[buyemune-sys]

The problem

Some bridge adapters are registered only under the newest glibc version of their symbol. A binary built against an older glibc imports an older version of the same symbol and gets the fail-loud stub instead of the adapter:

glibc bridge: called unimplemented ABI glob64@GLIBC_2.2.5
glibc bridge: called unimplemented ABI pthread_mutex_clocklock@GLIBC_2.30

A real-world case: the static build of Tarantool, built on CentOS 7 (glibc 2.17), aborts in glob64@GLIBC_2.2.5 when box.cfg starts. Also, every pthread_cleanup_push in code built before glibc 2.34 imports __pthread_register_cancel@GLIBC_2.3.3.

How the full list was found

A script (repro/version_gaps.py in our series) mirrors GlibcAdapter::GlibcAdapter(): a version the inventory knows registers as is, an unknown one registers under every inventory version. It then lists names where some glibc versions are not covered and musl has no provider of that name. Names in overrideNames resolve by name for any version, so they are excluded. On main:

symbol	registered	missing (x86_64)	missing (aarch64)
glob64	2.27	2.2.5	2.17
pthread_mutex_clocklock, pthread_cond_clockwait, sem_clockwait	2.34	2.30	2.30
pthread_clockjoin_np	2.34	2.31	2.31
pthread_rwlockattr_setkind_np	2.34	2.2.5	2.17
__pthread_register_cancel, __pthread_unregister_cancel, __pthread_unwind_next	2.34	2.3.3	2.17
pthread_attr_setaffinity_np	2.32	2.3.3, 2.3.4	2.17

The fix

The older version is added for every symbol whose ABI did not change. These are the pthread functions that simply moved from libpthread into libc in 2.34, plus glob64: its pre-2.27 version differs only in how gl_lstat behaves under GLOB_ALTDIRFUNC, which musl does not implement either. On aarch64 the hand-written x86-64 versions fan out to the platform's versions as before, so 2.17 is covered too.

One exception: pthread_attr_setaffinity_np@GLIBC_2.3.3. It is the old ABI without the cpusetsize argument, so it deliberately stays a stub (2.3.4 is added).

After the fix, the script reports only that one case.

Test

The guest (tst/glibc_guest_test.c) uses .symver to call glob64 at the architecture's baseline version (GLIBC_2.2.5 / GLIBC_2.17) and pthread_mutex_clocklock@GLIBC_2.30. Needle: guest old versions glob64=1 clocklock=0.

• on main: the guest aborts with called unimplemented ABI glob64@GLIBC_2.2.5;
• with the fix: ./build test passes.