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cap_init(3) — Linux manual page

CAP_INIT(3)             Linux Programmer's ManualCAP_INIT(3)

NAME        top

       cap_init, cap_free, cap_dup - capability data object storage       management

SYNOPSIS        top

       #include <sys/capability.h>       cap_t cap_init(void);       int cap_free(void *obj_d);       cap_t cap_dup(cap_t cap_p);       Link with-lcap.

DESCRIPTION        top

       The capabilities associated with a file or process are never       edited directly.  Instead, working storage is allocated to contain       a representation of the capability state.  Capabilities are edited       and manipulated only within this working storage area.  Once       editing of the capability state is complete, the updated       capability state is used to replace the capability state       associated with the file or process.cap_init() creates a capability state in working storage and       returns a pointer to the capability state.  The initial value of       all flags are cleared.  The caller should free any releasable       memory, when the capability state in working storage is no longer       required, by callingcap_free() with thecap_t as an argument.cap_free() liberates any releasable memory that has been allocated       to the capability state identified byobj_d.  Theobj_d argument       may identify either acap_t entity, or achar * entity allocated       by thecap_to_text() function.cap_dup() returns a duplicate capability state in working storage       given by the source objectcap_p, allocating any memory necessary,       and returning a pointer to the newly created capability state.       Once duplicated, no operation on either capability state affects       the other in any way.  When the duplicated capability state in       working storage is no longer required, the caller should free any       releasable memory by callingcap_free() with thecap_t as an       argument.

RETURN VALUE        top

cap_init() andcap_dup() return a non-NULL value on success, and       NULL on failure.cap_free() returns zero on success, and -1 on failure.       On failure,errno is set toEINVALorENOMEM.

CONFORMING TO        top

       These functions are specified in the withdrawn POSIX.1e draft       specification.

SEE ALSO        top

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

COLOPHON        top

       This page is part of thelibcap (capabilities commands and       library) project.  Information about the project can be found at       ⟨https://git.kernel.org/pub/scm/libs/libcap/libcap.git/⟩.  If you       have a bug report for this manual page, send it to       morgan@kernel.org (please put "libcap" in the Subject line).  This       page was obtained from the project's upstream Git repository       ⟨https://git.kernel.org/pub/scm/libs/libcap/libcap.git/⟩ on       2025-08-11.  (At that time, the date of the most recent commit       that was found in the repository was 2025-08-10.)  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 isnot part of the original manual page), send a       mail to man-pages@man7.org                                2021-03-06CAP_INIT(3)

Pages that refer to this page:cap_clear(3), cap_copy_ext(3), cap_from_text(3), cap_get_file(3), cap_get_proc(3), cap_iab(3), cap_launch(3), libcap(3), capabilities(7)

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