CAP_CLEAR(3) Linux Programmer's Manual CAP_CLEAR(3)
cap_clear, cap_clear_flag, cap_get_flag, cap_set_flag, cap_compare - capability data
int cap_clear(cap_t cap_p);
int cap_clear_flag(cap_t cap_p, cap_flag_t flag);
int cap_get_flag(cap_t cap_p, cap_value_t cap,
cap_flag_t flag, cap_flag_value_t *value_p);
int cap_set_flag(cap_t cap_p, cap_flag_t flag, int ncap,
const cap_value_t *caps, cap_flag_value_t value);
int cap_compare(cap_t cap_a, cap_t cap_b);
Link with -lcap.
These functions work on a capability state held in working storage. A cap_t holds infor-
mation about the capabilities in each of the three sets, Permitted, Inheritable, and
Effective. Each capability in a set may be clear (disabled, 0) or set (enabled, 1).
These functions work with the following data types:
cap_value_t identifies a capability, such as CAP_CHOWN.
cap_flag_t identifies one of the three flags associated with a capability (i.e., it
identifies one of the three capability sets). Valid values for this
type are CAP_EFFECTIVE, CAP_INHERITABLE or CAP_PERMITTED.
cap_flag_value_t identifies the setting of a particular capability flag (i.e, the value
of a capability in a set). Valid values for this type are CAP_CLEAR (0)
or CAP_SET (1).
cap_clear() initializes the capability state in working storage identified by cap_p so
that all capability flags are cleared.
cap_clear_flag() clears all of the capabilities of the specified capability flag, flag.
cap_get_flag() obtains the current value of the capability flag, flag, of the capability,
cap, from the capability state identified by cap_p and places it in the location pointed
to by value_p.
cap_set_flag() sets the flag, flag, of each capability in the array caps in the capability
state identified by cap_p to value. The argument, ncap, is used to specify the number of
capabilities in the array, caps.
cap_compare() compares two full capability sets and, in the spirit of memcmp(), returns
zero if the two capability sets are identical. A positive return value, status, indicates
there is a difference between them. The returned value carries further information about
which of three sets, cap_flag_t flag, differ. Specifically, the macro CAP_DIFFERS (status,
flag) evaluates to non-zero if the returned status differs in its flag components.
cap_clear(), cap_clear_flag(), cap_get_flag() cap_set_flag() and cap_compare() return zero
on success, and -1 on failure. Other return values for cap_compare() are described above.
On failure, errno is set to EINVAL, indicating that one of the arguments is invalid.
These functions are as per the withdrawn POSIX.1e draft specification. cap_clear_flag()
and cap_compare() are Linux extensions.
libcap(3), cap_copy_ext(3), cap_from_text(3), cap_get_file(3), cap_get_proc(3),