Blocksize and sectorsize are unique in that they must
be provided, unlike every other suffix which can be
calculated from constants.

Nothing protects against unspecified block & sector size,
so catch it if it happens and return a parsing error.

Signed-off-by: Eric Sandeen <redacted>
---

diff --git a/libxcmd/input.c b/libxcmd/input.c
index 7a69dc1..7b86225 100644
--- a/libxcmd/input.c
+++ b/libxcmd/input.c

@@ -330,8 +330,12 @@ cvtnum(
 	c = tolower(*sp);
 	switch (c) {
 	case 'b':
+		if (!blocksize)
+			return -1LL;
 		return i * blocksize;
 	case 's':
+		if (!sectorsize)
+			return -1LL;
 		return i * sectorsize;
 	case 'k':
 		return KILOBYTES(i);