Re: [gentoo-alt] [PREFIX] dynamic linking: moving the locations

[Armando Di Cianno]

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On Apr 11, 2007, at 3:10 PM, Fabian Groffen wrote:
> Yes we can!
> This was Solaris, Linux works the same.  Now let's check Darwin.
>
> Same test program.
<snip />
> Ok, prefix paths.  Darwin is MACH-O, which stores the full filename to
> the library in this case, so no rpath is there.  chrpath doesn't work
> here for that reason, but on Darwin, there is the install_name_tool
> tool.
<snip />
> So, install_name_tool does it a bit different than chrpath, but with
> some scripting both can do the same: change the location libraries are
> looked for.  What does this mean?  Well, let's look at this:
>
> [tefnut:/var/tmp] % install_name_tool -change /Library/Gentoo/usr/
> lib/libssl.0.9.8.dylib /var/tmp/libssl.0.9.8.dylib test
> [tefnut:/var/tmp] % cp /Library/Gentoo/usr/lib/libssl.0.9.8.dylib .
> [tefnut:/var/tmp] % ./test
> OpenSSL 0.9.8e 23 Feb 2007
> [tefnut:/var/tmp] % otool -L test
> test:
>         /var/tmp/libssl.0.9.8.dylib (compatibility version 0.9.8,
> current version 0.9.8)
>         /Library/Gentoo/usr/lib/libcrypto.0.9.8.dylib
> (compatibility version 0.9.8, current version 0.9.8)
<snip />

We use this feature, on Darwin, at lot at my company.  It's important  
to note that most binaries, on Darwin, may need to be compiled with "- 
headerpad_max_install_names" -- which is actually now antiquated / 32- 
bit only -- or, better "-headerpad [value]".

This option is needed for the cases where it's not /Y/Z -> /A/B but / 
Y/Z -> /A...A/B...B .

The fun starts with -headerpad_max_install_names when some apps think  
you're monkeying too much with the linkage options, and start to make  
only static versions.

Just, fyi.
__armando
aka fafhrd

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