strlcat.c 1.8 KB

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  1. /* $OpenBSD: strlcat.c,v 1.19 2019/01/25 00:19:25 millert Exp $ */
  2. /*
  3. * Copyright (c) 1998, 2015 Todd C. Miller <millert@openbsd.org>
  4. *
  5. * Permission to use, copy, modify, and distribute this software for any
  6. * purpose with or without fee is hereby granted, provided that the above
  7. * copyright notice and this permission notice appear in all copies.
  8. *
  9. * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10. * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11. * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12. * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13. * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14. * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15. * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16. */
  17. #include <string.h>
  18. /*
  19. * Appends src to string dst of size dsize (unlike strncat, dsize is the
  20. * full size of dst, not space left). At most dsize-1 characters
  21. * will be copied. Always NUL terminates (unless dsize <= strlen(dst)).
  22. * Returns strlen(src) + MIN(dsize, strlen(initial dst)).
  23. * If retval >= dsize, truncation occurred.
  24. */
  25. size_t
  26. strlcat(char *dst, const char *src, size_t dsize)
  27. {
  28. const char *odst = dst;
  29. const char *osrc = src;
  30. size_t n = dsize;
  31. size_t dlen;
  32. /* Find the end of dst and adjust bytes left but don't go past end. */
  33. while (n-- != 0 && *dst != '\0')
  34. dst++;
  35. dlen = dst - odst;
  36. n = dsize - dlen;
  37. if (n-- == 0)
  38. return (dlen + strlen(src));
  39. while (*src != '\0') {
  40. if (n != 0) {
  41. *dst++ = *src;
  42. n--;
  43. }
  44. src++;
  45. }
  46. *dst = '\0';
  47. return (dlen + (src - osrc)); /* count does not include NUL */
  48. }