1 // SPDX-License-Identifier: GPL-2.0-only
2 /* -*- linux-c -*- ------------------------------------------------------- *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright 2007 rPath, Inc. - All Rights Reserved
7 * ----------------------------------------------------------------------- */
10 * Very basic string functions
13 #include <linux/types.h>
14 #include <linux/compiler.h>
15 #include <linux/errno.h>
16 #include <linux/limits.h>
21 #define KSTRTOX_OVERFLOW (1U << 31)
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.
32 int memcmp(const void *s1, const void *s2, size_t len)
35 asm("repe; cmpsb" CC_SET(nz)
36 : CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len));
41 * Clang may lower `memcmp == 0` to `bcmp == 0`.
43 int bcmp(const void *s1, const void *s2, size_t len)
45 return memcmp(s1, s2, len);
48 int strcmp(const char *str1, const char *str2)
50 const unsigned char *s1 = (const unsigned char *)str1;
51 const unsigned char *s2 = (const unsigned char *)str2;
64 int strncmp(const char *cs, const char *ct, size_t count)
72 return c1 < c2 ? -1 : 1;
80 size_t strnlen(const char *s, size_t maxlen)
83 while (*es && maxlen) {
91 unsigned int atou(const char *s)
95 i = i * 10 + (*s++ - '0');
99 /* Works only for digits and letters, but small and fast */
100 #define TOLOWER(x) ((x) | 0x20)
102 static unsigned int simple_guess_base(const char *cp)
105 if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
115 * simple_strtoull - convert a string to an unsigned long long
116 * @cp: The start of the string
117 * @endp: A pointer to the end of the parsed string will be placed here
118 * @base: The number base to use
120 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
122 unsigned long long result = 0;
125 base = simple_guess_base(cp);
127 if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
130 while (isxdigit(*cp)) {
133 value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
136 result = result * base + value;
145 long simple_strtol(const char *cp, char **endp, unsigned int base)
148 return -simple_strtoull(cp + 1, endp, base);
150 return simple_strtoull(cp, endp, base);
154 * strlen - Find the length of a string
155 * @s: The string to be sized
157 size_t strlen(const char *s)
161 for (sc = s; *sc != '\0'; ++sc)
167 * strstr - Find the first substring in a %NUL terminated string
168 * @s1: The string to be searched
169 * @s2: The string to search for
171 char *strstr(const char *s1, const char *s2)
181 if (!memcmp(s1, s2, l2))
189 * strchr - Find the first occurrence of the character c in the string s.
190 * @s: the string to be searched
191 * @c: the character to search for
193 char *strchr(const char *s, int c)
195 while (*s != (char)c)
201 static inline u64 __div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
211 if (upper >= divisor) {
212 d.v32[1] = upper / divisor;
215 asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
216 "rm" (divisor), "0" (d.v32[0]), "1" (upper));
220 static inline u64 __div_u64(u64 dividend, u32 divisor)
224 return __div_u64_rem(dividend, divisor, &remainder);
227 static inline char _tolower(const char c)
232 static const char *_parse_integer_fixup_radix(const char *s, unsigned int *base)
236 if (_tolower(s[1]) == 'x' && isxdigit(s[2]))
243 if (*base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
249 * Convert non-negative integer string representation in explicitly given radix
251 * Return number of characters consumed maybe or-ed with overflow bit.
252 * If overflow occurs, result integer (incorrect) is still returned.
254 * Don't you dare use this function.
256 static unsigned int _parse_integer(const char *s,
258 unsigned long long *p)
260 unsigned long long res;
267 unsigned int lc = c | 0x20; /* don't tolower() this line */
270 if ('0' <= c && c <= '9')
272 else if ('a' <= lc && lc <= 'f')
280 * Check for overflow only if we are within range of
281 * it in the max base we support (16)
283 if (unlikely(res & (~0ull << 60))) {
284 if (res > __div_u64(ULLONG_MAX - val, base))
285 rv |= KSTRTOX_OVERFLOW;
287 res = res * base + val;
295 static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
297 unsigned long long _res;
300 s = _parse_integer_fixup_radix(s, &base);
301 rv = _parse_integer(s, base, &_res);
302 if (rv & KSTRTOX_OVERFLOW)
316 * kstrtoull - convert a string to an unsigned long long
317 * @s: The start of the string. The string must be null-terminated, and may also
318 * include a single newline before its terminating null. The first character
319 * may also be a plus sign, but not a minus sign.
320 * @base: The number base to use. The maximum supported base is 16. If base is
321 * given as 0, then the base of the string is automatically detected with the
322 * conventional semantics - If it begins with 0x the number will be parsed as a
323 * hexadecimal (case insensitive), if it otherwise begins with 0, it will be
324 * parsed as an octal number. Otherwise it will be parsed as a decimal.
325 * @res: Where to write the result of the conversion on success.
327 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
328 * Used as a replacement for the obsolete simple_strtoull. Return code must
331 int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
335 return _kstrtoull(s, base, res);
338 static int _kstrtoul(const char *s, unsigned int base, unsigned long *res)
340 unsigned long long tmp;
343 rv = kstrtoull(s, base, &tmp);
346 if (tmp != (unsigned long)tmp)
353 * boot_kstrtoul - convert a string to an unsigned long
354 * @s: The start of the string. The string must be null-terminated, and may also
355 * include a single newline before its terminating null. The first character
356 * may also be a plus sign, but not a minus sign.
357 * @base: The number base to use. The maximum supported base is 16. If base is
358 * given as 0, then the base of the string is automatically detected with the
359 * conventional semantics - If it begins with 0x the number will be parsed as a
360 * hexadecimal (case insensitive), if it otherwise begins with 0, it will be
361 * parsed as an octal number. Otherwise it will be parsed as a decimal.
362 * @res: Where to write the result of the conversion on success.
364 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
365 * Used as a replacement for the simple_strtoull.
367 int boot_kstrtoul(const char *s, unsigned int base, unsigned long *res)
370 * We want to shortcut function call, but
371 * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
373 if (sizeof(unsigned long) == sizeof(unsigned long long) &&
374 __alignof__(unsigned long) == __alignof__(unsigned long long))
375 return kstrtoull(s, base, (unsigned long long *)res);
377 return _kstrtoul(s, base, res);