mirror of
https://github.com/jart/cosmopolitan.git
synced 2024-05-17 02:52:40 +00:00
2ab9e9f7fd
- Introduce portable sched_getcpu() api - Support GCC's __target_clones__ feature - Make fma() go faster on x86 in default mode - Remove some asan checks from core libraries - WinMain() now ensures $HOME and $USER are defined
60 lines
2.8 KiB
C
60 lines
2.8 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et 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/assert.h"
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#include "libc/dce.h"
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#include "libc/str/str.h"
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static size_t strnlen_s_x64(const char *s, size_t n, size_t i) {
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uint64_t w;
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for (; i + 8 < n; i += 8) {
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w = *(uint64_t *)(s + i);
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if ((w = ~w & (w - 0x0101010101010101) & 0x8080808080808080)) {
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i += (unsigned)__builtin_ctzll(w) >> 3;
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break;
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}
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}
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return i;
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}
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/**
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* Returns length of NUL-terminated string... securely.
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*
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* This is like strnlen() except it'll return 0 if `s` is null. We also
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* make the assumption for the purposes of ASAN that `n` is the size of
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* the buffer if `s` is non-null.
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*
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* @param s is string
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* @param n is max length
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* @return byte length
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* @asyncsignalsafe
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*/
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size_t strnlen_s(const char *s, size_t n) {
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size_t i;
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if (!s) return 0;
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for (i = 0; (uintptr_t)(s + i) & 7; ++i) {
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if (i == n || !s[i]) return i;
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}
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i = strnlen_s_x64(s, n, i);
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for (;; ++i) {
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if (i == n || !s[i]) break;
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}
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unassert(i == n || (i < n && !s[i]));
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return i;
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}
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