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From: Stefan Beller <sbeller@google.com>
To: Jeff King <peff@peff.net>
Cc: Junio C Hamano <gitster@pobox.com>,
	"git@vger.kernel.org" <git@vger.kernel.org>,
	Orgad Shaneh <orgads@gmail.com>
Subject: Re: [PATCH 5/5] diff: handle NULs in get_string_hash()
Date: Thu, 19 Oct 2017 14:50:58 -0700
Message-ID: <CAGZ79kahvE=S_SwZqzC_VrAPURVCkqjaa9sVN-bCecYLoA4yRw@mail.gmail.com> (raw)
In-Reply-To: <20171019213958.d6rp2upiga5tsvys@sigill.intra.peff.net>

On Thu, Oct 19, 2017 at 2:39 PM, Jeff King <peff@peff.net> wrote:
> On Thu, Oct 19, 2017 at 02:31:20PM -0700, Stefan Beller wrote:
>
>> > This is unlikely to ever come up in practice since our line
>> > boundaries generally come from calling strlen() in the first
>> > place.
>>
>> get_string_hash is called from
>>  prepare_entry, which in turn is called from
>>   add_lines_to_move_detection or mark_color_as_moved
>>    diff_flush_patch_all_file_pairs
>>
>> that constructs the arguments in
>> diff_flush_patch
>>  run_diff
>>   run_diff_cmd
>>    builtin_diff (part "/* Crazy xdl interfaces.. */")
>>     xdi_diff_outf( fn_out_consume as arg!)
>>      xdi_diff
>>       xdl_diff
>>        xdl_call_hunk_func
>>         -> fn_out_consume(cb, line, len)
>>
>> xdl_call_hunk_func however uses pointer arithmetic instead
>> of strlen. So I think this sentence is not a good idea to put in
>> the commit message.
>>
>> It may not occur in practice, due to binary files detection using
>> NUL as a signal, but conceptually our move-colored(!) diffs
>> should be compatible with NULs with this patch now.
>
> Good catch. I just skimmed over all the diff_emit_* functions, which use
> strlen(). But at the bottom is emit_add_line(), which has a real length
> marker from xdiff.

Doh!
There is diff_emit_submodule_* but I presume you meant
emit_diff_* actually as there the strlen is legit, as we generate
known non-NUL data to print.

The submodule output may get mangled in diff_emit_submodule_{add,del}
as the input is coming from user data.

> I agree we wouldn't see NULs in general, but this is maybe fixing "diff
> --color-moved -a". I dunno. It's probably not worth digging too much,
> since it seems like the right thing to do regardless.

I agree, that this digging seems not worth it; I was just agitated at
the seemingly incorrect commit message.

Thanks,
Stefan

>
> -Peff

  reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-12 19:53 Out of memory with diff.colormoved enabled Orgad Shaneh
2017-10-12 20:05 ` Jeff King
2017-10-12 22:39   ` Stefan Beller
2017-10-12 23:33   ` [PATCH] diff.c: increment buffer pointer in all code path Stefan Beller
2017-10-13  0:18     ` Jeff King
2017-10-13  0:20       ` Jeff King
2017-10-13  0:24         ` Stefan Beller
2017-10-19  5:04         ` Jeff King
2017-10-19  5:24           ` Jeff King
2017-10-19  5:30             ` Junio C Hamano
2017-10-19  5:32               ` Junio C Hamano
2017-10-19  5:32                 ` Jeff King
2017-10-19  5:42               ` Jeff King
2017-10-19 19:55                 ` Stefan Beller
2017-10-19 20:23                 ` [PATCH 0/5] fix "diff --color-moved --ignore-space-at-eol" Jeff King
2017-10-19 20:24                   ` [PATCH 1/5] t4015: refactor --color-moved whitespace test Jeff King
2017-10-19 20:56                     ` Stefan Beller
2017-10-19 21:10                       ` Jeff King
2017-10-19 20:25                   ` [PATCH 2/5] t4015: check "negative" case for "-w --color-moved" Jeff King
2017-10-19 20:54                     ` Stefan Beller
2017-10-19 20:26                   ` [PATCH 3/5] t4015: test the output of "diff --color-moved -b" Jeff King
2017-10-19 21:03                     ` Stefan Beller
2017-10-19 21:14                       ` Jeff King
2017-10-19 20:29                   ` [PATCH 4/5] diff: fix whitespace-skipping with --color-moved Jeff King
2017-10-19 21:15                     ` Stefan Beller
2017-10-19 21:19                       ` Jeff King
2017-10-20  7:23                     ` Simon Ruderich
2017-10-20 22:37                       ` Jeff King
2017-10-19 20:31                   ` [PATCH 5/5] diff: handle NULs in get_string_hash() Jeff King
2017-10-19 21:31                     ` Stefan Beller
2017-10-19 21:39                       ` Jeff King
2017-10-19 21:50                         ` Stefan Beller [this message]
2017-10-19 19:53             ` [PATCH] diff.c: increment buffer pointer in all code path Stefan Beller
2017-10-19 19:55               ` Jeff King

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