Versioning libhl.so file on Linux

[l0go]

Hi,
I am currently working towards packaging HashLink for the Fedora Linux distribution. One of their guidelines is that .so libraries are versioned, preferably by upstream (you!). This means that libhl.so should be something like libhl.so.0 with 0 incrementing on ABI changes. Would it be possible for this to happen?

[andyli]

I think when building with CMake, the library is already versioned. See usage of SOVERSION in CMakeLists.txt.

Someone have to remember update it correctly though. It's a bit trickly - the software version number does not implies SOVERSION number. What I wrote initially in CMakeLists.txt that SOVERSION = ${HL_VERSION_MAJOR} is not quite correct. SOVERSION follows semver strictly, i.e. whenever there is any breaking change, it goes up.

[tobil4sk]

There are tools we can use that compare the ABI with previous versions to check if SOVERSION ought to have changed. We can set up github actions that fail if the ABI changes but the so version remains the same.

MbedTLS does this, and I know they are very diligent with changing the so version on any ABI change 😅 https://github.com/Mbed-TLS/mbedtls/blob/4b9141ccf45e92d42152f9ec19cc69fab31b066b/scripts/abi_check.py

[andyli]

Yes, I think it's a good direction. Debian's packaging system is able to do this as well.

Not sure if there is a standalone tool hashlink can adopt, or have to write a custom script like MbedTLS.

[l0go]

MbedTLS utilizes these tools, which are recommended by Fedora:

• https://github.com/lvc/abi-dumper/
• https://github.com/lvc/abi-compliance-checker

There is also abidiff