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214 lines
7 KiB
C++
214 lines
7 KiB
C++
#ifndef RBIMPL_INTERN_SELECT_LARGESIZE_H /*-*-C++-*-vi:se ft=cpp:*/
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#define RBIMPL_INTERN_SELECT_LARGESIZE_H
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/**
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* @file
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* @author Ruby developers <ruby-core@ruby-lang.org>
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* @copyright This file is a part of the programming language Ruby.
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* Permission is hereby granted, to either redistribute and/or
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* modify this file, provided that the conditions mentioned in the
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* file COPYING are met. Consult the file for details.
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* @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
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* implementation details. Don't take them as canon. They could
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* rapidly appear then vanish. The name (path) of this header file
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* is also an implementation detail. Do not expect it to persist
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* at the place it is now. Developers are free to move it anywhere
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* anytime at will.
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* @note To ruby-core: remember that this header can be possibly
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* recursively included from extension libraries written in C++.
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* Do not expect for instance `__VA_ARGS__` is always available.
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* We assume C99 for ruby itself but we don't assume languages of
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* extension libraries. They could be written in C++98.
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* @brief Public APIs to provide ::rb_fd_select().
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*
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* Several Unix platforms support file descriptors bigger than FD_SETSIZE in
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* `select(2)` system call.
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*
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* - Linux 2.2.12 (?)
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*
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* - NetBSD 1.2 (src/sys/kern/sys_generic.c:1.25)
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* `select(2)` documents how to allocate fd_set dynamically.
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* http://netbsd.gw.com/cgi-bin/man-cgi?select++NetBSD-4.0
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*
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* - FreeBSD 2.2 (src/sys/kern/sys_generic.c:1.19)
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*
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* - OpenBSD 2.0 (src/sys/kern/sys_generic.c:1.4)
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* `select(2)` documents how to allocate fd_set dynamically.
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* http://www.openbsd.org/cgi-bin/man.cgi?query=select&manpath=OpenBSD+4.4
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*
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* - Solaris 8 has `select_large_fdset`
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*
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* - Mac OS X 10.7 (Lion)
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* `select(2)` returns `EINVAL` if `nfds` is greater than `FD_SET_SIZE` and
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* `_DARWIN_UNLIMITED_SELECT` (or `_DARWIN_C_SOURCE`) isn't defined.
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* http://developer.apple.com/library/mac/#releasenotes/Darwin/SymbolVariantsRelNotes/_index.html
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*
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* When `fd_set` is not big enough to hold big file descriptors, it should be
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* allocated dynamically. Note that this assumes `fd_set` is structured as
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* bitmap.
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*
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* `rb_fd_init` allocates the memory.
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* `rb_fd_term` frees the memory.
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* `rb_fd_set` may re-allocate bitmap.
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*
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* So `rb_fd_set` doesn't reject file descriptors bigger than `FD_SETSIZE`.
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*/
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#include "ruby/internal/attr/nonnull.h"
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#include "ruby/internal/attr/pure.h"
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#include "ruby/internal/dllexport.h"
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/**@cond INTERNAL_MACRO */
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#define rb_fd_ptr rb_fd_ptr
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#define rb_fd_max rb_fd_max
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/** @endcond */
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struct timeval;
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/**
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* The data structure which wraps the fd_set bitmap used by select(2). This
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* allows Ruby to use FD sets larger than that allowed by historic limitations
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* on modern platforms.
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*/
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typedef struct {
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int maxfd; /**< Maximum allowed number of FDs. */
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fd_set *fdset; /**< File descriptors buffer */
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} rb_fdset_t;
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RBIMPL_SYMBOL_EXPORT_BEGIN()
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RBIMPL_ATTR_NONNULL(())
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/**
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* (Re-)initialises a fdset. One must be initialised before other `rb_fd_*`
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* operations. Analogous to calling `malloc(3)` to allocate an `fd_set`.
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*
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* @param[out] f An fdset to squash.
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* @post `f` holds no file descriptors.
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*/
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void rb_fd_init(rb_fdset_t *f);
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RBIMPL_ATTR_NONNULL(())
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/**
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* Destroys the ::rb_fdset_t, releasing any memory and resources it used. It
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* must be reinitialised using rb_fd_init() before future use. Analogous to
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* calling `free(3)` to release memory for an `fd_set`.
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*
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* @param[out] f An fdset to squash.
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* @post `f` holds no file descriptors.
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*/
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void rb_fd_term(rb_fdset_t *f);
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RBIMPL_ATTR_NONNULL(())
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/**
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* Wipes out the current set of FDs.
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*
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* @param[out] f The fdset to clear.
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* @post `f` has no FDs.
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*/
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void rb_fd_zero(rb_fdset_t *f);
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RBIMPL_ATTR_NONNULL(())
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/**
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* Sets an fd to a fdset.
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*
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* @param[in] fd A file descriptor.
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* @param[out] f Target fdset.
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* @post `f` holds `fd`.
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*/
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void rb_fd_set(int fd, rb_fdset_t *f);
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RBIMPL_ATTR_NONNULL(())
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/**
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* Releases a specific FD from the given fdset.
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*
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* @param[in] fd Target FD.
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* @param[out] f The fdset that holds `fd`.
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* @post `f` doesn't hold n.
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*/
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void rb_fd_clr(int fd, rb_fdset_t *f);
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RBIMPL_ATTR_NONNULL(())
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RBIMPL_ATTR_PURE()
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/**
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* Queries if the given FD is in the given set.
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*
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* @param[in] fd Target FD.
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* @param[in] f The fdset to scan.
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* @retval 1 Yes there is.
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* @retval 0 No there isn't.
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* @see http://www.freebsd.org/cgi/query-pr.cgi?pr=91421
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*/
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int rb_fd_isset(int fd, const rb_fdset_t *f);
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/**
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* Destructively overwrites an fdset with another.
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*
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* @param[out] dst Target fdset.
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* @param[in] src Source fdset.
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* @param[in] max Maximum number of file descriptors to copy.
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* @post `dst` is a copy of `src`.
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*/
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void rb_fd_copy(rb_fdset_t *dst, const fd_set *src, int max);
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/**
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* Identical to rb_fd_copy(), except it copies unlimited number of file
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* descriptors.
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*
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* @param[out] dst Target fdset.
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* @param[in] src Source fdset.
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* @post `dst` is a copy of `src`.
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*/
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void rb_fd_dup(rb_fdset_t *dst, const rb_fdset_t *src);
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/**
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* Waits for multiple file descriptors at once.
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*
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* @param[in] nfds Max FD in everything passed, plus one.
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* @param[in,out] rfds Set of FDs to wait for reads.
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* @param[in,out] wfds Set of FDs to wait for writes.
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* @param[in,out] efds Set of FDs to wait for OOBs.
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* @param[in,out] timeout Max blocking duration.
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* @retval -1 Failed, errno set.
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* @retval 0 Timeout exceeded.
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* @retval otherwise Total number of file descriptors returned.
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* @post `rfds` contains readable FDs.
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* @post `wfds` contains writable FDs.
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* @post `efds` contains exceptional FDs.
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* @post `timeout` is the time left.
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* @note All pointers are allowed to be null pointers.
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*/
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int rb_fd_select(int nfds, rb_fdset_t *rfds, rb_fdset_t *wfds, rb_fdset_t *efds, struct timeval *timeout);
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RBIMPL_SYMBOL_EXPORT_END()
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RBIMPL_ATTR_NONNULL(())
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RBIMPL_ATTR_PURE()
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/**
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* Raw pointer to `fd_set`.
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*
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* @param[in] f Target fdset.
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* @retval NULL `f` is already terminated by rb_fd_term().
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* @retval otherwise Underlying fd_set.
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*
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* @internal
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*
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* Extension library must not touch raw pointers. It was a bad idea to let
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* them use it.
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*/
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static inline fd_set *
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rb_fd_ptr(const rb_fdset_t *f)
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{
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return f->fdset;
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}
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RBIMPL_ATTR_NONNULL(())
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RBIMPL_ATTR_PURE()
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/**
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* It seems this function has no use. Maybe just remove?
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*
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* @param[in] f A set.
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* @return Number of file descriptors stored.
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*/
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static inline int
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rb_fd_max(const rb_fdset_t *f)
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{
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return f->maxfd;
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}
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#endif /* RBIMPL_INTERN_SELECT_LARGESIZE_H */
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