* Convert a string to a long integer. * * Ignores `locale' stuff. Assumes that the upper and lower case * alphabets and digits are each contiguous. */
| 49 | * alphabets and digits are each contiguous. |
| 50 | */ |
| 51 | long |
| 52 | strtol(const char *nptr, char **endptr, int base) |
| 53 | { |
| 54 | const char *s = nptr; |
| 55 | unsigned long acc; |
| 56 | unsigned char c; |
| 57 | unsigned long cutoff; |
| 58 | int neg = 0, any, cutlim; |
| 59 | |
| 60 | /* |
| 61 | * Skip white space and pick up leading +/- sign if any. |
| 62 | * If base is 0, allow 0x for hex and 0 for octal, else |
| 63 | * assume decimal; if base is already 16, allow 0x. |
| 64 | */ |
| 65 | do { |
| 66 | c = *s++; |
| 67 | } while (isspace(c)); |
| 68 | if (c == '-') { |
| 69 | neg = 1; |
| 70 | c = *s++; |
| 71 | } else if (c == '+') |
| 72 | c = *s++; |
| 73 | if ((base == 0 || base == 16) && |
| 74 | c == '0' && (*s == 'x' || *s == 'X')) { |
| 75 | c = s[1]; |
| 76 | s += 2; |
| 77 | base = 16; |
| 78 | } |
| 79 | if (base == 0) |
| 80 | base = c == '0' ? 8 : 10; |
| 81 | |
| 82 | /* |
| 83 | * Compute the cutoff value between legal numbers and illegal |
| 84 | * numbers. That is the largest legal value, divided by the |
| 85 | * base. An input number that is greater than this value, if |
| 86 | * followed by a legal input character, is too big. One that |
| 87 | * is equal to this value may be valid or not; the limit |
| 88 | * between valid and invalid numbers is then based on the last |
| 89 | * digit. For instance, if the range for longs is |
| 90 | * [-2147483648..2147483647] and the input base is 10, |
| 91 | * cutoff will be set to 214748364 and cutlim to either |
| 92 | * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated |
| 93 | * a value > 214748364, or equal but the next digit is > 7 (or 8), |
| 94 | * the number is too big, and we will return a range error. |
| 95 | * |
| 96 | * Set any if any `digits' consumed; make it negative to indicate |
| 97 | * overflow. |
| 98 | */ |
| 99 | cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX; |
| 100 | cutlim = cutoff % (unsigned long)base; |
| 101 | cutoff /= (unsigned long)base; |
| 102 | for (acc = 0, any = 0;; c = *s++) { |
| 103 | if (!isascii(c)) |
| 104 | break; |
| 105 | if (isdigit(c)) |
| 106 | c -= '0'; |
| 107 | else if (isalpha(c)) |
| 108 | c -= isupper(c) ? 'A' - 10 : 'a' - 10; |