mirror of https://github.com/mkerrisk/man-pages
174 lines
5.1 KiB
Plaintext
174 lines
5.1 KiB
Plaintext
|
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
|
||
|
.TH "SEND" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
|
||
|
.\" send
|
||
|
.SH NAME
|
||
|
send \- send a message on a socket
|
||
|
.SH SYNOPSIS
|
||
|
.LP
|
||
|
\fB#include <sys/socket.h>
|
||
|
.br
|
||
|
.sp
|
||
|
ssize_t send(int\fP \fIsocket\fP\fB, const void *\fP\fIbuffer\fP\fB,
|
||
|
size_t\fP \fIlength\fP\fB, int\fP
|
||
|
\fIflags\fP\fB);
|
||
|
.br
|
||
|
\fP
|
||
|
.SH DESCRIPTION
|
||
|
.LP
|
||
|
The \fIsend\fP() function shall initiate transmission of a message
|
||
|
from the specified socket to its peer. The \fIsend\fP()
|
||
|
function shall send a message only when the socket is connected (including
|
||
|
when the peer of a connectionless socket has been set
|
||
|
via \fIconnect\fP()).
|
||
|
.LP
|
||
|
The \fIsend\fP() function takes the following arguments:
|
||
|
.TP 7
|
||
|
\fIsocket\fP
|
||
|
Specifies the socket file descriptor.
|
||
|
.TP 7
|
||
|
\fIbuffer\fP
|
||
|
Points to the buffer containing the message to send.
|
||
|
.TP 7
|
||
|
\fIlength\fP
|
||
|
Specifies the length of the message in bytes.
|
||
|
.TP 7
|
||
|
\fIflags\fP
|
||
|
Specifies the type of message transmission. Values of this argument
|
||
|
are formed by logically OR'ing zero or more of the
|
||
|
following flags:
|
||
|
.TP 7
|
||
|
MSG_EOR
|
||
|
.RS
|
||
|
Terminates a record (if supported by the protocol).
|
||
|
.RE
|
||
|
.TP 7
|
||
|
MSG_OOB
|
||
|
.RS
|
||
|
Sends out-of-band data on sockets that support out-of-band communications.
|
||
|
The significance and semantics of out-of-band data
|
||
|
are protocol-specific.
|
||
|
.RE
|
||
|
.sp
|
||
|
.sp
|
||
|
.LP
|
||
|
The length of the message to be sent is specified by the \fIlength\fP
|
||
|
argument. If the message is too long to pass through the
|
||
|
underlying protocol, \fIsend\fP() shall fail and no data shall be
|
||
|
transmitted.
|
||
|
.LP
|
||
|
Successful completion of a call to \fIsend\fP() does not guarantee
|
||
|
delivery of the message. A return value of -1 indicates only
|
||
|
locally-detected errors.
|
||
|
.LP
|
||
|
If space is not available at the sending socket to hold the message
|
||
|
to be transmitted, and the socket file descriptor does not
|
||
|
have O_NONBLOCK set, \fIsend\fP() shall block until space is available.
|
||
|
If space is not available at the sending socket to hold
|
||
|
the message to be transmitted, and the socket file descriptor does
|
||
|
have O_NONBLOCK set, \fIsend\fP() shall fail. The \fIselect\fP() and
|
||
|
\fIpoll\fP() functions can be used to
|
||
|
determine when it is possible to send more data.
|
||
|
.LP
|
||
|
The socket in use may require the process to have appropriate privileges
|
||
|
to use the \fIsend\fP() function.
|
||
|
.SH RETURN VALUE
|
||
|
.LP
|
||
|
Upon successful completion, \fIsend\fP() shall return the number of
|
||
|
bytes sent. Otherwise, -1 shall be returned and
|
||
|
\fIerrno\fP set to indicate the error.
|
||
|
.SH ERRORS
|
||
|
.LP
|
||
|
The \fIsend\fP() function shall fail if:
|
||
|
.TP 7
|
||
|
.B EAGAIN \fRor\fP EWOULDBLOCK
|
||
|
.sp
|
||
|
The socket's file descriptor is marked O_NONBLOCK and the requested
|
||
|
operation would block.
|
||
|
.TP 7
|
||
|
.B EBADF
|
||
|
The \fIsocket\fP argument is not a valid file descriptor.
|
||
|
.TP 7
|
||
|
.B ECONNRESET
|
||
|
A connection was forcibly closed by a peer.
|
||
|
.TP 7
|
||
|
.B EDESTADDRREQ
|
||
|
.sp
|
||
|
The socket is not connection-mode and no peer address is set.
|
||
|
.TP 7
|
||
|
.B EINTR
|
||
|
A signal interrupted \fIsend\fP() before any data was transmitted.
|
||
|
.TP 7
|
||
|
.B EMSGSIZE
|
||
|
The message is too large to be sent all at once, as the socket requires.
|
||
|
.TP 7
|
||
|
.B ENOTCONN
|
||
|
The socket is not connected or otherwise has not had the peer pre-specified.
|
||
|
.TP 7
|
||
|
.B ENOTSOCK
|
||
|
The \fIsocket\fP argument does not refer to a socket.
|
||
|
.TP 7
|
||
|
.B EOPNOTSUPP
|
||
|
The \fIsocket\fP argument is associated with a socket that does not
|
||
|
support one or more of the values set in
|
||
|
\fIflags\fP.
|
||
|
.TP 7
|
||
|
.B EPIPE
|
||
|
The socket is shut down for writing, or the socket is connection-mode
|
||
|
and is no longer connected. In the latter case, and if
|
||
|
the socket is of type SOCK_STREAM, the SIGPIPE signal is generated
|
||
|
to the calling thread.
|
||
|
.sp
|
||
|
.LP
|
||
|
The \fIsend\fP() function may fail if:
|
||
|
.TP 7
|
||
|
.B EACCES
|
||
|
The calling process does not have the appropriate privileges.
|
||
|
.TP 7
|
||
|
.B EIO
|
||
|
An I/O error occurred while reading from or writing to the file system.
|
||
|
.TP 7
|
||
|
.B ENETDOWN
|
||
|
The local network interface used to reach the destination is down.
|
||
|
.TP 7
|
||
|
.B ENETUNREACH
|
||
|
.sp
|
||
|
No route to the network is present.
|
||
|
.TP 7
|
||
|
.B ENOBUFS
|
||
|
Insufficient resources were available in the system to perform the
|
||
|
operation.
|
||
|
.sp
|
||
|
.LP
|
||
|
\fIThe following sections are informative.\fP
|
||
|
.SH EXAMPLES
|
||
|
.LP
|
||
|
None.
|
||
|
.SH APPLICATION USAGE
|
||
|
.LP
|
||
|
The \fIsend\fP() function is equivalent to \fIsendto\fP() with a null
|
||
|
pointer
|
||
|
\fIdest_len\fP argument, and to \fIwrite\fP() if no flags are used.
|
||
|
.SH RATIONALE
|
||
|
.LP
|
||
|
None.
|
||
|
.SH FUTURE DIRECTIONS
|
||
|
.LP
|
||
|
None.
|
||
|
.SH SEE ALSO
|
||
|
.LP
|
||
|
\fIconnect\fP() , \fIgetsockopt\fP() , \fIpoll\fP() , \fIrecv\fP()
|
||
|
, \fIrecvfrom\fP() , \fIrecvmsg\fP() , \fIselect\fP() , \fIsendmsg\fP()
|
||
|
, \fIsendto\fP() , \fIsetsockopt\fP() , \fIshutdown\fP() , \fIsocket\fP()
|
||
|
, the Base Definitions volume of
|
||
|
IEEE\ Std\ 1003.1-2001, \fI<sys/socket.h>\fP
|
||
|
.SH COPYRIGHT
|
||
|
Portions of this text are reprinted and reproduced in electronic form
|
||
|
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
|
||
|
-- Portable Operating System Interface (POSIX), The Open Group Base
|
||
|
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
|
||
|
Electrical and Electronics Engineers, Inc and The Open Group. In the
|
||
|
event of any discrepancy between this version and the original IEEE and
|
||
|
The Open Group Standard, the original IEEE and The Open Group Standard
|
||
|
is the referee document. The original Standard can be obtained online at
|
||
|
http://www.opengroup.org/unix/online.html .
|