Parsing commandline arguments

ulib/string/conv.c

@@ -0,0 +1,159 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <machine/limits.h>
+#include <string/char.h>
+#include <uprintf.h>
+
+// https://android.googlesource.com/platform/bionic/+/ics-mr0/libc/stdlib/strtoul.c
+unsigned long string_conv_strtoul(const char *nptr, char **endptr, int base)
+{
+	const char *s;
+	unsigned long acc, cutoff;
+	int c;
+	int neg, any, cutlim;
+	/*
+	 * See strtol for comments as to the logic used.
+	 */
+	s = nptr;
+	do {
+		c = (unsigned char) *s++;
+	} while (string_chr_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;
+	cutoff = ULONG_MAX / (unsigned long)base;
+	cutlim = ULONG_MAX % (unsigned long)base;
+	for (acc = 0, any = 0;; c = (unsigned char) *s++) {
+		if (string_chr_isdigit(c))
+			c -= '0';
+		else if (string_chr_isalpha(c))
+			c -= string_chr_isupper(c) ? 'A' - 10 : 'a' - 10;
+		else
+			break;
+		if (c >= base)
+			break;
+		if (any < 0)
+			continue;
+		if (acc > cutoff || (acc == cutoff && c > cutlim)) {
+			any = -1;
+			acc = ULONG_MAX;
+		} else {
+			any = 1;
+			acc *= (unsigned long)base;
+			acc += c;
+		}
+	}
+	if (neg && any > 0)
+		acc = -acc;
+	if (endptr != 0)
+		*endptr = (char *) (any ? s - 1 : nptr);
+	return (acc);
+}
+
+// https://android.googlesource.com/platform/bionic/+/ics-mr0/libc/stdlib/strtol.c
+long string_conv_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 (string_chr_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 (string_chr_isdigit(c))
+			c -= '0';
+		else if (string_chr_isalpha(c))
+			c -= string_chr_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;
+			} else {
+				any = 1;
+				acc *= base;
+				acc -= c;
+			}
+		} else {
+			if (acc > cutoff || (acc == cutoff && c > cutlim)) {
+				any = -1;
+				acc = LONG_MAX;
+			} else {
+				any = 1;
+				acc *= base;
+				acc += c;
+			}
+		}
+	}
+	if (endptr != 0)
+		*endptr = (char *) (any ? s - 1 : nptr);
+	return (acc);
+}