From efa325f75db9a971c2cca9e28c9ac724cd537ade Mon Sep 17 00:00:00 2001
From:  <david__schmidt@users.sourceforge.net>
Date: Wed, 1 Aug 2012 21:35:54 +0000
Subject: [PATCH] Add read-only support for DC42 images

---
 .../applecommander/storage/Disk.java          | 25 ++++++++++++++++---
 .../applecommander/util/AppleUtil.java        | 14 +++++++++++
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/src/com/webcodepro/applecommander/storage/Disk.java b/src/com/webcodepro/applecommander/storage/Disk.java
index 994f878..9128f4f 100644
--- a/src/com/webcodepro/applecommander/storage/Disk.java
+++ b/src/com/webcodepro/applecommander/storage/Disk.java
@@ -178,6 +178,7 @@ public class Disk {
 		this.filename = filename;
 		int diskSize = 0;
 		byte[] diskImage = null;
+		byte[] diskImageDC42 = null;
 
 		if (isSDK() || isSHK()) {
 			// If we have an SDK, unpack it and send along the byte array
@@ -194,13 +195,31 @@ public class Disk {
 			StreamUtil.copy(input, diskImageByteArray);
 			diskImage = diskImageByteArray.toByteArray();
 		}
-		boolean is2img = false;
+		int offset = 0;
+		boolean is2img = false, isDC42 = false;
 		/* Does it have the 2IMG header? */
-		if ((diskImage[00] == 0x32) && (diskImage[01] == 0x49) && (diskImage[02] == 0x4D) && (diskImage[03]) == 0x47)
+		if ((diskImage[00] == 0x32) && (diskImage[01] == 0x49) && (diskImage[02] == 0x4D) && (diskImage[03]) == 0x47) {
 			is2img = true;
-		int offset = UniversalDiskImageLayout.OFFSET;
+			offset = UniversalDiskImageLayout.OFFSET;
+		}
+		/* Does it have the DiskCopy 4.2 header? */
+		else if (((diskImage[0x52] == 0x01) && (diskImage[0x53] == 0x00)) &&
+				((diskImage[0x51] == 0x02) || (diskImage[0x51] == 0x22) || (diskImage[0x51] == 0x24))) {
+			isDC42 = true;
+			offset = 84;
+			long end = AppleUtil.getLongValue(diskImage,0x40);
+			if (end < diskImage.length - 83) {
+				diskImageDC42 = new byte[(int)end];
+				System.arraycopy(diskImage, 84, diskImageDC42, 0, (int)end);
+				diskImageManager = new ByteArrayImageLayout(diskImageDC42);
+			}
+			else
+				throw new IllegalArgumentException(textBundle.get("Disk.ResizeDiskError")); // FIXME - need a better explanation of this
+		}
 		if (is2img == true || diskImage.length == APPLE_800KB_DISK + offset || diskImage.length == APPLE_5MB_HARDDISK + offset || diskImage.length == APPLE_10MB_HARDDISK + offset || diskImage.length == APPLE_20MB_HARDDISK + offset || diskImage.length == APPLE_32MB_HARDDISK + offset) {
 			diskImageManager = new UniversalDiskImageLayout(diskImage);
+		} else if (isDC42) {
+			diskImageManager = new ByteArrayImageLayout(diskImageDC42);
 		} else {
 			diskImageManager = new ByteArrayImageLayout(diskImage);
 		}
diff --git a/src/com/webcodepro/applecommander/util/AppleUtil.java b/src/com/webcodepro/applecommander/util/AppleUtil.java
index 924a870..13147b2 100644
--- a/src/com/webcodepro/applecommander/util/AppleUtil.java
+++ b/src/com/webcodepro/applecommander/util/AppleUtil.java
@@ -110,6 +110,20 @@ public class AppleUtil {
 			+ getUnsignedByte(buffer[offset+2])*65536;
 	}
 	
+	/**
+	 * Compute the value of a 4 byte value. This is specific to DC42 processing.
+	 * Pulls value from buffer given the offset, MSB first. 
+	 */
+	public static long getLongValue(byte[] buffer, int offset) {
+		if (offset+3 > buffer.length) {
+			return 0;
+		}
+		return getUnsignedByte(buffer[offset+3]) 
+			+ getUnsignedByte(buffer[offset+2])*256
+			+ getUnsignedByte(buffer[offset+1])*65536
+			+ getUnsignedByte(buffer[offset])*16777216;
+	}
+	
 	/**
 	 * Set the value of a 3 byte value.
 	 */