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Diffstat (limited to '')
| -rw-r--r-- | lib/libc/strtol.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/lib/libc/strtol.c b/lib/libc/strtol.c new file mode 100644 index 0000000..deb862c --- /dev/null +++ b/lib/libc/strtol.c @@ -0,0 +1,133 @@ +/*- + * SPDX-License-Identifier: BSD-3-Clause + * + * Copyright (c) 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * Copyright (c) 2011 The FreeBSD Foundation + * All rights reserved. + * Portions of this software were developed by David Chisnall + * under sponsorship from the FreeBSD Foundation. + * + * 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 <errno.h> +#include <limits.h> +#include <stddef.h> +#include <stdlib.h> + +/* + * Convert a string to a long integer. + * + * 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; + unsigned long acc; + char c; + unsigned long cutoff; + 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 = *s++; + } while (isspace((unsigned char)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') && + ((s[1] >= '0' && s[1] <= '9') || + (s[1] >= 'A' && s[1] <= 'F') || + (s[1] >= 'a' && s[1] <= 'f'))) { + c = s[1]; + s += 2; + base = 16; + } + if (base == 0) + base = c == '0' ? 8 : 10; + acc = any = 0; + + /* + * 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 ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX + : LONG_MAX; + cutlim = cutoff % base; + cutoff /= base; + for ( ; ; c = *s++) { + if (c >= '0' && c <= '9') + c -= '0'; + else if (c >= 'A' && c <= 'Z') + c -= 'A' - 10; + else if (c >= 'a' && c <= 'z') + c -= 'a' - 10; + else + break; + if (c >= base) + break; + if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim)) + any = -1; + else { + any = 1; + acc *= base; + acc += c; + } + } + if (any < 0) { + acc = neg ? LONG_MIN : LONG_MAX; + } else if (neg) + acc = -acc; + if (endptr != NULL) + *endptr = (char *)(any ? s - 1 : nptr); + return (acc); +} |