cosmopolitan/libc/calls/dup3.c
Justine Tunney ad97775370
Improve system call documentation
This change also introduces partial faccessat() support for zipos and
makes some slight breaking changes in errno results. close() is fixed
to use `EBADF` rather than `EINVAL` and we're now using `ENOTSUP` not
`EOPNOTSUPP` to indicate that zipos doesn't support a system call yet
2022-10-02 09:15:46 -07:00

65 lines
3.4 KiB
C

/*-*- 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 │
│ │
│ 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. │
│ │
│ 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. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/syscall-nt.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/intrin/strace.internal.h"
#include "libc/sysv/consts/o.h"
#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()
*/
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);
} else {
rc = sys_dup_nt(oldfd, newfd, flags, -1);
}
STRACE("dup3(%d, %d, %d) → %d% m", oldfd, newfd, flags, rc);
return rc;
}