src/commonlib/bsd/string.c

   1 /* SPDX-License-Identifier: BSD-3-Clause */
   2
   3 #include <commonlib/bsd/string.h>
   4 #include <ctype.h>
   5 #include <stddef.h>
   6
   7 size_t strlen(const char *str)
   8 {
   9         const char *ptr = str;
  10
  11         while (*ptr++)
  12                 ;
  13         return ptr - str - 1;
  14 }
  15
  16 size_t strnlen(const char *str, size_t maxlen)
  17 {
  18         const char *ptr = str;
  19         const char *end = str + maxlen;
  20
  21         if (!maxlen)
  22                 return 0;
  23
  24         while (*ptr++) {
  25                 /* Make sure this checks for ==, not >=, because the calculation
  26                    for `end` may overflow in some edge cases. */
  27                 if (ptr == end)
  28                         return maxlen;
  29         }
  30         return ptr - str - 1;
  31 }
  32
  33 char *strcat(char *dst, const char *src)
  34 {
  35         char *ptr = dst + strlen(dst);
  36
  37         while (*src)
  38                 *ptr++ = *src++;
  39
  40         *ptr = '\0';
  41         return dst;
  42 }
  43
  44 char *strncat(char *dst, const char *src, size_t n)
  45 {
  46         char *ptr = dst + strlen(dst);
  47
  48         /* Not using strncpy() because '\0' may not be appended. */
  49         while (n-- > 0 && *src)
  50                 *ptr++ = *src++;
  51
  52         *ptr = '\0';
  53         return dst;
  54 }
  55
  56 unsigned int skip_atoi(char **ptr)
  57 {
  58         unsigned int result = 0;
  59         char *str;
  60
  61         for (str = *ptr; isdigit(str[0]); str++)
  62                 result = result * 10 + (str[0] - '0');
  63         *ptr = str;
  64         return result;
  65 }