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https://github.com/jart/cosmopolitan.git
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1837dc2e85
- Introduce path module to redbean - Fix glitch with linenoise printing extra line on eof - Introduce closefrom() and close_range() system calls - Make file descriptor closing more secure in pledge.com
65 lines
3.3 KiB
C
65 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 2022 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/strace.internal.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/errno.h"
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#include "libc/limits.h"
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/**
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* Closes inclusive range of file descriptors, e.g.
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*
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* // close all non-stdio file descriptors
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* if (close_range(3, -1, 0) == -1) {
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* for (int i = 3; i < 256; ++i) {
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* close(i);
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* }
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* }
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*
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* This is supported on Linux 5.9+, FreeBSD, and OpenBSD. On FreeBSD,
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* `flags` must be zero. On OpenBSD, we call closefrom(int) so `last`
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* should be `-1` in order to get OpenBSD support, otherwise `ENOSYS`
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* will be returned. We also polyfill closefrom on FreeBSD since it's
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* available on older kernels.
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*
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* On Linux, the following flags are supported:
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*
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* - CLOSE_RANGE_UNSHARE
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* - CLOSE_RANGE_CLOEXEC
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*
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* @return 0 on success, or -1 w/ errno
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* @error ENOSYS if not Linux 5.9+ / FreeBSD / OpenBSD
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* @error EBADF on OpenBSD if `first` is greater than highest fd
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* @error EINVAL if flags are bad or first is greater than last
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* @error EMFILE if a weird race condition happens on Linux
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* @error EINTR possibly on OpenBSD
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* @error ENOMEM on Linux maybe
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*/
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int close_range(unsigned int first, unsigned int last, unsigned int flags) {
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int rc, err;
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err = errno;
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if ((rc = sys_close_range(first, last, flags)) == -1) {
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if (errno == ENOSYS && first <= INT_MAX && last == UINT_MAX && !flags) {
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errno = err;
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rc = sys_closefrom(first);
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}
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}
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STRACE("close_range(%d, %d, %#x) → %d% m", first, last, flags, rc);
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return rc;
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}
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