Re: Strange differences between unstripped binaries
Re: Strange differences between unstripped binaries
- Subject: Re: Strange differences between unstripped binaries
- From: Ken Thomases <email@hidden>
- Date: Mon, 02 Dec 2013 05:32:53 -0600
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
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