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Perform some code cleanup

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Justine Tunney 2022-06-23 10:21:07 -07:00
parent 0dd9629562
commit a4601a24d3
63 changed files with 350 additions and 1643 deletions
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61
libc/str/strnlen_s.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/dce.h"
#include "libc/intrin/asan.internal.h"
#include "libc/str/str.h"
static noasan size_t strnlen_s_x64(const char *s, size_t n, size_t i) {
uint64_t w;
for (; i + 8 < n; i += 8) {
w = *(uint64_t *)(s + i);
if ((w = ~w & (w - 0x0101010101010101) & 0x8080808080808080)) {
i += (unsigned)__builtin_ctzll(w) >> 3;
break;
}
}
return i;
}
/**
* Returns length of NUL-terminated string... securely.
*
* This is like strnlen() except it'll return 0 if `s` is null. We also
* make the assumption for the purposes of ASAN that `n` is the size of
* the buffer if `s` is non-null.
*
* @param s is string
* @param n is max length
* @return byte length
* @asyncsignalsafe
*/
noasan size_t strnlen_s(const char *s, size_t n) {
size_t i;
if (!s) return 0;
if (IsAsan()) __asan_verify(s, n);
for (i = 0; (uintptr_t)(s + i) & 7; ++i) {
if (i == n || !s[i]) return i;
}
i = strnlen_s_x64(s, n, i);
for (;; ++i) {
if (i == n || !s[i]) break;
}
assert(i == n || (i < n && !s[i]));
return i;
}