Re: Strange differences between unstripped binaries
Re: Strange differences between unstripped binaries
- Subject: Re: Strange differences between unstripped binaries
- From: Martin Redington <email@hidden>
- Date: Tue, 03 Dec 2013 04:08:11 +0000
otool -IV produces identical output (once you strip out the first line
of output, which reports the pathname).
400 or so 1 byte differences doesn't look like UDID's either ...
On Mon, Dec 2, 2013 at 11:32 AM, Ken Thomases <email@hidden> wrote:
> On Dec 2, 2013, at 4:38 AM, Martin Redington wrote:
>
>> Well ... my unsigned stripped binaries *are* identical.
>
> That's not something you can rely on.
>
>> In the absence
>> of __TIME__ macros or similar, yes I would expect the binaries to be
>> identical, unless the compiler/linker are intentionally adding their
>> own timestamps, which they do not appear to do.
>
> No. In the absence of a documented promise that the build tools produce identical output given identical input, you have to assume that they don't (at least sometimes).
>
>> The differences between unstripped binaries are clearly not
>> timestamps, or arbitrary differences. All 400 odd differences are
>> apparently of the same type, and the pattern/relationship between them
>> is clearly systematic - I think there's a more informative answer out
>> there than (to crudely paraphrase Ken's answer) "binaries always
>> differ, deal with it".
>
> I didn't claim that timestamps would be the only differences. There's also the UUID, for example. Check the output of "otool -lV" as applied to your binaries. That's another place (besides the output of "otool -t" as cited in your original question) that differences could show up.
>
> Regards,
> Ken
>
--
http://www.mildmanneredindustries.com/
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