content: /* ###
   * IP: GHIDRA
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package firmware.option_rom;
  
  import firmware.common.EFIDecompressor;
  import ghidra.app.util.bin.BinaryReader;
  import ghidra.app.util.bin.ByteArrayProvider;
  import ghidra.app.util.bin.ByteProvider;
  import ghidra.app.util.bin.ByteProviderWrapper;
  import ghidra.formats.gfilesystem.fileinfo.FileAttributes;
  import ghidra.program.model.data.ArrayDataType;
  import ghidra.program.model.data.DataType;
  import ghidra.program.model.data.Structure;
  import ghidra.program.model.data.StructureDataType;
  
  import java.io.IOException;
  
  /**
   * Parser for UEFI option ROM images. There are additional fields in the ROM header:
   *
   * <pre>
   *   ROM Header
   *   +---------+------+-------------------------------------------+
   *   | Type    | Size | Description                               |
   *   +---------+------+-------------------------------------------+
   *   | u16     |    2 | Signature (0xAA55, little endian)         |
   *   | u16     |    2 | Image Size (in units of 512 bytes)        |
   *   | u32     |    4 | EFI Signature (0x00000EF1, little endian) |
   *   | u16     |    2 | EFI Subsystem                             |
   *   | u16     |    2 | EFI Machine Type                          |
   *   | u16     |    2 | EFI Compression Type                      |
   *   | u8[8]   |    8 | Reserved                                  |
   *   | u16     |    2 | EFI Image Offset                          |
   *   | u16     |    2 | PCI Data Structure Offset                 |
   *   +---------+------+-------------------------------------------+
   * </pre>
   *
   * See OptionROMConstants for possible EFI Subsystem and Machine Type values.
   *
   * The EFI Image Offset field in the ROM header is used to locate the EFI PE32+ executable. If the
   * EFI Compression Type field is set to 1, the PE32+ executable is compressed with the EFI
   * Compression Algorithm, which is a combination of the LZ77 algorithm and Huffman coding. The
   * EFIDecompressor class is used to handle compressed images.
   */
  public class UEFIOptionROMHeader extends OptionROMHeader {
  	// Original header fields
  	private final short imageSize;
  	private final int efiSignature;
  	private final short efiSubsystem;
  	private final short efiMachineType;
  	private final short efiCompressionType;
  	private final short efiImageOffset;
  
  	private final ByteProvider provider;
  
  	/**
  	 * Constructs a UEFIOptionROMHeader from a specified BinaryReader.
  	 *
  	 * @param reader the specified BinaryReader
  	 */
  	public UEFIOptionROMHeader(BinaryReader reader) throws IOException {
  		super(reader);
  		byte codeType = getPCIRHeader().getCodeType();
  		if (codeType != OptionROMConstants.CodeType.EFI) {
  			throw new IOException("Code type mismatch: expected EFI (3), got " +
  					OptionROMConstants.CodeType.toString(codeType) + " (" + codeType + ')');
  		}
  
  		reader.setPointerIndex(0x2);
  		imageSize = reader.readNextShort();
  		efiSignature = reader.readNextInt();
  		if (efiSignature != OptionROMConstants.EFI_SIGNATURE) {
  			throw new IOException("Not a valid EFI PCI option ROM header");
  		}
  
  		efiSubsystem = reader.readNextShort();
  		efiMachineType = reader.readNextShort();
  		efiCompressionType = reader.readNextShort();
  		reader.setPointerIndex(0x16);
  		efiImageOffset = reader.readNextShort();
  
  		int efiExecutableSize = imageSize * OptionROMConstants.ROM_SIZE_UNIT - efiImageOffset;
  		if (efiCompressionType == 1) {
  			// Decompress EFI executables that were compressed with the EFI Compression Algorithm.
  			reader.setPointerIndex(efiImageOffset);
  			byte[] compressedExecutable = reader.readNextByteArray(efiExecutableSize);
  			provider = new ByteArrayProvider(EFIDecompressor.decompress(compressedExecutable));
  		} else {
  			provider = new ByteProviderWrapper(reader.getByteProvider(), efiImageOffset, efiExecutableSize);
  		}
  	}
  
  	/**
  	 * Returns a ByteProvider for the contents of the EFI PE32+ executable. Compressed executables
  	 * will be transparently decompressed before returning.
  	 *
  	 * @return a ByteProvider for the contents of the EFI PE32+ executable
  	 */
  	@Override
  	public ByteProvider getByteProvider() {
  		return provider;
  	}
  
  	/**
  	 * Returns FileAttributes for the current image.
  	 *
  	 * @return FileAttributes for the current image
  	 */
  	public FileAttributes getFileAttributes() {
  		FileAttributes attributes = super.getFileAttributes();
  		attributes.add("EFI Subsystem", OptionROMConstants.EFIImageSubsystem.toString(efiSubsystem));
  		attributes.add("EFI Machine Type", OptionROMConstants.EFIImageMachineType.toString(efiMachineType));
  		attributes.add("EFI Image Compressed", efiCompressionType == 1);
  		attributes.add("EFI Image Offset", efiImageOffset);
  		return attributes;
  	}
  
  	@Override
  	public DataType toDataType() {
  		Structure structure = new StructureDataType("uefi_option_rom_header_t", 0);
  		structure.add(WORD, 2,"signature", null);
  		structure.add(WORD, 2, "image_size", null);
  		structure.add(DWORD, 4, "efi_signature", null);
  		structure.add(WORD, 2, "efi_subsystem", null);
  		structure.add(WORD, 2, "efi_machine_type", null);
  		structure.add(WORD, 2, "efi_compression_type", null);
  		structure.add(new ArrayDataType(BYTE, 0x8, 1), "reserved", null);
  		structure.add(POINTER, 2,"efi_image_offset", null);
  		structure.add(POINTER, 2, "pcir_offset", null);
  		return structure;
  	}
  }
  