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