mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 11:37:35 +00:00
18bb5888e1
- Remove PAGESIZE constant
- Fix realloc() documentation
- Fix ttyname_r() error reporting
- Make forking more reliable on Windows
- Make execvp() a few microseconds faster
- Make system() a few microseconds faster
- Tighten up the socket-related magic numbers
- Loosen restrictions on mmap() offset alignment
- Improve GetProgramExecutableName() with getenv("_")
- Use mkstemp() as basis for mktemp(), tmpfile(), tmpfd()
- Fix flakes in pthread_cancel_test, unix_test, fork_test
- Fix recently introduced futex stack overflow regression
- Let sockets be passed as stdio to subprocesses on Windows
- Improve security of bind() on Windows w/ SO_EXCLUSIVEADDRUSE
63 lines
3.3 KiB
C
63 lines
3.3 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/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/strace.internal.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Duplicates file descriptor.
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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 fd remains open afterwards
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* @return some arbitrary new number for fd
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* @raise EPERM if pledge() is in play without stdio
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* @raise ENOTSUP if `fd` is a zip file descriptor
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* @raise EBADF if `fd` is negative or not open
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* @asyncsignalsafe
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* @vforksafe
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*/
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int dup(int fd) {
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int rc;
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if (__isfdkind(fd, kFdZip)) {
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rc = enotsup();
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} else if (!IsWindows()) {
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rc = sys_dup(fd);
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} else {
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rc = sys_dup_nt(fd, -1, 0, -1);
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}
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STRACE("%s(%d) → %d% m", "dup", fd, rc);
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return rc;
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}
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