[mirror_edk2.git] / MdeModulePkg / Universal / Disk / PartitionDxe / Mbr.c

/** @file\r
  Decode a hard disk partitioned with the legacy MBR found on most PC's\r
\r
  MBR - Master Boot Record is in the first sector of a partitioned hard disk.\r
        The MBR supports four partitions per disk. The MBR also contains legacy\r
        code that is not run on an EFI system. The legacy code reads the \r
        first sector of the active partition into memory and \r
\r
  BPB - Boot(?) Parameter Block is in the first sector of a FAT file system. \r
        The BPB contains information about the FAT file system. The BPB is \r
        always on the first sector of a media. The first sector also contains\r
        the legacy boot strap code.\r
\r
Copyright (c) 2006 - 2008, Intel Corporation. <BR>\r
All rights reserved. This program and the accompanying materials\r
are licensed and made available under the terms and conditions of the BSD License\r
which accompanies this distribution.  The full text of the license may be found at\r
http://opensource.org/licenses/bsd-license.php\r
\r
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
**/\r
\r
#include "Partition.h"\r
\r
/**\r
  Test to see if the Mbr buffer is a valid MBR.\r
\r
  @param  Mbr         Parent Handle.\r
  @param  LastLba     Last Lba address on the device.\r
   \r
  @retval TRUE        Mbr is a Valid MBR.\r
  @retval FALSE       Mbr is not a Valid MBR.\r
\r
**/\r
STATIC\r
BOOLEAN\r
PartitionValidMbr (\r
  IN  MASTER_BOOT_RECORD      *Mbr,\r
  IN  EFI_LBA                 LastLba\r
  )\r
{\r
  UINT32  StartingLBA;\r
  UINT32  EndingLBA;\r
  UINT32  NewEndingLBA;\r
  INTN    Index1;\r
  INTN    Index2;\r
  BOOLEAN MbrValid;\r
\r
  if (Mbr->Signature != MBR_SIGNATURE) {\r
    return FALSE;\r
  }\r
  //\r
  // The BPB also has this signature, so it can not be used alone.\r
  //\r
  MbrValid = FALSE;\r
  for (Index1 = 0; Index1 < MAX_MBR_PARTITIONS; Index1++) {\r
    if (Mbr->Partition[Index1].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) == 0) {\r
      continue;\r
    }\r
\r
    MbrValid    = TRUE;\r
    StartingLBA = UNPACK_UINT32 (Mbr->Partition[Index1].StartingLBA);\r
    EndingLBA   = StartingLBA + UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) - 1;\r
    if (EndingLBA > LastLba) {\r
      //\r
      // Compatibility Errata:\r
      //  Some systems try to hide drive space with their INT 13h driver\r
      //  This does not hide space from the OS driver. This means the MBR\r
      //  that gets created from DOS is smaller than the MBR created from\r
      //  a real OS (NT & Win98). This leads to BlockIo->LastBlock being\r
      //  wrong on some systems FDISKed by the OS.\r
      //\r
      // return FALSE since no block devices on a system are implemented\r
      // with INT 13h\r
      //\r
      return FALSE;\r
    }\r
\r
    for (Index2 = Index1 + 1; Index2 < MAX_MBR_PARTITIONS; Index2++) {\r
      if (Mbr->Partition[Index2].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) == 0) {\r
        continue;\r
      }\r
\r
      NewEndingLBA = UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) + UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) - 1;\r
      if (NewEndingLBA >= StartingLBA && UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) <= EndingLBA) {\r
        //\r
        // This region overlaps with the Index1'th region\r
        //\r
        return FALSE;\r
      }\r
    }\r
  }\r
  //\r
  // Non of the regions overlapped so MBR is O.K.\r
  //\r
  return MbrValid;\r
}\r
\r
\r
/**\r
  Install child handles if the Handle supports MBR format.\r
\r
  @param  This              Calling context.\r
  @param  Handle            Parent Handle.\r
  @param  DiskIo            Parent DiskIo interface.\r
  @param  BlockIo           Parent BlockIo interface.\r
  @param  DevicePath        Parent Device Path.\r
   \r
  @retval EFI_SUCCESS       A child handle was added.\r
  @retval EFI_MEDIA_CHANGED Media change was detected.\r
  @retval Others            MBR partition was not found.\r
\r
**/\r
EFI_STATUS\r
PartitionInstallMbrChildHandles (\r
  IN  EFI_DRIVER_BINDING_PROTOCOL  *This,\r
  IN  EFI_HANDLE                   Handle,\r
  IN  EFI_DISK_IO_PROTOCOL         *DiskIo,\r
  IN  EFI_BLOCK_IO_PROTOCOL        *BlockIo,\r
  IN  EFI_DEVICE_PATH_PROTOCOL     *DevicePath\r
  )\r
{\r
  EFI_STATUS                Status;\r
  MASTER_BOOT_RECORD        *Mbr;\r
  UINT32                    ExtMbrStartingLba;\r
  UINTN                     Index;\r
  HARDDRIVE_DEVICE_PATH     HdDev;\r
  HARDDRIVE_DEVICE_PATH     ParentHdDev;\r
  EFI_STATUS                Found;\r
  UINT32                    PartitionNumber;\r
  EFI_DEVICE_PATH_PROTOCOL  *DevicePathNode;\r
  EFI_DEVICE_PATH_PROTOCOL  *LastDevicePathNode;\r
\r
  Mbr             = NULL;\r
  Found           = EFI_NOT_FOUND;\r
\r
  Mbr             = AllocatePool (BlockIo->Media->BlockSize);\r
  if (Mbr == NULL) {\r
    goto Done;\r
  }\r
\r
  Status = BlockIo->ReadBlocks (\r
                      BlockIo,\r
                      BlockIo->Media->MediaId,\r
                      0,\r
                      BlockIo->Media->BlockSize,\r
                      Mbr\r
                      );\r
  if (EFI_ERROR (Status)) {\r
    Found = Status;\r
    goto Done;\r
  }\r
  if (!PartitionValidMbr (Mbr, BlockIo->Media->LastBlock)) {\r
    goto Done;\r
  }\r
  //\r
  // We have a valid mbr - add each partition\r
  //\r
  //\r
  // Get starting and ending LBA of the parent block device.\r
  //\r
  LastDevicePathNode = NULL;\r
  ZeroMem (&ParentHdDev, sizeof (ParentHdDev));\r
  DevicePathNode = DevicePath;\r
  while (!EfiIsDevicePathEnd (DevicePathNode)) {\r
    LastDevicePathNode  = DevicePathNode;\r
    DevicePathNode      = EfiNextDevicePathNode (DevicePathNode);\r
  }\r
\r
  if (LastDevicePathNode != NULL) {\r
    if (DevicePathType (LastDevicePathNode) == MEDIA_DEVICE_PATH &&\r
        DevicePathSubType (LastDevicePathNode) == MEDIA_HARDDRIVE_DP\r
        ) {\r
      CopyMem (&ParentHdDev, LastDevicePathNode, sizeof (ParentHdDev));\r
    } else {\r
      LastDevicePathNode = NULL;\r
    }\r
  }\r
\r
  PartitionNumber = 1;\r
\r
  ZeroMem (&HdDev, sizeof (HdDev));\r
  HdDev.Header.Type     = MEDIA_DEVICE_PATH;\r
  HdDev.Header.SubType  = MEDIA_HARDDRIVE_DP;\r
  SetDevicePathNodeLength (&HdDev.Header, sizeof (HdDev));\r
  HdDev.MBRType         = MBR_TYPE_PCAT;\r
  HdDev.SignatureType   = SIGNATURE_TYPE_MBR;\r
\r
  if (LastDevicePathNode == NULL) {\r
    //\r
    // This is a MBR, add each partition\r
    //\r
    for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {\r
      if (Mbr->Partition[Index].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA) == 0) {\r
        //\r
        // Don't use null MBR entries\r
        //\r
        continue;\r
      }\r
\r
      if (Mbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION) {\r
        //\r
        // This is the guard MBR for the GPT. If you ever see a GPT disk with zero partitions you can get here.\r
        //  We can not produce an MBR BlockIo for this device as the MBR spans the GPT headers. So formating \r
        //  this BlockIo would corrupt the GPT structures and require a recovery that would corrupt the format\r
        //  that corrupted the GPT partition. \r
        //\r
        continue;\r
      }\r
\r
      HdDev.PartitionNumber = PartitionNumber ++;\r
      HdDev.PartitionStart  = UNPACK_UINT32 (Mbr->Partition[Index].StartingLBA);\r
      HdDev.PartitionSize   = UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA);\r
      CopyMem (HdDev.Signature, &(Mbr->UniqueMbrSignature[0]), sizeof (UINT32));\r
\r
      Status = PartitionInstallChildHandle (\r
                This,\r
                Handle,\r
                DiskIo,\r
                BlockIo,\r
                DevicePath,\r
                (EFI_DEVICE_PATH_PROTOCOL *) &HdDev,\r
                HdDev.PartitionStart,\r
                HdDev.PartitionStart + HdDev.PartitionSize - 1,\r
                MBR_SIZE,\r
                (BOOLEAN) (Mbr->Partition[Index].OSIndicator == EFI_PARTITION)\r
                );\r
\r
      if (!EFI_ERROR (Status)) {\r
        Found = EFI_SUCCESS;\r
      }\r
    }\r
  } else {\r
    //\r
    // It's an extended partition. Follow the extended partition\r
    // chain to get all the logical drives\r
    //\r
    ExtMbrStartingLba = 0;\r
\r
    do {\r
\r
      Status = BlockIo->ReadBlocks (\r
                          BlockIo,\r
                          BlockIo->Media->MediaId,\r
                          ExtMbrStartingLba,\r
                          BlockIo->Media->BlockSize,\r
                          Mbr\r
                          );\r
      if (EFI_ERROR (Status)) {\r
        Found = Status;\r
        goto Done;\r
      }\r
\r
      if (UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA) == 0) {\r
        break;\r
      }\r
\r
      if ((Mbr->Partition[0].OSIndicator == EXTENDED_DOS_PARTITION) ||\r
          (Mbr->Partition[0].OSIndicator == EXTENDED_WINDOWS_PARTITION)) {\r
        ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA);\r
        continue;\r
      }\r
      HdDev.PartitionNumber = PartitionNumber ++;\r
      HdDev.PartitionStart  = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA) + ExtMbrStartingLba + ParentHdDev.PartitionStart;\r
      HdDev.PartitionSize   = UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA);\r
      if ((HdDev.PartitionStart + HdDev.PartitionSize - 1 >= ParentHdDev.PartitionStart + ParentHdDev.PartitionSize) ||\r
          (HdDev.PartitionStart <= ParentHdDev.PartitionStart)) {\r
        break;\r
      }\r
\r
      //\r
      // The signature in EBR(Extended Boot Record) should always be 0.\r
      //\r
      *((UINT32 *) &HdDev.Signature[0]) = 0;\r
\r
      Status = PartitionInstallChildHandle (\r
                This,\r
                Handle,\r
                DiskIo,\r
                BlockIo,\r
                DevicePath,\r
                (EFI_DEVICE_PATH_PROTOCOL *) &HdDev,\r
                HdDev.PartitionStart - ParentHdDev.PartitionStart,\r
                HdDev.PartitionStart - ParentHdDev.PartitionStart + HdDev.PartitionSize - 1,\r
                MBR_SIZE,\r
                (BOOLEAN) (Mbr->Partition[0].OSIndicator == EFI_PARTITION)\r
                );\r
      if (!EFI_ERROR (Status)) {\r
        Found = EFI_SUCCESS;\r
      }\r
\r
      if ((Mbr->Partition[1].OSIndicator != EXTENDED_DOS_PARTITION) &&\r
          (Mbr->Partition[1].OSIndicator != EXTENDED_WINDOWS_PARTITION)\r
          ) {\r
        break;\r
      }\r
\r
      ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[1].StartingLBA);\r
      //\r
      // Don't allow partition to be self referencing\r
      //\r
      if (ExtMbrStartingLba == 0) {\r
        break;\r
      }\r
    } while (ExtMbrStartingLba  < ParentHdDev.PartitionSize);\r
  }\r
\r
Done:\r
  FreePool (Mbr);\r
\r
  return Found;\r
}\r
Commit	Line	Data
f42be642	1	/** @file\r
adbcbf8f	2	Decode a hard disk partitioned with the legacy MBR found on most PC's\r
	3	\r
	4	MBR - Master Boot Record is in the first sector of a partitioned hard disk.\r
	5	The MBR supports four partitions per disk. The MBR also contains legacy\r
	6	code that is not run on an EFI system. The legacy code reads the \r
	7	first sector of the active partition into memory and \r
	8	\r
	9	BPB - Boot(?) Parameter Block is in the first sector of a FAT file system. \r
	10	The BPB contains information about the FAT file system. The BPB is \r
	11	always on the first sector of a media. The first sector also contains\r
	12	the legacy boot strap code.\r
	13	\r
f42be642	14	Copyright (c) 2006 - 2008, Intel Corporation. <BR>\r
	15	All rights reserved. This program and the accompanying materials\r
	16	are licensed and made available under the terms and conditions of the BSD License\r
	17	which accompanies this distribution. The full text of the license may be found at\r
	18	http://opensource.org/licenses/bsd-license.php\r
	19	\r
	20	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
	21	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	22	\r
	23	**/\r
adbcbf8f	24	\r
	25	#include "Partition.h"\r
	26	\r
a8d0c20e	27	/**\r
	28	Test to see if the Mbr buffer is a valid MBR.\r
	29	\r
	30	@param Mbr Parent Handle.\r
	31	@param LastLba Last Lba address on the device.\r
	32	\r
	33	@retval TRUE Mbr is a Valid MBR.\r
	34	@retval FALSE Mbr is not a Valid MBR.\r
	35	\r
	36	**/\r
adbcbf8f	37	STATIC\r
	38	BOOLEAN\r
	39	PartitionValidMbr (\r
	40	IN MASTER_BOOT_RECORD *Mbr,\r
	41	IN EFI_LBA LastLba\r
	42	)\r
adbcbf8f	43	{\r
	44	UINT32 StartingLBA;\r
	45	UINT32 EndingLBA;\r
	46	UINT32 NewEndingLBA;\r
	47	INTN Index1;\r
	48	INTN Index2;\r
	49	BOOLEAN MbrValid;\r
	50	\r
	51	if (Mbr->Signature != MBR_SIGNATURE) {\r
	52	return FALSE;\r
	53	}\r
	54	//\r
	55	// The BPB also has this signature, so it can not be used alone.\r
	56	//\r
	57	MbrValid = FALSE;\r
	58	for (Index1 = 0; Index1 < MAX_MBR_PARTITIONS; Index1++) {\r
	59	if (Mbr->Partition[Index1].OSIndicator == 0x00 \|\| UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) == 0) {\r
	60	continue;\r
	61	}\r
	62	\r
	63	MbrValid = TRUE;\r
	64	StartingLBA = UNPACK_UINT32 (Mbr->Partition[Index1].StartingLBA);\r
	65	EndingLBA = StartingLBA + UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) - 1;\r
	66	if (EndingLBA > LastLba) {\r
	67	//\r
	68	// Compatibility Errata:\r
	69	// Some systems try to hide drive space with their INT 13h driver\r
	70	// This does not hide space from the OS driver. This means the MBR\r
	71	// that gets created from DOS is smaller than the MBR created from\r
	72	// a real OS (NT & Win98). This leads to BlockIo->LastBlock being\r
	73	// wrong on some systems FDISKed by the OS.\r
	74	//\r
	75	// return FALSE since no block devices on a system are implemented\r
	76	// with INT 13h\r
	77	//\r
	78	return FALSE;\r
	79	}\r
	80	\r
	81	for (Index2 = Index1 + 1; Index2 < MAX_MBR_PARTITIONS; Index2++) {\r
	82	if (Mbr->Partition[Index2].OSIndicator == 0x00 \|\| UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) == 0) {\r
	83	continue;\r
	84	}\r
	85	\r
	86	NewEndingLBA = UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) + UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) - 1;\r
	87	if (NewEndingLBA >= StartingLBA && UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) <= EndingLBA) {\r
	88	//\r
	89	// This region overlaps with the Index1'th region\r
	90	//\r
	91	return FALSE;\r
	92	}\r
	93	}\r
	94	}\r
	95	//\r
	96	// Non of the regions overlapped so MBR is O.K.\r
	97	//\r
	98	return MbrValid;\r
	99	}\r
	100	\r
a8d0c20e	101	\r
	102	/**\r
	103	Install child handles if the Handle supports MBR format.\r
	104	\r
	105	@param This Calling context.\r
	106	@param Handle Parent Handle.\r
	107	@param DiskIo Parent DiskIo interface.\r
	108	@param BlockIo Parent BlockIo interface.\r
	109	@param DevicePath Parent Device Path.\r
	110	\r
	111	@retval EFI_SUCCESS A child handle was added.\r
	112	@retval EFI_MEDIA_CHANGED Media change was detected.\r
	113	@retval Others MBR partition was not found.\r
	114	\r
	115	**/\r
adbcbf8f	116	EFI_STATUS\r
	117	PartitionInstallMbrChildHandles (\r
	118	IN EFI_DRIVER_BINDING_PROTOCOL *This,\r
	119	IN EFI_HANDLE Handle,\r
	120	IN EFI_DISK_IO_PROTOCOL *DiskIo,\r
	121	IN EFI_BLOCK_IO_PROTOCOL *BlockIo,\r
	122	IN EFI_DEVICE_PATH_PROTOCOL *DevicePath\r
	123	)\r
adbcbf8f	124	{\r
	125	EFI_STATUS Status;\r
	126	MASTER_BOOT_RECORD *Mbr;\r
	127	UINT32 ExtMbrStartingLba;\r
	128	UINTN Index;\r
	129	HARDDRIVE_DEVICE_PATH HdDev;\r
	130	HARDDRIVE_DEVICE_PATH ParentHdDev;\r
	131	EFI_STATUS Found;\r
	132	UINT32 PartitionNumber;\r
	133	EFI_DEVICE_PATH_PROTOCOL *DevicePathNode;\r
	134	EFI_DEVICE_PATH_PROTOCOL *LastDevicePathNode;\r
	135	\r
	136	Mbr = NULL;\r
	137	Found = EFI_NOT_FOUND;\r
	138	\r
	139	Mbr = AllocatePool (BlockIo->Media->BlockSize);\r
	140	if (Mbr == NULL) {\r
	141	goto Done;\r
	142	}\r
	143	\r
	144	Status = BlockIo->ReadBlocks (\r
	145	BlockIo,\r
	146	BlockIo->Media->MediaId,\r
	147	0,\r
	148	BlockIo->Media->BlockSize,\r
	149	Mbr\r
	150	);\r
	151	if (EFI_ERROR (Status)) {\r
	152	Found = Status;\r
	153	goto Done;\r
	154	}\r
	155	if (!PartitionValidMbr (Mbr, BlockIo->Media->LastBlock)) {\r
	156	goto Done;\r
	157	}\r
	158	//\r
	159	// We have a valid mbr - add each partition\r
	160	//\r
	161	//\r
	162	// Get starting and ending LBA of the parent block device.\r
	163	//\r
	164	LastDevicePathNode = NULL;\r
	165	ZeroMem (&ParentHdDev, sizeof (ParentHdDev));\r
	166	DevicePathNode = DevicePath;\r
	167	while (!EfiIsDevicePathEnd (DevicePathNode)) {\r
	168	LastDevicePathNode = DevicePathNode;\r
	169	DevicePathNode = EfiNextDevicePathNode (DevicePathNode);\r
	170	}\r
	171	\r
	172	if (LastDevicePathNode != NULL) {\r
	173	if (DevicePathType (LastDevicePathNode) == MEDIA_DEVICE_PATH &&\r
	174	DevicePathSubType (LastDevicePathNode) == MEDIA_HARDDRIVE_DP\r
	175	) {\r
	176	CopyMem (&ParentHdDev, LastDevicePathNode, sizeof (ParentHdDev));\r
	177	} else {\r
	178	LastDevicePathNode = NULL;\r
	179	}\r
	180	}\r
	181	\r
	182	PartitionNumber = 1;\r
	183	\r
	184	ZeroMem (&HdDev, sizeof (HdDev));\r
	185	HdDev.Header.Type = MEDIA_DEVICE_PATH;\r
	186	HdDev.Header.SubType = MEDIA_HARDDRIVE_DP;\r
	187	SetDevicePathNodeLength (&HdDev.Header, sizeof (HdDev));\r
188	HdDev.MBRType = MBR_TYPE_PCAT;\r
189	HdDev.SignatureType = SIGNATURE_TYPE_MBR;\r
190	\r
191	if (LastDevicePathNode == NULL) {\r
192	//\r
193	// This is a MBR, add each partition\r
194	//\r
195	for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {\r
196	if (Mbr->Partition[Index].OSIndicator == 0x00 \|\| UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA) == 0) {\r
197	//\r
198	// Don't use null MBR entries\r
199	//\r
200	continue;\r
201	}\r
202	\r
203	if (Mbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION) {\r
204	//\r
205	// This is the guard MBR for the GPT. If you ever see a GPT disk with zero partitions you can get here.\r
206	// We can not produce an MBR BlockIo for this device as the MBR spans the GPT headers. So formating \r
207	// this BlockIo would corrupt the GPT structures and require a recovery that would corrupt the format\r
208	// that corrupted the GPT partition. \r
209	//\r
210	continue;\r
211	}\r
212	\r
213	HdDev.PartitionNumber = PartitionNumber ++;\r
214	HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[Index].StartingLBA);\r
215	HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA);\r
216	CopyMem (HdDev.Signature, &(Mbr->UniqueMbrSignature[0]), sizeof (UINT32));\r
217	\r
218	Status = PartitionInstallChildHandle (\r
219	This,\r
220	Handle,\r
221	DiskIo,\r
222	BlockIo,\r
223	DevicePath,\r
224	(EFI_DEVICE_PATH_PROTOCOL *) &HdDev,\r
225	HdDev.PartitionStart,\r
226	HdDev.PartitionStart + HdDev.PartitionSize - 1,\r
227	MBR_SIZE,\r
228	(BOOLEAN) (Mbr->Partition[Index].OSIndicator == EFI_PARTITION)\r
229	);\r
230	\r
231	if (!EFI_ERROR (Status)) {\r
232	Found = EFI_SUCCESS;\r
233	}\r
234	}\r
235	} else {\r
236	//\r
237	// It's an extended partition. Follow the extended partition\r
238	// chain to get all the logical drives\r
239	//\r
240	ExtMbrStartingLba = 0;\r
241	\r
242	do {\r
243	\r
244	Status = BlockIo->ReadBlocks (\r
245	BlockIo,\r
246	BlockIo->Media->MediaId,\r
247	ExtMbrStartingLba,\r
248	BlockIo->Media->BlockSize,\r
249	Mbr\r
250	);\r
251	if (EFI_ERROR (Status)) {\r
252	Found = Status;\r
253	goto Done;\r
254	}\r
255	\r
c63cd426	256	if (UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA) == 0) {\r
adbcbf8f	257	break;\r
	258	}\r
	259	\r
	260	if ((Mbr->Partition[0].OSIndicator == EXTENDED_DOS_PARTITION) \|\|\r
	261	(Mbr->Partition[0].OSIndicator == EXTENDED_WINDOWS_PARTITION)) {\r
	262	ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA);\r
	263	continue;\r
	264	}\r
	265	HdDev.PartitionNumber = PartitionNumber ++;\r
	266	HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA) + ExtMbrStartingLba + ParentHdDev.PartitionStart;\r
	267	HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA);\r
	268	if ((HdDev.PartitionStart + HdDev.PartitionSize - 1 >= ParentHdDev.PartitionStart + ParentHdDev.PartitionSize) \|\|\r
	269	(HdDev.PartitionStart <= ParentHdDev.PartitionStart)) {\r
	270	break;\r
	271	}\r
	272	\r
	273	//\r
	274	// The signature in EBR(Extended Boot Record) should always be 0.\r
	275	//\r
	276	((UINT32 ) &HdDev.Signature[0]) = 0;\r
	277	\r
	278	Status = PartitionInstallChildHandle (\r
	279	This,\r
	280	Handle,\r
	281	DiskIo,\r
	282	BlockIo,\r
	283	DevicePath,\r
	284	(EFI_DEVICE_PATH_PROTOCOL *) &HdDev,\r
	285	HdDev.PartitionStart - ParentHdDev.PartitionStart,\r
	286	HdDev.PartitionStart - ParentHdDev.PartitionStart + HdDev.PartitionSize - 1,\r
	287	MBR_SIZE,\r
	288	(BOOLEAN) (Mbr->Partition[0].OSIndicator == EFI_PARTITION)\r
	289	);\r
	290	if (!EFI_ERROR (Status)) {\r
	291	Found = EFI_SUCCESS;\r
	292	}\r
	293	\r
	294	if ((Mbr->Partition[1].OSIndicator != EXTENDED_DOS_PARTITION) &&\r
	295	(Mbr->Partition[1].OSIndicator != EXTENDED_WINDOWS_PARTITION)\r
	296	) {\r
	297	break;\r
	298	}\r
	299	\r
	300	ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[1].StartingLBA);\r
	301	//\r
	302	// Don't allow partition to be self referencing\r
	303	//\r
	304	if (ExtMbrStartingLba == 0) {\r
	305	break;\r
	306	}\r
	307	} while (ExtMbrStartingLba < ParentHdDev.PartitionSize);\r
	308	}\r
	309	\r
	310	Done:\r
	311	FreePool (Mbr);\r
	312	\r
	313	return Found;\r
	314	}\r