.\"-
.\" Copyright (c) 2000 Robert N. M. Watson
.\" Copyright (c) 2001 Thomas Moestl
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.Dd March 21, 2001
.Dt CAP_COPY_EXT 3
.Os
.Sh NAME
.Nm cap_copy_ext , cap_size
.Nd convert a capability state in working storage to an external representation
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/types.h
.In sys/capability.h
.Ft ssize_t
.Fn cap_copy_ext "void *ext_p" "cap_t cap" "ssize_t len"
.Ft ssize_t
.Fn cap_size "cap_t cap"
.Sh DESCRIPTION
The
.Fn cap_copy_ext
function converts the capability state in working storage identified by
.Fa cap
to an opaque contiguous external representation in the buffer
pointed to by
.Fa ext_p .
.Fa len
specifies the maximum number of bytes that may be written into the buffer.
.Pp
An application can use the
.Fn cap_size
function to determine the amount of storage in bytes that are needed for
the external representation of
.Fa cap .
.Sh IMPLEMENTATION NOTES
The format of the external representation is not specified in the POSIX.1e
draft.
Applications that need a portable representation should use
.Xr cap_to_text 3 .
.Pp
This function is appropriate in cases where a persistent representation is
needed that needs not to be portable.
Due to endianess issues, this format might
not even be portable between machines of different architectures running this
implementation.
.Pp
.Xr cap_copy_int 3
can be used to convert the external representation back to a
.Vt cap_t .
.Sh RETURN VALUES
Upon successful completion, the
.Fn cap_copy_ext
function returns the number of bytes written to
.Fa ext_p ,
and
.Fn cap_size
returns the number of bytes needed for the external representation of
.Fa cap .
Otherwise, the value \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn cap_copy_ext
fails if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa cap
argument does not refer to a capability state in working storage,
or the
.Fa len
argument is negative.
.It Bq Er ERANGE
The buffer size specified by
.Fa len
argument is too small to hold the external representation.
.El
.Pp
.Fn cap_size
fails if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa cap
argument does not refer to a capability state in working storage.
.El
.Sh SEE ALSO
.Xr cap_copy_int 3 ,
.Xr cap_free 3 ,
.Xr cap_from_text 3 ,
.Xr cap_get_flag 3 ,
.Xr cap_to_text 3 ,
.Xr posix1e 3
.Sh STANDARDS
This function is expected to conform to the withdrawn
IEEE draft 1003.1e
.Pq Dq POSIX.1e .
.Sh HISTORY
These functions first appeared in
.Fx 5.0 .
.Sh AUTHORS
.An Thomas Moestl Aq tmm@FreeBSD.org