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.fmap;
  
  import java.io.IOException;
  import java.nio.charset.StandardCharsets;
  
  import ghidra.app.util.bin.ByteProvider;
  import ghidra.formats.gfilesystem.FSRLRoot;
  import ghidra.formats.gfilesystem.FileSystemService;
  import ghidra.formats.gfilesystem.factory.GFileSystemFactoryByteProvider;
  import ghidra.formats.gfilesystem.factory.GFileSystemProbeByteProvider;
  import ghidra.util.Msg;
  import ghidra.util.task.TaskMonitor;
  
  public class FlashMapFileSystemFactory implements GFileSystemFactoryByteProvider<FlashMapFileSystem>,
  		GFileSystemProbeByteProvider {
  	@Override
  	public boolean probe(ByteProvider provider, FileSystemService fsService, TaskMonitor monitor) throws IOException {
  		return findFMapSignatureOffset(provider) != -1;
  	}
  
  	@Override
  	public FlashMapFileSystem create(FSRLRoot fsrlRoot, ByteProvider provider, FileSystemService fsService,
  			TaskMonitor monitor) throws IOException {
  		FlashMapFileSystem fs = new FlashMapFileSystem(fsrlRoot);
  		try {
  			long offset = findFMapSignatureOffset(provider);
  			if (offset < 0) {
  				throw new IOException("FMAP signature not found");
  			}
  
  			fs.mount(provider, offset, monitor);
  			return fs;
  		} catch (IOException ioe) {
  			fs.close();
  			throw ioe;
  		}
  	}
  
  	private long findFMapSignatureOffset(ByteProvider provider) throws IOException {
  		long remainingLength = provider.length();
  		long offset = 0;
  		while (remainingLength >= FlashMapConstants.FMAP_SIGNATURE.length()) {
  			String signature = new String(provider.readBytes(offset, FlashMapConstants.FMAP_SIGNATURE.length()),
  					StandardCharsets.US_ASCII);
  			if (signature.equals(FlashMapConstants.FMAP_SIGNATURE)) {
  				Msg.debug(this, String.format("Found FMAP signature at 0x%X", offset));
  				return offset;
  			}
  
  			offset += FlashMapConstants.FMAP_SIGNATURE.length();
  			remainingLength -= FlashMapConstants.FMAP_SIGNATURE.length();
  		}
  
  		return -1;
  	}
  }
  