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PEP 446: Issues: add examples in other projects

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Victor Stinner 2013-08-10 01:00:07 +02:00
parent 4410f51ce3
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1 changed files with 36 additions and 5 deletions
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@ -128,7 +128,7 @@ Most of the time, inheritable file descriptors "leaked" in child
processes are not noticed, because they don't cause major bugs. It does
not mean that these bugs must not be fixed.
Two examples of common issues with inherited file descriptors:
Two common issues with inherited file descriptors:
* On Windows, a directory cannot be removed before all file handles open
in the directory are closed. The same issue can be seen with files,
@ -153,6 +153,30 @@ for example a way to escape from a chroot. With a leaked listening
socket, a child process can accept new connections to read sensitive
data.
Example of issues in open source projects:
* `Mozilla (Firefox) <https://bugzilla.mozilla.org/show_bug.cgi?id=147659>`_:
open since 2002-05
* `dbus library <https://bugs.freedesktop.org/show_bug.cgi?id=15947>`_:
fixed in 2008-05 (`dbus commit
<http://cgit.freedesktop.org/dbus/dbus/commit/?id=e2bc7232069b14b7299cb8b2eab436f60a232007>`_),
close file descriptors in the child process
* `autofs <https://bugzilla.redhat.com/show_bug.cgi?id=390591>`_:
fixed in 2009-02, set the CLOEXEC flag
* `qemu <https://bugzilla.redhat.com/show_bug.cgi?id=528134>`_:
fixed in 2009-12 (`qemu commit
<http://git.qemu.org/?p=qemu.git;a=commit;h=40ff6d7e8dceca227e7f8a3e8e0d58b2c66d19b4>`_),
set CLOEXEC flag
* `Tor <https://trac.torproject.org/projects/tor/ticket/2029>`_:
fixed in 2010-12, set CLOEXEC flag
* `OCaml <http://caml.inria.fr/mantis/view.php?id=5256>`_: open since
2011-04, "PR#5256: Processes opened using Unix.open_process* inherit
all opened file descriptors (including sockets)"
* `ØMQ <https://zeromq.jira.com/browse/LIBZMQ-408>`_:
open since 2012-08
* `Squid <https://bugzilla.redhat.com/show_bug.cgi?id=837033>`_:
open since 2012-07
Issues fixed in the subprocess module
-------------------------------------
@ -327,8 +351,13 @@ On Linux, Python 3.3 gets the list of all open file descriptors from
``/proc/<PID>/fd/``, and so performances depends on the number of open
file descriptors, not on MAXFD.
See also the `issue #1663329: subprocess close_fds perform poor if
SC_OPEN_MAX is high <http://bugs.python.org/issue1663329>`_.
See also:
* `Python issue #1663329 <http://bugs.python.org/issue1663329>`_:
subprocess close_fds perform poor if ``SC_OPEN_MAX`` is high
* `Squid Bug #837033 <https://bugzilla.redhat.com/show_bug.cgi?id=837033>`_:
Squid should set CLOEXEC on opened FDs. "32k+ close() calls in each
child process take a long time ([12-56] seconds) in Xen PV guests."
Proposal
@ -425,8 +454,8 @@ The programming languages Go, Perl and Ruby make newly created file
descriptors non-inheritable by default: since Go 1.0 (2009), Perl 1.0
(1987) and Ruby 2.0 (2013).
The SCons project overrides builtin functions ``file()`` and ``open()``
to make files non-inheritable on Windows:
The SCons project, written in Python, overrides builtin functions
``file()`` and ``open()`` to make files non-inheritable on Windows:
see `win32.py
<https://bitbucket.org/scons/scons/src/c8dbbaa4598e7119ae80f72068386be105b5ad98/src/engine/SCons/Platform/win32.py?at=default#cl-68>`_.
@ -508,6 +537,8 @@ Other links:
* `Ghosts of Unix past, part 2: Conflated designs
<http://lwn.net/Articles/412131/>`_ (Neil Brown, 2010) explains the
history of ``O_CLOEXEC`` and ``O_NONBLOCK`` flags
* `File descriptor handling changes in 2.6.27
<http://lwn.net/Articles/292843/>`_
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