(instead of using a copy). Foolscap-0.12.3 fixes a problem with
allocate_tcp_port() that was causing intermittent test failures. I think
it makes more sense to use Foolscap's copy (and fixes) than to keep
re-copying it into Tahoe each time it changes.
If/when we manage to stop depending upon foolscap for server RPC, we can
re-copy this back into tahoe's source tree.
refs ticket:2795
The old copy had a bug which occasionally returns a port that was
actually in use, causing intermittent test failures (when large numbers
of ports were allocated). I finally figured out how to fix it in
Foolscap, so this is just a copy of the updated function.
closes ticket:2795
The udpprot.transport.connect() fails if we don't have a network
connection, but the port is still listening, so trial gives us a
DirtyReactorError. The fix is a "finally:" which does
port.stopListening() even in this case.
Closes ticket:2769
The stdlib 'subprocess' module in python-2.7.4 through 2.7.7 suffers
from http://bugs.python.org/issue18851 which causes unrelated file
descriptors to be closed when `subprocess.call()` fails the `exec()`,
such as when the executable being invoked does not actually exist. There
appears to be some randomness involved. This was fixed in python-2.7.8.
Tahoe's iputil.py uses subprocess.call on many different "ifconfig"-type
executables, most of which don't exist on any given platform (added in
git commit 8e31d66cd0b). This results in a lot of file-descriptor
closing, which (at least during unit tests) tends to clobber important
things like Tub TCP sockets. This seems to be the root cause behind
ticket:2121, in which normal code tries to close already-closed sockets,
crashing the unit tests. Since different platforms have different
ifconfigs, some platforms will experience more failed execs than others,
so this bug could easily behave differently on linux vs freebsd, as well
as working normally on python-2.7.8 or 2.7.4.
This patch inserts a guard to make sure that os.path.isfile() is true
before allowing Popen.call() to try executing the target. This ought to
be enough to avoid the bug. It changes both iputil.py and
allmydata.__init__ (which uses Popen for calling "lsb_release"), which
are all the places where 'subprocess' is used outside of unit tests.
Other potential fixes: use the 'subprocess32' module from PyPI (which is
a bug-free backport of the Python3 stdlib subprocess module, but would
introduce a new dependency), or require python >= 2.7.8 (but this would
rule out development/deployment on the current OS-X 10.9 release, which
ships with 2.7.5, as well as other distributions like Ubuntu 14.04 LTS).
I believe this closes ticket:2121, and given the apparent relationship
between 2121 and 2023, I think it also closes ticket:2023 (although
since 2023 doesn't have copies of the failing log files, it's hard to
tell). I'm hoping that this will tide us over until 1.11 is released, at
which point we can execute on the plan to remove iputil.py entirely by
changing the way that nodes learn their externally-facing IP address.
