strncat.c 2.3 KB

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  1. /* $OpenBSD: strncat.c,v 1.6 2015/08/31 02:53:57 guenther Exp $ */
  2. /*-
  3. * Copyright (c) 1990 The Regents of the University of California.
  4. * All rights reserved.
  5. *
  6. * This code is derived from software contributed to Berkeley by
  7. * Chris Torek.
  8. *
  9. * Redistribution and use in source and binary forms, with or without
  10. * modification, are permitted provided that the following conditions
  11. * are met:
  12. * 1. Redistributions of source code must retain the above copyright
  13. * notice, this list of conditions and the following disclaimer.
  14. * 2. Redistributions in binary form must reproduce the above copyright
  15. * notice, this list of conditions and the following disclaimer in the
  16. * documentation and/or other materials provided with the distribution.
  17. * 3. Neither the name of the University nor the names of its contributors
  18. * may be used to endorse or promote products derived from this software
  19. * without specific prior written permission.
  20. *
  21. * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24. * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31. * SUCH DAMAGE.
  32. */
  33. #include <string.h>
  34. /*
  35. * Concatenate src on the end of dst. At most strlen(dst)+n+1 bytes
  36. * are written at dst (at most n+1 bytes being appended). Return dst.
  37. */
  38. #ifdef _TLIBC_USE_INTEL_FAST_STRING_
  39. extern char *_intel_fast_strncat(char *, const char *, size_t);
  40. #endif
  41. char *
  42. strncat(char *dst, const char *src, size_t n)
  43. {
  44. #ifdef _TLIBC_USE_INTEL_FAST_STRING_
  45. return _intel_fast_strncat(dst, src, n);
  46. #else
  47. if (n != 0) {
  48. char *d = dst;
  49. const char *s = src;
  50. while (*d != 0)
  51. d++;
  52. do {
  53. if ((*d = *s++) == 0)
  54. break;
  55. d++;
  56. } while (--n != 0);
  57. *d = 0;
  58. }
  59. return (dst);
  60. #endif
  61. }