fs: reject NaN sizes and CountSuffix values that overflow

SizeSuffix.Set and CountSuffix.Set accepted "nan" before a suffix, so
--max-transfer nank became -1 ("off") without an error. CountSuffix.Set
also had no overflow check, unlike SizeSuffix, so 10E or infk wrapped
to the same value.

fs/countsuffix.go

@@ -139,10 +139,16 @@ func (x *CountSuffix) Set(s string) error {
 	if err != nil {
 		return err
 	}
+	if math.IsNaN(value) {
+		return fmt.Errorf("size must be a number %q", s)
+	}
 	if value < 0 {
 		return fmt.Errorf("size can't be negative %q", s)
 	}
 	value *= multiplier
+	if value >= float64(CountSuffixMaxValue) {
+		return fmt.Errorf("value can't be greater than %d", int64(CountSuffixMaxValue))
+	}
 	*x = CountSuffix(value)
 	return nil
 }

fs/countsuffix_test.go

@@ -95,6 +95,12 @@ func TestCountSuffixSet(t *testing.T) {
 		{"1iB", 0, true},
 		{"1Ki", 0, true},
 		{"1KiB", 0, true},
+		{"9E", 9 * 1000 * 1000 * 1000 * 1000 * 1000 * 1000, false},
+		{"9.3E", 0, true},
+		{"10E", 0, true},
+		{"infk", 0, true},
+		{"nank", 0, true},
+		{"NaNM", 0, true},
 	} {
 		ss := CountSuffix(0)
 		err := ss.Set(test.in)

fs/sizesuffix.go

@@ -190,6 +190,9 @@ func (x *SizeSuffix) Set(s string) error {
 	if err != nil {
 		return err
 	}
+	if math.IsNaN(value) {
+		return fmt.Errorf("size must be a number %q", s)
+	}
 	if value < 0 {
 		return fmt.Errorf("size can't be negative %q", s)
 	}

fs/sizesuffix_test.go

@@ -131,6 +131,8 @@ func TestSizeSuffixSet(t *testing.T) {
 		{"1i", 0, true},
 		{"1iB", 0, true},
 		{"1MB", 0, true},
+		{"nank", 0, true},
+		{"NaNM", 0, true},
 	} {
 		ss := SizeSuffix(0)
 		err := ss.Set(test.in)