strtoul.c 3.2 KB

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  1. /*-
  2. * SPDX-License-Identifier: BSD-3-Clause
  3. *
  4. * Copyright (c) 1990, 1993
  5. * The Regents of the University of California. All rights reserved.
  6. *
  7. * Copyright (c) 2011 The FreeBSD Foundation
  8. * All rights reserved.
  9. * Portions of this software were developed by David Chisnall
  10. * under sponsorship from the FreeBSD Foundation.
  11. *
  12. * Redistribution and use in source and binary forms, with or without
  13. * modification, are permitted provided that the following conditions
  14. * are met:
  15. * 1. Redistributions of source code must retain the above copyright
  16. * notice, this list of conditions and the following disclaimer.
  17. * 2. Redistributions in binary form must reproduce the above copyright
  18. * notice, this list of conditions and the following disclaimer in the
  19. * documentation and/or other materials provided with the distribution.
  20. * 3. Neither the name of the University nor the names of its contributors
  21. * may be used to endorse or promote products derived from this software
  22. * without specific prior written permission.
  23. *
  24. * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27. * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34. * SUCH DAMAGE.
  35. */
  36. #include <errno.h>
  37. #include <limits.h>
  38. #include <stddef.h>
  39. #include <stdlib.h>
  40. /*
  41. * Convert a string to an unsigned long integer.
  42. *
  43. * Assumes that the upper and lower case
  44. * alphabets and digits are each contiguous.
  45. */
  46. unsigned long strtoul(const char *nptr, char **endptr, int base)
  47. {
  48. const char *s;
  49. unsigned long acc;
  50. char c;
  51. unsigned long cutoff;
  52. int neg, any, cutlim;
  53. /*
  54. * See strtol for comments as to the logic used.
  55. */
  56. s = nptr;
  57. do {
  58. c = *s++;
  59. } while (isspace((unsigned char)c));
  60. if (c == '-') {
  61. neg = 1;
  62. c = *s++;
  63. } else {
  64. neg = 0;
  65. if (c == '+')
  66. c = *s++;
  67. }
  68. if ((base == 0 || base == 16) &&
  69. c == '0' && (*s == 'x' || *s == 'X') &&
  70. ((s[1] >= '0' && s[1] <= '9') ||
  71. (s[1] >= 'A' && s[1] <= 'F') ||
  72. (s[1] >= 'a' && s[1] <= 'f'))) {
  73. c = s[1];
  74. s += 2;
  75. base = 16;
  76. }
  77. if (base == 0)
  78. base = c == '0' ? 8 : 10;
  79. acc = any = 0;
  80. cutoff = ULONG_MAX / base;
  81. cutlim = ULONG_MAX % base;
  82. for ( ; ; c = *s++) {
  83. if (c >= '0' && c <= '9')
  84. c -= '0';
  85. else if (c >= 'A' && c <= 'Z')
  86. c -= 'A' - 10;
  87. else if (c >= 'a' && c <= 'z')
  88. c -= 'a' - 10;
  89. else
  90. break;
  91. if (c >= base)
  92. break;
  93. if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
  94. any = -1;
  95. else {
  96. any = 1;
  97. acc *= base;
  98. acc += c;
  99. }
  100. }
  101. if (any < 0) {
  102. acc = ULONG_MAX;
  103. } else if (neg)
  104. acc = -acc;
  105. if (endptr != NULL)
  106. *endptr = (char *)(any ? s - 1 : nptr);
  107. return (acc);
  108. }