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.Dd $Mdocdate: July 1 2010 $
.Dt GETPEEREID 3
.Os
.Sh NAME
.Nm getpeereid
.Nd get effective user and group identification of locally-connected peer
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/socket.h>
.Ft int
.Fn getpeereid "int s" "uid_t *euid" "gid_t *egid"
.Sh DESCRIPTION
.Fn getpeereid
returns the effective user ID and group ID of the peer connected to
a
.Ux Ns -domain
socket (see
.Xr unix 4 ) .
The argument
.Fa s
must be of type
.Dv SOCK_STREAM .
.Pp
One common use is for
.Ux Ns -domain
servers to determine the credentials of clients that have connected to it.
.Pp
.Fn getpeereid
takes three parameters:
.Bl -bullet
.It
.Fa s
contains the file descriptor of the socket whose peer credentials
should be looked up.
.It
.Fa euid
points to a
.Li uid_t
variable into which the effective user ID for the connected peer will
be stored.
.It
.Fa egid
points to a
.Li gid_t
variable into which the effective group ID for the connected peer will
be stored.
.El
.Sh RETURN VALUES
If the call succeeds, a 0 is returned and
.Fa euid
and
.Fa egid
are set to the effective user ID and group ID of the connected peer.
Otherwise,
.Va errno
is set and a value of \-1 is returned.
.Sh ERRORS
On failure,
.Va errno
is set to one of the following:
.Bl -tag -width Er
.It Bq Er EBADF
The argument
.Fa s
is not a valid descriptor.
.It Bq Er ENOTSOCK
The argument
.Fa s
is a file, not a socket.
.It Bq Er EOPNOTSUPP
The socket is not in the
.Ux Ns -domain .
.It Bq Er ENOTCONN
The socket is not connected.
.It Bq Er ENOBUFS
Insufficient resources were available in the system
to perform the operation.
.El
.Sh SEE ALSO
.Xr accept 2 ,
.Xr bind 2 ,
.Xr getpeername 2 ,
.Xr getsockname 2 ,
.Xr getsockopt 2 ,
.Xr socket 2 ,
.Xr unix 4
.Sh HISTORY
The
.Fn getpeereid
function call appeared in
.Ox 3.0 .