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Diffstat (limited to 'lib/libc/sys/select.2')
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diff --git a/lib/libc/sys/select.2 b/lib/libc/sys/select.2 deleted file mode 100644 index f8749cab4283..000000000000 --- a/lib/libc/sys/select.2 +++ /dev/null @@ -1,227 +0,0 @@ -.\" 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. 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. -.\" -.\" @(#)select.2 8.2 (Berkeley) 3/25/94 -.\" -.Dd June 25, 2020 -.Dt SELECT 2 -.Os -.Sh NAME -.Nm select -.Nd synchronous I/O multiplexing -.Sh LIBRARY -.Lb libc -.Sh SYNOPSIS -.In sys/select.h -.Ft int -.Fn select "int nfds" "fd_set *readfds" "fd_set *writefds" "fd_set *exceptfds" "struct timeval *timeout" -.Fn FD_SET fd &fdset -.Fn FD_CLR fd &fdset -.Fn FD_ISSET fd &fdset -.Fn FD_ZERO &fdset -.Sh DESCRIPTION -The -.Fn select -system call -examines the I/O descriptor sets whose addresses are passed in -.Fa readfds , -.Fa writefds , -and -.Fa exceptfds -to see if some of their descriptors -are ready for reading, are ready for writing, or have an exceptional -condition pending, respectively. -The only exceptional condition detectable is out-of-band -data received on a socket. -The first -.Fa nfds -descriptors are checked in each set; -i.e., the descriptors from 0 through -.Fa nfds Ns No -1 -in the descriptor sets are examined. -On return, -.Fn select -replaces the given descriptor sets -with subsets consisting of those descriptors that are ready -for the requested operation. -The -.Fn select -system call -returns the total number of ready descriptors in all the sets. -.Pp -The descriptor sets are stored as bit fields in arrays of integers. -The following macros are provided for manipulating such descriptor sets: -.Fn FD_ZERO &fdset -initializes a descriptor set -.Fa fdset -to the null set. -.Fn FD_SET fd &fdset -includes a particular descriptor -.Fa fd -in -.Fa fdset . -.Fn FD_CLR fd &fdset -removes -.Fa fd -from -.Fa fdset . -.Fn FD_ISSET fd &fdset -is non-zero if -.Fa fd -is a member of -.Fa fdset , -zero otherwise. -The behavior of these macros is undefined if -a descriptor value is less than zero or greater than or equal to -.Dv FD_SETSIZE , -which is normally at least equal -to the maximum number of descriptors supported by the system. -.Pp -If -.Fa timeout -is not a null pointer, it specifies the maximum interval to wait for the -selection to complete. -System activity can lengthen the interval by -an indeterminate amount. -.Pp -If -.Fa timeout -is a null pointer, the select blocks indefinitely. -.Pp -To effect a poll, the -.Fa timeout -argument should not be a null pointer, -but it should point to a zero-valued timeval structure. -.Pp -Any of -.Fa readfds , -.Fa writefds , -and -.Fa exceptfds -may be given as null pointers if no descriptors are of interest. -.Sh RETURN VALUES -The -.Fn select -system call -returns the number of ready descriptors that are contained in -the descriptor sets, -or -1 if an error occurred. -If the time limit expires, -.Fn select -returns 0. -If -.Fn select -returns with an error, -including one due to an interrupted system call, -the descriptor sets will be unmodified. -.Sh ERRORS -An error return from -.Fn select -indicates: -.Bl -tag -width Er -.It Bq Er EBADF -One of the descriptor sets specified an invalid descriptor. -.It Bq Er EFAULT -One of the arguments -.Fa readfds , writefds , exceptfds , -or -.Fa timeout -points to an invalid address. -.It Bq Er EINTR -A signal was delivered before the time limit expired and -before any of the selected events occurred. -.It Bq Er EINVAL -The specified time limit is invalid. -One of its components is -negative or too large. -.It Bq Er EINVAL -The -.Fa nfds -argument -was invalid. -.El -.Sh SEE ALSO -.Xr accept 2 , -.Xr connect 2 , -.Xr getdtablesize 2 , -.Xr gettimeofday 2 , -.Xr kqueue 2 , -.Xr poll 2 , -.Xr pselect 2 , -.Xr read 2 , -.Xr recv 2 , -.Xr send 2 , -.Xr write 2 , -.Xr clocks 7 -.Sh NOTES -The default size of -.Dv FD_SETSIZE -is currently 1024. -In order to accommodate programs which might potentially -use a larger number of open files with -.Fn select , -it is possible -to increase this size by having the program define -.Dv FD_SETSIZE -before the inclusion of any header which includes -.In sys/types.h . -.Pp -If -.Fa nfds -is greater than the number of open files, -.Fn select -is not guaranteed to examine the unused file descriptors. -For historical -reasons, -.Fn select -will always examine the first 256 descriptors. -.Sh STANDARDS -The -.Fn select -system call and -.Fn FD_CLR , -.Fn FD_ISSET , -.Fn FD_SET , -and -.Fn FD_ZERO -macros conform with -.St -p1003.1-2001 . -.Sh HISTORY -The -.Fn select -system call appeared in -.Bx 4.2 . -.Sh BUGS -.St -susv2 -allows systems to modify the original timeout in place. -Thus, it is unwise to assume that the timeout value will be unmodified -by the -.Fn select -system call. -.Fx -does not modify the return value, which can cause problems for applications -ported from other systems. |