From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Lars Schneider <larsxschneider@gmail.com>
Cc: git@vger.kernel.org, gitster@pobox.com, jnareb@gmail.com,
mlbright@gmail.com, e@80x24.org, peff@peff.net, ben@wijen.net
Subject: Re: [PATCH v5 15/15] read-cache: make sure file handles are not inherited by child processes
Date: Thu, 18 Aug 2016 16:23:42 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.20.1608181617240.4924@virtualbox> (raw)
In-Reply-To: <20160810130411.12419-16-larsxschneider@gmail.com>
Hi Lars,
On Wed, 10 Aug 2016, larsxschneider@gmail.com wrote:
> From: Lars Schneider <larsxschneider@gmail.com>
>
> Consider the case of a file that requires filtering and is present in branch A
> but not in branch B. If A is the current HEAD and we checkout B then the
> following happens:
>
> 1. ce_compare_data() opens the file
> 2. index_fd() detects that the file requires to run a clean filter and
> calls index_stream_convert_blob()
> 4. index_stream_convert_blob() calls convert_to_git_filter_fd()
> 5. convert_to_git_filter_fd() calls apply_filter() which creates a new
> long running filter process (in case it is the first file of this kind
> to be filtered)
> 6. The new filter process inherits all file handles. This is the default
> on Linux/OSX and is explicitly defined in the `CreateProcessW` call
> in `mingw.c` on Windows.
> 7. ce_compare_data() closes the file
> 8. Git unlinks the file as it is not present in B
>
> The unlink operation does not work on Windows because the filter process has
> still an open handle to the file. Apparently that is no problem on Linux/OSX.
> Probably because "[...] the two file descriptors share open file status flags"
> (see fork(2)).
We typically wrap the commit messages at 76 columns per row (personally,
I wrap already at 72, and it seems Junio wraps at 70).
> Fix this problem by opening files in read-cache with the `O_CLOEXEC` flag to
> ensure that the file descriptor does not remain open in a newly spawned process.
> `O_CLOEXEX` is defined as `O_NOINHERIT` on Windows. A similar fix for temporary
s/CLOEXEX/CLOEXEC/
> file handles was applied on Git for Windows already:
> https://github.com/git-for-windows/git/commit/667b8b51ec850c3e1c7d75dee69dc13c29d1f162
In response to your commit note on GitHub, I submitted this patch series
(slightly cleaned up) yesterday (and you already commented on it):
https://public-inbox.org/git/cover.1471437637.git.johannes.schindelin@gmx.de
The patch is obviously correct, and needs the patch series I submitted to
compile on Windows (this note is more for Junio's interest than a comment
on this patch).
Ciao,
Dscho
prev parent reply other threads:[~2016-08-18 14:24 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20160803164225.46355-1-larsxschneider@gmail.com/>
2016-08-10 13:03 ` [PATCH v5 00/15] Git filter protocol larsxschneider
2016-08-10 13:03 ` [PATCH v5 01/15] pkt-line: extract set_packet_header() larsxschneider
2016-08-10 13:03 ` [PATCH v5 02/15] pkt-line: call packet_trace() only if a packet is actually send larsxschneider
2016-08-10 13:13 ` Jeff King
2016-08-10 13:24 ` Lars Schneider
2016-08-10 13:30 ` Jeff King
2016-08-10 13:51 ` Lars Schneider
2016-08-10 14:33 ` Jeff King
2016-08-10 13:03 ` [PATCH v5 03/15] pkt-line: add `gentle` parameter to format_packet() larsxschneider
2016-08-10 13:15 ` Jeff King
2016-08-10 13:29 ` Lars Schneider
2016-08-10 13:37 ` Jeff King
2016-08-10 13:59 ` Lars Schneider
2016-08-10 14:34 ` Jeff King
2016-08-10 13:04 ` [PATCH v5 04/15] pkt-line: add packet_write_gently() larsxschneider
2016-08-10 13:28 ` Jeff King
2016-08-10 13:36 ` Lars Schneider
2016-08-10 13:40 ` Jeff King
2016-08-10 17:17 ` Junio C Hamano
2016-08-10 17:49 ` Lars Schneider
2016-08-10 18:21 ` Junio C Hamano
2016-08-10 19:15 ` Lars Schneider
2016-08-10 13:04 ` [PATCH v5 05/15] pkt-line: add packet_write_gently_fmt() larsxschneider
2016-08-10 13:43 ` Jeff King
2016-08-10 14:10 ` Lars Schneider
2016-08-10 15:01 ` Jeff King
2016-08-10 17:18 ` Junio C Hamano
2016-08-10 17:53 ` Lars Schneider
2016-08-10 18:42 ` Junio C Hamano
2016-08-10 13:04 ` [PATCH v5 06/15] pkt-line: add packet_flush_gently() larsxschneider
2016-08-10 13:04 ` [PATCH v5 07/15] pkt-line: add functions to read/write flush terminated packet streams larsxschneider
2016-08-10 13:04 ` [PATCH v5 08/15] pkt-line: rename packet_write() to packet_write_fmt() larsxschneider
2016-08-10 13:04 ` [PATCH v5 09/15] pack-protocol: fix maximum pkt-line size larsxschneider
2016-08-10 13:04 ` [PATCH v5 10/15] convert: quote filter names in error messages larsxschneider
2016-08-10 13:04 ` [PATCH v5 11/15] convert: modernize tests larsxschneider
2016-08-10 13:04 ` [PATCH v5 12/15] convert: generate large test files only once larsxschneider
2016-08-10 13:04 ` [PATCH v5 13/15] convert: make apply_filter() adhere to standard Git error handling larsxschneider
2016-08-10 13:04 ` [PATCH v5 14/15] convert: add filter.<driver>.process option larsxschneider
2016-08-12 16:33 ` Stefan Beller
2016-08-12 16:38 ` Jeff King
2016-08-12 16:48 ` Stefan Beller
2016-08-12 17:08 ` Lars Schneider
2016-08-12 17:13 ` Junio C Hamano
2016-08-12 17:21 ` Lars Schneider
2016-08-12 18:03 ` Junio C Hamano
2016-08-12 16:59 ` Lars Schneider
2016-08-12 17:07 ` Stefan Beller
2016-08-12 17:14 ` Lars Schneider
2016-08-10 13:04 ` [PATCH v5 15/15] read-cache: make sure file handles are not inherited by child processes larsxschneider
2016-08-18 14:23 ` Johannes Schindelin [this message]
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