Cannot find library that is on the system

[myz-dev]

Hi,

using WSL Ubuntu 20.04.6 LTS

for a while now I have been trying to cross compile my project with a specific GLIBC version on my target system.
I think zigbuild is exactly what I am looking for and I tried to follow the instructions and compile my program.

From the root directory of my project I run
cargo zigbuild --bin defect_map --release --target i686-unknown-linux-gnu (omitting the specific GLIBC version for the minimal example) and the compilation fails at the very last step, requiring the SQLITE development library: = note: ld.lld: error: unable to find library -lsqlite3.

I have checked my installation of the package dpkg -L libsqlite3-dev:i386 and everything is where it is supposed to be.

The library for the target system is under /usr/lib/i386-linux-gnu which is also configured in /etc/ld.so.conf.d/i386-linux-gnu.conf. Similarly the library exists for my host system, but I do not know if this is relevant for the cross compilation step.

So how can I tell zigbuild where to look for the library?

Best regards

[NobodyXu]

It's likely you are missing pkg-config for this

[myz-dev]

Hi.
My file /usr/lib/i386-linux-gnu/pkgconfig/libsqlite3.pc looks like this:

 # Package Information for pkg-config

prefix=/usr
exec_prefix=${prefix}
libdir=${prefix}/lib/i386-linux-gnu
includedir=${prefix}/include

Name: SQLite
Description: SQL database engine
Version: 3.31.1
Libs: -L${libdir} -lsqlite3
Libs.private: -lm -lm -ldl -lz -lpthread
Cflags: -I${includedir}

I think libdir resolves to /usr/lib/i386-linux-gnu where the library is installed. Do you think I have to change this line?

[NobodyXu]

I suspect that pkg-config loads the wrong libsqlite3.pc.

You can try setting PKG_CONFIG_PATH="/usr/lib/i386-linux-gnu/pkgconfig/", it might help.

[myz-dev]

Unfortunately that does not help. The library is not found during the build process. Thank you very much for your kind help so far, I will see what I can do about this :-)

[NobodyXu]

You can also try setting PKG_CONFIG to your own script that invokes pkg-config with the correct parameter.

[myz-dev]

Ok, thank you, I will check how that works and report the outcome here. Thank you again for your time!

[polarathene]

The library for the target system is under /usr/lib/i386-linux-gnu which is also configured in /etc/ld.so.conf.d/i386-linux-gnu.conf.

/etc/ld.so.conf.d/* is for building /etc/ld.so.cache DB, if you add a new config there you would need to run ldconfig to update the cache. However this is only for adding search paths for runtime linking (when a program starts, or you use ldd for example), similar to how LD_LIBRARY_PATH is for runtime not build time.

---

= note: ld.lld: error: unable to find library -lsqlite3

This is a link time error during build.

If you do not experience this problem with cargo build (perhaps try with matching host arch to verify compared to cargo zigbuild for that same host arch), then you likely just need to ensure you provide the expected search dir.

Are you certain the issue is with pkg-config? If it was at link time with Zig instead, when zig cc is provided a -target it will disable using system default search paths IIRC, so you need to add RUSTFLAGS='-L /usr/lib/i386-linux-gnu' if that is where your libsqlite3.so/libsqlite3.a` exists (which the error is trying to find for linking).

[myz-dev]

Hi, thank you very much for your reply!

A lot of time has passed since and unfortunately I do not have access to the project anymore.

As far as I remember, I had tried to solve this with cross and/or zigbuild for quite some time and, at the time, just was not able to. I am a little ashamed to say, that, if I remember correctly, to compile my project for the specific target, I created a container using images that had old tool chains installed, that targeted the specific glib-c version I needed.

[polarathene]

No shame, this type of task can get complicated and not always documented well. I am troubleshooting one situation myself where a -sys crate is building with zig correctly, but when another crate is built with that -sys crate as a dependency there is something else preventing it from respecting the older glibc version I configured zig target to use.

Sometimes it easier and more practical to just use what works, even if it is not ideal :)