Cpoy/paste strlcat() from FreeBSD 13.3-RELEASE

src/xpdev/genwrap.c

@@ -81,6 +81,34 @@ size_t strlcpy(char *dst, const char *src, size_t size)
 	*dst = 0;
 	return i;
 }
+
+size_t
+strlcat(char *dst, const char *src, size_t dsize)
+{
+	const char *odst = dst;
+	const char *osrc = src;
+	size_t n = dsize;
+	size_t dlen;
+
+	/* Find the end of dst and adjust bytes left but don't go past end. */
+	while (n-- != 0 && *dst != '\0')
+		dst++;
+	dlen = dst - odst;
+	n = dsize - dlen;
+
+	if (n-- == 0)
+		return(dlen + strlen(src));
+	while (*src != '\0') {
+		if (n != 0) {
+			*dst++ = *src;
+			n--;
+		}
+		src++;
+	}
+	*dst = '\0';
+
+	return(dlen + (src - osrc));    /* count does not include NUL */
+}
 #endif
 
 #ifdef _WIN32

src/xpdev/genwrap.h

@@ -260,6 +260,7 @@ extern "C" {
 
 #if defined(NEEDS_STRLCPY)
 	size_t strlcpy(char *dst, const char *src, size_t size);
+	size_t strlcat(char *dst, const char *src, size_t dstsize);
 #endif
 
 #if defined(_WIN32)