mirror of
https://github.com/jart/cosmopolitan.git
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94 lines
4.2 KiB
C
94 lines
4.2 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/struct/fd.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/intrin/weaken.h"
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#include "libc/sock/syscall_fd.internal.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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* Closes file descriptor.
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*
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* This function releases resources returned by functions such as:
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*
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* - openat()
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* - socket()
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* - accept()
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* - epoll_create()
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* - landlock_create_ruleset()
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*
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* This function should never be reattempted if an error is returned;
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* however, that doesn't mean the error should be ignored. This goes
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* against the conventional wisdom of looping on `EINTR`.
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*
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* @return 0 on success, or -1 w/ errno
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* @raise EINTR if signal was delivered; do *not* retry
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* @raise EBADF if `fd` is negative or not open; however, an exception
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* is made by Cosmopolitan Libc for `close(-1)` which returns zero
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* and does nothing, in order to assist with code that may wish to
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* close the same resource multiple times without dirtying `errno`
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* @raise EIO if a low-level i/o error occurred
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* @asyncsignalsafe
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* @vforksafe
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*/
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int close(int fd) {
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int rc;
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if (fd < 0) {
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rc = ebadf();
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} else {
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// for performance reasons we want to avoid holding __fds_lock()
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// while sys_close() is happening. this leaves the kernel / libc
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// having a temporarily inconsistent state. routines that obtain
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// file descriptors the way __zipos_open() does need to retry if
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// there's indication this race condition happened.
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if (__isfdkind(fd, kFdZip)) {
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rc = _weaken(__zipos_close)(fd);
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} else {
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if (!IsWindows() && !IsMetal()) {
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rc = sys_close(fd);
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} else if (IsMetal()) {
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rc = 0;
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} else {
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if (__isfdkind(fd, kFdEpoll)) {
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rc = _weaken(sys_close_epoll_nt)(fd);
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} else if (__isfdkind(fd, kFdSocket)) {
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rc = _weaken(sys_closesocket_nt)(g_fds.p + fd);
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} else if (__isfdkind(fd, kFdFile) || //
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__isfdkind(fd, kFdConsole) || //
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__isfdkind(fd, kFdProcess)) { //
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rc = sys_close_nt(g_fds.p + fd, fd);
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} else {
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rc = eio();
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}
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}
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}
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if (!__vforked) {
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__releasefd(fd);
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}
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}
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STRACE("close(%d) → %d% m", fd, rc);
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return rc;
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}
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