1 // SPDX-License-Identifier: GPL-2.0-only 2 /* -*- linux-c -*- ------------------------------------------------------- * 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * Copyright 2007 rPath, Inc. - All Rights Reserved 6 * 7 * ----------------------------------------------------------------------- */ 8 9 /* 10 * Very basic string functions 11 */ 12 13 #include <linux/types.h> 14 #include <linux/compiler.h> 15 #include <linux/errno.h> 16 #include <linux/limits.h> 17 #include <asm/asm.h> 18 #include "ctype.h" 19 #include "string.h" 20 21 #define KSTRTOX_OVERFLOW (1U << 31) 22 23 /* 24 * Undef these macros so that the functions that we provide 25 * here will have the correct names regardless of how string.h 26 * may have chosen to #define them. 27 */ 28 #undef memcpy 29 #undef memset 30 #undef memcmp 31 32 int memcmp(const void *s1, const void *s2, size_t len) 33 { 34 bool diff; 35 asm("repe; cmpsb" CC_SET(nz) 36 : CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len)); 37 return diff; 38 } 39 40 /* 41 * Clang may lower `memcmp == 0` to `bcmp == 0`. 42 */ 43 int bcmp(const void *s1, const void *s2, size_t len) 44 { 45 return memcmp(s1, s2, len); 46 } 47 48 int strcmp(const char *str1, const char *str2) 49 { 50 const unsigned char *s1 = (const unsigned char *)str1; 51 const unsigned char *s2 = (const unsigned char *)str2; 52 int delta; 53 54 while (*s1 || *s2) { 55 delta = *s1 - *s2; 56 if (delta) 57 return delta; 58 s1++; 59 s2++; 60 } 61 return 0; 62 } 63 64 int strncmp(const char *cs, const char *ct, size_t count) 65 { 66 unsigned char c1, c2; 67 68 while (count) { 69 c1 = *cs++; 70 c2 = *ct++; 71 if (c1 != c2) 72 return c1 < c2 ? -1 : 1; 73 if (!c1) 74 break; 75 count--; 76 } 77 return 0; 78 } 79 80 size_t strnlen(const char *s, size_t maxlen) 81 { 82 const char *es = s; 83 while (*es && maxlen) { 84 es++; 85 maxlen--; 86 } 87 88 return (es - s); 89 } 90 91 /* Works only for digits and letters, but small and fast */ 92 #define TOLOWER(x) ((x) | 0x20) 93 94 static unsigned int simple_guess_base(const char *cp) 95 { 96 if (cp[0] == '0') { 97 if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2])) 98 return 16; 99 else 100 return 8; 101 } else { 102 return 10; 103 } 104 } 105 106 /** 107 * simple_strtoull - convert a string to an unsigned long long 108 * @cp: The start of the string 109 * @endp: A pointer to the end of the parsed string will be placed here 110 * @base: The number base to use 111 */ 112 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base) 113 { 114 unsigned long long result = 0; 115 116 if (!base) 117 base = simple_guess_base(cp); 118 119 if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x') 120 cp += 2; 121 122 while (isxdigit(*cp)) { 123 unsigned int value; 124 125 value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10; 126 if (value >= base) 127 break; 128 result = result * base + value; 129 cp++; 130 } 131 if (endp) 132 *endp = (char *)cp; 133 134 return result; 135 } 136 137 long simple_strtol(const char *cp, char **endp, unsigned int base) 138 { 139 if (*cp == '-') 140 return -simple_strtoull(cp + 1, endp, base); 141 142 return simple_strtoull(cp, endp, base); 143 } 144 145 /** 146 * strlen - Find the length of a string 147 * @s: The string to be sized 148 */ 149 size_t strlen(const char *s) 150 { 151 const char *sc; 152 153 for (sc = s; *sc != '\0'; ++sc) 154 /* nothing */; 155 return sc - s; 156 } 157 158 /** 159 * strstr - Find the first substring in a %NUL terminated string 160 * @s1: The string to be searched 161 * @s2: The string to search for 162 */ 163 char *strstr(const char *s1, const char *s2) 164 { 165 size_t l1, l2; 166 167 l2 = strlen(s2); 168 if (!l2) 169 return (char *)s1; 170 l1 = strlen(s1); 171 while (l1 >= l2) { 172 l1--; 173 if (!memcmp(s1, s2, l2)) 174 return (char *)s1; 175 s1++; 176 } 177 return NULL; 178 } 179 180 /** 181 * strchr - Find the first occurrence of the character c in the string s. 182 * @s: the string to be searched 183 * @c: the character to search for 184 */ 185 char *strchr(const char *s, int c) 186 { 187 while (*s != (char)c) 188 if (*s++ == '\0') 189 return NULL; 190 return (char *)s; 191 } 192 193 static inline u64 __div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) 194 { 195 union { 196 u64 v64; 197 u32 v32[2]; 198 } d = { dividend }; 199 u32 upper; 200 201 upper = d.v32[1]; 202 d.v32[1] = 0; 203 if (upper >= divisor) { 204 d.v32[1] = upper / divisor; 205 upper %= divisor; 206 } 207 asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) : 208 "rm" (divisor), "0" (d.v32[0]), "1" (upper)); 209 return d.v64; 210 } 211 212 static inline u64 __div_u64(u64 dividend, u32 divisor) 213 { 214 u32 remainder; 215 216 return __div_u64_rem(dividend, divisor, &remainder); 217 } 218 219 static inline char _tolower(const char c) 220 { 221 return c | 0x20; 222 } 223 224 static const char *_parse_integer_fixup_radix(const char *s, unsigned int *base) 225 { 226 if (*base == 0) { 227 if (s[0] == '0') { 228 if (_tolower(s[1]) == 'x' && isxdigit(s[2])) 229 *base = 16; 230 else 231 *base = 8; 232 } else 233 *base = 10; 234 } 235 if (*base == 16 && s[0] == '0' && _tolower(s[1]) == 'x') 236 s += 2; 237 return s; 238 } 239 240 /* 241 * Convert non-negative integer string representation in explicitly given radix 242 * to an integer. 243 * Return number of characters consumed maybe or-ed with overflow bit. 244 * If overflow occurs, result integer (incorrect) is still returned. 245 * 246 * Don't you dare use this function. 247 */ 248 static unsigned int _parse_integer(const char *s, 249 unsigned int base, 250 unsigned long long *p) 251 { 252 unsigned long long res; 253 unsigned int rv; 254 255 res = 0; 256 rv = 0; 257 while (1) { 258 unsigned int c = *s; 259 unsigned int lc = c | 0x20; /* don't tolower() this line */ 260 unsigned int val; 261 262 if ('0' <= c && c <= '9') 263 val = c - '0'; 264 else if ('a' <= lc && lc <= 'f') 265 val = lc - 'a' + 10; 266 else 267 break; 268 269 if (val >= base) 270 break; 271 /* 272 * Check for overflow only if we are within range of 273 * it in the max base we support (16) 274 */ 275 if (unlikely(res & (~0ull << 60))) { 276 if (res > __div_u64(ULLONG_MAX - val, base)) 277 rv |= KSTRTOX_OVERFLOW; 278 } 279 res = res * base + val; 280 rv++; 281 s++; 282 } 283 *p = res; 284 return rv; 285 } 286 287 static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res) 288 { 289 unsigned long long _res; 290 unsigned int rv; 291 292 s = _parse_integer_fixup_radix(s, &base); 293 rv = _parse_integer(s, base, &_res); 294 if (rv & KSTRTOX_OVERFLOW) 295 return -ERANGE; 296 if (rv == 0) 297 return -EINVAL; 298 s += rv; 299 if (*s == '\n') 300 s++; 301 if (*s) 302 return -EINVAL; 303 *res = _res; 304 return 0; 305 } 306 307 /** 308 * kstrtoull - convert a string to an unsigned long long 309 * @s: The start of the string. The string must be null-terminated, and may also 310 * include a single newline before its terminating null. The first character 311 * may also be a plus sign, but not a minus sign. 312 * @base: The number base to use. The maximum supported base is 16. If base is 313 * given as 0, then the base of the string is automatically detected with the 314 * conventional semantics - If it begins with 0x the number will be parsed as a 315 * hexadecimal (case insensitive), if it otherwise begins with 0, it will be 316 * parsed as an octal number. Otherwise it will be parsed as a decimal. 317 * @res: Where to write the result of the conversion on success. 318 * 319 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error. 320 * Used as a replacement for the obsolete simple_strtoull. Return code must 321 * be checked. 322 */ 323 int kstrtoull(const char *s, unsigned int base, unsigned long long *res) 324 { 325 if (s[0] == '+') 326 s++; 327 return _kstrtoull(s, base, res); 328 } 329 330 static int _kstrtoul(const char *s, unsigned int base, unsigned long *res) 331 { 332 unsigned long long tmp; 333 int rv; 334 335 rv = kstrtoull(s, base, &tmp); 336 if (rv < 0) 337 return rv; 338 if (tmp != (unsigned long)tmp) 339 return -ERANGE; 340 *res = tmp; 341 return 0; 342 } 343 344 /** 345 * boot_kstrtoul - convert a string to an unsigned long 346 * @s: The start of the string. The string must be null-terminated, and may also 347 * include a single newline before its terminating null. The first character 348 * may also be a plus sign, but not a minus sign. 349 * @base: The number base to use. The maximum supported base is 16. If base is 350 * given as 0, then the base of the string is automatically detected with the 351 * conventional semantics - If it begins with 0x the number will be parsed as a 352 * hexadecimal (case insensitive), if it otherwise begins with 0, it will be 353 * parsed as an octal number. Otherwise it will be parsed as a decimal. 354 * @res: Where to write the result of the conversion on success. 355 * 356 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error. 357 * Used as a replacement for the simple_strtoull. 358 */ 359 int boot_kstrtoul(const char *s, unsigned int base, unsigned long *res) 360 { 361 /* 362 * We want to shortcut function call, but 363 * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0. 364 */ 365 if (sizeof(unsigned long) == sizeof(unsigned long long) && 366 __alignof__(unsigned long) == __alignof__(unsigned long long)) 367 return kstrtoull(s, base, (unsigned long long *)res); 368 else 369 return _kstrtoul(s, base, res); 370 } 371