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wcsmbs: Ensure wcstr worst-case linear execution time (BZ 23865)

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It uses the same two-way algorithm used on strstr, strcasestr, and
memmem.  Different than strstr, neither the "shift table" optimization
nor the self-adapting filtering check is used because it would result in
a too-large shift table (and it also simplifies the implementation bit).

Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
This commit is contained in:
Adhemerval Zanella
2024-03-19 10:15:28 -03:00
parent 4b717562c4
commit cf11e74b0d
3 changed files with 505 additions and 70 deletions
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172
string/test-strstr.c
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@ -59,6 +59,9 @@
# undef weak_alias
# define weak_alias(a, b)
# define WCSSTR c_wcsstr
# define __wmemcmp wmemcmp
# define __wcsnlen wcsnlen
# define __wcslen wcslen
# include "wcsstr.c"
# define C_IMPL WCSSTR
#endif
@ -217,6 +220,31 @@ check2 (void)
}
}
static void
check3 (void)
{
/* Check that a long periodic needle does not cause false positives. */
{
const CHAR input[] = L("F_BD_CE_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD"
"_C3_88_20_EF_BF_BD_EF_BF_BD_EF_BF_BD"
"_C3_A7_20_EF_BF_BD");
const CHAR need[] = L("_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD");
FOR_EACH_IMPL (impl, 0)
check_result (impl, input, need, NULL);
}
{
const CHAR input[] = L("F_BD_CE_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD"
"_C3_88_20_EF_BF_BD_EF_BF_BD_EF_BF_BD"
"_C3_A7_20_EF_BF_BD_DA_B5_C2_A6_20"
"_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD");
const CHAR need[] = L("_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD");
FOR_EACH_IMPL (impl, 0)
check_result (impl, input, need, (CHAR *) input + 115);
}
}
#define N 1024
static void
@ -243,6 +271,148 @@ pr23637 (void)
check_result (impl, h, n, exp_result);
}
static void
pr23865 (void)
{
/* Check that a very long haystack is handled quickly if the needle is
short and occurs near the beginning. */
{
size_t m = 1000000;
const CHAR *needle =
L("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA");
CHAR *haystack = xmalloc ((m + 1) * sizeof (CHAR));
MEMSET (haystack, L('A'), m);
haystack[0] = L('B');
haystack[m] = L('\0');
FOR_EACH_IMPL (impl, 0)
check_result (impl, haystack, needle, haystack + 1);
free (haystack);
}
/* Check that a very long needle is discarded quickly if the haystack is
short. */
{
size_t m = 1000000;
const CHAR *haystack =
L("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
"ABABABABABABABABABABABABABABABABABABABABABABABABABABABABABABABABABAB");
CHAR *needle = xmalloc ((m + 1) * sizeof (CHAR));
MEMSET (needle, L'A', m);
needle[m] = L('\0');
FOR_EACH_IMPL (impl, 0)
check_result (impl, haystack, needle, NULL);
free (needle);
}
/* Check that the asymptotic worst-case complexity is not quadratic. */
{
size_t m = 1000000;
CHAR *haystack = xmalloc ((2 * m + 2) * sizeof (CHAR));
CHAR *needle = xmalloc ((m + 2) * sizeof (CHAR));
MEMSET (haystack, L('A'), 2 * m);
haystack[2 * m] = L('B');
haystack[2 * m + 1] = L('\0');
MEMSET (needle, L('A'), m);
needle[m] = L('B');
needle[m + 1] = L('\0');
FOR_EACH_IMPL (impl, 0)
check_result (impl, haystack, needle, haystack + m);
free (needle);
free (haystack);
}
{
/* Ensure that with a barely periodic "short" needle, STRSTR's
search does not mistakenly skip just past the match point. */
const CHAR *haystack =
L("\n"
"with_build_libsubdir\n"
"with_local_prefix\n"
"with_gxx_include_dir\n"
"with_cpp_install_dir\n"
"enable_generated_files_in_srcdir\n"
"with_gnu_ld\n"
"with_ld\n"
"with_demangler_in_ld\n"
"with_gnu_as\n"
"with_as\n"
"enable_largefile\n"
"enable_werror_always\n"
"enable_checking\n"
"enable_coverage\n"
"enable_gather_detailed_mem_stats\n"
"enable_build_with_cxx\n"
"with_stabs\n"
"enable_multilib\n"
"enable___cxa_atexit\n"
"enable_decimal_float\n"
"enable_fixed_point\n"
"enable_threads\n"
"enable_tls\n"
"enable_objc_gc\n"
"with_dwarf2\n"
"enable_shared\n"
"with_build_sysroot\n"
"with_sysroot\n"
"with_specs\n"
"with_pkgversion\n"
"with_bugurl\n"
"enable_languages\n"
"with_multilib_list\n");
const CHAR *needle =
L("\n"
"with_gnu_ld\n");
FOR_EACH_IMPL (impl, 0)
check_result (impl, haystack, needle, (CHAR*) haystack + 114);
}
{
/* Same bug, shorter trigger. */
const CHAR *haystack = L("..wi.d.");
const CHAR *needle = L(".d.");
FOR_EACH_IMPL (impl, 0)
check_result (impl, haystack, needle, (CHAR*) haystack + 4);
}
/* Test case from Yves Bastide.
<https://www.openwall.com/lists/musl/2014/04/18/2> */
{
const CHAR *input = L("playing play play play always");
const CHAR *needle = L("play play play");
FOR_EACH_IMPL (impl, 0)
check_result (impl, input, needle, (CHAR*) input + 8);
}
/* Test long needles. */
{
size_t m = 1024;
CHAR *haystack = xmalloc ((2 * m + 1) * sizeof (CHAR));
CHAR *needle = xmalloc ((m + 1) * sizeof (CHAR));
haystack[0] = L('x');
MEMSET (haystack + 1, L(' '), m - 1);
MEMSET (haystack + m, L('x'), m);
haystack[2 * m] = L('\0');
MEMSET (needle, L('x'), m);
needle[m] = L('\0');
FOR_EACH_IMPL (impl, 0)
check_result (impl, haystack, needle, haystack + m);
free (needle);
free (haystack);
}
}
static int
test_main (void)
{
@ -250,7 +420,9 @@ test_main (void)
check1 ();
check2 ();
check3 ();
pr23637 ();
pr23865 ();
printf ("%23s", "");
FOR_EACH_IMPL (impl, 0)