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.FileAttributeUtils;
  import ghidra.app.util.bin.BinaryReader;
  import ghidra.app.util.bin.ByteProvider;
  import ghidra.app.util.bin.ByteProviderWrapper;
  import ghidra.app.util.bin.StructConverter;
  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;
  
  /**
   * Common parser for PCI expansion ROMs.
   *
   * A PCI expansion ROM may contain more than one image. Each image will contain the following
   * structures:
   *
   * <pre>
   *   ROM Header
   *   +---------+------+-------------------------------------------------------------------+
   *   | Type    | Size | Description                                                       |
   *   +---------+------+-------------------------------------------------------------------+
   *   | u16     |    2 | Signature (0xAA55, little endian)                                 |
   *   | u8[22]  |   22 | Reserved                                                          |
   *   | u16     |    2 | PCI Data Structure Offset                                         |
   *   +---------+------+-------------------------------------------------------------------+
   *
   *   PCI Data Structure
   *   +---------+------+-------------------------------------------------------------------+
   *   | Type    | Size | Description                                                       |
   *   +---------+------+-------------------------------------------------------------------+
   *   | char[4] |    4 | Signature ("PCIR")                                                |
   *   | u16     |    2 | Vendor ID                                                         |
   *   | u16     |    2 | Device ID                                                         |
   *   | u16     |    2 | Device List Offset (only for rev 3, otherwise Reserved)           |
   *   | u16     |    2 | PCI Data Structure Size (bytes)                                   |
   *   | u8      |    1 | PCI Data Structure Revision                                       |
   *   | u24     |    3 | Class Code                                                        |
   *   | u16     |    2 | Image Length (in units of 512 bytes)                              |
   *   | u16     |    2 | Vendor ROM Revision                                               |
   *   | u8      |    1 | Code Type                                                         |
   *   | u8      |    1 | Last Image Indicator                                              |
   *   | u16     |    2 | Maximum Runtime Image Length (only for rev 3, otherwise Reserved) |
   *   | u16     |    2 | Configuration Utility Code Offset (only for rev 3)                |
   *   | u16     |    2 | DMTF CLP Entry Point Offset (only for rev 3)                      |
   *   +---------+------+-------------------------------------------------------------------+
   * </pre>
   *
   * The ROM header must begin at the start of the each image's address space. The PCI Data
   * Structure Offset field in the ROM header is used to locate the PCI data structure. The PCI data
   * structure must be located within the first 64 KB of each image's address space.
   *
   * The Code Type field in the PCI data structure is used to determine the image type. Depending on
   * the image type, the Reserved field in the ROM header may contain additional fields. See
   * OptionROMConstants.CodeType for possible Code Type values.
   *
   * The Last Image Indicator field in the PCI data structure is used to determine if the current
   * image is the last one in the expansion ROM; bit 7 indicates this, while the remaining bits are
   * reserved. If this bit is not set, the address of the next image can be calculated as such:
   *
   *   addr(next_image) = addr(current_image->rom_header) + current_image->pci_data_struct->image_len * 512
   */
  public class OptionROMHeader implements StructConverter {
  	// Original header fields
  	private final short signature;
  	private final int pcirOffset;
  
  	private final PCIDataStructureHeader pcirHeader;
  	private DeviceList deviceList;
  	private final ByteProvider provider;
  
  	/**
  	 * Constructs an OptionROMHeader from a specified BinaryReader.
  	 *
  	 * @param reader the specified BinaryReader
  	 */
  	public OptionROMHeader(BinaryReader reader) throws IOException {
  		signature = reader.readNextShort();
  		if (signature != OptionROMConstants.ROM_SIGNATURE) {
  			throw new IOException("Not a valid PCI option ROM");
  		}
  
  		// Read the PCI data structure header.
  		reader.setPointerIndex(0x18);
  		pcirOffset = reader.readNextShort();
  		reader.setPointerIndex(pcirOffset);
  		pcirHeader = new PCIDataStructureHeader(reader);
  
  		// Read the device list (if present).
  		if (pcirHeader.getDeviceListOffset() != 0) {
  			reader.setPointerIndex(pcirOffset + pcirHeader.getDeviceListOffset());
  			deviceList = new DeviceList(reader);
  		}
  
  		// Copy the contents of the entire image.
  		provider = new ByteProviderWrapper(reader.getByteProvider(), 0, pcirHeader.getImageLength());
  	}
  
  	/**
  	 * Returns a ByteProvider for the contents of the image. Subclasses may override this to return
  	 * an enclosed executable instead of the raw image.
  	 *
  	 * @return a ByteProvider for the contents of the image
  	 */
  	public ByteProvider getByteProvider() {
  		// For a generic option ROM with an unknown code type, just return the entire ROM as the
  		// image. This will be overridden by subclasses (UEFIOptionROMHeader, etc) to only return
  		// the executable.
  		return provider;
  	}
  
  	/**
  	 * Returns the device list (if present).
  	 *
  	 * @return the device list; null if not present
  	 */
  	public DeviceList getDeviceList() {
  		return deviceList;
  	}
  
  	/**
  	 * Returns the PCIDataStructureHeader for the current image.
  	 *
  	 * @return the PCIDataStructureHeader for the current image
  	 */
  	public PCIDataStructureHeader getPCIRHeader() {
  		return pcirHeader;
  	}
  
  	/**
  	 * Returns the offset of the PCI data structure header in the current image.
  	 *
  	 * @return the offset of the PCI data structure header in the current image
  	 */
  	public int getPCIRHeaderOffset() {
  		return pcirOffset;
  	}
  
  	/**
  	 * Returns FileAttributes for the current image.
  	 *
  	 * @return FileAttributes for the current image
  	 */
  	public FileAttributes getFileAttributes() {
  		FileAttributes attributes = new FileAttributes();
  		attributes.add("PCI Data Structure Offset", pcirOffset);
  		FileAttributeUtils.addAll(attributes, pcirHeader.getFileAttributes());
  		if (deviceList != null) {
  			FileAttributeUtils.addAll(attributes, deviceList.getFileAttributes());
  		}
  
  		return attributes;
  	}
  
  	@Override
  	public DataType toDataType() {
  		Structure structure = new StructureDataType("option_rom_header_t", 0);
  		structure.add(WORD, 2, "signature", null);
  		structure.add(new ArrayDataType(BYTE, 0x16, 1), "reserved", null);
  		structure.add(POINTER, 2, "pcir_offset", null);
  		return structure;
  	}
  }
  