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From: <rsbecker@nexbridge•com>
To: "'Junio C Hamano'" <gitster@pobox•com>,
	"'Randall S. Becker'" <the.n.e.key@gmail•com>
Cc: <git@vger•kernel.org>
Subject: RE: [PATCH v1 2/4] builtin/receive-pack.c: change xwrite to write_in_full to allow large sizes.
Date: Mon, 26 Feb 2024 19:15:53 -0500	[thread overview]
Message-ID: <027101da6912$23cf31c0$6b6d9540$@nexbridge.com> (raw)
In-Reply-To: <xmqq34tekcoo.fsf@gitster.g>

On Monday, February 26, 2024 6:51 PM, Junio C Hamano wrote:
>"Randall S. Becker" <the.n.e.key@gmail•com> writes:
>
>> From: "Randall S. Becker" <rsbecker@nexbridge•com>
>>
>> This change is required because some platforms do not support file
>> writes of arbitrary sizes (e.g, NonStop). xwrite ends up truncating
>> the output to the maximum single I/O size possible for the destination
device.
>
>As msg[] here is 4k on-stack buffer, if the I/O size is small enough, the
above may happen, and I think write-in-full is warranted here.  If
>your I/O must be done in 1k chunks, it would be very slow to run things
like writing a pack stream to clone any non-toy projects,
>though X-<.

On the x86 platform, we get a size large enough not to trigger the failure
in t7704. However, on ia64, the limit is 56Kb, which apparently does. I'm
hoping no one else has a 1Kb limit - although some TCP stacks might
experience it. Either way, truncating a package is bad. Fortunately the I/O
subsystem on NonStop is very fast (basically DMA) between process memory
space.

>
>> Signed-off-by: Randall S. Becker <rsbecker@nexbridge•com>
>> ---
>>  builtin/receive-pack.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c index
>> db65607485..5064f3d300 100644
>> --- a/builtin/receive-pack.c
>> +++ b/builtin/receive-pack.c
>> @@ -455,8 +455,9 @@ static void report_message(const char *prefix,
>> const char *err, va_list params)
>>
>>  	if (use_sideband)
>>  		send_sideband(1, 2, msg, sz, use_sideband);
>> -	else
>> -		xwrite(2, msg, sz);
>> +	else {
>> +		write_in_full(2, msg, sz);
>> +	}
>>  }
>>
>>  __attribute__((format (printf, 1, 2)))


  reply	other threads:[~2024-02-27  0:16 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-26 22:05 [PATCH v1 0/4] Change xwrite() to write_in_full() in builtins Randall S. Becker
2024-02-26 22:05 ` [PATCH v1 1/4] builtin/index-pack.c: change xwrite to write_in_full to allow large sizes Randall S. Becker
2024-02-26 22:38   ` Taylor Blau
2024-02-26 22:51     ` rsbecker
2024-02-26 23:46       ` Junio C Hamano
2024-02-27  0:12         ` rsbecker
2024-02-26 23:30     ` rsbecker
2024-02-26 22:05 ` [PATCH v1 2/4] builtin/receive-pack.c: " Randall S. Becker
2024-02-26 23:02   ` rsbecker
2024-02-26 23:50   ` Junio C Hamano
2024-02-27  0:15     ` rsbecker [this message]
2024-02-26 22:05 ` [PATCH v1 3/4] builtin/repack.c: " Randall S. Becker
2024-02-26 23:54   ` Junio C Hamano
2024-02-27  8:20   ` Jeff King
2024-02-27  8:22     ` Jeff King
2024-02-26 22:05 ` [PATCH v1 4/4] builtin/unpack-objects.c: " Randall S. Becker
2024-02-26 23:56   ` Junio C Hamano
2024-02-27  0:18     ` rsbecker

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