tools: iio: iio_utils: fix digit calculation

The iio_utils uses a digit calculation in order to know length of the
file name containing a buffer number. The digit calculation does not
work for number 0.

This leads to allocation of one character too small buffer for the
file-name when file name contains value '0'. (Eg. buffer0).

Fix digit calculation by returning one digit to be present for number
'0'.

Fixes: 096f9b8 ("tools:iio:iio_utils: implement digit calculation")
Signed-off-by: Matti Vaittinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Cc: <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>

tools/iio/iio_utils.c

@@ -547,6 +547,10 @@ static int calc_digits(int num)
 {
 	int count = 0;
 
+	/* It takes a digit to represent zero */
+	if (!num)
+		return 1;
+
 	while (num != 0) {
 		num /= 10;
 		count++;