[mirror_edk2.git] / MdeModulePkg / Universal / Disk / Partition / Dxe / Mbr.c

/*++\r
\r
Copyright (c) 2006 - 2007, Intel Corporation                                                         \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
Module Name:\r
\r
  Mbr.c\r
  \r
Abstract:\r
\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
--*/\r
\r
#include "Partition.h"\r
\r
STATIC\r
BOOLEAN\r
PartitionValidMbr (\r
  IN  MASTER_BOOT_RECORD      *Mbr,\r
  IN  EFI_LBA                 LastLba\r
  )\r
/*++\r
\r
Routine Description:\r
  Test to see if the Mbr buffer is a valid MBR\r
\r
Arguments:       \r
  Mbr     - Parent Handle \r
  LastLba - Last Lba address on the device.\r
\r
Returns:\r
  TRUE  - Mbr is a Valid MBR\r
  FALSE - Mbr is not a Valid MBR\r
\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
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
\r
Routine Description:\r
  Install child handles if the Handle supports MBR format.\r
\r
Arguments:       \r
  This       - Calling context.\r
  Handle     - Parent Handle \r
  DiskIo     - Parent DiskIo interface\r
  BlockIo    - Parent BlockIo interface\r
  DevicePath - Parent Device Path\r
\r
Returns:\r
  EFI_SUCCESS       - If a child handle was added\r
  EFI_MEDIA_CHANGED - Media changed Detected\r
	!EFI_SUCCESS      - Not found MBR partition.\r
\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 (Mbr->Partition[0].OSIndicator == 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
79840ee1	1	/*++\r
	2	\r
	3	Copyright (c) 2006 - 2007, Intel Corporation \r
	4	All rights reserved. This program and the accompanying materials \r
	5	are licensed and made available under the terms and conditions of the BSD License \r
	6	which accompanies this distribution. The full text of the license may be found at \r
	7	http://opensource.org/licenses/bsd-license.php \r
	8	\r
	9	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r
	10	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r
	11	\r
	12	Module Name:\r
	13	\r
	14	Mbr.c\r
	15	\r
	16	Abstract:\r
	17	\r
	18	Decode a hard disk partitioned with the legacy MBR found on most PC's\r
	19	\r
	20	MBR - Master Boot Record is in the first sector of a partitioned hard disk.\r
	21	The MBR supports four partitions per disk. The MBR also contains legacy\r
	22	code that is not run on an EFI system. The legacy code reads the \r
	23	first sector of the active partition into memory and \r
	24	\r
	25	BPB - Boot(?) Parameter Block is in the first sector of a FAT file system. \r
	26	The BPB contains information about the FAT file system. The BPB is \r
	27	always on the first sector of a media. The first sector also contains\r
	28	the legacy boot strap code.\r
	29	\r
	30	--*/\r
	31	\r
79840ee1	32	#include "Partition.h"\r
	33	\r
	34	STATIC\r
	35	BOOLEAN\r
	36	PartitionValidMbr (\r
	37	IN MASTER_BOOT_RECORD *Mbr,\r
	38	IN EFI_LBA LastLba\r
	39	)\r
	40	/*++\r
	41	\r
	42	Routine Description:\r
	43	Test to see if the Mbr buffer is a valid MBR\r
	44	\r
	45	Arguments: \r
	46	Mbr - Parent Handle \r
	47	LastLba - Last Lba address on the device.\r
	48	\r
	49	Returns:\r
	50	TRUE - Mbr is a Valid MBR\r
	51	FALSE - Mbr is not a Valid MBR\r
	52	\r
	53	--*/\r
	54	{\r
	55	UINT32 StartingLBA;\r
	56	UINT32 EndingLBA;\r
	57	UINT32 NewEndingLBA;\r
	58	INTN Index1;\r
	59	INTN Index2;\r
	60	BOOLEAN MbrValid;\r
	61	\r
	62	if (Mbr->Signature != MBR_SIGNATURE) {\r
	63	return FALSE;\r
	64	}\r
	65	//\r
	66	// The BPB also has this signature, so it can not be used alone.\r
	67	//\r
	68	MbrValid = FALSE;\r
	69	for (Index1 = 0; Index1 < MAX_MBR_PARTITIONS; Index1++) {\r
	70	if (Mbr->Partition[Index1].OSIndicator == 0x00 \|\| UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) == 0) {\r
	71	continue;\r
	72	}\r
	73	\r
	74	MbrValid = TRUE;\r
	75	StartingLBA = UNPACK_UINT32 (Mbr->Partition[Index1].StartingLBA);\r
	76	EndingLBA = StartingLBA + UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) - 1;\r
	77	if (EndingLBA > LastLba) {\r
	78	//\r
	79	// Compatibility Errata:\r
	80	// Some systems try to hide drive space with their INT 13h driver\r
	81	// This does not hide space from the OS driver. This means the MBR\r
	82	// that gets created from DOS is smaller than the MBR created from\r
	83	// a real OS (NT & Win98). This leads to BlockIo->LastBlock being\r
	84	// wrong on some systems FDISKed by the OS.\r
	85	//\r
	86	// return FALSE since no block devices on a system are implemented\r
	87	// with INT 13h\r
	88	//\r
	89	return FALSE;\r
	90	}\r
	91	\r
	92	for (Index2 = Index1 + 1; Index2 < MAX_MBR_PARTITIONS; Index2++) {\r
	93	if (Mbr->Partition[Index2].OSIndicator == 0x00 \|\| UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) == 0) {\r
	94	continue;\r
	95	}\r
96	\r
97	NewEndingLBA = UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) + UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) - 1;\r
98	if (NewEndingLBA >= StartingLBA && UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) <= EndingLBA) {\r
99	//\r
100	// This region overlaps with the Index1'th region\r
101	//\r
102	return FALSE;\r
103	}\r
104	}\r
105	}\r
106	//\r
107	// Non of the regions overlapped so MBR is O.K.\r
108	//\r
109	return MbrValid;\r
110	}\r
111	\r
112	EFI_STATUS\r
113	PartitionInstallMbrChildHandles (\r
114	IN EFI_DRIVER_BINDING_PROTOCOL *This,\r
115	IN EFI_HANDLE Handle,\r
116	IN EFI_DISK_IO_PROTOCOL *DiskIo,\r
117	IN EFI_BLOCK_IO_PROTOCOL *BlockIo,\r
118	IN EFI_DEVICE_PATH_PROTOCOL *DevicePath\r
119	)\r
120	/*++\r
121	\r
122	Routine Description:\r
123	Install child handles if the Handle supports MBR format.\r
124	\r
125	Arguments: \r
126	This - Calling context.\r
127	Handle - Parent Handle \r
128	DiskIo - Parent DiskIo interface\r
129	BlockIo - Parent BlockIo interface\r
130	DevicePath - Parent Device Path\r
131	\r
132	Returns:\r
133	EFI_SUCCESS - If a child handle was added\r
134	EFI_MEDIA_CHANGED - Media changed Detected\r
135	!EFI_SUCCESS - Not found MBR partition.\r
136	\r
137	--*/\r
138	{\r
139	EFI_STATUS Status;\r
140	MASTER_BOOT_RECORD *Mbr;\r
141	UINT32 ExtMbrStartingLba;\r
142	UINTN Index;\r
143	HARDDRIVE_DEVICE_PATH HdDev;\r
144	HARDDRIVE_DEVICE_PATH ParentHdDev;\r
145	EFI_STATUS Found;\r
146	UINT32 PartitionNumber;\r
147	EFI_DEVICE_PATH_PROTOCOL *DevicePathNode;\r
148	EFI_DEVICE_PATH_PROTOCOL *LastDevicePathNode;\r
149	\r
150	Mbr = NULL;\r
151	Found = EFI_NOT_FOUND;\r
152	\r
153	Mbr = AllocatePool (BlockIo->Media->BlockSize);\r
154	if (Mbr == NULL) {\r
155	goto Done;\r
156	}\r
157	\r
158	Status = BlockIo->ReadBlocks (\r
159	BlockIo,\r
160	BlockIo->Media->MediaId,\r
161	0,\r
162	BlockIo->Media->BlockSize,\r
163	Mbr\r
164	);\r
165	if (EFI_ERROR (Status)) {\r
166	Found = Status;\r
167	goto Done;\r
168	}\r
169	if (!PartitionValidMbr (Mbr, BlockIo->Media->LastBlock)) {\r
170	goto Done;\r
171	}\r
172	//\r
173	// We have a valid mbr - add each partition\r
174	//\r
175	//\r
176	// Get starting and ending LBA of the parent block device.\r
177	//\r
178	LastDevicePathNode = NULL;\r
179	ZeroMem (&ParentHdDev, sizeof (ParentHdDev));\r
180	DevicePathNode = DevicePath;\r
181	while (!EfiIsDevicePathEnd (DevicePathNode)) {\r
182	LastDevicePathNode = DevicePathNode;\r
183	DevicePathNode = EfiNextDevicePathNode (DevicePathNode);\r
184	}\r
185	\r
186	if (LastDevicePathNode != NULL) {\r
187	if (DevicePathType (LastDevicePathNode) == MEDIA_DEVICE_PATH &&\r
188	DevicePathSubType (LastDevicePathNode) == MEDIA_HARDDRIVE_DP\r
189	) {\r
190	CopyMem (&ParentHdDev, LastDevicePathNode, sizeof (ParentHdDev));\r
191	} else {\r
192	LastDevicePathNode = NULL;\r
193	}\r
194	}\r
195	\r
196	PartitionNumber = 1;\r
197	\r
198	ZeroMem (&HdDev, sizeof (HdDev));\r
199	HdDev.Header.Type = MEDIA_DEVICE_PATH;\r
200	HdDev.Header.SubType = MEDIA_HARDDRIVE_DP;\r
201	SetDevicePathNodeLength (&HdDev.Header, sizeof (HdDev));\r
202	HdDev.MBRType = MBR_TYPE_PCAT;\r
203	HdDev.SignatureType = SIGNATURE_TYPE_MBR;\r
204	\r
205	if (LastDevicePathNode == NULL) {\r
206	//\r
207	// This is a MBR, add each partition\r
208	//\r
209	for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {\r
210	if (Mbr->Partition[Index].OSIndicator == 0x00 \|\| UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA) == 0) {\r
211	//\r
212	// Don't use null MBR entries\r
213	//\r
214	continue;\r
215	}\r
216	\r
217	if (Mbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION) {\r
218	//\r
219	// This is the guard MBR for the GPT. If you ever see a GPT disk with zero partitions you can get here.\r
220	// We can not produce an MBR BlockIo for this device as the MBR spans the GPT headers. So formating \r
221	// this BlockIo would corrupt the GPT structures and require a recovery that would corrupt the format\r
222	// that corrupted the GPT partition. \r
223	//\r
224	continue;\r
225	}\r
226	\r
227	HdDev.PartitionNumber = PartitionNumber ++;\r
228	HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[Index].StartingLBA);\r
229	HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA);\r
230	CopyMem (HdDev.Signature, &(Mbr->UniqueMbrSignature[0]), sizeof (UINT32));\r
231	\r
232	Status = PartitionInstallChildHandle (\r
233	This,\r
234	Handle,\r
235	DiskIo,\r
236	BlockIo,\r
237	DevicePath,\r
238	(EFI_DEVICE_PATH_PROTOCOL *) &HdDev,\r
239	HdDev.PartitionStart,\r
240	HdDev.PartitionStart + HdDev.PartitionSize - 1,\r
241	MBR_SIZE,\r
242	(BOOLEAN) (Mbr->Partition[Index].OSIndicator == EFI_PARTITION)\r
243	);\r
244	\r
245	if (!EFI_ERROR (Status)) {\r
246	Found = EFI_SUCCESS;\r
247	}\r
248	}\r
249	} else {\r
250	//\r
251	// It's an extended partition. Follow the extended partition\r
252	// chain to get all the logical drives\r
253	//\r
254	ExtMbrStartingLba = 0;\r
255	\r
256	do {\r
257	\r
258	Status = BlockIo->ReadBlocks (\r
259	BlockIo,\r
260	BlockIo->Media->MediaId,\r
261	ExtMbrStartingLba,\r
262	BlockIo->Media->BlockSize,\r
263	Mbr\r
264	);\r
265	if (EFI_ERROR (Status)) {\r
266	Found = Status;\r
267	goto Done;\r
268	}\r
269	\r
270	if (Mbr->Partition[0].OSIndicator == 0) {\r
271	break;\r
272	}\r
273	\r
274	if ((Mbr->Partition[0].OSIndicator == EXTENDED_DOS_PARTITION) \|\|\r
275	(Mbr->Partition[0].OSIndicator == EXTENDED_WINDOWS_PARTITION)) {\r
276	ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA);\r
277	continue;\r
278	}\r
279	HdDev.PartitionNumber = PartitionNumber ++;\r
280	HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA) + ExtMbrStartingLba + ParentHdDev.PartitionStart;\r
281	HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA);\r
282	if ((HdDev.PartitionStart + HdDev.PartitionSize - 1 >= ParentHdDev.PartitionStart + ParentHdDev.PartitionSize) \|\|\r
283	(HdDev.PartitionStart <= ParentHdDev.PartitionStart)) {\r
284	break;\r
285	}\r
286	\r
287	//\r
288	// The signature in EBR(Extended Boot Record) should always be 0.\r
289	//\r
290	((UINT32 ) &HdDev.Signature[0]) = 0;\r
291	\r
292	Status = PartitionInstallChildHandle (\r
293	This,\r
294	Handle,\r
295	DiskIo,\r
296	BlockIo,\r
297	DevicePath,\r
298	(EFI_DEVICE_PATH_PROTOCOL *) &HdDev,\r
299	HdDev.PartitionStart - ParentHdDev.PartitionStart,\r
300	HdDev.PartitionStart - ParentHdDev.PartitionStart + HdDev.PartitionSize - 1,\r
301	MBR_SIZE,\r
302	(BOOLEAN) (Mbr->Partition[0].OSIndicator == EFI_PARTITION)\r
303	);\r
304	if (!EFI_ERROR (Status)) {\r
305	Found = EFI_SUCCESS;\r
306	}\r
307	\r
308	if ((Mbr->Partition[1].OSIndicator != EXTENDED_DOS_PARTITION) &&\r
309	(Mbr->Partition[1].OSIndicator != EXTENDED_WINDOWS_PARTITION)\r
310	) {\r
311	break;\r
312	}\r
313	\r
314	ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[1].StartingLBA);\r
315	//\r
316	// Don't allow partition to be self referencing\r
317	//\r
318	if (ExtMbrStartingLba == 0) {\r
319	break;\r
320	}\r
321	} while (ExtMbrStartingLba < ParentHdDev.PartitionSize);\r
322	}\r
323	\r
324	Done:\r
325	FreePool (Mbr);\r
326	\r
327	return Found;\r
328	}\r