fix critical error where disk is wiped when deleting logical

The error occurred if there were 23 logical partitions defined for
a drive. FDISK then wrote a zeroed-out EMBR to sector 0.

Author: boeckmann

source/fdisk/pcompute.c

@@ -72,6 +72,11 @@ int Create_Logical_Drive( int numeric_type, unsigned long size_in_MB )
 
    int free_space_loc = pDrive->log_free_loc;
 
+   if ( ( (pDrive->num_of_log_drives >= MAX_LOGICAL_DRIVES ) && ( free_space_loc != 0 ) ) ||
+        ( (pDrive->num_of_log_drives > MAX_LOGICAL_DRIVES ) && ( free_space_loc == 0 ) ) ) {
+      /* ran out of data table space */
+      return 99;
+   }
    if ( !pDrive->usable || !pDrive->ext_usable ) {
       return 99;
    }

source/fdisk/pdiskio.c

@@ -835,6 +835,7 @@ int Delete_EMBR_Chain_Node( Partition_Table *pDrive,
       Clear_Partition( &pDrive->next_ext[MAX_LOGICAL_DRIVES - 1] );
       pDrive->log_drive_created[MAX_LOGICAL_DRIVES - 1] = FALSE;
       pDrive->next_ext_exists[MAX_LOGICAL_DRIVES - 1] = FALSE;
+      pDrive->next_ext_exists[MAX_LOGICAL_DRIVES - 2] = FALSE;
       pDrive->num_of_log_drives--;
    }
    else {