strcasestr.c 2.8 KB

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  1. /* $NetBSD: strcasestr.c,v 1.3 2005/11/29 03:12:00 christos Exp $ */
  2. /*-
  3. * Copyright (c) 1990, 1993
  4. * The Regents of the University of California. 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. #if defined(LIBC_SCCS) && !defined(lint)
  34. __RCSID("$NetBSD: strcasestr.c,v 1.3 2005/11/29 03:12:00 christos Exp $");
  35. __RCSID("$NetBSD: strncasecmp.c,v 1.2 2007/06/04 18:19:27 christos Exp $");
  36. #endif /* LIBC_SCCS and not lint */
  37. #include "file.h"
  38. #include <assert.h>
  39. #include <ctype.h>
  40. #include <string.h>
  41. static int
  42. _strncasecmp(const char *s1, const char *s2, size_t n)
  43. {
  44. if (n != 0) {
  45. const unsigned char *us1 = (const unsigned char *)s1,
  46. *us2 = (const unsigned char *)s2;
  47. do {
  48. if (tolower(*us1) != tolower(*us2++))
  49. return tolower(*us1) - tolower(*--us2);
  50. if (*us1++ == '\0')
  51. break;
  52. } while (--n != 0);
  53. }
  54. return 0;
  55. }
  56. /*
  57. * Find the first occurrence of find in s, ignore case.
  58. */
  59. char *
  60. strcasestr(const char *s, const char *find)
  61. {
  62. char c, sc;
  63. size_t len;
  64. if ((c = *find++) != 0) {
  65. c = tolower((unsigned char)c);
  66. len = strlen(find);
  67. do {
  68. do {
  69. if ((sc = *s++) == 0)
  70. return (NULL);
  71. } while ((char)tolower((unsigned char)sc) != c);
  72. } while (_strncasecmp(s, find, len) != 0);
  73. s--;
  74. }
  75. return (char *)(intptr_t)(s);
  76. }