NAME

       cap_copy_ext, cap_size, cap_copy_int - capability state external representation translation

SYNOPSIS

       #include <sys/capability.h>

       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.

DESCRIPTION

       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 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 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 necessary  to  convert  the  capability  state  from  the
       undefined internal format 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 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.

RETURN VALUE

       cap_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.

CONFORMING TO

       These functions are specified in the withdrawn POSIX.1e draft specification.

SEE ALSO

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

                                                   2008-05-11                                    CAP_COPY_EXT(3)