asterisk users - Jul 2018 - Recompiling Ast results in a binary with differing SHA256 sums?

Hi Guys

If I recompile Asterisk (on a Centos 7 test box, Asterisk 1.8.32.3) multiple
times in a row, e. g. 

make clean;configure;make menuselect;make

I note that the asterisk binary in the /main folder in the source tree, has
a different SHA256 hash each time I recompile Asterisk using the above
commands.

I do not change anything on the system or in the menuselect configs for each
run.

But each time the checksum for the "asterisk" binary is different.

Why is that? Shouldn't a freshly compiled binary off the same source, with
no changes in the Asterisk menuselect, with nothing changed on the rest of
the system, result each time in an IDENTICAL binary, down to the last byte?

Why am I getting a completely different "asterisk" ELF binary each
time I
recompile asterisk, according to checksum?

Can someone shed light...

Thanks,

Stefan

On Wed, Jul 18, 2018 at 4:37 AM, Stefan Viljoen <viljoens at
verishare.co.za>
wrote:
> Hi Guys
>
> If I recompile Asterisk (on a Centos 7 test box, Asterisk 1.8.32.3)
> multiple
> times in a row, e. g.
>
> make clean;configure;make menuselect;make
>
> I note that the asterisk binary in the /main folder in the source tree, has
> a different SHA256 hash each time I recompile Asterisk using the above
> commands.
>
> I do not change anything on the system or in the menuselect configs for
> each
> run.
>
> But each time the checksum for the "asterisk" binary is
different.
>
> Why is that? Shouldn't a freshly compiled binary off the same source,
with
> no changes in the Asterisk menuselect, with nothing changed on the rest of
> the system, result each time in an IDENTICAL binary, down to the last byte?
>
> Why am I getting a completely different "asterisk" ELF binary
each time I
> recompile asterisk, according to checksum?
>
> Can someone shed light...
>
A timestamp is added to the version string when you build Asterisk.  Thus
every
time you recompile Asterisk you get a different timestamp in the version
string.
Thus the checksum will be different every time.

Richard
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In article <007401d41e7a$edc7e190$c957a4b0$@verishare.co.za>,
Stefan Viljoen <viljoens at verishare.co.za>
wrote:
> Hi Guys
> 
> If I recompile Asterisk (on a Centos 7 test box, Asterisk 1.8.32.3)
multiple
> times in a row, e. g. 
> 
> make clean;configure;make menuselect;make
> 
> I note that the asterisk binary in the /main folder in the source tree, has
> a different SHA256 hash each time I recompile Asterisk using the above
> commands.
> 
> I do not change anything on the system or in the menuselect configs for
each
> run.
> 
> But each time the checksum for the "asterisk" binary is
different.
> 
> Why is that? Shouldn't a freshly compiled binary off the same source,
with
> no changes in the Asterisk menuselect, with nothing changed on the rest of
> the system, result each time in an IDENTICAL binary, down to the last byte?
> 
> Why am I getting a completely different "asterisk" ELF binary
each time I
> recompile asterisk, according to checksum?
> 
> Can someone shed light...
Most likely there is a text string in there somewhere indicating the date or
time of compilation.

Why don't you save the binary, recompile, then compare the first binary with
the recompiled one? At the simplest level use "cmp -l". Or maybe
convert
each binary to a hexdump with "hexdump -C", and then use diff or
vimdiff
to compare them.

Cheers
Tony
-- 
Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org