Refactor fmt_human() and fix a bug

It is not necessary to copy memory or anything. Just keep a pointer to
the active prefix-array and assign the length of the arrays to a
variable.

Make the code more readable by using a switch, be more strict when an
invalid base is passed to it and fix a small oversight in the bottom of
the code where the base 1024 was forgotten to generalized.

util.c

@@ -89,21 +89,29 @@ bprintf(const char *fmt, ...)
 const char *
 fmt_human(size_t num, int base)
 {
-	size_t i;
 	double scaled;
-	const char *siprefix[] = { "", "k", "M", "G", "T", "P", "E", "Z", "Y" };
-	const char *iecprefix[] = { "", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei",
-	                            "Zi", "Yi" };
-	char *prefix[9];
-
-	if (base == 1000) {
-		memcpy(prefix, siprefix, sizeof(prefix));
-	} else if (base == 1024) {
-		memcpy(prefix, iecprefix, sizeof(prefix));
+	size_t i, prefixlen;
+	const char **prefix;
+	const char *prefix_1000[] = { "", "k", "M", "G", "T", "P", "E", "Z", "Y" };
+	const char *prefix_1024[] = { "", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei",
+	                              "Zi", "Yi" };
+
+	switch (base) {
+	case 1000:
+		prefix = prefix_1000;
+		prefixlen = LEN(prefix_1000);
+		break;
+	case 1024:
+		prefix = prefix_1024;
+		prefixlen = LEN(prefix_1024);
+		break;
+	default:
+		warn("fmt_human: Invalid base");
+		return NULL;
 	}
 
 	scaled = num;
-	for (i = 0; i < LEN(prefix) && scaled >= 1024; i++) {
+	for (i = 0; i < prefixlen && scaled >= base; i++) {
 		scaled /= base;
 	}
 

util.h

@@ -10,5 +10,5 @@ void die(const char *, ...);
 
 int esnprintf(char *str, size_t size, const char *fmt, ...);
 const char *bprintf(const char *fmt, ...);
-const char *fmt_human(size_t num, int iec);
+const char *fmt_human(size_t num, int base);
 int pscanf(const char *path, const char *fmt, ...);