Consider the case of two threads operating simultaneously on a single cap_t value. There are cases where libcap APIs can observe partially updated state in such a cap_t value because one is reading properties of that set while the other is writing them. The Go API carefully locks Set values while operating on them, we should restore parity by having libcap do something similar. I'm going to use the __atomic_* primitives to avoid mandatory libthread/libpsx dependencies.
The following commits implemented this: https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=aca076443591ba18438b60e41294b59a324daf04 https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=5b16d336d009bc927a0545b9ecbb91942f1742f5 https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=73194f5369286e10c9e19cbd71de59c3b45b5789 https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=140fa8438bde4e6affe8aefa6fbf077eae968686 https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=3d60128581126f69e31ee963d47cef456ee9e371 These will all be part of the libcap-2.60 release.