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From: Rich Felker <dalias@libc.org>
To: git@vger.kernel.org
Cc: musl@lists.openwall.com
Subject: Regression: git no longer works with musl libc's regex impl
Date: Tue, 4 Oct 2016 11:08:48 -0400	[thread overview]
Message-ID: <20161004150848.GA7949@brightrain.aerifal.cx> (raw)

This commit broke support for using git with musl libc:

https://github.com/git/git/commit/2f8952250a84313b74f96abb7b035874854cf202

Rather than depending on non-portable GNU regex extensions, there is a
simple portable fix for the issue this code was added to work around:
When a text file is being mmapped for use with string functions which
depend on null termination, if the file size:

1. is nonzero mod page size, it just works; the remainder of the last
   page reads as zero bytes when mmapped.

2. if an exact multiple of the page size, then instead of directly
   mmapping the file, first mmap a mapping 1 byte (thus 1 page) larger
   with MAP_ANON, then use MAP_FIXED to map the file over top of all
   but the last page. Now the mmapped buffer can safely be used as a C
   string.

If such a solution is acceptable I can try to prepare a patch.

Rich

             reply	other threads:[~2016-10-04 15:08 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-04 15:08 Rich Felker [this message]
2016-10-04 15:27 ` Regression: git no longer works with musl libc's regex impl Jeff King
2016-10-04 15:40   ` Rich Felker
2016-10-04 16:08     ` Johannes Schindelin
2016-10-04 16:11       ` Rich Felker
2016-10-04 17:16         ` Johannes Schindelin
2016-10-04 18:00           ` Ray Donnelly
2016-10-04 17:39       ` [musl] " Rich Felker
2016-10-05 11:17         ` Johannes Schindelin
2016-10-05 13:01           ` Szabolcs Nagy
2016-10-05 13:15           ` Rich Felker
2016-10-04 22:06       ` James B
2016-10-04 22:33         ` Rich Felker
2016-10-04 22:48           ` Junio C Hamano
2016-10-05 13:11           ` Jakub Narębski
2016-10-05 16:15             ` [musl] " Rich Felker
2016-10-05 10:41         ` Johannes Schindelin
2016-10-05 11:59           ` James B
2016-10-05 16:11             ` Jeff King
2016-10-05 16:27               ` Rich Felker
2016-10-06 10:44             ` Johannes Schindelin
2016-10-06 19:18       ` Ævar Arnfjörð Bjarmason
2016-10-06 19:23         ` Jeff King
2016-10-06 19:25           ` Rich Felker
2016-10-06 19:28             ` Jeff King
2016-10-06 22:42         ` Ramsay Jones
2016-10-07 11:30           ` Jakub Narębski
2016-10-04 16:01   ` Johannes Schindelin

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