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1260f9d0ed
I asked ChatGPT o1 for an optimized version of strlcpy() but it couldn't produce an implementation that didn't crash. Eventually it just gave up.
121 lines
4.7 KiB
C
121 lines
4.7 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 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/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/safemacros.h"
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#include "libc/mem/gc.h"
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#include "libc/mem/mem.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/sysconf.h"
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#include "libc/stdio/rand.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/testlib/benchmark.h"
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#include "libc/testlib/ezbench.h"
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#include "libc/testlib/testlib.h"
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size_t todd(char *dst, const char *src, size_t dsize) {
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const char *osrc = src;
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size_t nleft = dsize;
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if (nleft != 0)
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while (--nleft != 0)
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if ((*dst++ = *src++) == '\0')
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break;
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if (nleft == 0) {
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if (dsize != 0)
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*dst = '\0';
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while (*src++)
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;
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}
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return src - osrc - 1;
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}
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TEST(strlcpy, fuzz) {
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int pagesz = sysconf(_SC_PAGESIZE);
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char *map1 = (char *)mmap(0, pagesz * 2, PROT_READ | PROT_WRITE,
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MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
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npassert(map1 != MAP_FAILED);
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npassert(!mprotect(map1 + pagesz, pagesz, PROT_NONE));
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char *map2 = (char *)mmap(0, pagesz * 2, PROT_READ | PROT_WRITE,
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MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
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npassert(map2 != MAP_FAILED);
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npassert(!mprotect(map2 + pagesz, pagesz, PROT_NONE));
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char *map3 = (char *)mmap(0, pagesz * 2, PROT_READ | PROT_WRITE,
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MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
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npassert(map3 != MAP_FAILED);
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npassert(!mprotect(map3 + pagesz, pagesz, PROT_NONE));
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for (int dsize = 1; dsize < 128; ++dsize) {
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char *volatile dst1 = map1 + pagesz - dsize;
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char *volatile dst2 = map1 + pagesz - dsize;
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for (int i = 0; i < dsize; ++i)
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dst1[i] = dst2[i] = max(rand() & 255, 1);
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for (int ssize = 1; ssize < dsize * 2; ++ssize) {
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char *volatile src = map3 + pagesz - (ssize + 1);
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for (int i = 0; i < ssize; ++i)
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src[i] = max(rand() & 255, 1);
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src[ssize] = 0;
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ASSERT_EQ(todd(dst1, src, dsize), strlcpy(dst2, src, dsize));
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ASSERT_EQ(0, memcmp(dst1, dst2, dsize));
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}
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}
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npassert(!munmap(map3, pagesz * 2));
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npassert(!munmap(map2, pagesz * 2));
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npassert(!munmap(map1, pagesz * 2));
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}
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TEST(strlcpy, testEmptyBuffer_doesNothing) {
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EXPECT_EQ(5, strlcpy(NULL, "hello", 0));
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}
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TEST(strlcpy, testShortBuffer_nulTerminates) {
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char buf[1] = {1};
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EXPECT_EQ(5, strlcpy(buf, "hello", 1));
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EXPECT_STREQ("", buf);
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}
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TEST(strlcpy, testShortBuffer_copies) {
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char buf[2] = {1, 1};
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EXPECT_EQ(5, strlcpy(buf, "hello", 2));
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EXPECT_STREQ("h", buf);
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}
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#define N 4096
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BENCH(strlcpy, bench) {
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char dst[N];
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char src[N + 1];
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printf("\n");
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for (int n = 1; n <= N; n *= 2) {
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for (int i = 0; i < n; ++i)
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src[i] = max(rand() & 255, 1);
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src[n] = 0;
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BENCHMARK(100, n, X(strlcpy(dst, src, V(N))));
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}
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printf("\n");
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for (int n = 1; n <= N; n *= 2) {
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for (int i = 0; i < n; ++i)
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src[i] = max(rand() & 255, 1);
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src[n] = 0;
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BENCHMARK(100, n, X(todd(dst, src, V(N))));
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}
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}
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