vfs: create copy at renaming to avoid file stat ambiguity if needed
In order to fix issue5418, bff5ccbe5ead made vfs.rename(checkambig=True)
omit advancing mtime of renamed file, if renamed file is owned by
another (EPERM is raised in this case).
But this omission causes rewinding mtime at restoration in such
situation, and makes avoiding file stat ambiguity difficult, because
ExactCacheValidationPlan assumes that mtime should be advanced, if a
file is changed in same ctime.
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
Ambiguity of file stat also requires issue5584 to be fixed with other
than file stat, but "hash of file", "generation ID" and so on were
already rejected ideas (please see original RFC linked from "Outline
of issue" in ExactCacheValidationPlan page).
This omission occurs:
- only for non append-only files (dirstate, bookmarks, and phaseroots), and
- only if previous transaction is rollbacked by another user
The latter means "sharing a repository clone via group permission".
This is reasonable usecase, but not ordinary for many users, IMHO.
"hg rollback" itself has been deprecated since Mercurial 2.7, too.
Therefore, increasing the cost at rollbacking previous transaction
executed by another a little seems reasonable, for avoidance of file
stat ambiguity.
This patch does:
- create copy of (already renamed) source file, if advancing mtime
fails for EPERM
- rename from copied file to destination file, and
- advance mtime of renamed file, which is now owned by current user
This patch also factors "self.join(src)" out to reduce redundancy.
[This file is here for historical purposes, all recent contributors
should appear in the changelog directly]
Andrea Arcangeli <andrea at suse.de>
Thomas Arendsen Hein <thomas at intevation.de>
Goffredo Baroncelli <kreijack at libero.it>
Muli Ben-Yehuda <mulix at mulix.org>
Mikael Berthe <mikael at lilotux.net>
Benoit Boissinot <bboissin at gmail.com>
Brendan Cully <brendan at kublai.com>
Vincent Danjean <vdanjean.ml at free.fr>
Jake Edge <jake at edge2.net>
Michael Fetterman <michael.fetterman at intel.com>
Edouard Gomez <ed.gomez at free.fr>
Eric Hopper <hopper at omnifarious.org>
Alecs King <alecsk at gmail.com>
Volker Kleinfeld <Volker.Kleinfeld at gmx.de>
Vadim Lebedev <vadim at mbdsys.com>
Christopher Li <hg at chrisli.org>
Chris Mason <mason at suse.com>
Colin McMillen <mcmillen at cs.cmu.edu>
Wojciech Milkowski <wmilkowski at interia.pl>
Chad Netzer <chad.netzer at gmail.com>
Bryan O'Sullivan <bos at serpentine.com>
Vicent Seguí Pascual <vseguip at gmail.com>
Sean Perry <shaleh at speakeasy.net>
Nguyen Anh Quynh <aquynh at gmail.com>
Ollivier Robert <roberto at keltia.freenix.fr>
Alexander Schremmer <alex at alexanderweb.de>
Arun Sharma <arun at sharma-home.net>
Josef "Jeff" Sipek <jeffpc at optonline.net>
Kevin Smith <yarcs at qualitycode.com>
TK Soh <teekaysoh at yahoo.com>
Radoslaw Szkodzinski <astralstorm at gorzow.mm.pl>
Samuel Tardieu <sam at rfc1149.net>
K Thananchayan <thananck at yahoo.com>
Andrew Thompson <andrewkt at aktzero.com>
Michael S. Tsirkin <mst at mellanox.co.il>
Rafael Villar Burke <pachi at mmn-arquitectos.com>
Tristan Wibberley <tristan at wibberley.org>
Mark Williamson <mark.williamson at cl.cam.ac.uk>