capng_have_capabilities man page
capng_have_capabilities, capng_have_permitted_capabilities — check for capabilities
capng_results_t capng_have_capabilities(capng_select_t set); capng_results_t capng_have_permitted_capabilities(void);
capng_have_capabilities will check the selected internal capabilities sets to see what the status is. The capabilities sets must be previously setup with calls to capng_get_caps_process, capng_get_caps_fd, or in some other way setup. The options are CAPNG_SELECT_CAPS for the traditional capabilities, CAPNG_SELECT_BOUNDS for the bounding set, or CAPNG_SELECT_BOTH if clearing both is desired. When capabilities are checked, it will only look at the effective capabilities.
If, however, the source of capabilities comes from a file, then you may need to additionally check the permitted capabilities. It's for this reason that capng_have_permitted_capabilities was created. It takes no arguments because it simply checks the permitted set.
This funtion will return one of the following four self explanatory values: CAPNG_FAIL, CAPNG_NONE, CAPNG_PARTIAL, CAPNG_FULL.
capng_get_caps_process(3), capng_get_caps_fd(3), capng_have_capability(3), capabilities(7)