drivers/firmware/efi/libstub/string.c

   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 }