small improvements in str -> num convertors
diff --git a/libbb/xatonum.c b/libbb/xatonum.c
index 910667c..0d487dd 100644
--- a/libbb/xatonum.c
+++ b/libbb/xatonum.c
@@ -52,6 +52,15 @@
 #endif
 
 #if UINT_MAX != ULONG_MAX
+extern inline unsigned bb_strtoui(const char *str, char **end, int b)
+{
+	unsigned long v = strtoul(str, end, b);
+	if (v > UINT_MAX) {
+		errno = ERANGE;
+		return UINT_MAX;
+	}
+	return v;
+}
 #define type int
 #define xstrtou(rest) xstrtou##rest
 #define xstrto(rest) xstrtoi##rest
@@ -60,7 +69,8 @@
 #define XSTR_UTYPE_MAX UINT_MAX
 #define XSTR_TYPE_MAX INT_MAX
 #define XSTR_TYPE_MIN INT_MIN
-#define XSTR_STRTOU strtoul
+/* libc has no strtoui, so we need to create/use our own */
+#define XSTR_STRTOU bb_strtoui
 #include "xatonum_template.c"
 #undef type
 #undef xstrtou
@@ -77,7 +87,7 @@
 
 int xatoi_u(const char *numstr)
 {
-	return xatoul_range(numstr, 0, INT_MAX);
+	return xatou_range(numstr, 0, INT_MAX);
 }
 
 uint32_t xatou32(const char *numstr)
@@ -87,5 +97,5 @@
 
 uint16_t xatou16(const char *numstr)
 {
-	return xatoul_range(numstr, 0, 0xffff);
+	return xatou_range(numstr, 0, 0xffff);
 }