tools:iio:generic_buffer: catch errors for arguments conversion

Add handler to catch errors on conversion of numerical arguments.
Signed-off-by: NHartmut Knaack <knaack.h@gmx.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

tools/iio/generic_buffer.c

@@ -206,13 +206,22 @@ int main(int argc, char **argv)
 			noevents = 1;
 			break;
 		case 'c':
+			errno = 0;
 			num_loops = strtoul(optarg, &dummy, 10);
+			if (errno)
+				return -errno;
 			break;
 		case 'w':
+			errno = 0;
 			timedelay = strtoul(optarg, &dummy, 10);
+			if (errno)
+				return -errno;
 			break;
 		case 'l':
+			errno = 0;
 			buf_len = strtoul(optarg, &dummy, 10);
+			if (errno)
+				return -errno;
 			break;
 		case 'g':
 			notrigger = 1;