cosmopolitan/libc/calls/dup3.c

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
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Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
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*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
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#include "libc/calls/syscall-nt.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
#include "libc/intrin/strace.internal.h"
#include "libc/sysv/consts/o.h"
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#include "libc/sysv/errfuns.h"
/**
* Duplicates file descriptor/handle.
*
* On Windows, we can't guarantee the desired file descriptor is used.
* We can however remap the standard handles (non-atomically) if their
* symbolic names are used.
*
* @param oldfd isn't closed afterwards
* @param newfd if already assigned, is silently closed beforehand;
* unless it's equal to oldfd, in which case dup2() is a no-op
* @param flags may have O_CLOEXEC which is needed to preserve the
* close-on-execve() state after file descriptor duplication
* @return newfd on success, or -1 w/ errno
* @raise ENOTSUP if `oldfd` is a zip file descriptor
* @raise EPERM if pledge() is in play without stdio
* @raise EINVAL if `flags` has unsupported bits
* @raise EINTR if a signal handler was called
* @raise EBADF is `newfd` negative or too big
* @raise EINVAL if `newfd` equals oldfd
* @raise EBADF is `oldfd` isn't open
* @see dup(), dup2()
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*/
int dup3(int oldfd, int newfd, int flags) {
int rc;
if (oldfd == newfd || (flags & ~O_CLOEXEC)) {
rc = einval(); // NetBSD doesn't do this
} else if (oldfd < 0 || newfd < 0) {
rc = ebadf();
} else if (__isfdkind(oldfd, kFdZip)) {
rc = enotsup();
} else if (!IsWindows()) {
rc = sys_dup3(oldfd, newfd, flags);
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} else {
rc = sys_dup_nt(oldfd, newfd, flags, -1);
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}
STRACE("dup3(%d, %d, %d) → %d% m", oldfd, newfd, flags, rc);
return rc;
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}