e2fsprogs: check for bogus new_size in resize2fs

Resolves RH Bug 465984 - resize2fs doesn't recognize bogus argument, ending in infinite loop

If we don't check for new_size == 0, bogus values send resize2fs into a tailspin:

resize2fs 1.41.0 (10-Jul-2008)
Illegal block number passed to ext2fs_test_block_bitmap #1 for block bitmap for /tmp/tmp.lntZtMFvz8/fake-disk
...the same message repeated zillion times...

Probably should see where that loop is, but at any rate we should error-check parse_num_blocks.

Thanks to Petr Muller for reporting this.

---

Index: e2fsprogs/resize/main.c
===================================================================
@@ -376,6 +376,11 @@ int main (int argc, char ** argv)
 	else if (new_size_str) {
 		new_size = parse_num_blocks(new_size_str,
 					    fs->super->s_log_block_size);
+		if (new_size == 0) {
+			com_err(program_name, 0,
+				_("Invalid new size: %s\n"), new_size_str);
+			exit(1);
+		}
 	} else {
 		new_size = max_size;
 		/* Round down to an even multiple of a pagesize */