cap_clear(3) — Linux manual page


CAP_CLEAR(3)              Linux Programmer's Manual             CAP_CLEAR(3)

NAME         top

       cap_clear,  cap_clear_flag, cap_get_flag, cap_set_flag, cap_compare -
       capability data object manipulation

SYNOPSIS         top

       #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         top

       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_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         top

       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         top

       These functions are as per the withdrawn POSIX.1e draft
       specification.  cap_clear_flag() and cap_compare() are Linux

SEE ALSO         top

       libcap(3), cap_copy_ext(3), cap_from_text(3), cap_get_file(3),
       cap_get_proc(3), cap_init(3), capabilities(7)

COLOPHON         top

       This page is part of the libcap (capabilities commands and library)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have
       a bug report for this manual page, send it to
       (please put "libcap" in the Subject line).  This page was obtained
       from the project's upstream Git repository
       ⟨⟩ on
       2020-11-01.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-10-28.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

                                 2008-05-11                     CAP_CLEAR(3)

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