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root/sys/lib/string.c

DEFINITIONS

1. strlcpy
2. strncmp
3. strnlen
4. memcpy
5. memset

   1 /*-
   2  * Copyright (c) 2005-2006, Kohsuke Ohtani
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  30 /*
  31  * string.c - Minimum string library for kernel
  32  */
  34 #include <kernel.h>
  36 /*
  37  * Safer version of strncpy
  38  * The destination string is always terminated with NULL character.
  39  */
size_t
strlcpy(char *dest, const char *src, size_t count)
  42 {
  43         char *d = dest;
  44         const char *s = src;
size_t n = count;
  47         /* Copy as many bytes as will fit */
  48         if (n != 0 && --n != 0) {
  49                 do {
  50                         if ((*d++ = *s++) == 0)
  51                                 break;
  52                 } while (--n != 0);
  53         }
  55         /* Not enough room in dst, add NUL and traverse rest of src */
  56         if (n == 0) {
  57                 if (count != 0)
  58                         *d = '\0';              /* NUL-terminate dst */
  59                 while (*s++)
  60                         ;
  61         }
  63         return (size_t)(s - src - 1);   /* count does not include NUL */
  64 }
  66 int
strncmp(const char *src, const char *tgt, size_t count)
  68 {
  69         signed char res = 0;
  71         while (count) {
  72                 if ((res = *src - *tgt++) != 0 || !*src++)
  73                         break;
count--;
  75         }
  76         return res;
  77 }
  79 /* The returned size does not include the last NULL char */
size_t
strnlen(const char *str, size_t count)
  82 {
  83         const char *tmp;
  85         for (tmp = str; count-- && *tmp != '\0'; ++tmp);
  86         return (size_t)(tmp - str);
  87 }
  89 void *
memcpy(void *dest, const void *src, size_t count)
  91 {
  92         char *tmp = (char *)dest, *s = (char *)src;
ASSERT(count != 0);
  96         while (count--)
  97                 *tmp++ = *s++;
  99         return dest;
 100 }
 102 void *
memset(void *dest, int ch, size_t count)
 104 {
 105         char *p = (char *)dest;
ASSERT(count != 0);
 109         while (count--)
 110                 *p++ = (char)ch;
 112         return dest;
 113 }