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Diffstat (limited to 'static/openbsd/man2/accept.2')
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diff --git a/static/openbsd/man2/accept.2 b/static/openbsd/man2/accept.2 new file mode 100644 index 00000000..5f2572a0 --- /dev/null +++ b/static/openbsd/man2/accept.2 @@ -0,0 +1,230 @@ +.\" $OpenBSD: accept.2,v 1.31 2025/08/04 04:59:31 guenther Exp $ +.\" $NetBSD: accept.2,v 1.7 1996/01/31 20:14:42 mycroft Exp $ +.\" +.\" 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. 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. +.\" +.\" @(#)accept.2 8.2 (Berkeley) 12/11/93 +.\" +.Dd $Mdocdate: August 4 2025 $ +.Dt ACCEPT 2 +.Os +.Sh NAME +.Nm accept , +.Nm accept4 +.Nd accept a connection on a socket +.Sh SYNOPSIS +.In sys/socket.h +.Ft int +.Fn accept "int s" "struct sockaddr *addr" "socklen_t *addrlen" +.Ft int +.Fn accept4 "int s" "struct sockaddr *addr" "socklen_t *addrlen" "int flags" +.Sh DESCRIPTION +The argument +.Fa s +is a socket that has been created with +.Xr socket 2 , +bound to an address with +.Xr bind 2 , +and is listening for connections after a +.Xr listen 2 . +The +.Fn accept +call extracts the first connection request on the queue of pending +connections, creates a new socket with the same non-blocking I/O mode as +.Fa s , +and allocates a new file descriptor for the socket with the +close-on-exec and close-on-fork flags clear. +.Pp +The +.Fn accept4 +system call is similar, however the non-blocking I/O mode, +close-on-exec flag, +and close-on-fork flag on the new file descriptor are +determined by the +.Dv SOCK_NONBLOCK , SOCK_CLOEXEC , +and +.Dv SOCK_CLOFORK +flags, respectively, in the +.Fa flags +argument. +.Pp +If no pending connections are present on the queue, +and the socket is not marked as non-blocking, +.Fn accept +blocks the caller until a connection is present. +If the socket is marked non-blocking and no pending +connections are present on the queue, +.Fn accept +returns an error as described below. +The accepted socket may not be used to accept more connections. +The original socket +.Fa s +remains open. +.Pp +The argument +.Fa addr +is a result parameter that is filled in with the address of the connecting +entity as known to the communications layer. +The exact format of the +.Fa addr +parameter is determined by the domain in which the communication +is occurring. +The structure +.Vt sockaddr_storage +exists for greater portability. +It is large enough to hold any of the types that may be returned in the +.Fa addr +parameter. +.Pp +The +.Fa addrlen +is a value-result parameter; it should initially contain the +amount of space pointed to by +.Fa addr ; +on return it will contain the actual length (in bytes) of the +address returned. +If +.Fa addrlen +does not point to enough space to hold the entire socket address, the +result will be truncated to the initial value of +.Fa addrlen +(in bytes). +This call is used with connection-based socket types, currently with +.Dv SOCK_STREAM . +.Pp +It is possible to +.Xr select 2 +or +.Xr poll 2 +a socket for the purposes of doing an +.Fn accept +by selecting it for read. +.Sh RETURN VALUES +If successful, +.Fn accept +and +.Fn accept4 +return a non-negative integer, the accepted socket file descriptor. +Otherwise, a value of \-1 is returned and +.Va errno +is set to indicate the error. +.Sh EXAMPLES +The following code uses struct +.Vt sockaddr_storage +to allocate enough space for the returned address: +.Bd -literal -offset indent +#include <sys/types.h> +#include <sys/socket.h> + +struct sockaddr_storage addr; +socklen_t len = sizeof(addr); +int retcode; + +retcode = accept(s, (struct sockaddr *)&addr, &len); +if (retcode == -1) + err(1, "accept"); +.Ed +.Sh ERRORS +.Fn accept +and +.Fn accept4 +will fail if: +.Bl -tag -width Er +.It Bq Er EBADF +The descriptor is invalid. +.It Bq Er ENOTSOCK +The descriptor doesn't reference a socket. +.It Bq Er EOPNOTSUPP +The referenced socket is not of type +.Dv SOCK_STREAM . +.It Bq Er EINTR +A signal was caught before a connection arrived. +.It Bq Er EINVAL +The referenced socket is not listening for connections (that is, +.Xr listen 2 +has not yet been called). +.It Bq Er EFAULT +The +.Fa addr +or +.Fa addrlen +parameter is not in a valid part of the process address space. +.It Bq Er EWOULDBLOCK +The socket is marked non-blocking and no connections +are present to be accepted. +.It Bq Er EMFILE +The per-process descriptor table is full. +.It Bq Er ENFILE +The system file table is full. +.It Bq Er ECONNABORTED +A connection has been aborted. +.El +.Pp +In addition, +.Fn accept4 +will fail if +.Bl -tag -width Er +.It Bq Er EINVAL +.Fa flags +is invalid. +.El +.Sh SEE ALSO +.Xr bind 2 , +.Xr connect 2 , +.Xr listen 2 , +.Xr poll 2 , +.Xr select 2 , +.Xr socket 2 +.Sh STANDARDS +The +.Fn accept +and +.Fn accept4 +functions conform to +.St -p1003.1-2024 . +.Sh HISTORY +The +.Fn accept +system call first appeared in +.Bx 4.1c +and +.Fn accept4 +in +.Ox 5.7 . +.Sh CAVEATS +When +.Er EMFILE +or +.Er ENFILE +is returned, +new connections are neither dequeued nor discarded. +Thus considerable care is required in +.Xr select 2 +and +.Xr poll 2 +loops. |