lib/strlfunc.c

   1 /*
   2  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #include <sys/types.h>
  18 #include <string.h>
  19
  20 /*
  21  * Appends src to string dst of size siz (unlike strncat, siz is the
  22  * full size of dst, not space left).  At most siz-1 characters
  23  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
  24  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
  25  * If retval >= siz, truncation occurred.
  26  */
  27 size_t strlcat(char *dst, const char *src, size_t siz) {
  28   register char *d = dst;
  29   register const char *s = src;
  30   register size_t n = siz;
  31   size_t dlen;
  32
  33   /* Find the end of dst and adjust bytes left but don't go past end */
  34   while((n-- != 0) && (*d != '\0'))
  35     d++;
  36
  37   dlen = d - dst;
  38   n = siz - dlen;
  39
  40   if(!n)
  41     return dlen + strlen(s);
  42
  43   while(*s != '\0') {
  44     if(n != 1) {
  45       *d++ = *s;
  46       n--;
  47     }
  48
  49     s++;
  50   }
  51
  52   *d = '\0';
  53
  54   return dlen + (s - src);       /* count does not include NUL */
  55 }
  56
  57 /*
  58  * Copy src to string dst of size siz.  At most siz-1 characters
  59  * will be copied.  Always NUL terminates (unless siz == 0).
  60  * Returns strlen(src); if retval >= siz, truncation occurred.
  61  */
  62 size_t strlcpy(char *dst, const char *src, size_t siz) {
  63   register char *d = dst;
  64   register const char *s = src;
  65   register size_t n = siz;
  66
  67   /* Copy as many bytes as will fit */
  68   if((n != 0) && (--n != 0))
  69     do {
  70       if((*d++ = *s++) == 0)
  71         break;
  72     } while(--n);
  73
  74   /* Not enough room in dst, add NUL and traverse rest of src */
  75   if (n == 0) {
  76     if (siz != 0)
  77       *d = '\0';              /* NUL-terminate dst */
  78     while(*s++) {
  79       /* Empty while */
  80     };
  81   }
  82
  83   return s - src - 1;    /* count does not include NUL */
  84 }