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4b7ba9a4c5
On UNIX if dup2(newfd) was a ZipOS file descriptor, then its resources weren't being released, and the newly created file descriptor would be mistaken for ZipOS due to its memory not being cleared. On Windows, an issue also existed relating to newfd resources not being released.
87 lines
4.5 KiB
C
87 lines
4.5 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/state.internal.h"
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#include "libc/calls/syscall-nt.internal.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/intrin/weaken.h"
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#include "libc/runtime/zipos.internal.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Duplicates file descriptor/handle.
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*
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* The `O_CLOEXEC` flag shall be cleared from the resulting file
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* descriptor; see dup3() to preserve it.
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*
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* One use case for duplicating file descriptors is to be able to
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* reassign an open()'d file or pipe() to the stdio of an executed
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* subprocess. On Windows, in order for this to work, the subprocess
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* needs to be a Cosmopolitan program that has socket() linked.
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*
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* Only small programs should duplicate sockets. That's because this
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* implementation uses DuplicateHandle() on Windows, which Microsoft
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* says might cause its resources to leak internally. Thus it likely
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* isn't a good idea to design a server that does it a lot and lives
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* a long time, without contributing a patch to this implementation.
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*
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* @param oldfd isn't closed afterwards
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* @param newfd if already assigned, is silently closed beforehand;
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* unless it's equal to oldfd, in which case dup2() is a no-op
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* @param flags may have O_CLOEXEC which is needed to preserve the
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* close-on-execve() state after file descriptor duplication
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* @return newfd on success, or -1 w/ errno
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* @raise ENOTSUP if `oldfd` is a zip file descriptor
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* @raise EPERM if pledge() is in play without stdio
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* @raise EINVAL if `flags` has unsupported bits
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* @raise EINTR if a signal handler was called
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* @raise EBADF is `newfd` negative or too big
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* @raise EINVAL if `newfd` equals oldfd
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* @raise EBADF is `oldfd` isn't open
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* @see dup(), dup2()
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*/
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int dup3(int oldfd, int newfd, int flags) {
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int rc;
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// helps guarantee stderr log gets duplicated before user closes
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if (_weaken(kloghandle)) _weaken(kloghandle)();
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if (oldfd == newfd || (flags & ~O_CLOEXEC)) {
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rc = einval(); // NetBSD doesn't do this
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} else if (oldfd < 0 || newfd < 0) {
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rc = ebadf();
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} else if (__isfdkind(oldfd, kFdZip)) {
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rc = enotsup();
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} else if (!IsWindows()) {
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rc = sys_dup3(oldfd, newfd, flags);
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if (rc != -1 && __isfdkind(newfd, kFdZip) && !__vforked) {
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_weaken(__zipos_free)(
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(struct ZiposHandle *)(intptr_t)g_fds.p[newfd].handle);
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bzero(g_fds.p + newfd, sizeof(*g_fds.p));
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}
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} else {
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rc = sys_dup_nt(oldfd, newfd, flags, -1);
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}
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STRACE("dup3(%d, %d, %d) → %d% m", oldfd, newfd, flags, rc);
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return rc;
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}
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