Failing against mismatch, make tape to require validation

Author: amissael95

messages/libltfs/root.txt

@@ -834,6 +834,7 @@ v
 		17290I:string { "Partitioning the medium with the destructive method." }
 		17291I:string { "Unpartitioning the medium with the destructive method." }
 		17292I:string { "Current position is (%llu, %llu), Error position is (%llu, %llu)." }
+	 	17293I:string { "Position mismatch. Cached tape position = %llu. Current tape position = %llu." }
 	 	17294I:string { "Continue signal (%d) received" }
 
 		// For Debug 19999I:string { "%s %s %d." }

src/libltfs/ltfs.c

@@ -2536,16 +2536,18 @@ int ltfs_write_index(char partition, char *reason, struct ltfs_volume *vol)
 	/* Get the tape position from the tape drive by using the SCSI command READPOS*/
 	ret = tape_update_position(vol->device, &current_position);
 	if (ret < 0) {
+		/* Return error since the current tape position was unable to be determined, so there could be an undetected position mismatch */
 		ltfsmsg(LTFS_ERR, 11081E, ret);
+		return -1;
 	}
 
 	/* Prior to writing the index, compare the current location of the head position to the head location 
 	that is kept in the cache of ltfs (physical_selfptr). If they are different return error (-1) */
-	ltfsmsg(LTFS_INFO, 11334I, "compare offset", (unsigned long long)physical_selfptr.block, (unsigned long long)current_position.block);
 	diff = ((unsigned long long)physical_selfptr.block - (unsigned long long)current_position.block);
-	if (abs(diff)) {
-		ltfsmsg(LTFS_DEBUG, 16503D, "diff not equal zero", "");
-		//return -1;
+	if (diff) {
+		/* Position mismatch, diff not equal zero */
+		ltfsmsg(LTFS_INFO, 17293I, (unsigned long long)physical_selfptr.block, (unsigned long long)current_position.block);
+		return -1;
 	}
 
 	old_selfptr = vol->index->selfptr;

src/libltfs/tape.c

@@ -1248,11 +1248,16 @@ ssize_t tape_write(struct device_data *dev, const char *buf, size_t count, bool
 		ltfsmsg(LTFS_DEBUG, 16503D, "ltfs_caught_sigcont", "tape_write");
 		ret_for_update_position = tape_update_position(dev, &current_position);
 		if (ret_for_update_position) {
-			// Implement the error handling
+			/* Return error since the current tape position was unable to be determined, so there could be an undetected position mismatch */
+			ltfsmsg(LTFS_ERR, 11081E, ret);
+			return -LTFS_WRITE_ERROR;
 		}
+
 		ltfsmsg(LTFS_INFO, 11334I, "compare offset in tape_write", (unsigned long long)dev->position.block, (unsigned long long)current_position.block);
 		diff = ((unsigned long long)dev->position.block - (unsigned long long)current_position.block);
 		if (diff) {
+			/* Position mismatch, diff not equal zero */
+			ltfsmsg(LTFS_INFO, 17293I, (unsigned long long)dev->position.block, (unsigned long long)current_position.block);
 			return -LTFS_WRITE_ERROR;
 		}
 	}