MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c

   1 /** @file
   2   Library instance that implement UEFI Device Path Library class based on protocol
   3   gEfiDevicePathUtilitiesProtocolGuid.
   4
   5   Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7
   8 **/
   9
  10
  11 #include <Uefi.h>
  12
  13 #include <Protocol/DevicePathUtilities.h>
  14 #include <Protocol/DevicePathToText.h>
  15 #include <Protocol/DevicePathFromText.h>
  16
  17 #include <Library/DevicePathLib.h>
  18 #include <Library/DebugLib.h>
  19 #include <Library/BaseLib.h>
  20 #include <Library/MemoryAllocationLib.h>
  21 #include <Library/BaseMemoryLib.h>
  22 #include <Library/UefiBootServicesTableLib.h>
  23 #include <Library/PcdLib.h>
  24
  25 GLOBAL_REMOVE_IF_UNREFERENCED EFI_DEVICE_PATH_UTILITIES_PROTOCOL *mDevicePathLibDevicePathUtilities = NULL;
  26 GLOBAL_REMOVE_IF_UNREFERENCED EFI_DEVICE_PATH_TO_TEXT_PROTOCOL   *mDevicePathLibDevicePathToText    = NULL;
  27 GLOBAL_REMOVE_IF_UNREFERENCED EFI_DEVICE_PATH_FROM_TEXT_PROTOCOL *mDevicePathLibDevicePathFromText  = NULL;
  28
  29 //
  30 // Template for an end-of-device path node.
  31 //
  32 GLOBAL_REMOVE_IF_UNREFERENCED CONST EFI_DEVICE_PATH_PROTOCOL  mUefiDevicePathLibEndDevicePath = {
  33   END_DEVICE_PATH_TYPE,
  34   END_ENTIRE_DEVICE_PATH_SUBTYPE,
  35   {
  36     END_DEVICE_PATH_LENGTH,
  37     0
  38   }
  39 };
  40
  41 /**
  42   The constructor function caches the pointer to DevicePathUtilites protocol.
  43
  44   The constructor function locates DevicePathUtilities protocol from protocol database.
  45   It will ASSERT() if that operation fails and it will always return EFI_SUCCESS.
  46
  47   @param  ImageHandle   The firmware allocated handle for the EFI image.
  48   @param  SystemTable   A pointer to the EFI System Table.
  49
  50   @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
  51
  52 **/
  53 EFI_STATUS
  54 EFIAPI
  55 DevicePathLibConstructor (
  56   IN      EFI_HANDLE                ImageHandle,
  57   IN      EFI_SYSTEM_TABLE          *SystemTable
  58   )
  59 {
  60   EFI_STATUS                        Status;
  61
  62   Status = gBS->LocateProtocol (
  63                   &gEfiDevicePathUtilitiesProtocolGuid,
  64                   NULL,
  65                   (VOID**) &mDevicePathLibDevicePathUtilities
  66                   );
  67   ASSERT_EFI_ERROR (Status);
  68   ASSERT (mDevicePathLibDevicePathUtilities != NULL);
  69   return Status;
  70 }
  71
  72 /**
  73   Determine whether a given device path is valid.
  74   If DevicePath is NULL, then ASSERT().
  75
  76   @param  DevicePath  A pointer to a device path data structure.
  77   @param  MaxSize     The maximum size of the device path data structure.
  78
  79   @retval TRUE        DevicePath is valid.
  80   @retval FALSE       The length of any node node in the DevicePath is less
  81                       than sizeof (EFI_DEVICE_PATH_PROTOCOL).
  82   @retval FALSE       If MaxSize is not zero, the size of the DevicePath
  83                       exceeds MaxSize.
  84   @retval FALSE       If PcdMaximumDevicePathNodeCount is not zero, the node
  85                       count of the DevicePath exceeds PcdMaximumDevicePathNodeCount.
  86 **/
  87 BOOLEAN
  88 EFIAPI
  89 IsDevicePathValid (
  90   IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath,
  91   IN       UINTN                    MaxSize
  92   )
  93 {
  94   UINTN Count;
  95   UINTN Size;
  96   UINTN NodeLength;
  97
  98   ASSERT (DevicePath != NULL);
  99
 100   if (MaxSize == 0) {
 101     MaxSize = MAX_UINTN;
 102   }
 103
 104   //
 105   // Validate the input size big enough to touch the first node.
 106   //
 107   if (MaxSize < sizeof (EFI_DEVICE_PATH_PROTOCOL)) {
 108     return FALSE;
 109   }
 110
 111   for (Count = 0, Size = 0; !IsDevicePathEnd (DevicePath); DevicePath = NextDevicePathNode (DevicePath)) {
 112     NodeLength = DevicePathNodeLength (DevicePath);
 113     if (NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL)) {
 114       return FALSE;
 115     }
 116
 117     if (NodeLength > MAX_UINTN - Size) {
 118       return FALSE;
 119     }
 120     Size += NodeLength;
 121
 122     //
 123     // Validate next node before touch it.
 124     //
 125     if (Size > MaxSize - END_DEVICE_PATH_LENGTH ) {
 126       return FALSE;
 127     }
 128
 129     if (PcdGet32 (PcdMaximumDevicePathNodeCount) > 0) {
 130       Count++;
 131       if (Count >= PcdGet32 (PcdMaximumDevicePathNodeCount)) {
 132         return FALSE;
 133       }
 134     }
 135
 136     //
 137     // FilePath must be a NULL-terminated string.
 138     //
 139     if (DevicePathType (DevicePath) == MEDIA_DEVICE_PATH &&
 140         DevicePathSubType (DevicePath) == MEDIA_FILEPATH_DP &&
 141         *(CHAR16 *)((UINT8 *)DevicePath + NodeLength - 2) != 0) {
 142       return FALSE;
 143     }
 144   }
 145
 146   //
 147   // Only return TRUE when the End Device Path node is valid.
 148   //
 149   return (BOOLEAN) (DevicePathNodeLength (DevicePath) == END_DEVICE_PATH_LENGTH);
 150 }
 151
 152 /**
 153   Returns the Type field of a device path node.
 154
 155   Returns the Type field of the device path node specified by Node.
 156
 157   If Node is NULL, then ASSERT().
 158
 159   @param  Node      A pointer to a device path node data structure.
 160
 161   @return The Type field of the device path node specified by Node.
 162
 163 **/
 164 UINT8
 165 EFIAPI
 166 DevicePathType (
 167   IN CONST VOID  *Node
 168   )
 169 {
 170   ASSERT (Node != NULL);
 171   return ((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Type;
 172 }
 173
 174 /**
 175   Returns the SubType field of a device path node.
 176
 177   Returns the SubType field of the device path node specified by Node.
 178
 179   If Node is NULL, then ASSERT().
 180
 181   @param  Node      A pointer to a device path node data structure.
 182
 183   @return The SubType field of the device path node specified by Node.
 184
 185 **/
 186 UINT8
 187 EFIAPI
 188 DevicePathSubType (
 189   IN CONST VOID  *Node
 190   )
 191 {
 192   ASSERT (Node != NULL);
 193   return ((EFI_DEVICE_PATH_PROTOCOL *)(Node))->SubType;
 194 }
 195
 196 /**
 197   Returns the 16-bit Length field of a device path node.
 198
 199   Returns the 16-bit Length field of the device path node specified by Node.
 200   Node is not required to be aligned on a 16-bit boundary, so it is recommended
 201   that a function such as ReadUnaligned16() be used to extract the contents of
 202   the Length field.
 203
 204   If Node is NULL, then ASSERT().
 205
 206   @param  Node      A pointer to a device path node data structure.
 207
 208   @return The 16-bit Length field of the device path node specified by Node.
 209
 210 **/
 211 UINTN
 212 EFIAPI
 213 DevicePathNodeLength (
 214   IN CONST VOID  *Node
 215   )
 216 {
 217   ASSERT (Node != NULL);
 218   return ReadUnaligned16 ((UINT16 *)&((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Length[0]);
 219 }
 220
 221 /**
 222   Returns a pointer to the next node in a device path.
 223
 224   Returns a pointer to the device path node that follows the device path node
 225   specified by Node.
 226
 227   If Node is NULL, then ASSERT().
 228
 229   @param  Node      A pointer to a device path node data structure.
 230
 231   @return a pointer to the device path node that follows the device path node
 232   specified by Node.
 233
 234 **/
 235 EFI_DEVICE_PATH_PROTOCOL *
 236 EFIAPI
 237 NextDevicePathNode (
 238   IN CONST VOID  *Node
 239   )
 240 {
 241   ASSERT (Node != NULL);
 242   return (EFI_DEVICE_PATH_PROTOCOL *)((UINT8 *)(Node) + DevicePathNodeLength(Node));
 243 }
 244
 245 /**
 246   Determines if a device path node is an end node of a device path.
 247   This includes nodes that are the end of a device path instance and nodes that
 248   are the end of an entire device path.
 249
 250   Determines if the device path node specified by Node is an end node of a device path.
 251   This includes nodes that are the end of a device path instance and nodes that are the
 252   end of an entire device path.  If Node represents an end node of a device path,
 253   then TRUE is returned.  Otherwise, FALSE is returned.
 254
 255   If Node is NULL, then ASSERT().
 256
 257   @param  Node      A pointer to a device path node data structure.
 258
 259   @retval TRUE      The device path node specified by Node is an end node of a device path.
 260   @retval FALSE     The device path node specified by Node is not an end node of
 261                     a device path.
 262
 263 **/
 264 BOOLEAN
 265 EFIAPI
 266 IsDevicePathEndType (
 267   IN CONST VOID  *Node
 268   )
 269 {
 270   ASSERT (Node != NULL);
 271   return (BOOLEAN) (DevicePathType (Node) == END_DEVICE_PATH_TYPE);
 272 }
 273
 274 /**
 275   Determines if a device path node is an end node of an entire device path.
 276
 277   Determines if a device path node specified by Node is an end node of an entire
 278   device path.
 279   If Node represents the end of an entire device path, then TRUE is returned.
 280   Otherwise, FALSE is returned.
 281
 282   If Node is NULL, then ASSERT().
 283
 284   @param  Node      A pointer to a device path node data structure.
 285
 286   @retval TRUE      The device path node specified by Node is the end of an entire device path.
 287   @retval FALSE     The device path node specified by Node is not the end of an entire device path.
 288
 289 **/
 290 BOOLEAN
 291 EFIAPI
 292 IsDevicePathEnd (
 293   IN CONST VOID  *Node
 294   )
 295 {
 296   ASSERT (Node != NULL);
 297   return (BOOLEAN) (IsDevicePathEndType (Node) && DevicePathSubType(Node) == END_ENTIRE_DEVICE_PATH_SUBTYPE);
 298 }
 299
 300 /**
 301   Determines if a device path node is an end node of a device path instance.
 302
 303   Determines if a device path node specified by Node is an end node of a device
 304   path instance.
 305   If Node represents the end of a device path instance, then TRUE is returned.
 306   Otherwise, FALSE is returned.
 307
 308   If Node is NULL, then ASSERT().
 309
 310   @param  Node      A pointer to a device path node data structure.
 311
 312   @retval TRUE      The device path node specified by Node is the end of a device
 313   path instance.
 314   @retval FALSE     The device path node specified by Node is not the end of a
 315   device path instance.
 316
 317 **/
 318 BOOLEAN
 319 EFIAPI
 320 IsDevicePathEndInstance (
 321   IN CONST VOID  *Node
 322   )
 323 {
 324   ASSERT (Node != NULL);
 325   return (BOOLEAN) (IsDevicePathEndType (Node) && DevicePathSubType(Node) == END_INSTANCE_DEVICE_PATH_SUBTYPE);
 326 }
 327
 328 /**
 329   Sets the length, in bytes, of a device path node.
 330
 331   Sets the length of the device path node specified by Node to the value specified
 332   by NodeLength.  NodeLength is returned.  Node is not required to be aligned on
 333   a 16-bit boundary, so it is recommended that a function such as WriteUnaligned16()
 334   be used to set the contents of the Length field.
 335
 336   If Node is NULL, then ASSERT().
 337   If NodeLength >= SIZE_64KB, then ASSERT().
 338   If NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL), then ASSERT().
 339
 340   @param  Node      A pointer to a device path node data structure.
 341   @param  Length    The length, in bytes, of the device path node.
 342
 343   @return Length
 344
 345 **/
 346 UINT16
 347 EFIAPI
 348 SetDevicePathNodeLength (
 349   IN OUT VOID  *Node,
 350   IN UINTN     Length
 351   )
 352 {
 353   ASSERT (Node != NULL);
 354   ASSERT ((Length >= sizeof (EFI_DEVICE_PATH_PROTOCOL)) && (Length < SIZE_64KB));
 355   return WriteUnaligned16 ((UINT16 *)&((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Length[0], (UINT16)(Length));
 356 }
 357
 358 /**
 359   Fills in all the fields of a device path node that is the end of an entire device path.
 360
 361   Fills in all the fields of a device path node specified by Node so Node represents
 362   the end of an entire device path.  The Type field of Node is set to
 363   END_DEVICE_PATH_TYPE, the SubType field of Node is set to
 364   END_ENTIRE_DEVICE_PATH_SUBTYPE, and the Length field of Node is set to
 365   END_DEVICE_PATH_LENGTH.  Node is not required to be aligned on a 16-bit boundary,
 366   so it is recommended that a function such as WriteUnaligned16() be used to set
 367   the contents of the Length field.
 368
 369   If Node is NULL, then ASSERT().
 370
 371   @param  Node      A pointer to a device path node data structure.
 372
 373 **/
 374 VOID
 375 EFIAPI
 376 SetDevicePathEndNode (
 377   OUT VOID  *Node
 378   )
 379 {
 380   ASSERT (Node != NULL);
 381   CopyMem (Node, &mUefiDevicePathLibEndDevicePath, sizeof (mUefiDevicePathLibEndDevicePath));
 382 }
 383
 384 /**
 385   Returns the size of a device path in bytes.
 386
 387   This function returns the size, in bytes, of the device path data structure
 388   specified by DevicePath including the end of device path node.
 389   If DevicePath is NULL or invalid, then 0 is returned.
 390
 391   @param  DevicePath  A pointer to a device path data structure.
 392
 393   @retval 0           If DevicePath is NULL or invalid.
 394   @retval Others      The size of a device path in bytes.
 395
 396 **/
 397 UINTN
 398 EFIAPI
 399 GetDevicePathSize (
 400   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
 401   )
 402 {
 403   return mDevicePathLibDevicePathUtilities->GetDevicePathSize (DevicePath);
 404 }
 405
 406 /**
 407   Creates a new copy of an existing device path.
 408
 409   This function allocates space for a new copy of the device path specified by
 410   DevicePath.  If DevicePath is NULL, then NULL is returned.
 411   If the memory is successfully allocated, then the
 412   contents of DevicePath are copied to the newly allocated buffer, and a pointer to that buffer
 413   is returned.  Otherwise, NULL is returned.
 414   The memory for the new device path is allocated from EFI boot services memory.
 415   It is the responsibility of the caller to free the memory allocated.
 416
 417   @param  DevicePath                 A pointer to a device path data structure.
 418
 419   @retval NULL    If DevicePath is NULL or invalid.
 420   @retval Others  A pointer to the duplicated device path.
 421
 422 **/
 423 EFI_DEVICE_PATH_PROTOCOL *
 424 EFIAPI
 425 DuplicateDevicePath (
 426   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
 427   )
 428 {
 429   return mDevicePathLibDevicePathUtilities->DuplicateDevicePath (DevicePath);
 430 }
 431
 432 /**
 433   Creates a new device path by appending a second device path to a first device path.
 434
 435   This function creates a new device path by appending a copy of SecondDevicePath to a copy of
 436   FirstDevicePath in a newly allocated buffer.  Only the end-of-device-path device node from
 437   SecondDevicePath is retained. The newly created device path is returned.
 438   If FirstDevicePath is NULL, then it is ignored, and a duplicate of SecondDevicePath is returned.
 439   If SecondDevicePath is NULL, then it is ignored, and a duplicate of FirstDevicePath is returned.
 440   If both FirstDevicePath and SecondDevicePath are NULL, then a copy of an end-of-device-path is
 441   returned.
 442   If there is not enough memory for the newly allocated buffer, then NULL is returned.
 443   The memory for the new device path is allocated from EFI boot services memory. It is the
 444   responsibility of the caller to free the memory allocated.
 445
 446   @param  FirstDevicePath            A pointer to a device path data structure.
 447   @param  SecondDevicePath           A pointer to a device path data structure.
 448
 449   @retval NULL      If there is not enough memory for the newly allocated buffer.
 450   @retval NULL      If FirstDevicePath or SecondDevicePath is invalid.
 451   @retval Others    A pointer to the new device path if success.
 452                     Or a copy an end-of-device-path if both FirstDevicePath and
 453                     SecondDevicePath are NULL.
 454
 455 **/
 456 EFI_DEVICE_PATH_PROTOCOL *
 457 EFIAPI
 458 AppendDevicePath (
 459   IN CONST EFI_DEVICE_PATH_PROTOCOL  *FirstDevicePath,  OPTIONAL
 460   IN CONST EFI_DEVICE_PATH_PROTOCOL  *SecondDevicePath  OPTIONAL
 461   )
 462 {
 463   return mDevicePathLibDevicePathUtilities->AppendDevicePath (FirstDevicePath, SecondDevicePath);
 464 }
 465
 466 /**
 467   Creates a new path by appending the device node to the device path.
 468
 469   This function creates a new device path by appending a copy of the device node
 470   specified by DevicePathNode to a copy of the device path specified by DevicePath
 471   in an allocated buffer.
 472   The end-of-device-path device node is moved after the end of the appended device node.
 473   If DevicePathNode is NULL then a copy of DevicePath is returned.
 474   If DevicePath is NULL then a copy of DevicePathNode, followed by an end-of-device
 475   path device node is returned.
 476   If both DevicePathNode and DevicePath are NULL then a copy of an end-of-device-path
 477   device node is returned.
 478   If there is not enough memory to allocate space for the new device path, then
 479   NULL is returned.
 480   The memory is allocated from EFI boot services memory. It is the responsibility
 481   of the caller to free the memory allocated.
 482
 483   @param  DevicePath                 A pointer to a device path data structure.
 484   @param  DevicePathNode             A pointer to a single device path node.
 485
 486   @retval NULL      If there is not enough memory for the new device path.
 487   @retval Others    A pointer to the new device path if success.
 488                     A copy of DevicePathNode followed by an end-of-device-path node
 489                     if both FirstDevicePath and SecondDevicePath are NULL.
 490                     A copy of an end-of-device-path node if both FirstDevicePath
 491                     and SecondDevicePath are NULL.
 492
 493 **/
 494 EFI_DEVICE_PATH_PROTOCOL *
 495 EFIAPI
 496 AppendDevicePathNode (
 497   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath,     OPTIONAL
 498   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePathNode  OPTIONAL
 499   )
 500 {
 501   return mDevicePathLibDevicePathUtilities->AppendDeviceNode (DevicePath, DevicePathNode);
 502 }
 503
 504 /**
 505   Creates a new device path by appending the specified device path instance to
 506   the specified device path.
 507
 508   This function creates a new device path by appending a copy of the device path
 509   instance specified by DevicePathInstance to a copy of the device path specified
 510   by DevicePath in a allocated buffer.
 511   The end-of-device-path device node is moved after the end of the appended device
 512   path instance and a new end-of-device-path-instance node is inserted between.
 513   If DevicePath is NULL, then a copy if DevicePathInstance is returned.
 514   If DevicePathInstance is NULL, then NULL is returned.
 515   If DevicePath or DevicePathInstance is invalid, then NULL is returned.
 516   If there is not enough memory to allocate space for the new device path, then
 517   NULL is returned.
 518   The memory is allocated from EFI boot services memory. It is the responsibility
 519   of the caller to free the memory allocated.
 520
 521   @param  DevicePath                 A pointer to a device path data structure.
 522   @param  DevicePathInstance         A pointer to a device path instance.
 523
 524   @return A pointer to the new device path.
 525
 526 **/
 527 EFI_DEVICE_PATH_PROTOCOL *
 528 EFIAPI
 529 AppendDevicePathInstance (
 530   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath,        OPTIONAL
 531   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePathInstance OPTIONAL
 532   )
 533 {
 534   return mDevicePathLibDevicePathUtilities->AppendDevicePathInstance (DevicePath, DevicePathInstance);
 535 }
 536
 537 /**
 538   Creates a copy of the current device path instance and returns a pointer to the
 539   next device path instance.
 540
 541   This function creates a copy of the current device path instance. It also updates
 542   DevicePath to point to the next device path instance in the device path (or NULL
 543   if no more) and updates Size to hold the size of the device path instance copy.
 544   If DevicePath is NULL, then NULL is returned.
 545   If there is not enough memory to allocate space for the new device path, then
 546   NULL is returned.
 547   The memory is allocated from EFI boot services memory. It is the responsibility
 548   of the caller to free the memory allocated.
 549   If Size is NULL, then ASSERT().
 550
 551   @param  DevicePath                 On input, this holds the pointer to the current
 552                                      device path instance. On output, this holds
 553                                      the pointer to the next device path instance
 554                                      or NULL if there are no more device path
 555                                      instances in the device path pointer to a
 556                                      device path data structure.
 557   @param  Size                       On output, this holds the size of the device
 558                                      path instance, in bytes or zero, if DevicePath
 559                                      is NULL.
 560
 561   @return A pointer to the current device path instance.
 562
 563 **/
 564 EFI_DEVICE_PATH_PROTOCOL *
 565 EFIAPI
 566 GetNextDevicePathInstance (
 567   IN OUT EFI_DEVICE_PATH_PROTOCOL    **DevicePath,
 568   OUT UINTN                          *Size
 569   )
 570 {
 571   ASSERT (Size != NULL);
 572   return mDevicePathLibDevicePathUtilities->GetNextDevicePathInstance (DevicePath, Size);
 573 }
 574
 575 /**
 576   Creates a device node.
 577
 578   This function creates a new device node in a newly allocated buffer of size
 579   NodeLength and initializes the device path node header with NodeType and NodeSubType.
 580   The new device path node is returned.
 581   If NodeLength is smaller than a device path header, then NULL is returned.
 582   If there is not enough memory to allocate space for the new device path, then
 583   NULL is returned.
 584   The memory is allocated from EFI boot services memory. It is the responsibility
 585   of the caller to free the memory allocated.
 586
 587   @param  NodeType                   The device node type for the new device node.
 588   @param  NodeSubType                The device node sub-type for the new device node.
 589   @param  NodeLength                 The length of the new device node.
 590
 591   @return The new device path.
 592
 593 **/
 594 EFI_DEVICE_PATH_PROTOCOL *
 595 EFIAPI
 596 CreateDeviceNode (
 597   IN UINT8                           NodeType,
 598   IN UINT8                           NodeSubType,
 599   IN UINT16                          NodeLength
 600   )
 601 {
 602   return mDevicePathLibDevicePathUtilities->CreateDeviceNode (NodeType, NodeSubType, NodeLength);
 603 }
 604
 605 /**
 606   Determines if a device path is single or multi-instance.
 607
 608   This function returns TRUE if the device path specified by DevicePath is
 609   multi-instance.
 610   Otherwise, FALSE is returned.
 611   If DevicePath is NULL or invalid, then FALSE is returned.
 612
 613   @param  DevicePath                 A pointer to a device path data structure.
 614
 615   @retval  TRUE                      DevicePath is multi-instance.
 616   @retval  FALSE                     DevicePath is not multi-instance, or DevicePath
 617                                      is NULL or invalid.
 618
 619 **/
 620 BOOLEAN
 621 EFIAPI
 622 IsDevicePathMultiInstance (
 623   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
 624   )
 625 {
 626   return mDevicePathLibDevicePathUtilities->IsDevicePathMultiInstance (DevicePath);
 627 }
 628
 629 /**
 630   Retrieves the device path protocol from a handle.
 631
 632   This function returns the device path protocol from the handle specified by Handle.
 633   If Handle is NULL or Handle does not contain a device path protocol, then NULL
 634   is returned.
 635
 636   @param  Handle                     The handle from which to retrieve the device
 637                                      path protocol.
 638
 639   @return The device path protocol from the handle specified by Handle.
 640
 641 **/
 642 EFI_DEVICE_PATH_PROTOCOL *
 643 EFIAPI
 644 DevicePathFromHandle (
 645   IN EFI_HANDLE                      Handle
 646   )
 647 {
 648   EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
 649   EFI_STATUS                Status;
 650
 651   Status = gBS->HandleProtocol (
 652                   Handle,
 653                   &gEfiDevicePathProtocolGuid,
 654                   (VOID *) &DevicePath
 655                   );
 656   if (EFI_ERROR (Status)) {
 657     DevicePath = NULL;
 658   }
 659   return DevicePath;
 660 }
 661
 662 /**
 663   Allocates a device path for a file and appends it to an existing device path.
 664
 665   If Device is a valid device handle that contains a device path protocol, then
 666   a device path for the file specified by FileName  is allocated and appended to
 667   the device path associated with the handle Device.  The allocated device path
 668   is returned.  If Device is NULL or Device is a handle that does not support the
 669   device path protocol, then a device path containing a single device path node
 670   for the file specified by FileName is allocated and returned.
 671   The memory for the new device path is allocated from EFI boot services memory.
 672   It is the responsibility of the caller to free the memory allocated.
 673
 674   If FileName is NULL, then ASSERT().
 675   If FileName is not aligned on a 16-bit boundary, then ASSERT().
 676
 677   @param  Device                     A pointer to a device handle.  This parameter
 678                                      is optional and may be NULL.
 679   @param  FileName                   A pointer to a Null-terminated Unicode string.
 680
 681   @return The allocated device path.
 682
 683 **/
 684 EFI_DEVICE_PATH_PROTOCOL *
 685 EFIAPI
 686 FileDevicePath (
 687   IN EFI_HANDLE                      Device,     OPTIONAL
 688   IN CONST CHAR16                    *FileName
 689   )
 690 {
 691   UINTN                     Size;
 692   FILEPATH_DEVICE_PATH      *FilePath;
 693   EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
 694   EFI_DEVICE_PATH_PROTOCOL  *FileDevicePath;
 695
 696   DevicePath = NULL;
 697
 698   Size = StrSize (FileName);
 699   FileDevicePath = AllocatePool (Size + SIZE_OF_FILEPATH_DEVICE_PATH + END_DEVICE_PATH_LENGTH);
 700   if (FileDevicePath != NULL) {
 701     FilePath = (FILEPATH_DEVICE_PATH *) FileDevicePath;
 702     FilePath->Header.Type    = MEDIA_DEVICE_PATH;
 703     FilePath->Header.SubType = MEDIA_FILEPATH_DP;
 704     CopyMem (&FilePath->PathName, FileName, Size);
 705     SetDevicePathNodeLength (&FilePath->Header, Size + SIZE_OF_FILEPATH_DEVICE_PATH);
 706     SetDevicePathEndNode (NextDevicePathNode (&FilePath->Header));
 707
 708     if (Device != NULL) {
 709       DevicePath = DevicePathFromHandle (Device);
 710     }
 711
 712     DevicePath = AppendDevicePath (DevicePath, FileDevicePath);
 713     FreePool (FileDevicePath);
 714   }
 715
 716   return DevicePath;
 717 }
 718
 719 /**
 720   Locate and return the protocol instance identified by the ProtocolGuid.
 721
 722   @param ProtocolGuid     The GUID of the protocol.
 723
 724   @return A pointer to the protocol instance or NULL when absent.
 725 **/
 726 VOID *
 727 UefiDevicePathLibLocateProtocol (
 728   EFI_GUID                         *ProtocolGuid
 729   )
 730 {
 731   EFI_STATUS Status;
 732   VOID       *Protocol;
 733   Status = gBS->LocateProtocol (
 734                   ProtocolGuid,
 735                   NULL,
 736                   (VOID**) &Protocol
 737                   );
 738   if (EFI_ERROR (Status)) {
 739     return NULL;
 740   } else {
 741     return Protocol;
 742   }
 743 }
 744
 745 /**
 746   Converts a device node to its string representation.
 747
 748   @param DeviceNode        A Pointer to the device node to be converted.
 749   @param DisplayOnly       If DisplayOnly is TRUE, then the shorter text representation
 750                            of the display node is used, where applicable. If DisplayOnly
 751                            is FALSE, then the longer text representation of the display node
 752                            is used.
 753   @param AllowShortcuts    If AllowShortcuts is TRUE, then the shortcut forms of text
 754                            representation for a device node can be used, where applicable.
 755
 756   @return A pointer to the allocated text representation of the device node or NULL if DeviceNode
 757           is NULL or there was insufficient memory.
 758
 759 **/
 760 CHAR16 *
 761 EFIAPI
 762 ConvertDeviceNodeToText (
 763   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DeviceNode,
 764   IN BOOLEAN                         DisplayOnly,
 765   IN BOOLEAN                         AllowShortcuts
 766   )
 767 {
 768   if (mDevicePathLibDevicePathToText == NULL) {
 769     mDevicePathLibDevicePathToText = UefiDevicePathLibLocateProtocol (&gEfiDevicePathToTextProtocolGuid);
 770   }
 771   if (mDevicePathLibDevicePathToText != NULL) {
 772     return mDevicePathLibDevicePathToText->ConvertDeviceNodeToText (DeviceNode, DisplayOnly, AllowShortcuts);
 773   } else {
 774     return NULL;
 775   }
 776 }
 777
 778 /**
 779   Converts a device path to its text representation.
 780
 781   @param DevicePath      A Pointer to the device to be converted.
 782   @param DisplayOnly     If DisplayOnly is TRUE, then the shorter text representation
 783                          of the display node is used, where applicable. If DisplayOnly
 784                          is FALSE, then the longer text representation of the display node
 785                          is used.
 786   @param AllowShortcuts  If AllowShortcuts is TRUE, then the shortcut forms of text
 787                          representation for a device node can be used, where applicable.
 788
 789   @return A pointer to the allocated text representation of the device path or
 790           NULL if DeviceNode is NULL or there was insufficient memory.
 791
 792 **/
 793 CHAR16 *
 794 EFIAPI
 795 ConvertDevicePathToText (
 796   IN CONST EFI_DEVICE_PATH_PROTOCOL   *DevicePath,
 797   IN BOOLEAN                          DisplayOnly,
 798   IN BOOLEAN                          AllowShortcuts
 799   )
 800 {
 801   if (mDevicePathLibDevicePathToText == NULL) {
 802     mDevicePathLibDevicePathToText = UefiDevicePathLibLocateProtocol (&gEfiDevicePathToTextProtocolGuid);
 803   }
 804   if (mDevicePathLibDevicePathToText != NULL) {
 805     return mDevicePathLibDevicePathToText->ConvertDevicePathToText (DevicePath, DisplayOnly, AllowShortcuts);
 806   } else {
 807     return NULL;
 808   }
 809 }
 810
 811 /**
 812   Convert text to the binary representation of a device node.
 813
 814   @param TextDeviceNode  TextDeviceNode points to the text representation of a device
 815                          node. Conversion starts with the first character and continues
 816                          until the first non-device node character.
 817
 818   @return A pointer to the EFI device node or NULL if TextDeviceNode is NULL or there was
 819           insufficient memory or text unsupported.
 820
 821 **/
 822 EFI_DEVICE_PATH_PROTOCOL *
 823 EFIAPI
 824 ConvertTextToDeviceNode (
 825   IN CONST CHAR16 *TextDeviceNode
 826   )
 827 {
 828   if (mDevicePathLibDevicePathFromText == NULL) {
 829     mDevicePathLibDevicePathFromText = UefiDevicePathLibLocateProtocol (&gEfiDevicePathFromTextProtocolGuid);
 830   }
 831   if (mDevicePathLibDevicePathFromText != NULL) {
 832     return mDevicePathLibDevicePathFromText->ConvertTextToDeviceNode (TextDeviceNode);
 833   } else {
 834     return NULL;
 835   }
 836 }
 837
 838 /**
 839   Convert text to the binary representation of a device path.
 840
 841
 842   @param TextDevicePath  TextDevicePath points to the text representation of a device
 843                          path. Conversion starts with the first character and continues
 844                          until the first non-device node character.
 845
 846   @return A pointer to the allocated device path or NULL if TextDeviceNode is NULL or
 847           there was insufficient memory.
 848
 849 **/
 850 EFI_DEVICE_PATH_PROTOCOL *
 851 EFIAPI
 852 ConvertTextToDevicePath (
 853   IN CONST CHAR16 *TextDevicePath
 854   )
 855 {
 856   if (mDevicePathLibDevicePathFromText == NULL) {
 857     mDevicePathLibDevicePathFromText = UefiDevicePathLibLocateProtocol (&gEfiDevicePathFromTextProtocolGuid);
 858   }
 859   if (mDevicePathLibDevicePathFromText != NULL) {
 860     return mDevicePathLibDevicePathFromText->ConvertTextToDevicePath (TextDevicePath);
 861   } else {
 862     return NULL;
 863   }
 864 }
 865