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Re: [ANNOUNCE] Git v2.9.1

From
Junio C Hamano <gitster@pobox.com>
Date
Jul 12, 2016, 14:34 UTC
Message-ID
<xmqqpoqj6i3d.fsf@gitster.mtv.corp.google.com>
In-Reply-To
<alpine.DEB.2.20.1607120927410.6426@virtualbox>
Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> Git's source code assumes that unsigned long is at least as precise as
> time_t. Well, Git's source code is wrong.
> ...

That is correct. As people mentioned downthread already, "unsigned long" has two problems, it may not be wide enough, and it cannot represent time before the epoch.

But moving the internal time representation used in various fields like commit->date to time_t is likely to be a wrong thing to do, because the first problem with "unsigned long", i.e. "may not be wide enough", is not limited to "not wide enough to hold time_t". It also includes "it may not be wide enough to hold time somebody else recorded in existing objects".

Since some platforms have time_t that is not wide enough, but still have intmax_t that is wider, I think we would be better off to pick an integral type to use for the internal representation that is the widest throughout the API, and use time_t only at places that we interact with the system libraries (e.g. when we ask "what is the time now?" to time(2), when we ask "break down this timestamp" to gmtime(3)).

Thanks for starting this, and from a brief read, the hotfix to skip the test downthread looked good. The places this "starting point" patch covers look like a good set that interacts with time obtained locally (e.g. prune that compares with filesystem timestamp); just make sure you don't go too far and end up shoving timestamps from other people into time_t, which may not fit.

Thanks.
Previous: Johannes SchindelinNext: Jeff King
Message 39 of 56 in “[ANNOUNCE] Git v2.9.1”
  1. Junio C HamanoJul 11, 2016
  2. Andreas SchwabJul 11, 2016
  3. Jeff KingJul 11, 2016
  4. Anders KaseorgJul 12, 2016
  5. Jeff KingJul 12, 2016
  6. Eric WongJul 12, 2016
  7. Jeff KingJul 12, 2016
  8. Junio C HamanoJul 12, 2016
  9. Jeff KingJul 12, 2016
  10. Junio C HamanoJul 12, 2016
  11. Johannes SchindelinJul 12, 2016
  12. Jeff KingJul 12, 2016
  13. Johannes SchindelinJul 12, 2016
  14. Jeff KingJul 12, 2016
  15. Johannes SchindelinJul 13, 2016
  16. Junio C HamanoJul 13, 2016
  17. Johannes SchindelinJul 13, 2016
  18. Junio C HamanoJul 13, 2016
  19. Johannes SchindelinJul 14, 2016
  20. Junio C HamanoJul 12, 2016
  21. Junio C HamanoJul 13, 2016
  22. Jeff KingJul 13, 2016
  23. Junio C HamanoJul 13, 2016
  24. Johannes SchindelinJul 13, 2016
  25. Junio C HamanoJul 13, 2016
  26. Johannes SchindelinJul 14, 2016
  27. Andreas SchwabJul 14, 2016
  28. Jeff KingJul 14, 2016
  29. Johannes SchindelinJul 14, 2016
  30. Andreas SchwabJul 12, 2016
  31. Johannes SchindelinJul 12, 2016
  32. Andreas SchwabJul 12, 2016
  33. Johannes SchindelinJul 12, 2016
  34. Andreas SchwabJul 12, 2016
  35. Jeff KingJul 12, 2016
  36. Duy NguyenJul 12, 2016
  37. Johannes SchindelinJul 13, 2016
  38. Johannes SchindelinJul 13, 2016
  39. Junio C HamanoJul 12, 2016
  40. Jeff KingJul 12, 2016
  41. Junio C HamanoJul 12, 2016
  42. Jeff KingJul 12, 2016
  43. Junio C HamanoJul 12, 2016
  44. Jeff KingJul 12, 2016
  45. Junio C HamanoJul 12, 2016
  46. Johannes SchindelinJul 13, 2016
  47. Junio C HamanoJul 13, 2016
  48. Johannes SchindelinJul 13, 2016
  49. Andreas SchwabJul 12, 2016
  50. Junio C HamanoJul 13, 2016
  51. Lars SchneiderJul 14, 2016
  52. Duy NguyenJul 16, 2016
  53. 32-bit Travis, was Re: [ANNOUNCE] Git v2.9.1Johannes Schindelin, Jul 14, 2016
  54. Mike HommeyJul 14, 2016
  55. Johannes SchindelinJul 14, 2016
  56. Mike HommeyJul 15, 2016

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