1#define _GNU_SOURCE
2#include <ctype.h>
3#include <string.h>
4
5int strverscmp(const char *l0, const char *r0)
6{
7	const unsigned char *l = (const void *)l0;
8	const unsigned char *r = (const void *)r0;
9	size_t i, dp, j;
10	int z = 1;
11
12	/* Find maximal matching prefix and track its maximal digit
13	 * suffix and whether those digits are all zeros. */
14	for (dp=i=0; l[i]==r[i]; i++) {
15		int c = l[i];
16		if (!c) return 0;
17		if (!isdigit(c)) dp=i+1, z=1;
18		else if (c!='0') z=0;
19	}
20
21	if (l[dp]!='0' && r[dp]!='0') {
22		/* If we're not looking at a digit sequence that began
23		 * with a zero, longest digit string is greater. */
24		for (j=i; isdigit(l[j]); j++)
25			if (!isdigit(r[j])) return 1;
26		if (isdigit(r[j])) return -1;
27	} else if (z && dp<i && (isdigit(l[i]) || isdigit(r[i]))) {
28		/* Otherwise, if common prefix of digit sequence is
29		 * all zeros, digits order less than non-digits. */
30		return (unsigned char)(l[i]-'0') - (unsigned char)(r[i]-'0');
31	}
32
33	return l[i] - r[i];
34}
35