1 #include <precomp.h> 2 3 /* 4 * @implemented 5 */ 6 long 7 CDECL 8 strtol(const char *nptr, char **endptr, int base) 9 { 10 const char *s = nptr; 11 unsigned long acc; 12 int c; 13 unsigned long cutoff; 14 int neg = 0, any, cutlim; 15 16 /* 17 * Skip white space and pick up leading +/- sign if any. 18 * If base is 0, allow 0x for hex and 0 for octal, else 19 * assume decimal; if base is already 16, allow 0x. 20 */ 21 do { 22 c = *s++; 23 } while (isspace(c)); 24 if (c == '-') 25 { 26 neg = 1; 27 c = *s++; 28 } 29 else if (c == '+') 30 c = *s++; 31 if ((base == 0 || base == 16) && 32 c == '0' && (*s == 'x' || *s == 'X')) 33 { 34 c = s[1]; 35 s += 2; 36 base = 16; 37 } 38 if (base == 0) 39 base = c == '0' ? 8 : 10; 40 41 /* 42 * Compute the cutoff value between legal numbers and illegal 43 * numbers. That is the largest legal value, divided by the 44 * base. An input number that is greater than this value, if 45 * followed by a legal input character, is too big. One that 46 * is equal to this value may be valid or not; the limit 47 * between valid and invalid numbers is then based on the last 48 * digit. For instance, if the range for longs is 49 * [-2147483648..2147483647] and the input base is 10, 50 * cutoff will be set to 214748364 and cutlim to either 51 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 52 * a value > 214748364, or equal but the next digit is > 7 (or 8), 53 * the number is too big, and we will return a range error. 54 * 55 * Set any if any `digits' consumed; make it negative to indicate 56 * overflow. 57 */ 58 cutoff = neg ? ((unsigned long)LONG_MAX+1) : LONG_MAX; 59 cutlim = cutoff % (unsigned long)base; 60 cutoff /= (unsigned long)base; 61 for (acc = 0, any = 0;; c = *s++) 62 { 63 if (isdigit(c)) 64 c -= '0'; 65 else if (isalpha(c)) 66 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 67 else 68 break; 69 if (c >= base) 70 break; 71 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim)) 72 any = -1; 73 else 74 { 75 any = 1; 76 acc *= base; 77 acc += c; 78 } 79 } 80 if (any < 0) 81 { 82 acc = neg ? LONG_MIN : LONG_MAX; 83 #ifndef _LIBCNT_ 84 _set_errno(ERANGE); 85 #endif 86 } 87 else if (neg) 88 acc = 0-acc; 89 if (endptr != 0) 90 *endptr = any ? (char *)((size_t)(s - 1)) : (char *)((size_t)nptr); 91 return acc; 92 } 93