1 files changed, 91 insertions, 0 deletions
diff --git a/lib/libc/string/strverscmp.c b/lib/libc/string/strverscmp.c
new file mode 100644
index 000000000000..6051adb35499
--- /dev/null
+++ b/lib/libc/string/strverscmp.c
@@ -0,0 +1,91 @@
+/*-
+* SPDX-License-Identifier: BSD-2-Clause
+* Copyright (c) 2022 Aymeric Wibo <obiwac@gmail.com>
+*/
+
+#include <ctype.h>
+#include <stddef.h>
+
+int
+strverscmp(const char *s1, const char *s2)
+{
+	size_t digit_count_1, digit_count_2;
+	size_t zeros_count_1, zeros_count_2;
+	const unsigned char *num_1, *num_2;
+	const unsigned char *u1 = __DECONST(const unsigned char *, s1);
+	const unsigned char *u2 = __DECONST(const unsigned char *, s2);
+
+	/*
+	 * If pointers are the same, no need to go through to process of
+	 * comparing them.
+	 */
+	if (s1 == s2)
+		return (0);
+
+	while (*u1 != '\0' && *u2 != '\0') {
+		/* If either character is not a digit, act like strcmp(3). */
+
+		if (!isdigit(*u1) || !isdigit(*u2)) {
+			if (*u1 != *u2)
+				return (*u1 - *u2);
+			u1++;
+			u2++;
+			continue;
+		}
+		if (*u1 == '0' || *u2 == '0') {
+			/*
+			 * Treat leading zeros as if they were the fractional
+			 * part of a number, i.e. as if they had a decimal point
+			 * in front. First, count the leading zeros (more zeros
+			 * == smaller number).
+			 */
+			zeros_count_1 = 0;
+			zeros_count_2 = 0;
+			for (; *u1 == '0'; u1++)
+				zeros_count_1++;
+			for (; *u2 == '0'; u2++)
+				zeros_count_2++;
+			if (zeros_count_1 != zeros_count_2)
+				return (zeros_count_2 - zeros_count_1);
+
+			/* Handle the case where 0 < 09. */
+			if (!isdigit(*u1) && isdigit(*u2))
+				return (1);
+			if (!isdigit(*u2) && isdigit(*u1))
+				return (-1);
+		} else {
+			/*
+			 * No leading zeros; we're simply comparing two numbers.
+			 * It is necessary to first count how many digits there
+			 * are before going back to compare each digit, so that
+			 * e.g. 7 is not considered larger than 60.
+			 */
+			num_1 = u1;
+			num_2 = u2;
+
+			/* Count digits (more digits == larger number). */
+			for (; isdigit(*u1); u1++)
+				;
+			for (; isdigit(*u2); u2++)
+				;
+			digit_count_1 = u1 - num_1;
+			digit_count_2 = u2 - num_2;
+			if (digit_count_1 != digit_count_2)
+				return (digit_count_1 - digit_count_2);
+
+			/*
+			 * If there are the same number of digits, go back to
+			 * the start of the number.
+			 */
+			u1 = num_1;
+			u2 = num_2;
+		}
+
+		/* Compare each digit until there are none left. */
+		for (; isdigit(*u1) && isdigit(*u2); u1++, u2++) {
+			if (*u1 != *u2)
+				return (*u1 - *u2);
+		}
+	}
+	return (*u1 - *u2);
+}