/* $OpenBSD: strtol.c,v 1.7 2005/08/08 08:05:37 espie Exp $ */ | |

/*- | |

* Copyright (c) 1990 The Regents of the University of California. | |

* All rights reserved. | |

* | |

* Redistribution and use in source and binary forms, with or without | |

* modification, are permitted provided that the following conditions | |

* are met: | |

* 1. Redistributions of source code must retain the above copyright | |

* notice, this list of conditions and the following disclaimer. | |

* 2. Redistributions in binary form must reproduce the above copyright | |

* notice, this list of conditions and the following disclaimer in the | |

* documentation and/or other materials provided with the distribution. | |

* 3. Neither the name of the University nor the names of its contributors | |

* may be used to endorse or promote products derived from this software | |

* without specific prior written permission. | |

* | |

* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |

* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |

* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |

* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |

* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |

* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |

* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |

* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |

* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |

* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |

* SUCH DAMAGE. | |

*/ | |

#include <ctype.h> | |

#include <errno.h> | |

#include <limits.h> | |

#include <stdlib.h> | |

/* | |

* Convert a string to a long integer. | |

* | |

* Ignores `locale' stuff. Assumes that the upper and lower case | |

* alphabets and digits are each contiguous. | |

*/ | |

long | |

strtol(const char *nptr, char **endptr, int base) | |

{ | |

const char *s; | |

long acc, cutoff; | |

int c; | |

int neg, any, cutlim; | |

/* | |

* Skip white space and pick up leading +/- sign if any. | |

* If base is 0, allow 0x for hex and 0 for octal, else | |

* assume decimal; if base is already 16, allow 0x. | |

*/ | |

s = nptr; | |

do { | |

c = (unsigned char) *s++; | |

} while (isspace(c)); | |

if (c == '-') { | |

neg = 1; | |

c = *s++; | |

} else { | |

neg = 0; | |

if (c == '+') | |

c = *s++; | |

} | |

if ((base == 0 || base == 16) && | |

c == '0' && (*s == 'x' || *s == 'X')) { | |

c = s[1]; | |

s += 2; | |

base = 16; | |

} | |

if (base == 0) | |

base = c == '0' ? 8 : 10; | |

/* | |

* Compute the cutoff value between legal numbers and illegal | |

* numbers. That is the largest legal value, divided by the | |

* base. An input number that is greater than this value, if | |

* followed by a legal input character, is too big. One that | |

* is equal to this value may be valid or not; the limit | |

* between valid and invalid numbers is then based on the last | |

* digit. For instance, if the range for longs is | |

* [-2147483648..2147483647] and the input base is 10, | |

* cutoff will be set to 214748364 and cutlim to either | |

* 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated | |

* a value > 214748364, or equal but the next digit is > 7 (or 8), | |

* the number is too big, and we will return a range error. | |

* | |

* Set any if any `digits' consumed; make it negative to indicate | |

* overflow. | |

*/ | |

cutoff = neg ? LONG_MIN : LONG_MAX; | |

cutlim = cutoff % base; | |

cutoff /= base; | |

if (neg) { | |

if (cutlim > 0) { | |

cutlim -= base; | |

cutoff += 1; | |

} | |

cutlim = -cutlim; | |

} | |

for (acc = 0, any = 0;; c = (unsigned char) *s++) { | |

if (isdigit(c)) | |

c -= '0'; | |

else if (isalpha(c)) | |

c -= isupper(c) ? 'A' - 10 : 'a' - 10; | |

else | |

break; | |

if (c >= base) | |

break; | |

if (any < 0) | |

continue; | |

if (neg) { | |

if (acc < cutoff || (acc == cutoff && c > cutlim)) { | |

any = -1; | |

acc = LONG_MIN; | |

errno = ERANGE; | |

} else { | |

any = 1; | |

acc *= base; | |

acc -= c; | |

} | |

} else { | |

if (acc > cutoff || (acc == cutoff && c > cutlim)) { | |

any = -1; | |

acc = LONG_MAX; | |

errno = ERANGE; | |

} else { | |

any = 1; | |

acc *= base; | |

acc += c; | |

} | |

} | |

} | |

if (endptr != 0) | |

*endptr = (char *) (any ? s - 1 : nptr); | |

return (acc); | |

} |