NAME

sys/un.h - definitions for UNIX domain sockets

SYNOPSIS

#include <sys/un.h>

DESCRIPTION

The <sys/un.h> header shall define the sockaddr_un structure that includes at least the following members:

sa_family_t  sun_family  Address family. 
char         sun_path[]  Socket pathname. 

The sockaddr_un structure is used to store addresses for UNIX domain sockets. Values of this type shall be cast by applications to struct sockaddr for use with socket functions.

The sa_family_t type shall be defined as described in <sys/socket.h>.

APPLICATION USAGE

The size of sun_path has intentionally been left undefined. This is because different implementations use different sizes. For example, 4.3 BSD uses a size of 108, and 4.4 BSD uses a size of 104. Since most implementations originate from BSD versions, the size is typically in the range 92 to 108.

Applications should not assume a particular length for sun_path or assume that it can hold {_POSIX_PATH_MAX} characters (255).

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

<sys/socket.h>, the System Interfaces volume of IEEE Std 1003.1-2001, bind(), socket(), socketpair()

CHANGE HISTORY

First released in Issue 6. Derived from the XNS, Issue 5.2 specification.