[Python-Dev] Deterministic builds of the interpreter

[INADA Naoki]

As reading [4], mtime is not 0.

    data = bytearray(MAGIC_NUMBER)
    data.extend(_w_long(mtime))
    data.extend(_w_long(source_size))
    data.extend(marshal.dumps(code))

First 4 bytes are magic.
Next 4 bytes are mtime.

│ │ │ │ -00000000: 160d 0d0a 6b2e 9c58 6c21 0000 e300 0000 ....k..Xl!......
│ │ │ │ +00000000: 160d 0d0a e631 9c58 6c21 0000 e300 0000 .....1.Xl!......

mtime is 6b2e9c58 vs e6319c53 (little endian)

maybe, you failed to use customized py_compile when building?


On Thu, Feb 9, 2017 at 6:27 PM, Freddy Rietdijk <freddyrietdijk at fridh.nl> wrote:
> Hi,
>
> I'm attempting to make the builds of the Python interpreters for Nixpkgs [1]
> deterministic.
>
> In the case of Python 2.7 we have a patch [2] that fixes the timestamp used
> in .pyc files in case the env var `DETERMINISTIC_BUILD` is set. We also
> remove `wininst*.exe`. This works fine, although there are 4 small issues
> left [3]. Do you have any idea what is going on in these files that could
> make them indeterministic?
>
> For Python 3.x I disabled ensurepip, removed `wininst*.exe`, and modified
> `py_compile` to use `0` instead of `source_stats['mtime']`. The builds are
> not yet deterministic [4]. Any suggestions what could be fixed here?
>
> Kind regards,
>
> Freddy
>
>
> [1] https://github.com/NixOS/nixpkgs
> [2]
> https://github.com/NixOS/nixpkgs/blob/1da6775/pkgs/development/interpreters/python/cpython/2.7/deterministic-build.patch
> [3] https://github.com/NixOS/nixpkgs/issues/22570#issuecomment-278474082
> [4] https://gist.github.com/anonymous/7cc147af6511dee2dc5a5b8d110f0e6b
>
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