1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Taken from: 4 * linux/lib/string.c 5 * 6 * Copyright (C) 1991, 1992 Linus Torvalds 7 */ 8 9 #include <linux/ctype.h> 10 #include <linux/kernel.h> 11 #include <linux/types.h> 12 #include <linux/string.h> 13 14 #ifndef __HAVE_ARCH_STRSTR 15 /** 16 * strstr - Find the first substring in a %NUL terminated string 17 * @s1: The string to be searched 18 * @s2: The string to search for 19 */ 20 char *strstr(const char *s1, const char *s2) 21 { 22 size_t l1, l2; 23 24 l2 = strlen(s2); 25 if (!l2) 26 return (char *)s1; 27 l1 = strlen(s1); 28 while (l1 >= l2) { 29 l1--; 30 if (!memcmp(s1, s2, l2)) 31 return (char *)s1; 32 s1++; 33 } 34 return NULL; 35 } 36 #endif 37 38 #ifndef __HAVE_ARCH_STRNCMP 39 /** 40 * strncmp - Compare two length-limited strings 41 * @cs: One string 42 * @ct: Another string 43 * @count: The maximum number of bytes to compare 44 */ 45 int strncmp(const char *cs, const char *ct, size_t count) 46 { 47 unsigned char c1, c2; 48 49 while (count) { 50 c1 = *cs++; 51 c2 = *ct++; 52 if (c1 != c2) 53 return c1 < c2 ? -1 : 1; 54 if (!c1) 55 break; 56 count--; 57 } 58 return 0; 59 } 60 #endif 61 62 /* Works only for digits and letters, but small and fast */ 63 #define TOLOWER(x) ((x) | 0x20) 64 65 static unsigned int simple_guess_base(const char *cp) 66 { 67 if (cp[0] == '0') { 68 if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2])) 69 return 16; 70 else 71 return 8; 72 } else { 73 return 10; 74 } 75 } 76 77 /** 78 * simple_strtoull - convert a string to an unsigned long long 79 * @cp: The start of the string 80 * @endp: A pointer to the end of the parsed string will be placed here 81 * @base: The number base to use 82 */ 83 84 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base) 85 { 86 unsigned long long result = 0; 87 88 if (!base) 89 base = simple_guess_base(cp); 90 91 if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x') 92 cp += 2; 93 94 while (isxdigit(*cp)) { 95 unsigned int value; 96 97 value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10; 98 if (value >= base) 99 break; 100 result = result * base + value; 101 cp++; 102 } 103 if (endp) 104 *endp = (char *)cp; 105 106 return result; 107 } 108 109 long simple_strtol(const char *cp, char **endp, unsigned int base) 110 { 111 if (*cp == '-') 112 return -simple_strtoull(cp + 1, endp, base); 113 114 return simple_strtoull(cp, endp, base); 115 } 116