| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame] | 1 | /* $OpenBSD: strtol.c,v 1.7 2005/08/08 08:05:37 espie Exp $ */ |
| 2 | /*- |
| 3 | * Copyright (c) 1990 The Regents of the University of California. |
| 4 | * All rights reserved. |
| 5 | * |
| 6 | * Redistribution and use in source and binary forms, with or without |
| 7 | * modification, are permitted provided that the following conditions |
| 8 | * are met: |
| 9 | * 1. Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * 2. Redistributions in binary form must reproduce the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer in the |
| 13 | * documentation and/or other materials provided with the distribution. |
| 14 | * 3. Neither the name of the University nor the names of its contributors |
| 15 | * may be used to endorse or promote products derived from this software |
| 16 | * without specific prior written permission. |
| 17 | * |
| 18 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 19 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 20 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 21 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 22 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 23 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 24 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 25 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 26 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 27 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 28 | * SUCH DAMAGE. |
| 29 | */ |
| 30 | |
| 31 | #include <ctype.h> |
| 32 | #include <errno.h> |
| 33 | #include <limits.h> |
| 34 | #include <stdlib.h> |
| 35 | |
| 36 | |
| 37 | /* |
| 38 | * Convert a string to a long integer. |
| 39 | * |
| 40 | * Ignores `locale' stuff. Assumes that the upper and lower case |
| 41 | * alphabets and digits are each contiguous. |
| 42 | */ |
| 43 | long |
| 44 | strtol(const char *nptr, char **endptr, int base) |
| 45 | { |
| 46 | const char *s; |
| 47 | long acc, cutoff; |
| 48 | int c; |
| 49 | int neg, any, cutlim; |
| 50 | |
| 51 | /* |
| 52 | * Skip white space and pick up leading +/- sign if any. |
| 53 | * If base is 0, allow 0x for hex and 0 for octal, else |
| 54 | * assume decimal; if base is already 16, allow 0x. |
| 55 | */ |
| 56 | s = nptr; |
| 57 | do { |
| 58 | c = (unsigned char) *s++; |
| 59 | } while (isspace(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 | c = s[1]; |
| 71 | s += 2; |
| 72 | base = 16; |
| 73 | } |
| 74 | if (base == 0) |
| 75 | base = c == '0' ? 8 : 10; |
| 76 | |
| 77 | /* |
| 78 | * Compute the cutoff value between legal numbers and illegal |
| 79 | * numbers. That is the largest legal value, divided by the |
| 80 | * base. An input number that is greater than this value, if |
| 81 | * followed by a legal input character, is too big. One that |
| 82 | * is equal to this value may be valid or not; the limit |
| 83 | * between valid and invalid numbers is then based on the last |
| 84 | * digit. For instance, if the range for longs is |
| 85 | * [-2147483648..2147483647] and the input base is 10, |
| 86 | * cutoff will be set to 214748364 and cutlim to either |
| 87 | * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated |
| 88 | * a value > 214748364, or equal but the next digit is > 7 (or 8), |
| 89 | * the number is too big, and we will return a range error. |
| 90 | * |
| 91 | * Set any if any `digits' consumed; make it negative to indicate |
| 92 | * overflow. |
| 93 | */ |
| 94 | cutoff = neg ? LONG_MIN : LONG_MAX; |
| 95 | cutlim = cutoff % base; |
| 96 | cutoff /= base; |
| 97 | if (neg) { |
| 98 | if (cutlim > 0) { |
| 99 | cutlim -= base; |
| 100 | cutoff += 1; |
| 101 | } |
| 102 | cutlim = -cutlim; |
| 103 | } |
| 104 | for (acc = 0, any = 0;; c = (unsigned char) *s++) { |
| 105 | if (isdigit(c)) |
| 106 | c -= '0'; |
| 107 | else if (isalpha(c)) |
| 108 | c -= isupper(c) ? 'A' - 10 : 'a' - 10; |
| 109 | else |
| 110 | break; |
| 111 | if (c >= base) |
| 112 | break; |
| 113 | if (any < 0) |
| 114 | continue; |
| 115 | if (neg) { |
| 116 | if (acc < cutoff || (acc == cutoff && c > cutlim)) { |
| 117 | any = -1; |
| 118 | acc = LONG_MIN; |
| 119 | errno = ERANGE; |
| 120 | } else { |
| 121 | any = 1; |
| 122 | acc *= base; |
| 123 | acc -= c; |
| 124 | } |
| 125 | } else { |
| 126 | if (acc > cutoff || (acc == cutoff && c > cutlim)) { |
| 127 | any = -1; |
| 128 | acc = LONG_MAX; |
| 129 | errno = ERANGE; |
| 130 | } else { |
| 131 | any = 1; |
| 132 | acc *= base; |
| 133 | acc += c; |
| 134 | } |
| 135 | } |
| 136 | } |
| 137 | if (endptr != 0) |
| 138 | *endptr = (char *) (any ? s - 1 : nptr); |
| 139 | return (acc); |
| 140 | } |