ifd: Handle IFDs without zero vector

Closes #21.
al3xtjames · Jul 19, 2022 · b7339d2 · b7339d2
1 parent 7370071
commit b7339d2
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Showing 2 changed files with 12 additions and 5 deletions.
diff --git a/src/main/java/firmware/ifd/IntelFlashDescriptor.java b/src/main/java/firmware/ifd/IntelFlashDescriptor.java
@@ -151,10 +151,13 @@ public class IntelFlashDescriptor {
 	 *
 	 * @param reader the specified BinaryReader
 	 */
-	public IntelFlashDescriptor(BinaryReader reader) throws IOException {
-		// Skip the IFD vector (16 0xFF bytes).
+	public IntelFlashDescriptor(BinaryReader reader, boolean hasZeroVector) throws IOException {
+		// Skip the IFD vector (16 0xFF bytes) if it's present.
+		// Some BIOSes may not include this (observed on HP Compaq dc7900).
 		headerOffset = reader.getPointerIndex();
-		reader.setPointerIndex(reader.getPointerIndex() + 16);
+		if (hasZeroVector) {
+			reader.setPointerIndex(reader.getPointerIndex() + 16);
+		}
 
 		signature = reader.readNextInt();
 		if (signature != IntelFlashDescriptorConstants.IFD_SIGNATURE) {

diff --git a/src/main/java/firmware/ifd/IntelFlashFileSystem.java b/src/main/java/firmware/ifd/IntelFlashFileSystem.java
@@ -40,9 +40,13 @@ public IntelFlashFileSystem(FSRLRoot fsFSRL) {
 	public void mount(ByteProvider provider, long offset, TaskMonitor monitor) throws IOException {
 		this.provider = provider;
 		BinaryReader reader = new BinaryReader(provider, true);
+		boolean hasZeroVector = offset >= 16;
 
-		reader.setPointerIndex(offset - 16);
-		IntelFlashDescriptor ifd = new IntelFlashDescriptor(reader);
+		if (hasZeroVector) {
+			reader.setPointerIndex(offset - 16);
+		}
+
+		IntelFlashDescriptor ifd = new IntelFlashDescriptor(reader, hasZeroVector);
 		List<IntelFlashRegion> regions = ifd.getRegions();
 
 		for (IntelFlashRegion region : regions) {