fwvolread.c

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                          Buffer. On output, *BufferSize contains the number
                          of bytes required to read the file.
    FoundType         -   FoundType is a pointer to a caller allocated
                          EFI_FV_FILETYPE that on successful return from Read()
                          contains the type of file read.  This output reflects
                          the file type irrespective of the value of the
                          SectionType input.
    FileAttributes    -   FileAttributes is a pointer to a caller allocated
                          EFI_FV_FILE_ATTRIBUTES.  On successful return from
                          Read(), *FileAttributes contains the attributes of
                          the file read.
    AuthenticationStatus -  AuthenticationStatus is a pointer to a caller
                          allocated UINTN in which the authentication status
                          is returned.
Returns:
    EFI_SUCCESS                   - Successfully read to memory buffer.
    EFI_WARN_BUFFER_TOO_SMALL     - Buffer too small.
    EFI_NOT_FOUND                 - Not found.
    EFI_DEVICE_ERROR              - Device error.
    EFI_ACCESS_DENIED             - Could not read.
    EFI_INVALID_PARAMETER         - Invalid parameter.
    EFI_OUT_OF_RESOURCES          - Not enough buffer to be allocated.

--*/
{
  EFI_STATUS                        Status;
  FV_DEVICE                         *FvDevice;
  EFI_GUID                          SearchNameGuid;
  EFI_FV_FILETYPE                   LocalFoundType;
  EFI_FV_FILE_ATTRIBUTES            LocalAttributes;
  UINTN                             FileSize;
  UINT8                             *SrcPtr;
  EFI_FFS_FILE_HEADER               *FfsHeader;
  UINTN                             InputBufferSize;
  
  if (NULL == NameGuid) {
    return EFI_INVALID_PARAMETER;
  }

  FvDevice = FV_DEVICE_FROM_THIS (This);
  

  //
  // Keep looking until we find the matching NameGuid.
  // The Key is really an FfsFileEntry
  //
  FvDevice->LastKey = 0;
  do {
    LocalFoundType = 0;
    Status = FvGetNextFile (
              This,
              &FvDevice->LastKey,
              &LocalFoundType,
              &SearchNameGuid,
              &LocalAttributes,
              &FileSize
              );
    if (EFI_ERROR (Status)) {
      return EFI_NOT_FOUND;
    }
  } while (!EfiCompareGuid (&SearchNameGuid, NameGuid));

  //
  // Get a pointer to the header
  //
  FfsHeader = FvDevice->LastKey->FfsHeader;

  //
  // Remember callers buffer size
  //
  InputBufferSize = *BufferSize;

  //
  // Calculate return values
  //
  *FoundType = FfsHeader->Type;
  *FileAttributes = FfsAttributes2FvFileAttributes (FfsHeader->Attributes);
  *AuthenticationStatus = 0;
  *BufferSize = FileSize;

  if (Buffer == NULL) {
    //
    // If Buffer is NULL, we only want to get the information colected so far
    //
    return EFI_SUCCESS;
  }

  //
  // Skip over file header
  //
  SrcPtr = ((UINT8 *)FfsHeader) + sizeof (EFI_FFS_FILE_HEADER);

  Status = EFI_SUCCESS;
  if (*Buffer == NULL) {
    //
    // Caller passed in a pointer so allocate buffer for them
    //
    *Buffer = CoreAllocateBootServicesPool (FileSize);
    if (*Buffer == NULL) {
      return EFI_OUT_OF_RESOURCES;
    }
  } else if (FileSize > InputBufferSize) {
    //
    // Callers buffer was not big enough
    // 
    Status = EFI_WARN_BUFFER_TOO_SMALL;
    FileSize = InputBufferSize;
  }
  
  //
  // Copy data into callers buffer 
  //
  EfiCommonLibCopyMem (*Buffer, SrcPtr, FileSize);

  return Status;
}


EFI_STATUS
EFIAPI
FvReadFileSection (
  IN     EFI_FIRMWARE_VOLUME_PROTOCOL   *This,
  IN     EFI_GUID                       *NameGuid,
  IN     EFI_SECTION_TYPE               SectionType,
  IN     UINTN                          SectionInstance,
  IN OUT VOID                           **Buffer,
  IN OUT UINTN                          *BufferSize,
  OUT    UINT32                         *AuthenticationStatus
  )
/*++

  Routine Description:
    Locates a section in a given FFS File and
    copies it to the supplied buffer (not including section header).

  Arguments:
    This              -   Indicates the calling context.
    NameGuid          -   Pointer to an EFI_GUID, which is the filename.
    SectionType       -   Indicates the section type to return.
    SectionInstance   -   Indicates which instance of sections with a type of
                          SectionType to return.
    Buffer            -   Buffer is a pointer to pointer to a buffer in which
                          the file or section contents or are returned.
    BufferSize        -   BufferSize is a pointer to caller allocated UINTN.
    AuthenticationStatus -AuthenticationStatus is a pointer to a caller
                          allocated UINT32 in which the authentication status
                          is returned.

  Returns:
    EFI_SUCCESS                     - Successfully read the file section into buffer.
    EFI_WARN_BUFFER_TOO_SMALL       - Buffer too small.
    EFI_NOT_FOUND                   - Section not found.
    EFI_DEVICE_ERROR                - Device error.
    EFI_ACCESS_DENIED               - Could not read.
    EFI_INVALID_PARAMETER           - Invalid parameter.

--*/
{
  EFI_STATUS                        Status;
  FV_DEVICE                         *FvDevice;
  EFI_FV_FILETYPE                   FileType;
  EFI_FV_FILE_ATTRIBUTES            FileAttributes;
  UINTN                             FileSize;
  UINT8                             *FileBuffer;
  EFI_SECTION_EXTRACTION_PROTOCOL   *Sep;
  FFS_FILE_LIST_ENTRY               *FfsEntry;
 
  if (NULL == NameGuid || Buffer == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  FvDevice = FV_DEVICE_FROM_THIS (This);

  //
  // Read the whole file into buffer
  //
  FileBuffer = NULL;
  Status = FvReadFile (
            This,
            NameGuid,
            &FileBuffer,
            &FileSize,
            &FileType,
            &FileAttributes,
            AuthenticationStatus
            );             
  //
  // Get the last key used by our call to FvReadFile as it is the FfsEntry for this file.
  //  
  FfsEntry = (FFS_FILE_LIST_ENTRY *)FvDevice->LastKey;

  if (EFI_ERROR (Status)) {
    return Status;
  }
  
  //
  // Check to see that the file actually HAS sections before we go any further.
  //
  if (FileType == EFI_FV_FILETYPE_RAW) {
    Status = EFI_NOT_FOUND;
    goto Done;
  }

  //
  // Use FfsEntry to cache Section Extraction Protocol Inforomation
  //
  if (FfsEntry->StreamHandle == 0) {
    //
    // Located the protocol
    //
    Status = CoreLocateProtocol (&gEfiSectionExtractionProtocolGuid, NULL, &Sep);
    //
    // Section Extraction Protocol is part of Dxe Core so this should never fail
    //
    ASSERT_EFI_ERROR (Status);

    Status = Sep->OpenSectionStream (
                    Sep,
                    FileSize,
                    FileBuffer,
                    &FfsEntry->StreamHandle
                    );
    if (EFI_ERROR (Status)) {
      goto Done;
    }

    FfsEntry->Sep = Sep;
  } else {
    //
    // Get cached copy of Sep
    //
    Sep = FfsEntry->Sep;
  }

  //
  // If SectionType == 0 We need the whole section stream
  //
  Status = Sep->GetSection (
                  Sep,
                            FfsEntry->StreamHandle,
                            (SectionType == 0) ? NULL : &SectionType,
                            NULL,
                            (SectionType == 0) ? 0 : SectionInstance,
                            Buffer,
                            BufferSize,
                            AuthenticationStatus
                            );

  //
  // Close of stream defered to close of FfsHeader list to allow SEP to cache data
  //

Done:
  CoreFreePool (FileBuffer);

  return Status;
}