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.\"     @(#)bind.2	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dt BIND 2
.Os BSD 4.2
.Sh NAME
.Nm bind
.Nd assign a local protocol address to a socket.
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/socket.h>
.Ft int
.Fn bind "int s" "const struct sockaddr *addr" "int addrlen"
.Sh DESCRIPTION
.Fn Bind
assigns the local protocol address to a socket.
When a socket is created 
with
.Xr socket 2
it exists in an address family space but has no protocol address assigned.
.Fn Bind
requests that
.Fa addr
be assigned to the socket.
.Sh NOTES
Binding an address in the UNIX domain creates a socket in the file
system that must be deleted by the caller when it is no longer
needed (using
.Xr unlink 2 ) .
.Pp
The rules used in address binding vary between communication domains.
Consult the manual entries in section 4 for detailed information.
.Sh IMPLEMENTATION NOTES
.Pp
In the non-threaded library
.Fn bind
is implemented as the
.Va bind
syscall.
.Pp
In the threaded library, the
.Va bind
syscall is assembled to
.Fn _thread_sys_bind
and
.Fn bind
is implemented as a function which locks
.Va s
for read and write, then calls
.Fn _thread_sys_bind .
Before returning,
.Fn bind
unlocks
.Va s .
.Sh RETURN VALUES
If the bind is successful, a 0 value is returned.
A return value of -1 indicates an error, which is
further specified in the global
.Va errno .
.Sh ERRORS
The
.Fn bind
call will fail if:
.Bl -tag -width EADDRNOTAVA
.It Bq Er EAGAIN
Kernel resources to complete the request are 
temporarily unavilable.
.It Bq Er EBADF
.Fa S
is not a valid descriptor.
.It Bq Er ENOTSOCK
.Fa S
is not a socket.
.It Bq Er EADDRNOTAVAIL
The specified address is not available from the local machine.
.It Bq Er EADDRINUSE
The specified address is already in use.
.It Bq Er EACCES
The requested address is protected, and the current user
has inadequate permission to access it.
.It Bq Er EFAULT
The
.Fa addr
parameter is not in a valid part of the user
address space.
.El
.Pp
The following errors are specific to binding addresses in the UNIX domain.
.Bl -tag -width EADDRNOTAVA
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
.It Bq Er ENOENT
A prefix component of the path name does not exist.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EIO
An I/O error occurred while making the directory entry or allocating the inode.
.It Bq Er EROFS
The name would reside on a read-only file system.
.It Bq Er EISDIR
An empty pathname was specified.
.El
.Sh SEE ALSO
.Xr connect 2 ,
.Xr getsockname 2 ,
.Xr listen 2 ,
.Xr socket 2
.Sh HISTORY
The
.Fn bind
function call appeared in
.Bx 4.2 .