Tiny Core Linux

Tiny Core Base => TCB Q&A Forum => Topic started by: polikuo on March 18, 2021, 08:01:07 AM

Title: How do I specify the priority for alternative libraries ?
Post by: polikuo on March 18, 2021, 08:01:07 AM

I just compiled a batch of FLTK libraries that supports Xft.

Traditionally, to deal with alternatives in the older extensions.

The approach was to replace the current libraries via the tce.installed script.

This time, I passed --libdir=/usr/local/lib/fltk-xft to configure script as a custom path.

I want to keep them both, and ideally to pick the one I need with /etc/ld.so.conf in the startup script.

What is the proper way for that ?

I tried switching order, then calling ldconfig, but it doesn't yield.

P.S. I had to use attachment cause the forum kept reporting Internal Server Error

Title: Re: How do I specify the priority for alternative libraries ?
Post by: andyj on March 18, 2021, 08:50:56 AM

Have you tried using LD_LIBRARY_PATH before your execute statement?

Title: Re: How do I specify the priority for alternative libraries ?
Post by: polikuo on March 18, 2021, 09:02:30 AM

Quote from: andyj on March 18, 2021, 08:50:56 AM

Have you tried using LD_LIBRARY_PATH before your execute statement?

I know that trick.

The thing is, I want to create an extension that co-exists with the other.

Make the change system wide by telling ldconfig or something like that.

Such that when I manually delete the newer libraries, the system would fall back to older ones.

Of course a quick reboot would do the trick, but I can't help wanting to know if there's a different approach for linux in general.

Title: Re: How do I specify the priority for alternative libraries ?
Post by: curaga on March 18, 2021, 10:42:10 AM

ld.so.conf is correct, but according to "man ld.so", the binary's RPATH has higher priority than the ld.so cache. If the binary happens to have a RPATH for /usr/local/lib, that dir comes first.

Many binaries do add a rpath for non-standard lib dirs like /usr/local/lib, you can check with "readelf -d /path/to/bin".

Title: Re: How do I specify the priority for alternative libraries ?
Post by: GNUser on March 18, 2021, 11:34:18 AM

Hi, polikuo. Using RPATH sounds like the best option. You can change a binary's RPATH after compilation using the patchelf tool.

If you don't feel like compiling patchelf, you can download it for your architecture from here:
https://packages.debian.org/buster/patchelf

This is how you'd extract the .deb package (assuming you downloaded the amd64 package):

Code: [Select]

$ ar x patchelf_0.9\+52.20180509-1_amd64.deb
$ tar -xvf data.tar.xzThe patchelf binary will be inside the usr/bin/ directory.

Then something like this would do the trick for you:

Code: [Select]

$ patchelf --set-rpath <directory> <binary>For example:

Code: [Select]

$ patchelf --set-rpath /usr/local/lib/fltk-xft coolappNow  coolapp  looks in  /usr/local/lib/fltk-xft  for libraries first, before looking in the system's default directories.