CAP_CLEAR
Section: Linux Programmer's Manual (3)
Updated: 2008-05-11
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NAME
cap_clear, cap_clear_flag, cap_get_flag, cap_set_flag, cap_compare - capability data object manipulation
SYNOPSIS
#include <sys/capability.h>
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.
DESCRIPTION
These functions work on a capability state held in working storage.
A
cap_t
holds information 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.
RETURN VALUE
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.
CONFORMING TO
These functions are as per the withdrawn POSIX.1e draft specification.
cap_clear_flag()
and
cap_compare()
are Linux extensions.
SEE ALSO
libcap(3),
cap_copy_ext(3),
cap_from_text(3),
cap_get_file(3),
cap_get_proc(3),
cap_init(3),
capabilities(7)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- CONFORMING TO
-
- SEE ALSO
-
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