commit d1c3c8db724eb17c754c26f66016315d0524a74a Author: Damian Johnson atagar@torproject.org Date: Sat Nov 12 15:46:13 2011 -0800
Standardizing on suppress_exc args for sys util
The system functions are mostly best-effort, platform specific attempts to retrieve data and usually don't have meaningful information to provide back to the caller via exceptions. I'm defaulting to have them return None, with an optional arg for having them raise IOError exceptions on failure instead.
I've gone back and forth on the fencepost here a few times, and I'm still not positive if this is the right choice. Might change this later if it doesn't work out. --- stem/util/proc.py | 2 +- stem/util/system.py | 101 +++++++++++++++++++++++++++++++++++++++---------- test/integ/system.py | 8 ++-- test/runner.py | 11 +---- 4 files changed, 87 insertions(+), 35 deletions(-)
diff --git a/stem/util/proc.py b/stem/util/proc.py index 30fab6a..79cf92a 100644 --- a/stem/util/proc.py +++ b/stem/util/proc.py @@ -109,7 +109,7 @@ def get_physical_memory():
return SYS_PHYSICAL_MEMORY
-def get_pwd(pid): +def get_cwd(pid): """ Provides the current working directory for the given process.
diff --git a/stem/util/system.py b/stem/util/system.py index 467787c..fd7277d 100644 --- a/stem/util/system.py +++ b/stem/util/system.py @@ -93,7 +93,7 @@ def is_running(command, suppress_exc = True): if suppress_exc: return None else: raise OSError("Unable to check via 'ps -A co command'")
-def get_pid(process_name, process_port = None): +def get_pid(process_name, process_port = None, suppress_exc = True): """ Attempts to determine the process id for a running process, using the following: @@ -110,14 +110,20 @@ def get_pid(process_name, process_port = None): are discarded (since only netstat can differentiate using a bound port).
Arguments: - process_name (str) - process name for which to fetch the pid - process_port (int) - port that the process we're interested in is bound to, - this is used to disambiguate if there's multiple - instances running + process_name (str) - process name for which to fetch the pid + process_port (int) - port that the process we're interested in is bound + to, this is used to disambiguate if there's multiple + instances running + suppress_exc (bool) - if True then None is returned on failure, otherwise + this raises the exception
Returns: - int with the process id, None if either no running process exists or it - can't be determined + int with the process id, None if it can't be determined and suppress_exc is + True + + Raises: + IOError if either no running process exists or it can't be determined and + suppress_exc is True """
# attempts to resolve using pgrep, failing if: @@ -241,30 +247,39 @@ def get_pid(process_name, process_port = None): if pid.isdigit(): return int(pid) except IOError: pass
- return None + exc_msg = "failed to resolve a pid for %s" % process_name + + if suppress_exc: + LOGGER.debug(exc_msg) + return None + else: + raise IOError(exc_msg)
-def get_pwd(pid): +def get_cwd(pid, suppress_exc = True): """ Provices the working directory of the given process.
Arguments: - pid (int) - process id of the process to be queried + pid (int) - process id of the process to be queried + suppress_exc (bool) - if True then None is returned on failure, otherwise + this raises the exception
Returns: - str with the absolute path for the process' present working directory + str with the absolute path for the process' present working directory, None + if it can't be determined and suppress_exc is True
Raises: - IOError if it can't be determined + IOError if this fails and suppress_exc is False """
# try fetching via the proc contents if it's available if stem.util.proc.is_available(): - try: return stem.util.proc.get_pwd(pid) + try: return stem.util.proc.get_cwd(pid) except IOError: pass
# Fall back to a pwdx query. This isn't available on BSD. If we attempt this - # lookup then it trumps lsof when reporting an exception at the end since - # it's the better lookup method for this information. + # lookup then it trumps lsof when logging isssues at the end since it's the + # better lookup method for this information.
exc_msg = None
@@ -304,14 +319,18 @@ def get_pwd(pid): exc_msg = "we got unexpected output from lsof: %s" % results except OSError, exc: if not exc_msg: - exc_msg = "lsof query for the pwd of %s failed: %s" % (pid, exc) + exc_msg = "lsof query for the cwd of %s failed: %s" % (pid, exc)
if not exc_msg: # shouldn't happen, somehow we never registered a failure... - exc_msg = "unable to query pwdx or lsof" + exc_msg = "unable to query pwdx or lsof for the cwd of %s" % pid
- # we failed all lookups, raise - raise IOError(exc_msg) + # we failed all lookups, either raise or log the issue and return None + if suppress_exc: + LOGGER.debug(exc_msg) + return None + else: + raise IOError(exc_msg)
def get_bsd_jail_id(pid): """ @@ -341,6 +360,47 @@ def get_bsd_jail_id(pid): LOGGER.warn("Failed to figure out the FreeBSD jail id. Assuming 0.") return 0
+def is_relative_path(path): + """ + Checks if the path can be expanded by the expand_path function. + + Returns: + bool that's True if the path is relative or begins with an expandable home, + False otherwise + """ + + return path and not path.startswith("/") + +def expand_path(path, cwd = None): + """ + Provides an absolute path, expanding tildas with the user's home and + appending a current working directory if the path was relative. + + Arguments: + path (str) - path to be expanded + cwd (str) - current working directory to expand relative paths with, our + process' if this is None. + + Returns: + str of the path expanded to be an absolute path + """ + + if not path or path[0] == "/": + # empty or already absolute - nothing to do + return path + elif path.startswith("~"): + # prefixed with a ~ or ~user entry + return os.path.expanduser(path) + else: + # relative path, expand with the cwd + if not cwd: cwd = os.getcwd() + + # we'll be dealing with both "my/path/" and "./my/path" entries, so + # cropping the later + if path.startswith("./"): path = path[2:] + + return os.path.join(cwd, path) + def call(command, suppress_exc = True): """ Issues a command in a subprocess, blocking until completion and returning the @@ -373,8 +433,7 @@ def call(command, suppress_exc = True): if stdout: return stdout.split("\n") else: return [] except OSError, exc: - msg = "system call (failed): %s (error: %s)" % (command, exc) - LOGGER.debug(msg) + LOGGER.debug("system call (failed): %s (error: %s)" % (command, exc))
if suppress_exc: return None else: raise exc diff --git a/test/integ/system.py b/test/integ/system.py index 6e3370e..4aa5d15 100644 --- a/test/integ/system.py +++ b/test/integ/system.py @@ -41,15 +41,15 @@ class TestSystemFunctions(unittest.TestCase): self.assertEquals(runner.get_pid(), system.get_pid("tor", runner.get_control_port())) self.assertEquals(None, system.get_pid("blarg_and_stuff"))
- def test_get_pwd(self): + def test_get_cwd(self): """ - Checks the util.system.get_pwd function. + Checks the util.system.get_cwd function. """
# tor's pwd will match our process since we started it runner = test.runner.get_runner() - self.assertEquals(os.getcwd(), system.get_pwd(runner.get_pid())) - self.assertRaises(IOError, system.get_pwd, 99999) + self.assertEquals(os.getcwd(), system.get_cwd(runner.get_pid())) + self.assertRaises(IOError, system.get_cwd, 99999)
def test_get_bsd_jail_id(self): """ diff --git a/test/runner.py b/test/runner.py index 21cf1e5..613b3b2 100644 --- a/test/runner.py +++ b/test/runner.py @@ -105,11 +105,7 @@ class Runner: config_test_dir = self._config["test.integ.test_directory"]
if config_test_dir: - # makes paths relative of stem's base directory - if config_test_dir.startswith("./"): - config_test_dir = STEM_BASE + config_test_dir[1:] - - self._test_dir = os.path.expanduser(config_test_dir) + self._test_dir = stem.util.system.expand_path(config_test_dir, STEM_BASE) else: self._test_dir = tempfile.mktemp("-stem-integ")
@@ -333,10 +329,7 @@ class Runner: logging_path = self._config["test.integ.log"]
if logging_path: - # makes paths relative of stem's base directory - if logging_path.startswith("./"): - logging_path = STEM_BASE + logging_path[1:] - + logging_path = stem.util.system.expand_path(logging_path, STEM_BASE) _print_status(" configuring logger (%s)... " % logging_path, STATUS_ATTR, quiet)
# delete the old log