commit d5956193b096aec35520cb99602fb91fde078f14 Author: teor teor@torproject.org Date: Fri Jan 24 10:46:26 2020 +1000

TorNet: Add function comments to the path functions

Documentation for 32969. --- lib/chutney/TorNet.py | 46 +++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 43 insertions(+), 3 deletions(-)

diff --git a/lib/chutney/TorNet.py b/lib/chutney/TorNet.py index 66e19d2..395bb4a 100644 --- a/lib/chutney/TorNet.py +++ b/lib/chutney/TorNet.py @@ -123,6 +123,10 @@ def make_datadir_subdirectory(datadir, subdir): mkdir_p(os.path.join(datadir, subdir))

def get_absolute_chutney_path(): + """ + Returns the absolute path of the directory containing the chutney + executable script. + """ # use the current directory as the default # (./chutney already sets CHUTNEY_PATH using the path to the script) # use tools/test-network.sh if you want chutney to try really hard to find @@ -131,27 +135,63 @@ def get_absolute_chutney_path(): return os.path.abspath(relative_chutney_path)

def get_absolute_net_path(): + """ + Returns the absolute path of the "net" directory that chutney should + use to store "node*" directories containing torrcs and tor runtime data. + + If the CHUTNEY_DATA_DIR environmental variable is an absolute path, it + is returned unmodified, regardless of whether the path actually exists. + (Chutney creates any directories that do not exist.) + + Otherwise, if it is a relative path, and there is an existing directory + with that name in the directory containing the chutney executable + script, return that path (this check exists for legacy reasons). + + Finally, return the path relative to the current working directory, + regardless of whether the path actually exists. + """ data_dir = os.environ.get('CHUTNEY_DATA_DIR', 'net') if os.path.isabs(data_dir): # if we are given an absolute path, we should use it + # regardless of whether the directory exists return data_dir # use the chutney path as the default absolute_chutney_path = get_absolute_chutney_path() relative_net_path = data_dir # but what is it relative to? - # let's check if it's in CHUTNEY_PATH first, to preserve - # backwards-compatible behaviour + # let's check if there's an existing directory with this name in + # CHUTNEY_PATH first, to preserve backwards-compatible behaviour chutney_net_path = os.path.join(absolute_chutney_path, relative_net_path) if os.path.isdir(chutney_net_path): return chutney_net_path - # ok, it's relative to the current directory, whatever that is + # ok, it's relative to the current directory, whatever that is, and whether + # or not the path actually exists return os.path.abspath(relative_net_path)

def get_absolute_nodes_path(): + """ + Returns the absolute path of the "nodes" symlink that points to the + "nodes*" directory that chutney should use to store the current + network's torrcs and tor runtime data. + + See get_new_absolute_nodes_path() for more details. + """ # there's no way to customise this: we really don't need more options return os.path.join(get_absolute_net_path(), 'nodes')

def get_new_absolute_nodes_path(now=time.time()): + """ + Returns the absolute path of a unique "nodes*" directory that chutney + should use to store the current network's torrcs and tor runtime data. + + The nodes directory suffix is based on the current timestamp, + incremented if necessary to avoid collisions with existing directories. + + (The existing directory check contains known race conditions: running + multiple simultaneous chutney instances on the same "net" directory is + not supported. The uniqueness check is only designed to avoid + collisions if the clock is set backwards.) + """ # automatically chosen to prevent path collisions, and result in an ordered # series of directory path names # should only be called by 'chutney configure', all other chutney commands