view CONTRIBUTORS @ 45716:9628d3cd9d13

record: when backing up, avoid generating very long filenames

If the original file's path is longer than the individual filename maximum
length (256 on Linux, I believe?), then this mechanism of "replace slashes with
underscores" causes an error.

Now, we'll produce just the "basename" of the file, plus some stuff to ensure
it's unique. This can be potentially confusing for users if there's a file with
the same name in multiple directories, but I suspect that this is better than
just breaking.

Example:
`<reporoot>/a/long/path/to/somefile.txt` used to be backed up as
`<reporoot>/.hg/record-backups/a_long_path_to_somefile.txt.abcdefgh`, it will
now be backed up as `<reporoot>/.hg/record-backups/somefile.txt.abcdefgh`

We could do the naive thing (what we were doing before) and have it to doing
something with either subdirectories
(`<backuproot>/a/long/path/to/somefile.txt.abcdefgh` or minimize #dirs with
`<backuproot>/a_long_path/to_somefile.txt.abcdefgh`), prefix-truncated paths
(such as `<backuproot>/__ath_to_somefile.txt.abcdefgh`, where that `__` elides
enough to get us under 255 chars (counting the +9 we need to add!)), or
hash-of-dirname (`<backuproot>/<sha1sum_of_dirname>/somefile.txt.abcdefgh`), but
ultimately every option felt over engineered and that it would be more likely to
cause problems than it would be to solve any, especially if it was conditional
on directory length.

Differential Revision: https://phab.mercurial-scm.org/D9207

[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>