From: Thomas Braun <thomas.braun@virtuell-zuhause.de>
To: Jeff King <peff@peff.net>
Cc: Florian Adamus <florian-adamus@gmx.de>, git@vger.kernel.org
Subject: Re: Commiting files larger than 4 GB on Windows
Date: Wed, 15 Mar 2017 19:23:04 +0100 [thread overview]
Message-ID: <217dc281-e767-b2b3-07b9-c1d243261d27@virtuell-zuhause.de> (raw)
In-Reply-To: <20170315161308.sbyoxzst7ffcu6qs@sigill.intra.peff.net>
Am 15.03.2017 um 17:13 schrieb Jeff King:
> On Wed, Mar 15, 2017 at 11:59:52AM -0400, Jeff King wrote:
>
>> I agree that detecting the situation in the meantime is a good idea.
>> The patch above probably handles the bulk-checkin code path, I'd guess.
>> It might be nice to have similar checks in other places, too:
>>
>> - when reading from an existing packfile
>>
>> Looks like we may already have such a check in
>> unpack_object_header_buffer().
>>
>> - when taking in new objects via index-pack or unpack-objects (to
>> catch a fetch of a too-big object)
>>
>> I think index-pack.c:unpack_raw_entry() would want a similar check
>> to what is in unpack_object_header_buffer().
>
> Here are the results of a few quick experiments using two versions of
> git, one built for 32-bit and one for 64-bit:
>
> $ git init
> $ dd if=/dev/zero of=foo.zero bs=1M count=4097
> $ git32 add foo.zero
> fatal: Cannot handle files this big
>
> That comes from the xsize_t() wrapper. I guess it wouldn't trigger on
> Windows, though, because it is measuring size_t, not "unsigned long" (on
> my 32-bit build they are the same, of course).
>
> $ git64 add foo.zero
> $ git32 cat-file blob :foo.zero
> error: bad object header
> fatal: packed object df6f032f301d1ce40477eefa505f2fac1de5e243 (stored in .git/objects/pack/pack-57d422f19904e9651bec43d10b7a9cd882de48ac.pack) is corrupt
>
> So we notice, which is good. This is the message from
> unpack_object_header_buffer(). It might be worth improving the error
> message to mention the integer overflow.
>
> And here's what index-pack looks like:
>
> $ git32 index-pack --stdin <.git/objects/pack/*.pack
> fatal: pack has bad object at offset 12: inflate returned -5
>
> It's good that we notice, but the error message isn't great. What
> happens is that we overflow the size integer, allocate a too-small
> buffer, and then zlib complains when we run out of buffer but there's
> still content to inflate. We probably ought to notice the integer
> overflow in the first place and complain there.
Thanks for the pointers Peff. I'll try to come up with a patch in the
next weeks. If somebody else steps in the meantime I'm not mad at all.
Thomas
next prev parent reply other threads:[~2017-03-15 18:25 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-15 13:00 Commiting files larger than 4 GB on Windows Florian Adamus
2017-03-15 13:48 ` Thomas Braun
2017-03-15 15:59 ` Jeff King
2017-03-15 16:13 ` Jeff King
2017-03-15 18:23 ` Thomas Braun [this message]
2017-03-15 21:15 ` Torsten Bögershausen
2017-03-15 21:29 ` Junio C Hamano
2017-03-17 5:29 ` Torsten Bögershausen
2017-03-18 13:03 ` Thomas Braun
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