shutdown()--End Receiving and/or Sending of Data on Socket

  #include <sys/types.h>
  #include <sys/socket.h>

 int shutdown(int socket_descriptor,
              int how)

  #define _XOPEN_SOURCE 520
  #include <sys/socket.h>

 int shutdown(int socket_descriptor,
              int how)

The shutdown() function is used to disable reading, writing, or reading and writing on a socket.

There are two versions of the API, as shown above. The base i5/OS API uses BSD 4.3 structures and syntax. The other uses syntax and structures compatible with the UNIX 98 programming interface specifications. You can select the UNIX 98 compatible interface with the _XOPEN_SOURCE macro.

Parameters

socket_descriptor

(Input) The descriptor of the socket to be shut down.

how

(Input) The data flow path to be disabled:

SHUT_RD or 0	No more data can be received.
SHUT_WR or 1	No more data can be sent.
SHUT_RDWR or 2	No more data can be sent or received.

Authorities

No authorization is required.

Return Value

shutdown() returns an integer. Possible values are:

• -1 (unsuccessful)
  
  
• 0 (successful)

Error Conditions

When shutdown() fails, errno can be set to one of the following:

[EBADF]	Descriptor not valid.
[EINVAL]	Parameter not valid. This error code indicates one of the following: The socket pointed to by the socket_descriptor parameter is using a connection-oriented transport service. Also, the transport service is in a state in which sends and receives are disallowed (for example, connection has been reset by peer). The how parameter specifies a value that is not valid.
[ENOTCONN]	The specified descriptor does not reference a connected socket.
[ENOTSOCK]	The specified descriptor does not reference a socket.
[EIO]	Input/output error.
[EUNATCH]	The protocol required to support the specified address family is not available at this time. Note: This errno is not returned if the how parameter is 0.
[EUNKNOWN]	Unknown system state.

Error Messages

Usage Notes

1. Issuing a shutdown() with a how parameter of 0 causes any new data received for the socket to be discarded. Any input functions for this socket complete with a 0, meaning that end-of-file has been reached. If the socket is being shared across multiple processes, any blocking input operations are deblocked by this action.
   
   
2. Issuing a shutdown() with a how parameter of 1 results in all output functions being failed with an error of [epipe]. The process issuing the output operation will receive a synchronous sigpipe signal. This also sends a normal close sequence to the partner program. Receive operations issued by the partner program receive a return value of 0 once all previous data has been received. If the socket is being shared across multiple processes or threads, any blocking output functions are deblocked with a return value of -1 and an error code of [epipe].
   
   
3. Issuing a shutdown() with a how parameter of 2 results in the actions listed for a how parameter of 0 being performed first, followed by the actions listed for a how parameter of 1.
   
   
4. Issuing a shutdown() on socket connected through a SOCKS server is not supported.
   
   
5. When you develop in C-based languages and an application is compiled with the _XOPEN_SOURCE macro defined to the value 520 or greater, the shutdown() API is mapped to qso_shutdown98().

Related Information

• _XOPEN_SOURCE--Using _XOPEN_SOURCE for the UNIX 98 compatible interface
  
  
• close()--Close File or Socket Descriptor