mirror of
https://github.com/jart/cosmopolitan.git
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75 lines
3.5 KiB
C
75 lines
3.5 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/strace.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/weaken.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/zipos/zipos.internal.h"
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/**
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* Does things with file descriptor, via re-imagined hourglass api, e.g.
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*
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* CHECK_NE(-1, fcntl(fd, F_SETFD, FD_CLOEXEC));
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*
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* This function lets you duplicate file descriptors without running
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* into an edge case where they take over stdio handles:
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*
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* CHECK_GE((newfd = fcntl(oldfd, F_DUPFD, 3)), 3);
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* CHECK_GE((newfd = fcntl(oldfd, F_DUPFD_CLOEXEC, 3)), 3);
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*
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* This function implements POSIX Advisory Locks, e.g.
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*
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* CHECK_NE(-1, fcntl(zfd, F_SETLKW, &(struct flock){F_WRLCK}));
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* // ...
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* CHECK_NE(-1, fcntl(zfd, F_SETLK, &(struct flock){F_UNLCK}));
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*
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* Please be warned that locks currently do nothing on Windows since
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* figuring out how to polyfill them correctly is a work in progress.
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*
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* @param cmd can be F_{GET,SET}{FD,FL}, etc.
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* @param arg can be FD_CLOEXEC, etc. depending
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* @return 0 on success, or -1 w/ errno
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* @asyncsignalsafe
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* @restartable
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*/
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int fcntl(int fd, int cmd, ...) {
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int rc;
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va_list va;
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uintptr_t arg;
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va_start(va, cmd);
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arg = va_arg(va, uintptr_t);
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va_end(va);
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if (fd >= 0) {
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if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip) {
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rc = weaken(__zipos_fcntl)(fd, cmd, arg);
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} else if (!IsWindows()) {
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rc = sys_fcntl(fd, cmd, arg);
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} else {
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rc = sys_fcntl_nt(fd, cmd, arg);
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}
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} else {
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rc = einval();
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}
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STRACE("fcntl(%d, %d, %p) → %#x% m", fd, cmd, arg, rc);
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return rc;
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}
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