appears to be + Linux specific and has the max of 15 characters. Source: + http://stackoverflow.com/questions/564695/is-there-a-way-to-change-effective... + """ + + libc = ctypes.CDLL(ctypes.util.find_library("c")) + nameBuffer = ctypes.create_string_buffer(len(processName)+1) + nameBuffer.value = processName + libc.prctl(PR_SET_NAME, ctypes.byref(nameBuffer), 0, 0, 0) + +def _setProcTitle(processName): + """ + 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")) + nameBuffer = ctypes.create_string_buffer(len(processName)+1) + nameBuffer.value = processName + libc.setproctitle(ctypes.byref(nameBuffer)) +