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| 1 | +/* |
| 2 | + * SPDX-License-Identifier: BSD-3-Clause |
| 3 | + * |
| 4 | + * Copyright © 2025 Keith Packard |
| 5 | + * |
| 6 | + * Redistribution and use in source and binary forms, with or without |
| 7 | + * modification, are permitted provided that the following conditions |
| 8 | + * are met: |
| 9 | + * |
| 10 | + * 1. Redistributions of source code must retain the above copyright |
| 11 | + * notice, this list of conditions and the following disclaimer. |
| 12 | + * |
| 13 | + * 2. Redistributions in binary form must reproduce the above |
| 14 | + * copyright notice, this list of conditions and the following |
| 15 | + * disclaimer in the documentation and/or other materials provided |
| 16 | + * with the distribution. |
| 17 | + * |
| 18 | + * 3. Neither the name of the copyright holder nor the names of its |
| 19 | + * contributors may be used to endorse or promote products derived |
| 20 | + * from this software without specific prior written permission. |
| 21 | + * |
| 22 | + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 23 | + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 24 | + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| 25 | + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| 26 | + * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
| 27 | + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| 28 | + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| 29 | + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 30 | + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| 31 | + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 32 | + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| 33 | + * OF THE POSSIBILITY OF SUCH DAMAGE. |
| 34 | + */ |
| 35 | + |
| 36 | +#define _GNU_SOURCE |
| 37 | +#include <string.h> |
| 38 | +#include <stdio.h> |
| 39 | +#include <stdlib.h> |
| 40 | +#include <inttypes.h> |
| 41 | + |
| 42 | +#ifdef __MSP430__ |
| 43 | +#define HAY_MAX 256 |
| 44 | +#define NEEDLE_MAX 16 |
| 45 | +#else |
| 46 | +#define HAY_MAX 2048 |
| 47 | +#define NEEDLE_MAX 256 |
| 48 | +#endif |
| 49 | + |
| 50 | +#define SEED 42 |
| 51 | + |
| 52 | +static uint8_t hay[HAY_MAX]; |
| 53 | +static uint8_t needle[NEEDLE_MAX]; |
| 54 | + |
| 55 | +/* Generate random uint8_t */ |
| 56 | +static uint8_t |
| 57 | +rand_byte(void) |
| 58 | +{ |
| 59 | + return rand() & 0xff; |
| 60 | +} |
| 61 | + |
| 62 | +/* Generate random size_t */ |
| 63 | +static size_t |
| 64 | +rand_size_t(void) |
| 65 | +{ |
| 66 | + size_t r = 0; |
| 67 | + size_t i; |
| 68 | + |
| 69 | + for (i = 0; i < SIZE_WIDTH; i += 8) { |
| 70 | + r |= (size_t) rand_byte() << i; |
| 71 | + } |
| 72 | + return r; |
| 73 | +} |
| 74 | + |
| 75 | +/* Generate random number between 0 and max inclusive */ |
| 76 | +static size_t |
| 77 | +rand_range(size_t max) |
| 78 | +{ |
| 79 | + size_t mask = ~(size_t)0; |
| 80 | + size_t ret; |
| 81 | + |
| 82 | + if (max == 0) |
| 83 | + return 0; |
| 84 | + while (mask >> 1 > max) |
| 85 | + mask >>= 1; |
| 86 | + for (;;) { |
| 87 | + ret = rand_size_t() & mask; |
| 88 | + if (ret <= max) |
| 89 | + return ret; |
| 90 | + } |
| 91 | +} |
| 92 | + |
| 93 | +static size_t |
| 94 | +rand_size(size_t max) |
| 95 | +{ |
| 96 | + for (;;) { |
| 97 | + size_t ret = rand_range(max); |
| 98 | + if (ret) |
| 99 | + return ret; |
| 100 | + } |
| 101 | +} |
| 102 | + |
| 103 | +static size_t |
| 104 | +rand_pos(size_t max) |
| 105 | +{ |
| 106 | + return rand_range(max); |
| 107 | +} |
| 108 | + |
| 109 | +static size_t |
| 110 | +rand_elt(size_t max) |
| 111 | +{ |
| 112 | + return rand_range(max-1); |
| 113 | +} |
| 114 | + |
| 115 | +#ifdef __MSP430__ |
| 116 | +/* MSP430 emulator is rather slow */ |
| 117 | +#define LOOPS 4 |
| 118 | +#else |
| 119 | +#define LOOPS 10 |
| 120 | +#endif |
| 121 | + |
| 122 | +static void |
| 123 | +generate_hay(uint8_t *dst, size_t size) |
| 124 | +{ |
| 125 | + while (size) { |
| 126 | + *dst++ = rand_byte(); |
| 127 | + size--; |
| 128 | + } |
| 129 | +} |
| 130 | + |
| 131 | +static void |
| 132 | +fixup_hay(uint8_t *hay, size_t hay_size, uint8_t *needle, size_t needle_size) |
| 133 | +{ |
| 134 | + uint8_t *fix_pos = &needle[rand_elt(needle_size)]; |
| 135 | + uint8_t fix = *fix_pos; |
| 136 | + |
| 137 | + while (hay_size) { |
| 138 | + if (*hay == fix) |
| 139 | + *hay ^= 0x55; |
| 140 | + hay++; |
| 141 | + hay_size--; |
| 142 | + } |
| 143 | + |
| 144 | + while (needle_size) { |
| 145 | + if (needle != fix_pos && *needle == fix) |
| 146 | + *needle ^= 0xaa; |
| 147 | + needle++; |
| 148 | + needle_size--; |
| 149 | + } |
| 150 | +} |
| 151 | + |
| 152 | +int main(void) |
| 153 | +{ |
| 154 | + static size_t hay_start, hay_size; |
| 155 | + static size_t needle_start, needle_size; |
| 156 | + static size_t needle_pos; |
| 157 | + int ret = 0; |
| 158 | + int hay_size_loop, needle_size_loop; |
| 159 | + int needle_pos_loop; |
| 160 | + |
| 161 | + srand(SEED); |
| 162 | + |
| 163 | + /* Check long alignments for hay and needle */ |
| 164 | + for (hay_start = 0; hay_start < sizeof(long); hay_start++) { |
| 165 | + printf("loop %zd of %zd\n", hay_start, sizeof(long)); |
| 166 | + |
| 167 | + for (needle_start = 0; needle_start < sizeof(long); needle_start++) { |
| 168 | + |
| 169 | + /* Generate LOOPS random hay sizes */ |
| 170 | + for (hay_size_loop = 0; hay_size_loop < LOOPS; hay_size_loop++) { |
| 171 | + hay_size = rand_size(HAY_MAX - hay_start); |
| 172 | + size_t needle_max = NEEDLE_MAX - needle_start; |
| 173 | + if (needle_max > hay_size) |
| 174 | + needle_max = hay_size; |
| 175 | + |
| 176 | + /* Generate LOOPS random needle sizes */ |
| 177 | + for (needle_size_loop = 0; needle_size_loop < LOOPS; needle_size_loop++) { |
| 178 | + needle_size = rand_size(needle_max); |
| 179 | + |
| 180 | + /* Generate LOOPS random needle locations */ |
| 181 | + for (needle_pos_loop = 0; needle_pos_loop < LOOPS; needle_pos_loop++) { |
| 182 | + needle_pos = rand_pos(hay_size - needle_size); |
| 183 | + |
| 184 | + uint8_t *hay_cur = &hay[hay_start]; |
| 185 | + uint8_t *needle_cur = &needle[needle_start]; |
| 186 | + |
| 187 | +#if 0 |
| 188 | + printf("hay_start %zu hay_size %zu needle_start %zu needle_size %zu needle_pos %zu\n", |
| 189 | + hay_start, hay_size, needle_start, needle_size, needle_pos); |
| 190 | +#endif |
| 191 | + |
| 192 | + /* Set up the data */ |
| 193 | + memset(hay, 0, HAY_MAX); |
| 194 | + memset(needle, 0, NEEDLE_MAX); |
| 195 | + generate_hay(hay_cur, hay_size); |
| 196 | + generate_hay(needle_cur, needle_size); |
| 197 | + |
| 198 | + /* |
| 199 | + * Make sure the needle doesn't already exist in hay by |
| 200 | + * adjusting both |
| 201 | + */ |
| 202 | + fixup_hay(hay_cur, hay_size, needle_cur, needle_size); |
| 203 | + |
| 204 | + /* Place the needle in the haystack */ |
| 205 | + memcpy(&hay_cur[needle_pos], needle_cur, needle_size); |
| 206 | + |
| 207 | + uint8_t *result; |
| 208 | + |
| 209 | + result = memmem(hay_cur, hay_size, needle_cur, needle_size); |
| 210 | + |
| 211 | + if (result != hay_cur + needle_pos) { |
| 212 | + printf("expected needle at %zu got %zu\n", |
| 213 | + needle_pos, result - hay_cur); |
| 214 | + printf("hay_start %zu hay_size %zu needle_start %zu needle_size %zu needle_pos %zu\n", |
| 215 | + hay_start, hay_size, needle_start, needle_size, needle_pos); |
| 216 | + ret = 1; |
| 217 | + } |
| 218 | + |
| 219 | + /* |
| 220 | + * Introduce a single bit error in the hay |
| 221 | + * so that it no longer matches anywhere |
| 222 | + */ |
| 223 | + size_t damage_pos = rand_elt(needle_size); |
| 224 | + hay_cur[needle_pos + damage_pos] ^= 1; |
| 225 | + |
| 226 | + result = memmem(hay_cur, hay_size, needle_cur, needle_size); |
| 227 | + |
| 228 | + if (result != NULL) { |
| 229 | + printf("expected no needle, got %zu\n", result - hay_cur); |
| 230 | + printf("hay_start %zu hay_size %zu needle_start %zu needle_size %zu needle_pos %zu\n", |
| 231 | + hay_start, hay_size, needle_start, needle_size, needle_pos); |
| 232 | + ret = 1; |
| 233 | + } |
| 234 | + } |
| 235 | + } |
| 236 | + } |
| 237 | + } |
| 238 | + } |
| 239 | + return ret; |
| 240 | +} |
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