partitions/ibm: Introduce defines for magic string length values

The length values for volume label type and volume label id are
hard-coded in several places. Provide defines for those values and
replace all occurrences accordingly.

Note that the length is defined and used, and not the size since the
volume label type string and volume label id string are not
nul-terminated.
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://lore.kernel.org/r/20230915131001.697070-4-sth@linux.ibm.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/partitions/ibm.c

@@ -61,6 +61,10 @@ static sector_t cchhb2blk(struct vtoc_cchhb *ptr, struct hd_geometry *geo)
 		ptr->b;
 }
 
+/* Volume Label Type/ID Length */
+#define DASD_VOL_TYPE_LEN	4
+#define DASD_VOL_ID_LEN		6
+
 /* Volume Label Types */
 #define DASD_VOLLBL_TYPE_VOL1 0
 #define DASD_VOLLBL_TYPE_LNX1 1
@@ -91,7 +95,7 @@ static int get_label_by_type(const char *type)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(dasd_vollabels); i++) {
-		if (!memcmp(type, dasd_vollabels[i].type, 4))
+		if (!memcmp(type, dasd_vollabels[i].type, DASD_VOL_TYPE_LEN))
 			return dasd_vollabels[i].idx;
 	}
 
@@ -138,19 +142,19 @@ static int find_label(struct parsed_partitions *state,
 		if (data == NULL)
 			continue;
 		memcpy(label, data, sizeof(*label));
-		memcpy(type, data, 4);
-		EBCASC(type, 4);
+		memcpy(type, data, DASD_VOL_TYPE_LEN);
+		EBCASC(type, DASD_VOL_TYPE_LEN);
 		put_dev_sector(sect);
 		switch (get_label_by_type(type)) {
 		case DASD_VOLLBL_TYPE_VOL1:
-			memcpy(name, label->vol.volid, 6);
-			EBCASC(name, 6);
+			memcpy(name, label->vol.volid, DASD_VOL_ID_LEN);
+			EBCASC(name, DASD_VOL_ID_LEN);
 			*labelsect = testsect[i];
 			return 1;
 		case DASD_VOLLBL_TYPE_LNX1:
 		case DASD_VOLLBL_TYPE_CMS1:
-			memcpy(name, label->lnx.volid, 6);
-			EBCASC(name, 6);
+			memcpy(name, label->lnx.volid, DASD_VOL_ID_LEN);
+			EBCASC(name, DASD_VOL_ID_LEN);
 			*labelsect = testsect[i];
 			return 1;
 		default:
@@ -328,8 +332,8 @@ int ibm_partition(struct parsed_partitions *state)
 	sector_t nr_sectors;
 	dasd_information2_t *info;
 	struct hd_geometry *geo;
-	char type[5] = {0,};
-	char name[7] = {0,};
+	char type[DASD_VOL_TYPE_LEN + 1] = "";
+	char name[DASD_VOL_ID_LEN + 1] = "";
 	sector_t labelsect;
 	union label_t *label;