1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #if defined(LIBC_SCCS) && !defined(lint) 9 static char sccsid[] = "@(#)strtol.c 5.3 (Berkeley) 05/17/90"; 10 #endif /* LIBC_SCCS and not lint */ 11 12 #include <limits.h> 13 #include <ctype.h> 14 #include <errno.h> 15 #include <stdlib.h> 16 17 18 /* 19 * Convert a string to a long integer. 20 * 21 * Ignores `locale' stuff. Assumes that the upper and lower case 22 * alphabets and digits are each contiguous. 23 */ 24 long 25 strtol(nptr, endptr, base) 26 char *nptr, **endptr; 27 register int base; 28 { 29 register char *s = nptr; 30 register unsigned long acc; 31 register int c; 32 register unsigned long cutoff; 33 register int neg = 0, any, cutlim; 34 35 /* 36 * Skip white space and pick up leading +/- sign if any. 37 * If base is 0, allow 0x for hex and 0 for octal, else 38 * assume decimal; if base is already 16, allow 0x. 39 */ 40 do { 41 c = *s++; 42 } while (isspace(c)); 43 if (c == '-') { 44 neg = 1; 45 c = *s++; 46 } else if (c == '+') 47 c = *s++; 48 if ((base == 0 || base == 16) && 49 c == '0' && (*s == 'x' || *s == 'X')) { 50 c = s[1]; 51 s += 2; 52 base = 16; 53 } 54 if (base == 0) 55 base = c == '0' ? 8 : 10; 56 57 /* 58 * Compute the cutoff value between legal numbers and illegal 59 * numbers. That is the largest legal value, divided by the 60 * base. An input number that is greater than this value, if 61 * followed by a legal input character, is too big. One that 62 * is equal to this value may be valid or not; the limit 63 * between valid and invalid numbers is then based on the last 64 * digit. For instance, if the range for longs is 65 * [-2147483648..2147483647] and the input base is 10, 66 * cutoff will be set to 214748364 and cutlim to either 67 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 68 * a value > 214748364, or equal but the next digit is > 7 (or 8), 69 * the number is too big, and we will return a range error. 70 * 71 * Set any if any `digits' consumed; make it negative to indicate 72 * overflow. 73 */ 74 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX; 75 cutlim = cutoff % (unsigned long)base; 76 cutoff /= (unsigned long)base; 77 for (acc = 0, any = 0;; c = *s++) { 78 if (isdigit(c)) 79 c -= '0'; 80 else if (isalpha(c)) 81 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 82 else 83 break; 84 if (c >= base) 85 break; 86 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim) 87 any = -1; 88 else { 89 any = 1; 90 acc *= base; 91 acc += c; 92 } 93 } 94 if (any < 0) { 95 acc = neg ? LONG_MIN : LONG_MAX; 96 errno = ERANGE; 97 } else if (neg) 98 acc = -acc; 99 if (endptr != 0) 100 *endptr = any ? s - 1 : nptr; 101 return (acc); 102 } 103