basicmbr.h

/* basicmbr.h -- MBR data structure definitions, types, and functions */

/* This program is copyright (c) 2009 by Roderick W. Smith. It is distributed
  under the terms of the GNU GPL version 2, as detailed in the COPYING file. */

#include <stdint.h>
#include <sys/types.h>
#include "partnotes.h"
#include "diskio.h"

#ifndef __BASICMBRSTRUCTS
#define __BASICMBRSTRUCTS

#define MBR_SIGNATURE UINT16_C(0xAA55)
#define MAX_HEADS 255        /* numbered 0 - 254 */
#define MAX_SECSPERTRACK 63  /* numbered 1 - 63 */
#define MAX_CYLINDERS 1024   /* numbered 0 - 1023 */

// Maximum number of MBR partitions
#define MAX_MBR_PARTS 128

using namespace std;

class PartNotes;

/****************************************
 *                                      *
 * MBRData class and related structures *
 *                                      *
 ****************************************/

// Data for a single MBR partition record
// Note that firstSector and lastSector are in CHS addressing, which
// splits the bits up in a weird way.
// On read or write of MBR entries, firstLBA is an absolute disk sector.
// On read of logical entries, it's relative to the EBR record for that
// partition. When writing EBR records, it's relative to the extended
// partition's start.
#pragma pack(1)
struct MBRRecord {
   uint8_t status;
   uint8_t firstSector[3];
   uint8_t partitionType;
   uint8_t lastSector[3];
   uint32_t firstLBA; // see above
   uint32_t lengthLBA;
}; // struct MBRRecord

// A 512-byte data structure into which the MBR can be loaded in one
// go. Also used when loading logical partitions.
#pragma pack(1)
struct TempMBR {
   uint8_t code[440];
   uint32_t diskSignature;
   uint16_t nulls;
   struct MBRRecord partitions[4];
   uint16_t MBRSignature;
}; // struct TempMBR

// Possible states of the MBR
enum MBRValidity {invalid, gpt, hybrid, mbr};

// Full data in tweaked MBR format
class BasicMBRData {
protected:
   uint8_t code[440];
   uint32_t diskSignature;
   uint16_t nulls;
   // MAX_MBR_PARTS defaults to 128. This array holds both the primary and
   // the logical partitions, to simplify data retrieval for GPT conversions.
   struct MBRRecord partitions[MAX_MBR_PARTS];
   uint16_t MBRSignature;

   // Above are basic MBR data; now add more stuff....
   uint32_t blockSize; // block size (usually 512)
   uint64_t diskSize; // size in blocks
   uint64_t numHeads; // number of heads, in CHS scheme
   uint64_t numSecspTrack; // number of sectors per track, in CHS scheme
   DiskIO* myDisk;
   int canDeleteMyDisk;
   string device;
   MBRValidity state;
   struct MBRRecord* GetPartition(int i); // Return primary or logical partition
public:
   BasicMBRData(void);
   BasicMBRData(string deviceFilename);
   ~BasicMBRData(void);
   BasicMBRData & operator=(const BasicMBRData & orig);

   // File I/O functions...
   int ReadMBRData(const string & deviceFilename);
   int ReadMBRData(DiskIO * theDisk, int checkBlockSize = 1);
   // ReadLogicalPart() returns last partition # read to logicals[] array,
   // or -1 if there was a problem....
   int ReadLogicalPart(uint32_t extendedStart, uint32_t diskOffset,
                       int partNum);
   int WriteMBRData(void);
   int WriteMBRData(DiskIO *theDisk);
   int WriteMBRData(const string & deviceFilename);
   int WriteMBRData(struct TempMBR & mbr, DiskIO *theDisk, uint64_t sector);
   void SetDisk(DiskIO *theDisk) {myDisk = theDisk; canDeleteMyDisk = 0;}

   // Display data for user...
   void DisplayMBRData(int maxParts = 4);
   void ShowState(void);

   // Functions that set or get disk metadata (size, CHS geometry, etc.)
   void SetDiskSize(uint64_t ds) {diskSize = ds;}
   void SetBlockSize(uint32_t bs) {blockSize = bs;}
   MBRValidity GetValidity(void) {return state;}
   void SetHybrid(void) {state = hybrid;} // Set hybrid flag
   void SetCHSGeom(uint32_t h, uint32_t s);
   int LBAtoCHS(uint64_t lba, uint8_t * chs); // Convert LBA to CHS
   int Verify(void);

   // Functions to create, delete, or change partitions
   // Pass EmptyMBR 1 to clear the boot loader code, 0 to leave it intact
   void EmptyMBR(int clearBootloader = 1);
   void EmptyBootloader(void);
   void MakePart(int num, uint32_t startLBA, uint32_t lengthLBA, int type = 0x07,
                 int bootable = 0);
   int SetPartType(int num, int type);
   int SetPartBootable(int num, int bootable = 1);
   int MakeBiggestPart(int i, int type); // Make partition filling most space
   void DeletePartition(int i);
   void RecomputeCHS(int partNum);
   int CreateLogicals(PartNotes * notes);

   // Functions to find information on free space....
   uint32_t FindFirstAvailable(uint32_t start = 1);
   uint32_t FindLastInFree(uint32_t start);
   uint32_t FindFirstInFree(uint32_t start);
   int IsFree(uint32_t sector);

   // Functions to extract data on specific partitions....
   uint8_t GetStatus(int i);
   uint8_t GetType(int i);
   uint32_t GetFirstSector(int i);
   uint32_t GetLength(int i);
}; // struct BasicMBRData

#endif