CAP_COPY_EXT(3) Linux Programmer's Manual CAP_COPY_EXT(3)NAME
cap_copy_ext, cap_size, cap_copy_int - capability state external repre‐
ssize_t cap_size(cap_t cap_p);
ssize_t cap_copy_ext(void *ext_p, cap_t cap_p, ssize_t size);
cap_t cap_copy_int(const void *ext_p);
Link with -lcap.
These functions translate between internal and external representations
of a capability state. The external representation is an exportable,
contiguous, persistent representation of a capability state in user-
managed space. The internal representation is managed by the capabil‐
ity functions in working storage.
cap_size() returns the total length (in bytes) that the capability
state in working storage identified by cap_p would require when con‐
verted by cap_copy_ext(). This function is used primarily to determine
the amount of buffer space that must be provided to the cap_copy_ext()
function in order to hold the capability data record created from
cap_copy_ext() copies a capability state in working storage, identified
by cap_p, from system managed space to user-managed space (pointed to
by ext_p) and returns the length of the resulting data record. The
size parameter represents the maximum size, in bytes, of the resulting
data record. The cap_copy_ext() function will do any conversions nec‐
essary to convert the capability state from the undefined internal for‐
mat to an exportable, contiguous, persistent data record. It is the
responsibility of the user to allocate a buffer large enough to hold
the copied data. The buffer length required to hold the copied data
may be obtained by a call to the cap_size() function.
cap_copy_int() copies a capability state from a capability data record
in user-managed space to a new capability state in working storage,
allocating any memory necessary, and returning a pointer to the newly
created capability state. The function initializes the capability
state and then copies the capability state from the record pointed to
by ext_p into the capability state, converting, if necessary, the data
from a contiguous, persistent format to an undefined, internal format.
Once copied into internal format, the object can be manipulated by the
capability state manipulation functions (see cap_clear(3)). Note that
the record pointed to by ext_p must have been obtained from a previous,
successful call to cap_copy_ext() for this function to work success‐
fully. The caller should free any releasable memory, when the capabil‐
ity state in working storage is no longer required, by calling
cap_free() with the cap_t as an argument.
RETURN VALUEcap_size() returns the length required to hold a capability data record
on success, and -1 on failure.
cap_copy_ext() returns the number of bytes placed in the user managed
space pointed to by ext_p on success, and -1 on failure.
cap_copy_int() returns a pointer to the newly created capability state
in working storage on success, and NULL on failure.
On failure, errno is set to EINVAL, ENOMEM, or ERANGE.
These functions are specified in the withdrawn POSIX.1e draft specifi‐
SEE ALSOlibcap(3), cap_clear(3), cap_from_text(3), cap_get_file(3),
cap_get_proc(3), cap_init(3), capabilities(7)