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authorArnold D. Robbins <arnold@skeeve.com>2010-07-16 12:04:45 +0300
committerArnold D. Robbins <arnold@skeeve.com>2010-07-16 12:04:45 +0300
commitdbd583bd2b8a6dd40c622875a4e197360cb5aba7 (patch)
treed9fb7b6595cb44fefb4e32d70af9ac6d057af14a /missing/strtol.c
parentb8c608200919aa3f7b3fef289a7bece2d2961412 (diff)
downloadegawk-dbd583bd2b8a6dd40c622875a4e197360cb5aba7.tar.gz
egawk-dbd583bd2b8a6dd40c622875a4e197360cb5aba7.tar.bz2
egawk-dbd583bd2b8a6dd40c622875a4e197360cb5aba7.zip
Move to 2.13.3 (from 2.13.tar.gz - sigh).
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+/*
+Article 4291 of comp.lang.c:
+From: chris@mimsy.umd.edu (Chris Torek)
+Newsgroups: comp.lang.c
+Subject: Re: error checking strtol
+Message-ID: <24445@mimsy.umd.edu>
+Date: 17 May 90 09:31:17 GMT
+Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
+
+The following is a working strtol. It depends only on the existence of
+correct header files (including <limits.h>) and on ASCII (IBM programmers
+will have to use strchr()). It does not support locales other than `C'.
+System V programmers should be able to replace their current strtol with
+this one. (After writing this, I checked the SVR2 source; it did not
+handle several cases correctly.)
+*/
+
+#ifdef __STDC__
+#include <limits.h>
+#else
+#define LONG_MIN (-0x80000000) /* for 32-bit 2s-complement at least */
+#define LONG_MAX 0x7fffffff
+#endif
+
+#if 0
+#include <limits.h>
+#include <ctype.h>
+#include <errno.h>
+#endif
+
+#ifndef _MSC_VER
+int errno;
+#endif
+
+/*
+ * 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(nptr, endptr, base)
+ const char *nptr;
+ char **endptr;
+ register int base;
+{
+ register const char *s = nptr;
+ register unsigned long acc;
+ register int c;
+ register unsigned long cutoff;
+ register int neg = 0, 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.
+ */
+ do {
+ c = *s++;
+ } while (isspace(c));
+ if (c == '-') {
+ neg = 1;
+ c = *s++;
+ } else 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 ? -(unsigned long)LONG_MIN : LONG_MAX;
+ cutlim = cutoff % (unsigned long)base;
+ cutoff /= (unsigned long)base;
+ for (acc = 0, any = 0;; c = *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 || acc > cutoff || acc == cutoff && c > cutlim)
+ any = -1;
+ else {
+ any = 1;
+ acc *= base;
+ acc += c;
+ }
+ }
+ if (any < 0) {
+ acc = neg ? LONG_MIN : LONG_MAX;
+ errno = ERANGE;
+ } else if (neg)
+ acc = -acc;
+ if (endptr != 0)
+ *endptr = (char *) (any ? s - 1 : nptr);
+ return (acc);
+}