nixpkgs/pkgs
Will Dietz b11f3bc8e3 cpython: don't use lchmod() on Linux, fix w/musl
upstream issue:
https://bugs.python.org/issue31940

There are two PR's proposed to fix this,
but both seem to be stalling waiting for review.

I previously used what appears to be the favored
of the two approaches[1] to fix this,
with plan of keeping it musl-only until PR was merged.

However, while writing up a commit message
explaining the problem and why it needed fixing...

I investigated a bit and found it increasingly
hard to justify anything other than ...
simply not using lchmod.

Here's what I found:
* lchmod is non-POSIX, seems BSD-only these days
* Functionality of lchmod isn't supported on Linux
  * best scenario on Linux would be an error
* POSIX does provide lchmod-esque functionality
  with fchmodat(), which AFAICT is generally preferred.
* Python intentionally overlooks fchmodat()[2]
  electing instead to use lchmod() behavior
  as a proxy for whether fchmodat() "works".
  I'm not sure I follow their reasoning...
* both glibc and musl provide lchmod impls:
  * glibc returns ENOSYS "not implemented"
  * musl implements lchmod with fchmodat(),
    and so returns EOPNOTSUPP "op not supported"
* Python doesn't expect EOPNOTSUPP from lchmod,
  since it's not valid on BSD's lchmod.
* "configure" doesn't actually check lchmod usefully,
  instead checks for glibc preprocessor defines
  to indicate if the function is just a stub[3];
  somewhat fittingly, if the magic macros are defined
  then the next line of the C source is "choke me",
  causing the compiler to trip, fall, and point
  a finger at whatever is near where it ends up.
  (somewhat amusing, but AFAIK effective way to get an error :P)

I'm leaving out links to threads on mailing lists and such,
but for now I hope I've convinced you
(or to those reading commit history: explained my reasons)
that this is a bit of a mess[4].

And so instead of making a big mess messier,
and with hopes of never thinking about this again,
I propose we simply tell Python "don't use lchmod" on Linux.

[1] https://github.com/python/cpython/pull/4783
[2] 28453feaa8/Lib/os.py (L144)
[3] 28453feaa8/configure (L2198)
[4] Messes happen, no good intention goes unpunished :).
2018-04-25 21:46:13 -05:00
..
applications tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part) 2018-04-25 04:18:46 +00:00
build-support Merge remote-tracking branch 'origin/master' into staging 2018-04-24 19:58:44 -05:00
common-updater common-updater: support updating source URL 2018-03-16 23:17:07 +09:00
data tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part) 2018-04-25 04:18:46 +00:00
desktops tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part) 2018-04-25 04:18:46 +00:00
development cpython: don't use lchmod() on Linux, fix w/musl 2018-04-25 21:46:13 -05:00
games openarena: needs libcurl for fast assets downloads 2018-04-24 17:06:58 +02:00
misc tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part) 2018-04-25 04:18:46 +00:00
os-specific tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part) 2018-04-25 04:18:46 +00:00
servers tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part) 2018-04-25 04:18:46 +00:00
shells xonsh: 0.6.0 -> 0.6.1 2018-04-23 10:56:41 +03:00
stdenv Merge remote-tracking branch 'upstream/master' into HEAD 2018-04-22 22:31:30 +03:00
test
tools tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part) 2018-04-25 04:18:46 +00:00
top-level tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part) 2018-04-25 04:18:46 +00:00