1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #if defined(LIBC_SCCS) && !defined(lint) 9 static char sccsid[] = "@(#)strtol.c 8.1 (Berkeley) 06/04/93"; 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 const char *nptr; 27 char **endptr; 28 register int base; 29 { 30 register const char *s = nptr; 31 register unsigned long acc; 32 register int c; 33 register unsigned long cutoff; 34 register int neg = 0, any, cutlim; 35 36 /* 37 * Skip white space and pick up leading +/- sign if any. 38 * If base is 0, allow 0x for hex and 0 for octal, else 39 * assume decimal; if base is already 16, allow 0x. 40 */ 41 do { 42 c = *s++; 43 } while (isspace(c)); 44 if (c == '-') { 45 neg = 1; 46 c = *s++; 47 } else if (c == '+') 48 c = *s++; 49 if ((base == 0 || base == 16) && 50 c == '0' && (*s == 'x' || *s == 'X')) { 51 c = s[1]; 52 s += 2; 53 base = 16; 54 } 55 if (base == 0) 56 base = c == '0' ? 8 : 10; 57 58 /* 59 * Compute the cutoff value between legal numbers and illegal 60 * numbers. That is the largest legal value, divided by the 61 * base. An input number that is greater than this value, if 62 * followed by a legal input character, is too big. One that 63 * is equal to this value may be valid or not; the limit 64 * between valid and invalid numbers is then based on the last 65 * digit. For instance, if the range for longs is 66 * [-2147483648..2147483647] and the input base is 10, 67 * cutoff will be set to 214748364 and cutlim to either 68 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 69 * a value > 214748364, or equal but the next digit is > 7 (or 8), 70 * the number is too big, and we will return a range error. 71 * 72 * Set any if any `digits' consumed; make it negative to indicate 73 * overflow. 74 */ 75 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX; 76 cutlim = cutoff % (unsigned long)base; 77 cutoff /= (unsigned long)base; 78 for (acc = 0, any = 0;; c = *s++) { 79 if (isdigit(c)) 80 c -= '0'; 81 else if (isalpha(c)) 82 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 83 else 84 break; 85 if (c >= base) 86 break; 87 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim) 88 any = -1; 89 else { 90 any = 1; 91 acc *= base; 92 acc += c; 93 } 94 } 95 if (any < 0) { 96 acc = neg ? LONG_MIN : LONG_MAX; 97 errno = ERANGE; 98 } else if (neg) 99 acc = -acc; 100 if (endptr != 0) 101 *endptr = (char *)(any ? s - 1 : nptr); 102 return (acc); 103 } 104