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Diffstat (limited to 'lib/libc/sys/recv.2')
| -rw-r--r-- | lib/libc/sys/recv.2 | 291 |
1 files changed, 0 insertions, 291 deletions
diff --git a/lib/libc/sys/recv.2 b/lib/libc/sys/recv.2 deleted file mode 100644 index fdf02e3..0000000 --- a/lib/libc/sys/recv.2 +++ /dev/null @@ -1,291 +0,0 @@ -.\" Copyright (c) 1983, 1990, 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. -.\" -.\" @(#)recv.2 8.3 (Berkeley) 2/21/94 -.\" -.Dd February 21, 1994 -.Dt RECV 2 -.Os BSD 4.3r -.Sh NAME -.Nm recv , -.Nm recvfrom , -.Nm recvmsg -.Nd receive a message from a socket -.Sh SYNOPSIS -.Fd #include <sys/types.h> -.Fd #include <sys/socket.h> -.Ft ssize_t -.Fn recv "int s" "void *buf" "size_t len" "int flags" -.Ft ssize_t -.Fn recvfrom "int s" "void *buf" "size_t len" "int flags" "struct sockaddr *from" "int *fromlen" -.Ft ssize_t -.Fn recvmsg "int s" "struct msghdr *msg" "int flags" -.Sh DESCRIPTION -.Fn Recvfrom -and -.Fn recvmsg -are used to receive messages from a socket, -and may be used to receive data on a socket whether or not -it is connection-oriented. -.Pp -If -.Fa from -is non-nil, and the socket is not connection-oriented, -the source address of the message is filled in. -.Fa Fromlen -is a value-result parameter, initialized to the size of -the buffer associated with -.Fa from , -and modified on return to indicate the actual size of the -address stored there. -.Pp -The -.Fn recv -call is normally used only on a -.Em connected -socket (see -.Xr connect 2 ) -and is identical to -.Fn recvfrom -with a nil -.Fa from -parameter. -As it is redundant, it may not be supported in future releases. -.Pp -All three routines return the length of the message on successful -completion. -If a message is too long to fit in the supplied buffer, -excess bytes may be discarded depending on the type of socket -the message is received from (see -.Xr socket 2 ) . -.Pp -If no messages are available at the socket, the -receive call waits for a message to arrive, unless -the socket is nonblocking (see -.Xr fcntl 2 ) -in which case the value --1 is returned and the external variable -.Va errno -set to -.Er EAGAIN . -The receive calls normally return any data available, -up to the requested amount, -rather than waiting for receipt of the full amount requested; -this behavior is affected by the socket-level options -.Dv SO_RCVLOWAT -and -.Dv SO_RCVTIMEO -described in -.Xr getsockopt 2 . -.Pp -The -.Xr select 2 -call may be used to determine when more data arrive. -.Pp -The -.Fa flags -argument to a recv call is formed by -.Em or Ap ing -one or more of the values: -.Bl -column MSG_WAITALL -offset indent -.It Dv MSG_OOB Ta process out-of-band data -.It Dv MSG_PEEK Ta peek at incoming message -.It Dv MSG_WAITALL Ta wait for full request or error -.El -The -.Dv MSG_OOB -flag requests receipt of out-of-band data -that would not be received in the normal data stream. -Some protocols place expedited data at the head of the normal -data queue, and thus this flag cannot be used with such protocols. -The MSG_PEEK flag causes the receive operation to return data -from the beginning of the receive queue without removing that -data from the queue. -Thus, a subsequent receive call will return the same data. -The MSG_WAITALL flag requests that the operation block until -the full request is satisfied. -However, the call may still return less data than requested -if a signal is caught, an error or disconnect occurs, -or the next data to be received is of a different type than that returned. -.Pp -The -.Fn recvmsg -call uses a -.Fa msghdr -structure to minimize the number of directly supplied parameters. -This structure has the following form, as defined in -.Ao Pa sys/socket.h Ac : -.Pp -.Bd -literal -struct msghdr { - caddr_t msg_name; /* optional address */ - u_int msg_namelen; /* size of address */ - struct iovec *msg_iov; /* scatter/gather array */ - u_int msg_iovlen; /* # elements in msg_iov */ - caddr_t msg_control; /* ancillary data, see below */ - u_int msg_controllen; /* ancillary data buffer len */ - int msg_flags; /* flags on received message */ -}; -.Ed -.Pp -Here -.Fa msg_name -and -.Fa msg_namelen -specify the destination address if the socket is unconnected; -.Fa msg_name -may be given as a null pointer if no names are desired or required. -.Fa Msg_iov -and -.Fa msg_iovlen -describe scatter gather locations, as discussed in -.Xr read 2 . -.Fa Msg_control , -which has length -.Fa msg_controllen , -points to a buffer for other protocol control related messages -or other miscellaneous ancillary data. -The messages are of the form: -.Bd -literal -struct cmsghdr { - u_int cmsg_len; /* data byte count, including hdr */ - int cmsg_level; /* originating protocol */ - int cmsg_type; /* protocol-specific type */ -/* followed by - u_char cmsg_data[]; */ -}; -.Ed -As an example, one could use this to learn of changes in the data-stream -in XNS/SPP, or in ISO, to obtain user-connection-request data by requesting -a recvmsg with no data buffer provided immediately after an -.Fn accept -call. -.Pp -Open file descriptors are now passed as ancillary data for -.Dv AF_UNIX -domain sockets, with -.Fa cmsg_level -set to -.Dv SOL_SOCKET -and -.Fa cmsg_type -set to -.Dv SCM_RIGHTS . -.Pp -Process credentials can also be passed as ancillary data for -.Dv AF_UNIX -domain sockets using a -.Fa cmsg_type -of -.Dv SCM_CREDS. -In this case, -.Fa cmsg_data -should be a structure of type -.Fa cmsgcred , -which is defined in -.Ao Pa sys/socket.h Ac -as follows: -.Pp -.Bd -literal -struct cmsgcred { - pid_t cmcred_pid; /* PID of sending process */ - uid_t cmcred_uid; /* real UID of sending process */ - uid_t cmcred_euid; /* effective UID of sending process */ - gid_t cmcred_gid; /* real GID of sending process */ - short cmcred_ngroups; /* number or groups */ - gid_t cmcred_groups[CMGROUP_MAX]; /* groups */ -}; -.Ed -.Pp -The kernel will fill in the credential information of the sending process -and deliver it to the receiver. -.Pp -The -.Fa msg_flags -field is set on return according to the message received. -.Dv MSG_EOR -indicates end-of-record; -the data returned completed a record (generally used with sockets of type -.Dv SOCK_SEQPACKET ) . -.Dv MSG_TRUNC -indicates that -the trailing portion of a datagram was discarded because the datagram -was larger than the buffer supplied. -.Dv MSG_CTRUNC -indicates that some -control data were discarded due to lack of space in the buffer -for ancillary data. -.Dv MSG_OOB -is returned to indicate that expedited or out-of-band data were received. -.Pp -.Sh RETURN VALUES -These calls return the number of bytes received, or -1 -if an error occurred. -.Sh ERRORS -The calls fail if: -.Bl -tag -width ENOTCONNAA -.It Bq Er EBADF -The argument -.Fa s -is an invalid descriptor. -.It Bq Er ENOTCONN -The socket is associated with a connection-oriented protocol -and has not been connected (see -.Xr connect 2 -and -.Xr accept 2 ). -.It Bq Er ENOTSOCK -The argument -.Fa s -does not refer to a socket. -.It Bq Er EAGAIN -The socket is marked non-blocking, and the receive operation -would block, or -a receive timeout had been set, -and the timeout expired before data were received. -.It Bq Er EINTR -The receive was interrupted by delivery of a signal before -any data were available. -.It Bq Er EFAULT -The receive buffer pointer(s) point outside the process's -address space. -.El -.Sh SEE ALSO -.Xr fcntl 2 , -.Xr getsockopt 2 , -.Xr read 2 , -.Xr select 2 , -.Xr socket 2 -.Sh HISTORY -The -.Fn recv -function call appeared in -.Bx 4.2 . |
