freebsd/lib/libc/sys/getpeername.2

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.\"     @(#)getpeername.2	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dt GETPEERNAME 2
.Os BSD 4.2
.Sh NAME
.Nm getpeername
.Nd get name of connected peer
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/socket.h>
.Ft int
.Fn getpeername "int s" "struct sockaddr *name" "socklen_t *namelen"
.Sh DESCRIPTION
.Fn Getpeername
returns the name of the peer connected to
socket
.Fa s .
The
.Fa namelen
parameter should be initialized to indicate
the amount of space pointed to by
.Fa name .
On return it contains the actual size of the name
returned (in bytes).
The name is truncated if the buffer provided is too small.
.Sh IMPLEMENTATION NOTES
.Pp
In the non-threaded library
.Fn getpeername
is implemented as the
.Va getpeername
syscall.
.Pp
In the threaded library, the
.Va getpeername
syscall is assembled to
.Fn _thread_sys_getpeername
and
.Fn getpeername
is implemented as a function which locks
.Va s
for read and write, then calls
.Fn _thread_sys_getpeername .
Before returning,
.Fn getpeername
unlocks
.Va s .
.Sh RETURN VALUES
A 0 is returned if the call succeeds, -1 if it fails.
.Sh ERRORS
The call succeeds unless:
.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 ENOTCONN
The socket is not connected.
.It Bq Er ENOBUFS
Insufficient resources were available in the system
to perform the operation.
.It Bq Er EFAULT
The 
.Fa name
parameter points to memory not in a valid part of the
process address space.
.El
.Sh SEE ALSO
.Xr accept 2 ,
.Xr bind 2 ,
.Xr getsockname 2 ,
.Xr socket 2
.Sh HISTORY
The
.Fn getpeername
function call appeared in
.Bx 4.2 .