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glibc/string/test-strncmp.c
H.J. Lu f7e3f92b7c strncmp: Add a testcase for page boundary [BZ #25933] 
Add a strncmp testcase to cover cases where one of strings ends on the
page boundary with the maximum string length less than the number bytes
of each AVX2 loop iteration and different offsets from page boundary.

The updated string/test-strncmp fails on Intel Core i7-8559U without

ommit 1c6432316bc434a72108d7b0c7cfbfdde64c3124
Author: Sunil K Pandey <skpgkp1@gmail.com>
Date:   Fri Jun 12 08:57:16 2020 -0700

    Fix avx2 strncmp offset compare condition check [BZ #25933]
2020-09-24 07:06:03 -07:00

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/* Test strncmp and wcsncmp functions.
Copyright (C) 1999-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Jakub Jelinek <jakub@redhat.com>, 1999.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#define TEST_MAIN
#ifdef WIDE
# define TEST_NAME "wcsncmp"
#else
# define TEST_NAME "strncmp"
#endif
#include "test-string.h"
#ifdef WIDE
# include <wchar.h>
# define L(str) L##str
# define STRNCMP wcsncmp
# define STRCPY wcscpy
# define STRDUP wcsdup
# define MEMCPY wmemcpy
# define SIMPLE_STRNCMP simple_wcsncmp
# define STUPID_STRNCMP stupid_wcsncmp
# define CHAR wchar_t
# define UCHAR wchar_t
# define CHARBYTES 4
# define CHAR__MAX WCHAR_MAX
# define CHAR__MIN WCHAR_MIN
/* Wcsncmp uses signed semantics for comparison, not unsigned.
Avoid using substraction since possible overflow */
int
simple_wcsncmp (const CHAR *s1, const CHAR *s2, size_t n)
{
wchar_t c1, c2;
while (n--)
{
c1 = *s1++;
c2 = *s2++;
if (c1 == L('\0') || c1 != c2)
return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
}
return 0;
}
int
stupid_wcsncmp (const CHAR *s1, const CHAR *s2, size_t n)
{
wchar_t c1, c2;
size_t ns1 = wcsnlen (s1, n) + 1, ns2 = wcsnlen (s2, n) + 1;
n = ns1 < n ? ns1 : n;
n = ns2 < n ? ns2 : n;
while (n--)
{
c1 = *s1++;
c2 = *s2++;
if (c1 != c2)
return c1 > c2 ? 1 : -1;
}
return 0;
}
#else
# define L(str) str
# define STRNCMP strncmp
# define STRCPY strcpy
# define STRDUP strdup
# define MEMCPY memcpy
# define SIMPLE_STRNCMP simple_strncmp
# define STUPID_STRNCMP stupid_strncmp
# define CHAR char
# define UCHAR unsigned char
# define CHARBYTES 1
# define CHAR__MAX CHAR_MAX
# define CHAR__MIN CHAR_MIN
/* Strncmp uses unsigned semantics for comparison. */
int
simple_strncmp (const char *s1, const char *s2, size_t n)
{
int ret = 0;
while (n-- && (ret = *(unsigned char *) s1 - * (unsigned char *) s2++) == 0
&& *s1++);
return ret;
}
int
stupid_strncmp (const char *s1, const char *s2, size_t n)
{
size_t ns1 = strnlen (s1, n) + 1, ns2 = strnlen (s2, n) + 1;
int ret = 0;
n = ns1 < n ? ns1 : n;
n = ns2 < n ? ns2 : n;
while (n-- && (ret = *(unsigned char *) s1++ - * (unsigned char *) s2++) == 0);
return ret;
}
#endif
typedef int (*proto_t) (const CHAR *, const CHAR *, size_t);
IMPL (STUPID_STRNCMP, 0)
IMPL (SIMPLE_STRNCMP, 0)
IMPL (STRNCMP, 1)
static int
check_result (impl_t *impl, const CHAR *s1, const CHAR *s2, size_t n,
int exp_result)
{
int result = CALL (impl, s1, s2, n);
if ((exp_result == 0 && result != 0)
|| (exp_result < 0 && result >= 0)
|| (exp_result > 0 && result <= 0))
{
error (0, 0, "Wrong result in function %s %d %d", impl->name,
result, exp_result);
ret = 1;
return -1;
}
return 0;
}
static void
do_one_test (impl_t *impl, const CHAR *s1, const CHAR *s2, size_t n,
int exp_result)
{
if (check_result (impl, s1, s2, n, exp_result) < 0)
return;
}
static void
do_test_limit (size_t align1, size_t align2, size_t len, size_t n, int max_char,
int exp_result)
{
size_t i, align_n;
CHAR *s1, *s2;
align1 &= ~(CHARBYTES - 1);
align2 &= ~(CHARBYTES - 1);
if (n == 0)
{
s1 = (CHAR *) (buf1 + page_size);
s2 = (CHAR *) (buf2 + page_size);
FOR_EACH_IMPL (impl, 0)
do_one_test (impl, s1, s2, n, 0);
return;
}
align1 &= 15;
align2 &= 15;
align_n = (page_size - n * CHARBYTES) & 15;
s1 = (CHAR *) (buf1 + page_size - n * CHARBYTES);
s2 = (CHAR *) (buf2 + page_size - n * CHARBYTES);
if (align1 < align_n)
s1 = (CHAR *) ((char *) s1 - (align_n - align1));
if (align2 < align_n)
s2 = (CHAR *) ((char *) s2 - (align_n - align2));
for (i = 0; i < n; i++)
s1[i] = s2[i] = 1 + 23 * i % max_char;
if (len < n)
{
s1[len] = 0;
s2[len] = 0;
if (exp_result < 0)
s2[len] = 32;
else if (exp_result > 0)
s1[len] = 64;
}
FOR_EACH_IMPL (impl, 0)
do_one_test (impl, s1, s2, n, exp_result);
}
static void
do_test (size_t align1, size_t align2, size_t len, size_t n, int max_char,
int exp_result)
{
size_t i;
CHAR *s1, *s2;
align1 &= ~(CHARBYTES - 1);
align2 &= ~(CHARBYTES - 1);
if (n == 0)
return;
align1 &= 63;
if (align1 + (n + 1) * CHARBYTES >= page_size)
return;
align2 &= 63;
if (align2 + (n + 1) * CHARBYTES >= page_size)
return;
s1 = (CHAR *) (buf1 + align1);
s2 = (CHAR *) (buf2 + align2);
for (i = 0; i < n; i++)
s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % max_char;
s1[n] = 24 + exp_result;
s2[n] = 23;
s1[len] = 0;
s2[len] = 0;
if (exp_result < 0)
s2[len] = 32;
else if (exp_result > 0)
s1[len] = 64;
if (len >= n)
s2[n - 1] -= exp_result;
FOR_EACH_IMPL (impl, 0)
do_one_test (impl, s1, s2, n, exp_result);
}
static void
do_page_test (size_t offset1, size_t offset2, CHAR *s2)
{
CHAR *s1;
int exp_result;
if (offset1 * CHARBYTES >= page_size || offset2 * CHARBYTES >= page_size)
return;
s1 = (CHAR *) buf1;
s1 += offset1;
s2 += offset2;
exp_result= *s1;
FOR_EACH_IMPL (impl, 0)
{
check_result (impl, s1, s2, page_size, -exp_result);
check_result (impl, s2, s1, page_size, exp_result);
}
}
static void
do_random_tests (void)
{
size_t i, j, n, align1, align2, pos, len1, len2, size;
int result;
long r;
UCHAR *p1 = (UCHAR *) (buf1 + page_size - 512 * CHARBYTES);
UCHAR *p2 = (UCHAR *) (buf2 + page_size - 512 * CHARBYTES);
for (n = 0; n < ITERATIONS; n++)
{
align1 = random () & 31;
if (random () & 1)
align2 = random () & 31;
else
align2 = align1 + (random () & 24);
pos = random () & 511;
size = random () & 511;
j = align1 > align2 ? align1 : align2;
if (pos + j >= 511)
pos = 510 - j - (random () & 7);
len1 = random () & 511;
if (pos >= len1 && (random () & 1))
len1 = pos + (random () & 7);
if (len1 + j >= 512)
len1 = 511 - j - (random () & 7);
if (pos >= len1)
len2 = len1;
else
len2 = len1 + (len1 != 511 - j ? random () % (511 - j - len1) : 0);
j = (pos > len2 ? pos : len2) + align1 + 64;
if (j > 512)
j = 512;
for (i = 0; i < j; ++i)
{
p1[i] = random () & 255;
if (i < len1 + align1 && !p1[i])
{
p1[i] = random () & 255;
if (!p1[i])
p1[i] = 1 + (random () & 127);
}
}
for (i = 0; i < j; ++i)
{
p2[i] = random () & 255;
if (i < len2 + align2 && !p2[i])
{
p2[i] = random () & 255;
if (!p2[i])
p2[i] = 1 + (random () & 127);
}
}
result = 0;
MEMCPY (p2 + align2, p1 + align1, pos);
if (pos < len1)
{
if (p2[align2 + pos] == p1[align1 + pos])
{
p2[align2 + pos] = random () & 255;
if (p2[align2 + pos] == p1[align1 + pos])
p2[align2 + pos] = p1[align1 + pos] + 3 + (random () & 127);
}
if (pos < size)
{
if (p1[align1 + pos] < p2[align2 + pos])
result = -1;
else
result = 1;
}
}
p1[len1 + align1] = 0;
p2[len2 + align2] = 0;
FOR_EACH_IMPL (impl, 1)
{
r = CALL (impl, (CHAR *) (p1 + align1), (CHAR *) (p2 + align2), size);
/* Test whether on 64-bit architectures where ABI requires
callee to promote has the promotion been done. */
asm ("" : "=g" (r) : "0" (r));
if ((r == 0 && result)
|| (r < 0 && result >= 0)
|| (r > 0 && result <= 0))
{
error (0, 0, "Iteration %zd - wrong result in function %s (%zd, %zd, %zd, %zd, %zd, %zd) %ld != %d, p1 %p p2 %p",
n, impl->name, align1, align2, len1, len2, pos, size, r, result, p1, p2);
ret = 1;
}
}
}
}
static void
check1 (void)
{
CHAR *s1 = (CHAR *) (buf1 + 0xb2c);
CHAR *s2 = (CHAR *) (buf1 + 0xfd8);
size_t i, offset;
int exp_result;
STRCPY(s1, L("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrs"));
STRCPY(s2, L("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijkLMNOPQRSTUV"));
/* Check possible overflow bug for wcsncmp */
s1[4] = CHAR__MAX;
s2[4] = CHAR__MIN;
for (offset = 0; offset < 6; offset++)
{
for (i = 0; i < 80; i++)
{
exp_result = SIMPLE_STRNCMP (s1 + offset, s2 + offset, i);
FOR_EACH_IMPL (impl, 0)
check_result (impl, s1 + offset, s2 + offset, i, exp_result);
}
}
}
static void
check2 (void)
{
size_t i;
CHAR *s1, *s2;
s1 = (CHAR *) buf1;
for (i = 0; i < (page_size / CHARBYTES) - 1; i++)
s1[i] = 23;
s1[i] = 0;
s2 = STRDUP (s1);
for (i = 0; i < 64; ++i)
do_page_test ((3988 / CHARBYTES) + i, (2636 / CHARBYTES), s2);
free (s2);
}
static void
check3 (void)
{
/* To trigger bug 25933, we need a size that is equal to the vector
length times 4. In the case of AVX2 for Intel, we need 32 * 4. We
make this test generic and run it for all architectures as additional
boundary testing for such related algorithms. */
size_t size = 32 * 4;
CHAR *s1 = (CHAR *) (buf1 + (BUF1PAGES - 1) * page_size);
CHAR *s2 = (CHAR *) (buf2 + (BUF1PAGES - 1) * page_size);
int exp_result;
memset (s1, 'a', page_size);
memset (s2, 'a', page_size);
s1[(page_size / CHARBYTES) - 1] = (CHAR) 0;
/* Iterate over a size that is just below where we expect the bug to
trigger up to the size we expect will trigger the bug e.g. [99-128].
Likewise iterate the start of two strings between 30 and 31 bytes
away from the boundary to simulate alignment changes. */
for (size_t s = 99; s <= size; s++)
for (size_t s1a = 30; s1a < 32; s1a++)
for (size_t s2a = 30; s2a < 32; s2a++)
{
CHAR *s1p = s1 + (page_size / CHARBYTES - s) - s1a;
CHAR *s2p = s2 + (page_size / CHARBYTES - s) - s2a;
exp_result = SIMPLE_STRNCMP (s1p, s2p, s);
FOR_EACH_IMPL (impl, 0)
check_result (impl, s1p, s2p, s, exp_result);
}
}
int
test_main (void)
{
size_t i;
test_init ();
check1 ();
check2 ();
check3 ();
printf ("%23s", "");
FOR_EACH_IMPL (impl, 0)
printf ("\t%s", impl->name);
putchar ('\n');
for (i =0; i < 16; ++i)
{
do_test (0, 0, 8, i, 127, 0);
do_test (0, 0, 8, i, 127, -1);
do_test (0, 0, 8, i, 127, 1);
do_test (i, i, 8, i, 127, 0);
do_test (i, i, 8, i, 127, 1);
do_test (i, i, 8, i, 127, -1);
do_test (i, 2 * i, 8, i, 127, 0);
do_test (2 * i, i, 8, i, 127, 1);
do_test (i, 3 * i, 8, i, 127, -1);
do_test (0, 0, 8, i, 255, 0);
do_test (0, 0, 8, i, 255, -1);
do_test (0, 0, 8, i, 255, 1);
do_test (i, i, 8, i, 255, 0);
do_test (i, i, 8, i, 255, 1);
do_test (i, i, 8, i, 255, -1);
do_test (i, 2 * i, 8, i, 255, 0);
do_test (2 * i, i, 8, i, 255, 1);
do_test (i, 3 * i, 8, i, 255, -1);
}
for (i = 1; i < 8; ++i)
{
do_test (0, 0, 8 << i, 16 << i, 127, 0);
do_test (0, 0, 8 << i, 16 << i, 127, 1);
do_test (0, 0, 8 << i, 16 << i, 127, -1);
do_test (0, 0, 8 << i, 16 << i, 255, 0);
do_test (0, 0, 8 << i, 16 << i, 255, 1);
do_test (0, 0, 8 << i, 16 << i, 255, -1);
do_test (8 - i, 2 * i, 8 << i, 16 << i, 127, 0);
do_test (8 - i, 2 * i, 8 << i, 16 << i, 127, 1);
do_test (2 * i, i, 8 << i, 16 << i, 255, 0);
do_test (2 * i, i, 8 << i, 16 << i, 255, 1);
}
do_test_limit (0, 0, 0, 0, 127, 0);
do_test_limit (4, 0, 21, 20, 127, 0);
do_test_limit (0, 4, 21, 20, 127, 0);
do_test_limit (8, 0, 25, 24, 127, 0);
do_test_limit (0, 8, 25, 24, 127, 0);
for (i = 0; i < 8; ++i)
{
do_test_limit (0, 0, 17 - i, 16 - i, 127, 0);
do_test_limit (0, 0, 17 - i, 16 - i, 255, 0);
do_test_limit (0, 0, 15 - i, 16 - i, 127, 0);
do_test_limit (0, 0, 15 - i, 16 - i, 127, 1);
do_test_limit (0, 0, 15 - i, 16 - i, 127, -1);
do_test_limit (0, 0, 15 - i, 16 - i, 255, 0);
do_test_limit (0, 0, 15 - i, 16 - i, 255, 1);
do_test_limit (0, 0, 15 - i, 16 - i, 255, -1);
}
do_random_tests ();
return ret;
}
#include <support/test-driver.c>
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