send (BPX1SND, BPX4SND) — Send data on a socket

Function

The send callable service sends data on a socket.

Requirements

Operation	Environment
Authorization:	Supervisor state or problem state, any PSW key
Dispatchable unit mode:	Task or SRB
Cross memory mode:	PASN = HASN
AMODE (BPX1SND):	31-bit task or SRB mode
AMODE (BPX4SND):	64-bit task mode only
ASC mode:	Primary mode
Interrupt status:	Enabled for interrupts
Locks:	Unlocked
Control parameters:	All parameters must be addressable by the caller and in the primary address space.

Format

The syntax format is as follows:

CALL BPX1SND,(Socket_descriptor,
              Buffer_length,
              Buffer,
              Buffer_alet,
              Flags,
              Return_value,
              Return_code,
              Reason_code)

AMODE 64 callers use BPX4SND with the same parameters.

Parameters

Socket_descriptor

Supplied parameter

Type:: Integer
Length:: Fullword

The name of a fullword that contains the socket file descriptor for which the send is to be done.

Buffer_length

Supplied and returned parameter

Type:: Integer
Length:: Fullword

The name of a field that contains the length of Buffer.

Buffer

Supplied parameter

Type:: Character
Length:: Length specified by Buffer_length

The name of a field that contains the data that is to be transmitted.

Buffer_alet

Supplied parameter

Type:: Integer
Length:: Fullword

The name of a field that contains the ALET for Buffer.

You should specify a Buffer_alet of 0 for the normal case of a buffer in the user's address space (current primary address space). If a value other than 0 is specified for the Buffer_alet, the value must represent a valid entry in the dispatchable unit access list (DUAL).

Flags

Supplied parameter

Type:: Structure
Length:: Fullword

The name of a field that contains information about how the data is to be sent. See BPXYMSGF — Map the message flags for more information about the format of this field.

Return_value

Returned parameter

Type:: Integer
Length:: Fullword

The name of a fullword in which the send service returns one of the following:

The number of bytes sent from the buffer, if the request is successful. A value of 0 indicates that the connection is closed.
-1, if the request is not successful.

Return_code

Returned parameter

Type:: Integer
Length:: Fullword

The name of a fullword in which the send service stores the return code. The send service returns Return_code only if Return_value is -1. For a list of return code values, see Return codes (errnos) in z/OS UNIX System Services Messages and Codes. The send service can return one of the following values in the Return_code parameter:

Return_code	Explanation
EBADF	Socket_descriptor does not refer to a valid descriptor. The following reason codes can accompany the return code: JRFileDesNotInUse, JRFileNotOpen.
ECONNRESET	Connection reset by peer.
EINTR	A signal interrupted the send before any data was written. The following reason code can accompany the return code: JRSockRdwrSignal.
EIO	There has been a network or transport failure. The following reason code can accompany the return code: JRPrevSockError.
EMSGSIZE	The message is too large to be sent all at once, as the socket requires. The following reason code can accompany the return code: JRSockBufMax.
ENOBUFS	A buffer could not be obtained. The following reason code can accompany the return code: JROutofSocketCells.
ENOTCONN	The socket is not connected. The following reason code can accompany the return code: JRSocketNotCon.
ENOTSOCK	Socket_descriptor does not refer to a valid socket descriptor. The following reason code can accompany the return code: JRMustBeSocket.
EPIPE	An attempt was made to send to a socket that is shut down or closed. The following reason code can accompany the return code: JRSocketClosed. This error also generates a SIGPIPE signal.
EWOULDBLOCK	The socket is marked nonblocking and no space is available for data to be written, or the SO_SNDTIMEO timeout value was reached before space became available. The socket is marked blocking. The call is blocked, without sending any data, for that time period which was specified in the SO_SNDTIMEO option. The following reason codes can accompany the return code: JRWouldBlock, JRTimeout.

Reason_code

Returned parameter

Type:: Integer
Length:: Fullword

The name of a fullword in which the send service stores the reason code. The send service returns Reason_code only if Return_value is -1. Reason_code further qualifies the Return_code value. For a list of reason codes, see Reason codes in z/OS UNIX System Services Messages and Codes.

Usage notes

The socket must be connected.
If there is not enough room to write the data to the output buffer, the service either blocks waiting for room, or returns an EWOULDBLOCK (depending on whether the socket is marked as blocking or nonblocking, and whether SO_SNDTIMEO timeout value was reached before space became available).
See Callable services for SRB mode routines for more information about programming considerations for SRB mode.

Related services

recv (BPX1RCV, BPX4RCV) — Receive data on a socket and store it in a buffer

Characteristics and restrictions

None.

Examples

See BPX1SND (send) example.