338 lines
7.0 KiB
C
338 lines
7.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright 2007 rPath, Inc. - All Rights Reserved
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*
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* ----------------------------------------------------------------------- */
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/*
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* Very basic string functions
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*/
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#include <linux/types.h>
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#include <linux/compiler.h>
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#include <linux/errno.h>
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#include <linux/limits.h>
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#include <asm/asm.h>
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#include "ctype.h"
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#include "string.h"
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#define KSTRTOX_OVERFLOW (1U << 31)
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/*
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* Undef these macros so that the functions that we provide
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* here will have the correct names regardless of how string.h
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* may have chosen to #define them.
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*/
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#undef memcpy
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#undef memset
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#undef memcmp
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int memcmp(const void *s1, const void *s2, size_t len)
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{
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bool diff;
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asm("repe; cmpsb" CC_SET(nz)
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: CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len));
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return diff;
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}
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/*
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* Clang may lower `memcmp == 0` to `bcmp == 0`.
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*/
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int bcmp(const void *s1, const void *s2, size_t len)
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{
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return memcmp(s1, s2, len);
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}
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int strcmp(const char *str1, const char *str2)
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{
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const unsigned char *s1 = (const unsigned char *)str1;
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const unsigned char *s2 = (const unsigned char *)str2;
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int delta = 0;
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while (*s1 || *s2) {
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delta = *s1 - *s2;
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if (delta)
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return delta;
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s1++;
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s2++;
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}
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return 0;
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}
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int strncmp(const char *cs, const char *ct, size_t count)
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{
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unsigned char c1, c2;
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while (count) {
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c1 = *cs++;
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c2 = *ct++;
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if (c1 != c2)
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return c1 < c2 ? -1 : 1;
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if (!c1)
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break;
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count--;
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}
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return 0;
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}
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size_t strnlen(const char *s, size_t maxlen)
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{
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const char *es = s;
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while (*es && maxlen) {
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es++;
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maxlen--;
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}
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return (es - s);
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}
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unsigned int atou(const char *s)
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{
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unsigned int i = 0;
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while (isdigit(*s))
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i = i * 10 + (*s++ - '0');
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return i;
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}
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/* Works only for digits and letters, but small and fast */
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#define TOLOWER(x) ((x) | 0x20)
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static unsigned int simple_guess_base(const char *cp)
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{
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if (cp[0] == '0') {
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if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
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return 16;
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else
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return 8;
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} else {
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return 10;
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}
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}
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/**
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* simple_strtoull - convert a string to an unsigned long long
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* @cp: The start of the string
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* @endp: A pointer to the end of the parsed string will be placed here
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* @base: The number base to use
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*/
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unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
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{
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unsigned long long result = 0;
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if (!base)
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base = simple_guess_base(cp);
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if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
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cp += 2;
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while (isxdigit(*cp)) {
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unsigned int value;
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value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
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if (value >= base)
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break;
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result = result * base + value;
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cp++;
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}
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if (endp)
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*endp = (char *)cp;
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return result;
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}
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long simple_strtol(const char *cp, char **endp, unsigned int base)
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{
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if (*cp == '-')
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return -simple_strtoull(cp + 1, endp, base);
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return simple_strtoull(cp, endp, base);
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}
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/**
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* strlen - Find the length of a string
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* @s: The string to be sized
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*/
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size_t strlen(const char *s)
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{
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const char *sc;
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for (sc = s; *sc != '\0'; ++sc)
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/* nothing */;
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return sc - s;
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}
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/**
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* strstr - Find the first substring in a %NUL terminated string
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* @s1: The string to be searched
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* @s2: The string to search for
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*/
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char *strstr(const char *s1, const char *s2)
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{
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size_t l1, l2;
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l2 = strlen(s2);
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if (!l2)
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return (char *)s1;
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l1 = strlen(s1);
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while (l1 >= l2) {
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l1--;
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if (!memcmp(s1, s2, l2))
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return (char *)s1;
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s1++;
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}
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return NULL;
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}
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/**
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* strchr - Find the first occurrence of the character c in the string s.
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* @s: the string to be searched
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* @c: the character to search for
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*/
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char *strchr(const char *s, int c)
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{
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while (*s != (char)c)
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if (*s++ == '\0')
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return NULL;
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return (char *)s;
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}
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static inline u64 __div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
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{
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union {
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u64 v64;
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u32 v32[2];
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} d = { dividend };
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u32 upper;
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upper = d.v32[1];
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d.v32[1] = 0;
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if (upper >= divisor) {
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d.v32[1] = upper / divisor;
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upper %= divisor;
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}
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asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
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"rm" (divisor), "0" (d.v32[0]), "1" (upper));
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return d.v64;
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}
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static inline u64 __div_u64(u64 dividend, u32 divisor)
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{
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u32 remainder;
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return __div_u64_rem(dividend, divisor, &remainder);
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}
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static inline char _tolower(const char c)
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{
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return c | 0x20;
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}
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static const char *_parse_integer_fixup_radix(const char *s, unsigned int *base)
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{
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if (*base == 0) {
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if (s[0] == '0') {
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if (_tolower(s[1]) == 'x' && isxdigit(s[2]))
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*base = 16;
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else
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*base = 8;
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} else
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*base = 10;
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}
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if (*base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
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s += 2;
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return s;
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}
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/*
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* Convert non-negative integer string representation in explicitly given radix
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* to an integer.
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* Return number of characters consumed maybe or-ed with overflow bit.
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* If overflow occurs, result integer (incorrect) is still returned.
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*
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* Don't you dare use this function.
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*/
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static unsigned int _parse_integer(const char *s,
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unsigned int base,
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unsigned long long *p)
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{
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unsigned long long res;
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unsigned int rv;
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res = 0;
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rv = 0;
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while (1) {
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unsigned int c = *s;
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unsigned int lc = c | 0x20; /* don't tolower() this line */
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unsigned int val;
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if ('0' <= c && c <= '9')
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val = c - '0';
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else if ('a' <= lc && lc <= 'f')
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val = lc - 'a' + 10;
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else
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break;
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if (val >= base)
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break;
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/*
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* Check for overflow only if we are within range of
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* it in the max base we support (16)
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*/
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if (unlikely(res & (~0ull << 60))) {
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if (res > __div_u64(ULLONG_MAX - val, base))
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rv |= KSTRTOX_OVERFLOW;
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}
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res = res * base + val;
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rv++;
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s++;
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}
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*p = res;
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return rv;
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}
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static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
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{
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unsigned long long _res;
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unsigned int rv;
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s = _parse_integer_fixup_radix(s, &base);
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rv = _parse_integer(s, base, &_res);
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if (rv & KSTRTOX_OVERFLOW)
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return -ERANGE;
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if (rv == 0)
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return -EINVAL;
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s += rv;
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if (*s == '\n')
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s++;
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if (*s)
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return -EINVAL;
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*res = _res;
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return 0;
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}
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/**
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* kstrtoull - convert a string to an unsigned long long
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* @s: The start of the string. The string must be null-terminated, and may also
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* include a single newline before its terminating null. The first character
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* may also be a plus sign, but not a minus sign.
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* @base: The number base to use. The maximum supported base is 16. If base is
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* given as 0, then the base of the string is automatically detected with the
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* conventional semantics - If it begins with 0x the number will be parsed as a
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* hexadecimal (case insensitive), if it otherwise begins with 0, it will be
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* parsed as an octal number. Otherwise it will be parsed as a decimal.
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* @res: Where to write the result of the conversion on success.
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*
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* Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
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* Used as a replacement for the obsolete simple_strtoull. Return code must
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* be checked.
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*/
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int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
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{
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if (s[0] == '+')
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s++;
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return _kstrtoull(s, base, res);
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}
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