CAP_COPY_EXT(3) Linux Programmer's Manual CAP_COPY_EXT(3)
cap_copy_ext, cap_size, cap_copy_int - capability state external representation transla-
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);
cc ... -lcap
These functions translate a capability state from an internal representation into an
external one. The external representation is an exportable, contiguous, persistent repre-
sentation of a capability state in user-managed space. The internal representation is
managed by the capability 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 converted 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_p.
cap_copy_ext copies a capability state in working storage, identified by cap_p, from sys-
tem 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 necessary to
convert the capability state from the undefined internal format to an exportable, contigu-
ous, 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 return-
ing a pointer to the newly created capability state. The function initializes the capa-
bility state and then copies the capability state from the record painted 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. 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 successfully. The caller should free any
releasable memory, when the capability state in working storage is no longer required, by
calling cap_free with the cap_t as an argument.
cap_size returns the length required to hold a capability data record on success, and -1
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(3) is set to EINVAL, ENOMEM, or ERANGE.
These functions are specified by POSIX.1e.
cap_clear(3), cap_from_text(3), cap_get_file(3), cap_get_proc(3), cap_init(3)
26th May 1997 CAP_COPY_EXT(3)