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Diffstat (limited to 'lib/libc/sys/send.2')
| -rw-r--r-- | lib/libc/sys/send.2 | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/lib/libc/sys/send.2 b/lib/libc/sys/send.2 new file mode 100644 index 0000000..327307c --- /dev/null +++ b/lib/libc/sys/send.2 @@ -0,0 +1,198 @@ +.\" Copyright (c) 1983, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" From: @(#)send.2 8.2 (Berkeley) 2/21/94 +.\" $FreeBSD$ +.\" +.Dd February 15, 1995 +.Dt SEND 2 +.Os BSD 4.2 +.Sh NAME +.Nm send , +.Nm sendto , +.Nm sendmsg +.Nd send a message from a socket +.Sh SYNOPSIS +.Fd #include <sys/types.h> +.Fd #include <sys/socket.h> +.Ft ssize_t +.Fn send "int s" "const void *msg" "size_t len" "int flags" +.Ft ssize_t +.Fn sendto "int s" "const void *msg" "size_t len" "int flags" "const struct sockaddr *to" "socklen_t tolen" +.Ft ssize_t +.Fn sendmsg "int s" "const struct msghdr *msg" "int flags" +.Sh DESCRIPTION +.Fn Send , +.Fn sendto , +and +.Fn sendmsg +are used to transmit a message to another socket. +.Fn Send +may be used only when the socket is in a +.Em connected +state, while +.Fn sendto +and +.Fn sendmsg +may be used at any time. +.Pp +The address of the target is given by +.Fa to +with +.Fa tolen +specifying its size. +The length of the message is given by +.Fa len . +If the message is too long to pass atomically through the +underlying protocol, the error +.Er EMSGSIZE +is returned, and +the message is not transmitted. +.Pp +No indication of failure to deliver is implicit in a +.Fn send . +Locally detected errors are indicated by a return value of -1. +.Pp +If no messages space is available at the socket to hold +the message to be transmitted, then +.Fn send +normally blocks, unless the socket has been placed in +non-blocking I/O mode. +The +.Xr select 2 +call may be used to determine when it is possible to +send more data. +.Pp +The +.Fa flags +parameter may include one or more of the following: +.Bd -literal +#define MSG_OOB 0x1 /* process out-of-band data */ +#define MSG_PEEK 0x2 /* peek at incoming message */ +#define MSG_DONTROUTE 0x4 /* bypass routing, use direct interface */ +#define MSG_EOR 0x8 /* data completes record */ +#define MSG_EOF 0x100 /* data completes transaction */ +.Ed +.Pp +The flag +.Dv MSG_OOB +is used to send +.Dq out-of-band +data on sockets that support this notion (e.g. +.Dv SOCK_STREAM ) ; +the underlying protocol must also support +.Dq out-of-band +data. +.Dv MSG_EOR +is used to indicate a record mark for protocols which support the +concept. +.Dv MSG_EOF +requests that the sender side of a socket be shut down, and that an +appropriate indication be sent at the end of the specified data; +this flag is only implemented for +.Dv SOCK_STREAM +sockets in the +.Dv PF_INET +protocol family, and is used to implement Transaction +.Tn TCP +(see +.Xr ttcp 4 ) . +.Dv MSG_DONTROUTE +is usually used only by diagnostic or routing programs. +.Pp +See +.Xr recv 2 +for a description of the +.Fa msghdr +structure. +.Sh RETURN VALUES +The call returns the number of characters sent, or -1 +if an error occurred. +.Sh ERRORS +.Fn Send , +.Fn sendto , +and +.Fn sendmsg +fail if: +.Bl -tag -width Er +.It Bq Er EBADF +An invalid descriptor was specified. +.It Bq Er EACCES +The destination address is a broadcast address, and +.Dv SO_BROADCAST +has not been set on the socket. +.It Bq Er ENOTSOCK +The argument +.Fa s +is not a socket. +.It Bq Er EFAULT +An invalid user space address was specified for a parameter. +.It Bq Er EMSGSIZE +The socket requires that message be sent atomically, +and the size of the message to be sent made this impossible. +.It Bq Er EAGAIN +The socket is marked non-blocking and the requested operation +would block. +.It Bq Er ENOBUFS +The system was unable to allocate an internal buffer. +The operation may succeed when buffers become available. +.It Bq Er ENOBUFS +The output queue for a network interface was full. +This generally indicates that the interface has stopped sending, +but may be caused by transient congestion. +.It Bq Er EHOSTUNREACH +The remote host was unreachable. +.El +.Sh BUGS +Because +.Fn sendmsg +doesn't necessarily block until the data has been transferred, it +is possible to transfer an open file descriptor across an +.Dv AF_UNIX +domain socket +.Pq see Xr recv 2 , +then +.Fn close +it before it has actually been sent, the result being that the receiver +gets a closed file descriptor. It is left to the application to +implement an acknowlegment mechanism to prevent this from happening. +.Sh SEE ALSO +.Xr fcntl 2 , +.Xr getsockopt 2 , +.Xr recv 2 , +.Xr select 2 , +.Xr socket 2 , +.Xr write 2 +.Sh HISTORY +The +.Fn send +function call appeared in +.Bx 4.2 . |
