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From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: Kevin Daudt <git@lists.ikke.info>
Cc: git@vger.kernel.org, larsxschneider@gmail.com
Subject: Re: t0028-working-tree-encoding.sh failing on musl based systems (Alpine Linux)
Date: Fri, 8 Feb 2019 00:17:05 +0000	[thread overview]
Message-ID: <20190208001705.GC11927@genre.crustytoothpaste.net> (raw)
In-Reply-To: <20190207215935.GA31515@alpha>

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On Thu, Feb 07, 2019 at 10:59:35PM +0100, Kevin Daudt wrote:
> I'm trying to get the git test suite passing on Alpine Linux, which is
> based on musl libc.
> 
> All tests in t0028-working-tree-encoding.sh are currently failing,
> because musl iconv does not support statefull output of UTF-16/32 (eg,
> it does not output a BOM), while git is expecting that to be present:
> 
> > hint: The file 'test.utf16' is missing a byte order mark (BOM). Please
> > use UTF-16BE or UTF-16LE (depending on the byte order) as
> > working-tree-encoding.
> > fatal: BOM is required in 'test.utf16' if encoded as utf-16
> 
> Because adding the file to get fails, all the other tests fail as well
> as they expect the file to be present in the repository.
> 
> Any idea how to get around this?

I think musl needs to patch their libc. RFC 2781 says that if there's no
BOM in UTF-16, then "the text SHOULD be interpreted as being
big-endian."

Unfortunately for all of us, many Windows-based programs have chosen to
ignore that advice (technically, it's only a SHOULD) and interpret it as
little-endian instead. Git can't safely assume anything about the
endianness of a UTF-16 stream that doesn't contain a BOM. Technically,
since the RFC doesn't specify a MUST requirement, musl can't, either.

Even if Git were to produce a BOM to work around this issue, then we'd
still have the problem that any program using musl will write data in
UTF-16 without a BOM. Moreover, because musl, in violation of the RFC,
doesn't read and process BOMs, someone using little-endian UTF-16 (with
a proper BOM) with musl and Git will have their data corrupted,
according to my reading of the musl website.

In other words, I believe this test is failing legitimately.
-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204

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  reply	other threads:[~2019-02-08  0:17 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-07 21:59 t0028-working-tree-encoding.sh failing on musl based systems (Alpine Linux) Kevin Daudt
2019-02-08  0:17 ` brian m. carlson [this message]
2019-02-08  6:04   ` Rich Felker
2019-02-08 11:45     ` brian m. carlson
2019-02-08 11:55       ` Kevin Daudt
2019-02-08 13:51         ` brian m. carlson
2019-02-08 17:50           ` Junio C Hamano
2019-02-08 20:23             ` Kevin Daudt
2019-02-08 20:42               ` brian m. carlson
2019-02-08 23:12                 ` Junio C Hamano
2019-02-09  0:24                   ` brian m. carlson
2019-02-09 14:57                 ` Kevin Daudt
2019-02-09 20:08                   ` [PATCH] utf8: handle systems that don't write BOM for UTF-16 brian m. carlson
2019-02-10  1:45                     ` Eric Sunshine
2019-02-10 18:14                       ` brian m. carlson
2019-02-10  8:04                     ` Torsten Bögershausen
2019-02-10 18:55                       ` brian m. carlson
2019-02-11 17:14                         ` Junio C Hamano
2019-02-11  0:23                     ` [PATCH v2] " brian m. carlson
2019-02-11  1:16                       ` Eric Sunshine
2019-02-11  1:20                         ` brian m. carlson
2019-02-11  1:26                     ` [PATCH v3] " brian m. carlson
2019-02-11 21:43                       ` Kevin Daudt
2019-02-11 23:58                         ` brian m. carlson
2019-02-12  0:31                           ` Junio C Hamano
2019-02-12  0:53                             ` brian m. carlson
2019-02-12  2:43                               ` Junio C Hamano
2019-02-12  0:52                     ` [PATCH v4] " brian m. carlson
2019-02-08 16:13         ` t0028-working-tree-encoding.sh failing on musl based systems (Alpine Linux) Rich Felker
2019-02-09  8:09     ` Torsten Bögershausen

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