From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: Thomas Braun via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
Thomas Braun <thomas.braun@byte-physics.de>
Subject: Re: [PATCH 1/1] mingw: optionally disable side-band-64k for transport
Date: Mon, 29 Apr 2019 23:19:28 +0000 [thread overview]
Message-ID: <20190429231928.GQ6316@genre.crustytoothpaste.net> (raw)
In-Reply-To: <31aa7bfcab834b753cc9f52fc9cc187f65e2d964.1556575475.git.gitgitgadget@gmail.com>
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On Mon, Apr 29, 2019 at 03:04:36PM -0700, Thomas Braun via GitGitGadget wrote:
> From: Thomas Braun <thomas.braun@byte-physics.de>
>
> Since commit 0c499ea60f (send-pack: demultiplex a sideband stream with
> status data, 2010-02-05) the built-in send-pack uses the side-band-64k
> capability if advertised by the server.
>
> Unfortunately this breaks pushing over the dump git protocol if used
> over a network connection when using MinGW (but *not* when using
> mingw-w64).
>
> The detailed reasons for this, are courtesy of Jeff Preshing, quoted
> from https://groups.google.com/d/msg/msysgit/at8D7J-h7mw/eaLujILGUWoJ:
>
> MinGW wraps Windows sockets in CRT file descriptors in order to
> mimic the functionality of POSIX sockets. This causes msvcrt.dll
> to treat sockets as Installable File System (IFS) handles,
> calling ReadFile, WriteFile, DuplicateHandle and CloseHandle on
> them. This approach works well in simple cases on recent
> versions of Windows, but does not support all usage patterns.
> In particular, using this approach, any attempt to read & write
> concurrently on the same socket (from one or more processes)
> will deadlock in a scenario where the read waits for a response
> from the server which is only invoked after the write. This is
> what send_pack currently attempts to do in the use_sideband
> codepath.
Since this is a platform-specific issue, can we address this using a
compile-time constant instead of a config option? It would be better to
do the right thing automatically in this case and not have to have
people set a config option. It will also allow us to not to have to
maintain a config option indefinitely if MinGW becomes more capable in
the future.
--
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204
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next prev parent reply other threads:[~2019-04-29 23:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-29 22:04 [PATCH 0/1] Support git:// with old MinGW Johannes Schindelin via GitGitGadget
2019-04-29 22:04 ` [PATCH 1/1] mingw: optionally disable side-band-64k for transport Thomas Braun via GitGitGadget
2019-04-29 22:10 ` Eric Sunshine
2019-04-29 23:17 ` Johannes Schindelin
2019-04-30 6:21 ` Johannes Sixt
2019-04-30 22:33 ` Johannes Schindelin
2019-04-30 22:55 ` Johannes Sixt
2019-05-03 8:42 ` Johannes Schindelin
2019-04-29 23:19 ` brian m. carlson [this message]
2019-04-30 22:37 ` Johannes Schindelin
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