Re: [PATCH 3/5] gnu: Enable tests in Python 3.

[ludo@gnu.org (Ludovic Courtès)]

Cyril Roelandt <tipecaml@gmail.com> skribis:

> On 03/07/2014 10:40 AM, Ludovic Courtès wrote:
>> Cyril Roelandt <tipecaml@gmail.com> skribis:

[...]

>>> +--- Lib/test/test_posixpath.py	2014-03-01 05:46:56.984311000 +0100
>>> ++++ Lib/test/test_posixpath.py	2014-03-01 06:20:50.704311000 +0100
>>> +@@ -319,7 +319,11 @@
>>> +                 del env['HOME']
>>> +                 home = pwd.getpwuid(os.getuid()).pw_dir
>>> +                 # $HOME can end with a trailing /, so strip it (see #17809)
>>> +-                self.assertEqual(posixpath.expanduser("~"), home.rstrip("/"))
>>> ++		# The Guix builders have '/' as a home directory, so
>>> ++		# home.rstrip("/") will be an empty string and the test will
>>> ++		# fail. Let's just disable it since it does not really make
>>> ++		# sense with such a bizarre setup.
>>> ++                # self.assertEqual(posixpath.expanduser("~"), home.rstrip("/"))
>>
>> I see that the recipe’s ‘pre-check’ phase does:
>>
>>    (setenv "HOME" (getcwd))
>>
>> so $HOME should actually be /tmp/nix-build-xxx, not just /, no?
>>
>
> Yes, but I think it uses getpwent() or something that does not use
> $HOME to retrieve the home directory in this case.

Here’s what I see, with nscd turned off (this uses getpwnam(2)):

--8<---------------cut here---------------start------------->8---
$ strace guile -c '(getpw "ludo")'
[...]
open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 5
fstat(5, {st_mode=S_IFREG|0644, st_size=2072, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f264dea5000
read(5, "root:x:0:0:System administrator:"..., 4096) = 2072
--8<---------------cut here---------------end--------------->8---

Normally the chroot environment has all that too.  And indeed, the
equivalent of the above Python snippet seems to work:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> ,use(guix)
scheme@(guile-user)> ,use(guix monads)
scheme@(guile-user)> (define s (open-connection))
scheme@(guile-user)> (derivation-expression "getpw" '(pk (getpw (getuid))))
$11 = #<procedure 3da30f0 at guix/monads.scm:297:6 (store)>
scheme@(guile-user)> (run-with-store s $11)
$12 = #<derivation /gnu/store/bhmd5bg9s64an3s8ssmwx6l90dkr56hx-getpw.drv => /gnu/store/z68rzri3myxx1dg931fb1ksxdg7c29zg-getpw 33dfa00>
scheme@(guile-user)> (build-derivations s (list $12))
building path(s) `/gnu/store/z68rzri3myxx1dg931fb1ksxdg7c29zg-getpw'

;;; (#("nixbld" "x" 30001 30000 "Nix build user" "/" "/noshell"))
builder for `/gnu/store/bhmd5bg9s64an3s8ssmwx6l90dkr56hx-getpw.drv' failed to produce output path `/gnu/store/z68rzri3myxx1dg931fb1ksxdg7c29zg-getpw'
--8<---------------cut here---------------end--------------->8---

Libguile implements this using getpwuid(3).  I wonder if CPython is
doing something else.

Thanks,
Ludo’.