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From: Jeff King <peff@peff.net>
To: Derrick Stolee <stolee@gmail.com>
Cc: "SZEDER Gábor" <szeder.dev@gmail.com>,
	"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>,
	git@vger.kernel.org, "Junio C Hamano" <gitster@pobox.com>,
	"Derrick Stolee" <dstolee@microsoft.com>
Subject: Re: [PATCH 1/1] upload-pack: fix race condition in error messages
Date: Thu, 29 Aug 2019 10:13:07 -0400	[thread overview]
Message-ID: <20190829141307.GE1797@sigill.intra.peff.net> (raw)
In-Reply-To: <4d5773f9-4637-d8a3-d683-82624950f319@gmail.com>

On Thu, Aug 29, 2019 at 08:58:55AM -0400, Derrick Stolee wrote:

> However, I do have a theory: the process exits before flushing the
> packet line. Adding this line before exit(1) should fix it:
> 
> 	packet_writer_flush(writer);
> 
> I can send this in a v2, but it would be nice if you could test this
> in your environment that already demonstrated the failure.

I don't think we should need such a call. For one thing, if it were
necessary, that would mean we're not writing out the packet at all. But
your whole problem is that we're writing the message twice, one of which
comes from the packet.

Second is that this is not "flush the output stream", but "write a flush
packet". The packet_writer_error() function immediately calls write()
without buffering. And no matter where we are in the conversation, a
flush packet would not be necessary, because the error packet we send
would be interpreted immediately by the client as aborting the
connection.

-Peff

  reply	other threads:[~2019-08-29 14:13 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-28  1:43 [PATCH 0/1] upload-pack: fix race condition in t5516 Derrick Stolee via GitGitGadget
2019-08-28  1:43 ` [PATCH 1/1] upload-pack: fix race condition in error messages Derrick Stolee via GitGitGadget
2019-08-28  9:34   ` SZEDER Gábor
2019-08-28 14:54     ` Jeff King
2019-08-28 15:39       ` Jeff King
2019-08-28 16:15         ` SZEDER Gábor
2019-08-29 12:58           ` Derrick Stolee
2019-08-29 14:13             ` Jeff King [this message]
2019-08-29 14:27               ` Derrick Stolee
2019-08-29 14:38                 ` Jeff King
2019-08-29 21:58                   ` SZEDER Gábor
2019-08-29 22:06                     ` SZEDER Gábor
2019-08-30 12:10                       ` SZEDER Gábor
2019-09-04  5:04                         ` Jeff King
2019-09-10 12:08                           ` SZEDER Gábor

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