From c639d229c699c20bd5bf5b10527b74b3248911d9 Mon Sep 17 00:00:00 2001
From: Ben Gruver <bgruv@google.com>
Date: Wed, 7 Aug 2019 11:33:37 -0700
Subject: [PATCH] Add support for the new debug offset table for cdex files

---
 .../dexlib2/dexbacked/CDexBackedDexFile.java  |  12 ++
 .../CDexBackedMethodImplementation.java       |  28 ++++-
 .../dexbacked/raw/CdexDebugOffsetTable.java   | 111 ++++++++++++++++++
 .../dexlib2/dexbacked/raw/CdexHeaderItem.java |  16 +++
 .../jf/dexlib2/dexbacked/raw/HeaderItem.java  |   5 +
 .../dexbacked/raw/util/DexAnnotator.java      |   7 ++
 6 files changed, 177 insertions(+), 2 deletions(-)
 create mode 100644 dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/CdexDebugOffsetTable.java

diff --git a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/CDexBackedDexFile.java b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/CDexBackedDexFile.java
index 15df46bc..956d64c0 100644
--- a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/CDexBackedDexFile.java
+++ b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/CDexBackedDexFile.java
@@ -90,6 +90,18 @@ public class CDexBackedDexFile extends DexBackedDexFile {
         return getBuffer().readSmallUint(HeaderItem.DATA_START_OFFSET);
     }
 
+    public int getDebugInfoOffsetsPos() {
+        return getBuffer().readSmallUint(CdexHeaderItem.DEBUG_INFO_OFFSETS_POS_OFFSET);
+    }
+
+    public int getDebugInfoOffsetsTableOffset() {
+        return getBuffer().readSmallUint(CdexHeaderItem.DEBUG_INFO_OFFSETS_TABLE_OFFSET);
+    }
+
+    public int getDebugInfoBase() {
+        return getBuffer().readSmallUint(CdexHeaderItem.DEBUG_INFO_BASE);
+    }
+
     @Override
     protected DexBackedMethodImplementation createMethodImplementation(
             @Nonnull DexBackedDexFile dexFile, @Nonnull DexBackedMethod method, int codeOffset) {
diff --git a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/CDexBackedMethodImplementation.java b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/CDexBackedMethodImplementation.java
index 85378bde..62d529eb 100644
--- a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/CDexBackedMethodImplementation.java
+++ b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/CDexBackedMethodImplementation.java
@@ -113,7 +113,31 @@ public class CDexBackedMethodImplementation extends DexBackedMethodImplementatio
 
     @Override
     protected int getDebugOffset() {
-        // TODO: figure out the new debug stuff in cdex
-        return 0;
+        CDexBackedDexFile cdexFile = ((CDexBackedDexFile) dexFile);
+
+        int debugTableItemOffset = (method.methodIndex / 16) * 4;
+        int bitIndex = method.methodIndex % 16;
+
+        int debugInfoOffsetsPos = cdexFile.getDebugInfoOffsetsPos();
+        int debugTableOffset = debugInfoOffsetsPos + cdexFile.getDebugInfoOffsetsTableOffset();
+
+        int debugOffsetsOffset = cdexFile.getDataBuffer().readSmallUint(debugTableOffset + debugTableItemOffset);
+
+        DexReader reader = cdexFile.getDataBuffer().readerAt(debugInfoOffsetsPos + debugOffsetsOffset);
+
+        int bitMask = reader.readUbyte() << 8;
+        bitMask += reader.readUbyte();
+
+        if ((bitMask & (1 << bitIndex)) == 0) {
+            return 0;
+        }
+
+        int offsetCount = Integer.bitCount(bitMask & 0xFFFF >> (16-bitIndex));
+        int baseDebugOffset = cdexFile.getDebugInfoBase();
+        for (int i=0; i<offsetCount; i++) {
+            baseDebugOffset += reader.readBigUleb128();
+        }
+        baseDebugOffset += reader.readBigUleb128();
+        return baseDebugOffset;
     }
 }
diff --git a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/CdexDebugOffsetTable.java b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/CdexDebugOffsetTable.java
new file mode 100644
index 00000000..2247f2f4
--- /dev/null
+++ b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/CdexDebugOffsetTable.java
@@ -0,0 +1,111 @@
+/*
+ * Copyright 2019, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.jf.dexlib2.dexbacked.raw;
+
+import org.jf.dexlib2.dexbacked.CDexBackedDexFile;
+import org.jf.dexlib2.dexbacked.DexBuffer;
+import org.jf.dexlib2.dexbacked.DexReader;
+import org.jf.dexlib2.dexbacked.raw.util.DexAnnotator;
+
+import javax.annotation.Nonnull;
+
+/**
+ * This table maps a method index to the offset to the debug_info_item associated with that method.
+ *
+ * There are 2 sections in the table. Each section is 32-bit aligned.
+ *
+ * The first section is arranged into chunks of data. Each chunk represents 16 method indices, starting at 0.
+ *
+ * The first two bytes of a chunk contain a 16-bit bitmask, encoded as a big-endian unsigned short. The least
+ * significant bit corresponds with the first index in the chunk of 16 method indexes, with each bit being the next
+ * index.
+ *
+ * Next, there are a series of uleb128 values, one for each set bit in the bitmask. Nothing is written for bits that are
+ * not set. The first uleb128 value is associated with the least significant set bit in the mask.
+ *
+ * Each uleb128 value is the offset from the start of the data section to the debug_info_item that is associated with
+ * the method having that method_index. It is encoded as the difference in offset from the previously encoded offset,
+ * with the first offset in that chunk being relative to the first debug_info_item (e.g. the debug_info_base field in
+ * the cdex header).
+ *
+ * It's worth noting that the offsets in each chunk of 16 are not necessarily in order. If a later offset is smaller
+ * than an earlier offset, the uleb128 is a large value that, when added to the previous offset, causes integer
+ * overflow, and wraps back around to the lower offset. Or, to put it another way, the uleb128 should actually be
+ * interpreted as a signed number, even though it's encoded in a format that is nominally for unsigned values.
+ *
+ * The second part of the table contains a simple list of 32-bit offsets to each chunk. The offsets are relative to
+ * the beginning of the debug offset table.
+ */
+public class CdexDebugOffsetTable {
+    @Nonnull
+    public static void annotate(@Nonnull DexAnnotator annotator, DexBuffer buffer) {
+        DexReader reader = buffer.readerAt(annotator.getCursor());
+
+        SectionAnnotator debugInfoAnnotator = annotator.getAnnotator(ItemType.DEBUG_INFO_ITEM);
+
+        int methodCount = annotator.dexFile.getMethodSection().size();
+
+        for (int methodIndex = 0; methodIndex < methodCount; methodIndex += 16) {
+            annotator.annotate(0, "Offset chuck for methods %d-%d", methodIndex, Math.min(methodIndex+16, methodCount));
+            annotator.indent();
+
+            int bitmask = reader.readUbyte() << 8;
+            bitmask |= reader.readUbyte();
+            StringBuilder sb = new StringBuilder();
+            for (int i=0; i<16; i++) {
+                sb.append((bitmask >> i) & 1);
+            }
+            annotator.annotate(2, "bitmask: 0b%s", sb.reverse());
+
+            int debugOffset = ((CDexBackedDexFile) annotator.dexFile).getDebugInfoBase();
+            for (int i=0; i<16; i++) {
+                if ((bitmask & 1) != 0) {
+                    int offsetDelta = reader.readBigUleb128();
+
+                    debugOffset += offsetDelta;
+
+                    annotator.annotateTo(reader.getOffset(), "[method_id: %d]: offset_delta: %d  (offset=0x%x)",
+                            methodIndex + i,
+                            offsetDelta, debugOffset);
+
+                    debugInfoAnnotator.setItemIdentity(debugOffset,
+                            annotator.dexFile.getMethodSection().get(methodIndex + i).toString());
+                }
+
+                bitmask >>= 1;
+            }
+
+            annotator.deindent();
+        }
+
+    }
+}
diff --git a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/CdexHeaderItem.java b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/CdexHeaderItem.java
index 6e7c1d61..e8d566eb 100644
--- a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/CdexHeaderItem.java
+++ b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/CdexHeaderItem.java
@@ -31,11 +31,20 @@
 
 package org.jf.dexlib2.dexbacked.raw;
 
+import org.jf.dexlib2.dexbacked.DexBuffer;
+import org.jf.dexlib2.util.AnnotatedBytes;
+
+import javax.annotation.Nonnull;
+
 public class CdexHeaderItem {
 
     private static final byte[] MAGIC_VALUE = new byte[] { 0x63, 0x64, 0x65, 0x78, 0x00, 0x00, 0x00, 0x00 };
     private static final int[] SUPPORTED_CDEX_VERSIONS = new int[] { 1 };
 
+    public static final int FEATURE_FLAGS_OFFSET = 112;
+    public static final int DEBUG_INFO_OFFSETS_POS_OFFSET = 116;
+    public static final int DEBUG_INFO_OFFSETS_TABLE_OFFSET = 120;
+    public static final int DEBUG_INFO_BASE = 124;
 
     /**
      * Verifies the magic value at the beginning of a cdex file
@@ -98,4 +107,11 @@ public class CdexHeaderItem {
         }
         return false;
     }
+
+    public static void annotateCdexHeaderFields(@Nonnull AnnotatedBytes out, DexBuffer buf) {
+        out.annotate(4, "feature_flags: 0x%x", buf.readInt(out.getCursor()));
+        out.annotate(4, "debug_info_offsets_pos: 0x%x", buf.readInt(out.getCursor()));
+        out.annotate(4, "debug_info_offsets_table_offset: 0x%x", buf.readInt(out.getCursor()));
+        out.annotate(4, "debug_info_base: 0x%x", buf.readInt(out.getCursor()));
+    }
 }
diff --git a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/HeaderItem.java b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/HeaderItem.java
index 06b058be..99150618 100644
--- a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/HeaderItem.java
+++ b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/HeaderItem.java
@@ -32,6 +32,7 @@
 package org.jf.dexlib2.dexbacked.raw;
 
 import org.jf.dexlib2.VersionMap;
+import org.jf.dexlib2.dexbacked.CDexBackedDexFile;
 import org.jf.dexlib2.dexbacked.DexBackedDexFile;
 import org.jf.dexlib2.dexbacked.DexBuffer;
 import org.jf.dexlib2.dexbacked.raw.util.DexAnnotator;
@@ -211,6 +212,10 @@ public class HeaderItem {
                 out.annotate(4, "data_size: %d", dexFile.getBuffer().readInt(out.getCursor()));
                 out.annotate(4, "data_off: 0x%x", dexFile.getBuffer().readInt(out.getCursor()));
 
+                if (annotator.dexFile instanceof CDexBackedDexFile) {
+                    CdexHeaderItem.annotateCdexHeaderFields(out, dexFile.getBuffer());
+                }
+
                 if (headerSize > ITEM_SIZE) {
                     out.annotateTo(headerSize, "header padding");
                 }
diff --git a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/util/DexAnnotator.java b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/util/DexAnnotator.java
index 3b3195d2..0f570cb4 100644
--- a/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/util/DexAnnotator.java
+++ b/dexlib2/src/main/java/org/jf/dexlib2/dexbacked/raw/util/DexAnnotator.java
@@ -34,6 +34,7 @@ package org.jf.dexlib2.dexbacked.raw.util;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Ordering;
 import com.google.common.primitives.Ints;
+import org.jf.dexlib2.dexbacked.CDexBackedDexFile;
 import org.jf.dexlib2.dexbacked.DexBackedDexFile;
 import org.jf.dexlib2.dexbacked.raw.*;
 import org.jf.dexlib2.util.AnnotatedBytes;
@@ -170,6 +171,12 @@ public class DexAnnotator extends AnnotatedBytes {
         mapItems = ordering.immutableSortedCopy(mapItems);
 
         try {
+            // Need to annotate the debug info offset table first, to propagate the debug info identities
+            if (dexFile instanceof CDexBackedDexFile) {
+                moveTo(dexFile.getBaseDataOffset() + ((CDexBackedDexFile) dexFile).getDebugInfoOffsetsPos());
+                CdexDebugOffsetTable.annotate(this, dexFile.getBuffer());
+            }
+
             for (MapItem mapItem: mapItems) {
                 try {
                     SectionAnnotator annotator = annotators.get(mapItem.getType());