dexlib2/src/main/java/org/jf/dexlib2/dexbacked/OatFile.java - platform/external/smali - Git at Google

 /*
  * Copyright 2014, 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;

 import com.google.common.io.ByteStreams;
 import org.jf.dexlib2.Opcodes;
 import org.jf.dexlib2.dexbacked.OatFile.SymbolTable.Symbol;
 import org.jf.dexlib2.dexbacked.raw.HeaderItem;
 import org.jf.util.AbstractForwardSequentialList;

 import javax.annotation.Nonnull;
 import java.io.EOFException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.charset.Charset;
 import java.util.AbstractList;
 import java.util.Iterator;
 import java.util.List;

 public class OatFile extends BaseDexBuffer {
     private static final byte[] ELF_MAGIC = new byte[] { 0x7f, 'E', 'L', 'F' };
     private static final byte[] OAT_MAGIC = new byte[] { 'o', 'a', 't', '\n' };
     private static final int MIN_ELF_HEADER_SIZE = 52;

     // These are the "known working" versions that I have manually inspected the source for.
     // Later version may or may not work, depending on what changed.
     private static final int MIN_OAT_VERSION = 56;
     private static final int MAX_OAT_VERSION = 71;

     public static final int UNSUPPORTED = 0;
     public static final int SUPPORTED = 1;
     public static final int UNKNOWN = 2;

     private final boolean is64bit;
     @Nonnull private final OatHeader oatHeader;
     @Nonnull private final Opcodes opcodes;

     public OatFile(@Nonnull byte[] buf) {
         super(buf);

         if (buf.length < MIN_ELF_HEADER_SIZE) {
             throw new NotAnOatFileException();
         }

         verifyMagic(buf);

         if (buf[4] == 1) {
             is64bit = false;
         } else if (buf[4] == 2) {
             is64bit = true;
         } else {
             throw new InvalidOatFileException(String.format("Invalid word-size value: %x", buf[5]));
         }

         OatHeader oatHeader = null;
         SymbolTable symbolTable = getSymbolTable();
         for (Symbol symbol: symbolTable.getSymbols()) {
             if (symbol.getName().equals("oatdata")) {
                 oatHeader = new OatHeader(symbol.getFileOffset());
                 break;
             }
         }

         if (oatHeader == null) {
             throw new InvalidOatFileException("Oat file has no oatdata symbol");
         }
         this.oatHeader = oatHeader;

         if (!oatHeader.isValid()) {
             throw new InvalidOatFileException("Invalid oat magic value");
         }

         this.opcodes = Opcodes.forArtVersion(oatHeader.getVersion());
     }

     private static void verifyMagic(byte[] buf) {
         for (int i = 0; i < ELF_MAGIC.length; i++) {
             if (buf[i] != ELF_MAGIC[i]) {
                 throw new NotAnOatFileException();
             }
         }
     }

     public static OatFile fromInputStream(@Nonnull InputStream is)
             throws IOException {
         if (!is.markSupported()) {
             throw new IllegalArgumentException("InputStream must support mark");
         }
         is.mark(4);
         byte[] partialHeader = new byte[4];
         try {
             ByteStreams.readFully(is, partialHeader);
         } catch (EOFException ex) {
             throw new NotAnOatFileException();
         } finally {
             is.reset();
         }

         verifyMagic(partialHeader);

         is.reset();

         byte[] buf = ByteStreams.toByteArray(is);
         return new OatFile(buf);
     }

     public int getOatVersion() {
         return oatHeader.getVersion();
     }

     public int isSupportedVersion() {
         int version = getOatVersion();
         if (version < MIN_OAT_VERSION) {
             return UNSUPPORTED;
         }
         if (version <= MAX_OAT_VERSION) {
             return SUPPORTED;
         }
         return UNKNOWN;
     }

     @Nonnull
     public List<OatDexFile> getDexFiles() {
         return new AbstractForwardSequentialList<OatDexFile>() {
             @Override public int size() {
                 return oatHeader.getDexFileCount();
             }

             @Nonnull @Override public Iterator<OatDexFile> iterator() {
                 return new Iterator<OatDexFile>() {
                     int index = 0;
                     int offset = oatHeader.getDexListStart();

                     @Override public boolean hasNext() {
                         return index < size();
                     }

                     @Override public OatDexFile next() {
                         int filenameLength = readSmallUint(offset);
                         offset += 4;

                         // TODO: what is the correct character encoding?
                         String filename = new String(buf, offset, filenameLength, Charset.forName("US-ASCII"));
                         offset += filenameLength;

                         offset += 4; // checksum

                         int dexOffset = readSmallUint(offset) + oatHeader.offset;
                         offset += 4;

                         int classCount = readSmallUint(dexOffset + HeaderItem.CLASS_COUNT_OFFSET);
                         offset += 4 * classCount;

                         index++;

                         return new OatDexFile(dexOffset, filename);
                     }

                     @Override public void remove() {
                         throw new UnsupportedOperationException();
                     }
                 };
             }
         };
     }

     public class OatDexFile extends DexBackedDexFile {
         @Nonnull public final String filename;

         public OatDexFile(int offset, @Nonnull String filename) {
             super(opcodes, OatFile.this.buf, offset);
             this.filename = filename;
         }

         public int getOatVersion() {
             return OatFile.this.getOatVersion();
         }

         @Override public boolean hasOdexOpcodes() {
             return true;
         }
     }

     private class OatHeader {
         private final int offset;

         public OatHeader(int offset) {
             this.offset = offset;
         }

         public boolean isValid() {
             for (int i=0; i<OAT_MAGIC.length; i++) {
                 if (buf[offset + i] != OAT_MAGIC[i]) {
                     return false;
                 }
             }

             for (int i=4; i<7; i++) {
                 if (buf[offset + i] < '0' || buf[offset + i] > '9') {
                     return false;
                 }
             }

             return buf[offset + 7] == 0;
         }

         public int getVersion() {
             return Integer.valueOf(new String(buf, offset + 4, 3));
         }

         public int getDexFileCount() {
             return readSmallUint(offset + 20);
         }

         public int getKeyValueStoreSize() {
             int version = getVersion();
             if (version < 56) {
                 throw new IllegalStateException("Unsupported oat version");
             }
             int fieldOffset = 17 * 4;
             return readSmallUint(offset + fieldOffset);
         }

         public int getHeaderSize() {
             int version = getVersion();
              if (version >= 56) {
                 return 18*4 + getKeyValueStoreSize();
             } else {
                 throw new IllegalStateException("Unsupported oat version");
             }

         }

         public int getDexListStart() {
             return offset + getHeaderSize();
         }
     }

     @Nonnull
     private List<SectionHeader> getSections() {
         final int offset;
         final int entrySize;
         final int entryCount;
         if (is64bit) {
             offset = readLongAsSmallUint(40);
             entrySize = readUshort(58);
             entryCount = readUshort(60);
         } else {
             offset = readSmallUint(32);
             entrySize = readUshort(46);
             entryCount = readUshort(48);
         }

         if (offset + (entrySize * entryCount) > buf.length) {
             throw new InvalidOatFileException("The ELF section headers extend past the end of the file");
         }

         return new AbstractList<SectionHeader>() {
             @Override public SectionHeader get(int index) {
                 if (index < 0 || index >= entryCount) {
                     throw new IndexOutOfBoundsException();
                 }
                 if (is64bit) {
                     return new SectionHeader64Bit(offset + (index * entrySize));
                 } else {
                     return new SectionHeader32Bit(offset + (index * entrySize));
                 }
             }

             @Override public int size() {
                 return entryCount;
             }
         };
     }

     @Nonnull
     private SymbolTable getSymbolTable() {
         for (SectionHeader header: getSections()) {
             if (header.getType() == SectionHeader.TYPE_DYNAMIC_SYMBOL_TABLE) {
                 return new SymbolTable(header);
             }
         }
         throw new InvalidOatFileException("Oat file has no symbol table");
     }

     @Nonnull
     private StringTable getSectionNameStringTable() {
         int index = readUshort(50);
         if (index == 0) {
             throw new InvalidOatFileException("There is no section name string table");
         }

         try {
             return new StringTable(getSections().get(index));
         } catch (IndexOutOfBoundsException ex) {
             throw new InvalidOatFileException("The section index for the section name string table is invalid");
         }
     }

     private abstract class SectionHeader {
         protected final int offset;
         public static final int TYPE_DYNAMIC_SYMBOL_TABLE = 11;
         public SectionHeader(int offset) { this.offset = offset; }
         @Nonnull public String getName() { return getSectionNameStringTable().getString(readSmallUint(offset)); }
         public int getType() { return readInt(offset + 4); }
         public abstract long getAddress();
         public abstract int getOffset();
         public abstract int getSize();
         public abstract int getLink();
         public abstract int getEntrySize();
     }

     private class SectionHeader32Bit extends SectionHeader {
         public SectionHeader32Bit(int offset) { super(offset); }
         @Override public long getAddress() { return readInt(offset + 12) & 0xFFFFFFFFL; }
         @Override public int getOffset() { return readSmallUint(offset + 16); }
         @Override public int getSize() { return readSmallUint(offset + 20); }
         @Override public int getLink() { return readSmallUint(offset + 24); }
         @Override public int getEntrySize() { return readSmallUint(offset + 36); }
     }

     private class SectionHeader64Bit extends SectionHeader {
         public SectionHeader64Bit(int offset) { super(offset); }
         @Override public long getAddress() { return readLong(offset + 16); }
         @Override public int getOffset() { return readLongAsSmallUint(offset + 24); }
         @Override public int getSize() { return readLongAsSmallUint(offset + 32); }
         @Override public int getLink() { return readSmallUint(offset + 40); }
         @Override public int getEntrySize() { return readLongAsSmallUint(offset + 56); }
     }

     class SymbolTable {
         @Nonnull private final StringTable stringTable;
         private final int offset;
         private final int entryCount;
         private final int entrySize;

         public SymbolTable(@Nonnull SectionHeader header) {
             try {
                 this.stringTable = new StringTable(getSections().get(header.getLink()));
             } catch (IndexOutOfBoundsException ex) {
                 throw new InvalidOatFileException("String table section index is invalid");
             }
             this.offset = header.getOffset();
             this.entrySize = header.getEntrySize();
             this.entryCount = header.getSize() / entrySize;

             if (offset + entryCount * entrySize > buf.length) {
                 throw new InvalidOatFileException("Symbol table extends past end of file");
             }
         }

         @Nonnull
         public List<Symbol> getSymbols() {
             return new AbstractList<Symbol>() {
                 @Override public Symbol get(int index) {
                     if (index < 0 || index >= entryCount) {
                         throw new IndexOutOfBoundsException();
                     }
                     if (is64bit) {
                         return new Symbol64(offset + index * entrySize);
                     } else {
                         return new Symbol32(offset + index * entrySize);
                     }
                 }

                 @Override public int size() {
                     return entryCount;
                 }
             };
         }

         public abstract class Symbol {
             protected final int offset;
             public Symbol(int offset) { this.offset = offset; }
             @Nonnull public abstract String getName();
             public abstract long getValue();
             public abstract int getSize();
             public abstract int getSectionIndex();

             public int getFileOffset() {
                 SectionHeader sectionHeader;
                 try {
                     sectionHeader = getSections().get(getSectionIndex());
                 } catch (IndexOutOfBoundsException ex) {
                     throw new InvalidOatFileException("Section index for symbol is out of bounds");
                 }

                 long sectionAddress = sectionHeader.getAddress();
                 int sectionOffset = sectionHeader.getOffset();
                 int sectionSize = sectionHeader.getSize();

                 long symbolAddress = getValue();

                 if (symbolAddress < sectionAddress || symbolAddress >= sectionAddress + sectionSize) {
                     throw new InvalidOatFileException("symbol address lies outside it's associated section");
                 }

                 long fileOffset = (sectionOffset + (getValue() - sectionAddress));
                 assert fileOffset <= Integer.MAX_VALUE;
                 return (int)fileOffset;
             }
         }

         public class Symbol32 extends Symbol {
             public Symbol32(int offset) { super(offset); }

             @Nonnull
             public String getName() { return stringTable.getString(readSmallUint(offset)); }
             public long getValue() { return readSmallUint(offset + 4); }
             public int getSize() { return readSmallUint(offset + 8); }
             public int getSectionIndex() { return readUshort(offset + 14); }
         }

         public class Symbol64 extends Symbol {
             public Symbol64(int offset) { super(offset); }

             @Nonnull
             public String getName() { return stringTable.getString(readSmallUint(offset)); }
             public long getValue() { return readLong(offset + 8); }
             public int getSize() { return readLongAsSmallUint(offset + 16); }
             public int getSectionIndex() { return readUshort(offset + 6); }
         }
     }

     private class StringTable {
         private final int offset;
         private final int size;

         public StringTable(@Nonnull SectionHeader header) {
             this.offset = header.getOffset();
             this.size = header.getSize();

             if (offset + size > buf.length) {
                 throw new InvalidOatFileException("String table extends past end of file");
             }
         }

         @Nonnull
         public String getString(int index) {
             if (index >= size) {
                 throw new InvalidOatFileException("String index is out of bounds");
             }

             int start = offset + index;
             int end = start;
             while (buf[end] != 0) {
                 end++;
                 if (end >= offset + size) {
                     throw new InvalidOatFileException("String extends past end of string table");
                 }
             }

             return new String(buf, start, end-start, Charset.forName("US-ASCII"));
         }

     }

     public static class InvalidOatFileException extends RuntimeException {
         public InvalidOatFileException(String message) {
             super(message);
         }
     }

     public static class NotAnOatFileException extends RuntimeException {
         public NotAnOatFileException() {}
     }
 }
	/*
	* Copyright 2014, 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;

	import com.google.common.io.ByteStreams;
	import org.jf.dexlib2.Opcodes;
	import org.jf.dexlib2.dexbacked.OatFile.SymbolTable.Symbol;
	import org.jf.dexlib2.dexbacked.raw.HeaderItem;
	import org.jf.util.AbstractForwardSequentialList;

	import javax.annotation.Nonnull;
	import java.io.EOFException;
	import java.io.IOException;
	import java.io.InputStream;
	import java.nio.charset.Charset;
	import java.util.AbstractList;
	import java.util.Iterator;
	import java.util.List;

	public class OatFile extends BaseDexBuffer {
	private static final byte[] ELF_MAGIC = new byte[] { 0x7f, 'E', 'L', 'F' };
	private static final byte[] OAT_MAGIC = new byte[] { 'o', 'a', 't', '\n' };
	private static final int MIN_ELF_HEADER_SIZE = 52;

	// These are the "known working" versions that I have manually inspected the source for.
	// Later version may or may not work, depending on what changed.
	private static final int MIN_OAT_VERSION = 56;
	private static final int MAX_OAT_VERSION = 71;

	public static final int UNSUPPORTED = 0;
	public static final int SUPPORTED = 1;
	public static final int UNKNOWN = 2;

	private final boolean is64bit;
	@Nonnull private final OatHeader oatHeader;
	@Nonnull private final Opcodes opcodes;

	public OatFile(@Nonnull byte[] buf) {
	super(buf);

	if (buf.length < MIN_ELF_HEADER_SIZE) {
	throw new NotAnOatFileException();
	}

	verifyMagic(buf);

	if (buf[4] == 1) {
	is64bit = false;
	} else if (buf[4] == 2) {
	is64bit = true;
	} else {
	throw new InvalidOatFileException(String.format("Invalid word-size value: %x", buf[5]));
	}

	OatHeader oatHeader = null;
	SymbolTable symbolTable = getSymbolTable();
	for (Symbol symbol: symbolTable.getSymbols()) {
	if (symbol.getName().equals("oatdata")) {
	oatHeader = new OatHeader(symbol.getFileOffset());
	break;
	}
	}

	if (oatHeader == null) {
	throw new InvalidOatFileException("Oat file has no oatdata symbol");
	}
	this.oatHeader = oatHeader;

	if (!oatHeader.isValid()) {
	throw new InvalidOatFileException("Invalid oat magic value");
	}

	this.opcodes = Opcodes.forArtVersion(oatHeader.getVersion());
	}

	private static void verifyMagic(byte[] buf) {
	for (int i = 0; i < ELF_MAGIC.length; i++) {
	if (buf[i] != ELF_MAGIC[i]) {
	throw new NotAnOatFileException();
	}
	}
	}

	public static OatFile fromInputStream(@Nonnull InputStream is)
	throws IOException {
	if (!is.markSupported()) {
	throw new IllegalArgumentException("InputStream must support mark");
	}
	is.mark(4);
	byte[] partialHeader = new byte[4];
	try {
	ByteStreams.readFully(is, partialHeader);
	} catch (EOFException ex) {
	throw new NotAnOatFileException();
	} finally {
	is.reset();
	}

	verifyMagic(partialHeader);

	is.reset();

	byte[] buf = ByteStreams.toByteArray(is);
	return new OatFile(buf);
	}

	public int getOatVersion() {
	return oatHeader.getVersion();
	}

	public int isSupportedVersion() {
	int version = getOatVersion();
	if (version < MIN_OAT_VERSION) {
	return UNSUPPORTED;
	}
	if (version <= MAX_OAT_VERSION) {
	return SUPPORTED;
	}
	return UNKNOWN;
	}

	@Nonnull
	public List<OatDexFile> getDexFiles() {
	return new AbstractForwardSequentialList<OatDexFile>() {
	@Override public int size() {
	return oatHeader.getDexFileCount();
	}

	@Nonnull @Override public Iterator<OatDexFile> iterator() {
	return new Iterator<OatDexFile>() {
	int index = 0;
	int offset = oatHeader.getDexListStart();

	@Override public boolean hasNext() {
	return index < size();
	}

	@Override public OatDexFile next() {
	int filenameLength = readSmallUint(offset);
	offset += 4;

	// TODO: what is the correct character encoding?
	String filename = new String(buf, offset, filenameLength, Charset.forName("US-ASCII"));
	offset += filenameLength;

	offset += 4; // checksum

	int dexOffset = readSmallUint(offset) + oatHeader.offset;
	offset += 4;

	int classCount = readSmallUint(dexOffset + HeaderItem.CLASS_COUNT_OFFSET);
	offset += 4 * classCount;

	index++;

	return new OatDexFile(dexOffset, filename);
	}

	@Override public void remove() {
	throw new UnsupportedOperationException();
	}
	};
	}
	};
	}

	public class OatDexFile extends DexBackedDexFile {
	@Nonnull public final String filename;

	public OatDexFile(int offset, @Nonnull String filename) {
	super(opcodes, OatFile.this.buf, offset);
	this.filename = filename;
	}

	public int getOatVersion() {
	return OatFile.this.getOatVersion();
	}

	@Override public boolean hasOdexOpcodes() {
	return true;
	}
	}

	private class OatHeader {
	private final int offset;

	public OatHeader(int offset) {
	this.offset = offset;
	}

	public boolean isValid() {
	for (int i=0; i<OAT_MAGIC.length; i++) {
	if (buf[offset + i] != OAT_MAGIC[i]) {
	return false;
	}
	}

	for (int i=4; i<7; i++) {
	if (buf[offset + i] < '0' \|\| buf[offset + i] > '9') {
	return false;
	}
	}

	return buf[offset + 7] == 0;
	}

	public int getVersion() {
	return Integer.valueOf(new String(buf, offset + 4, 3));
	}

	public int getDexFileCount() {
	return readSmallUint(offset + 20);
	}

	public int getKeyValueStoreSize() {
	int version = getVersion();
	if (version < 56) {
	throw new IllegalStateException("Unsupported oat version");
	}
	int fieldOffset = 17 * 4;
	return readSmallUint(offset + fieldOffset);
	}

	public int getHeaderSize() {
	int version = getVersion();
	if (version >= 56) {
	return 18*4 + getKeyValueStoreSize();
	} else {
	throw new IllegalStateException("Unsupported oat version");
	}

	}

	public int getDexListStart() {
	return offset + getHeaderSize();
	}
	}

	@Nonnull
	private List<SectionHeader> getSections() {
	final int offset;
	final int entrySize;
	final int entryCount;
	if (is64bit) {
	offset = readLongAsSmallUint(40);
	entrySize = readUshort(58);
	entryCount = readUshort(60);
	} else {
	offset = readSmallUint(32);
	entrySize = readUshort(46);
	entryCount = readUshort(48);
	}

	if (offset + (entrySize * entryCount) > buf.length) {
	throw new InvalidOatFileException("The ELF section headers extend past the end of the file");
	}

	return new AbstractList<SectionHeader>() {
	@Override public SectionHeader get(int index) {
	if (index < 0 \|\| index >= entryCount) {
	throw new IndexOutOfBoundsException();
	}
	if (is64bit) {
	return new SectionHeader64Bit(offset + (index * entrySize));
	} else {
	return new SectionHeader32Bit(offset + (index * entrySize));
	}
	}

	@Override public int size() {
	return entryCount;
	}
	};
	}

	@Nonnull
	private SymbolTable getSymbolTable() {
	for (SectionHeader header: getSections()) {
	if (header.getType() == SectionHeader.TYPE_DYNAMIC_SYMBOL_TABLE) {
	return new SymbolTable(header);
	}
	}
	throw new InvalidOatFileException("Oat file has no symbol table");
	}

	@Nonnull
	private StringTable getSectionNameStringTable() {
	int index = readUshort(50);
	if (index == 0) {
	throw new InvalidOatFileException("There is no section name string table");
	}

	try {
	return new StringTable(getSections().get(index));
	} catch (IndexOutOfBoundsException ex) {
	throw new InvalidOatFileException("The section index for the section name string table is invalid");
	}
	}

	private abstract class SectionHeader {
	protected final int offset;
	public static final int TYPE_DYNAMIC_SYMBOL_TABLE = 11;
	public SectionHeader(int offset) { this.offset = offset; }
	@Nonnull public String getName() { return getSectionNameStringTable().getString(readSmallUint(offset)); }
	public int getType() { return readInt(offset + 4); }
	public abstract long getAddress();
	public abstract int getOffset();
	public abstract int getSize();
	public abstract int getLink();
	public abstract int getEntrySize();
	}

	private class SectionHeader32Bit extends SectionHeader {
	public SectionHeader32Bit(int offset) { super(offset); }
	@Override public long getAddress() { return readInt(offset + 12) & 0xFFFFFFFFL; }
	@Override public int getOffset() { return readSmallUint(offset + 16); }
	@Override public int getSize() { return readSmallUint(offset + 20); }
	@Override public int getLink() { return readSmallUint(offset + 24); }
	@Override public int getEntrySize() { return readSmallUint(offset + 36); }
	}

	private class SectionHeader64Bit extends SectionHeader {
	public SectionHeader64Bit(int offset) { super(offset); }
	@Override public long getAddress() { return readLong(offset + 16); }
	@Override public int getOffset() { return readLongAsSmallUint(offset + 24); }
	@Override public int getSize() { return readLongAsSmallUint(offset + 32); }
	@Override public int getLink() { return readSmallUint(offset + 40); }
	@Override public int getEntrySize() { return readLongAsSmallUint(offset + 56); }
	}

	class SymbolTable {
	@Nonnull private final StringTable stringTable;
	private final int offset;
	private final int entryCount;
	private final int entrySize;

	public SymbolTable(@Nonnull SectionHeader header) {
	try {
	this.stringTable = new StringTable(getSections().get(header.getLink()));
	} catch (IndexOutOfBoundsException ex) {
	throw new InvalidOatFileException("String table section index is invalid");
	}
	this.offset = header.getOffset();
	this.entrySize = header.getEntrySize();
	this.entryCount = header.getSize() / entrySize;

	if (offset + entryCount * entrySize > buf.length) {
	throw new InvalidOatFileException("Symbol table extends past end of file");
	}
	}

	@Nonnull
	public List<Symbol> getSymbols() {
	return new AbstractList<Symbol>() {
	@Override public Symbol get(int index) {
	if (index < 0 \|\| index >= entryCount) {
	throw new IndexOutOfBoundsException();
	}
	if (is64bit) {
	return new Symbol64(offset + index * entrySize);
	} else {
	return new Symbol32(offset + index * entrySize);
	}
	}

	@Override public int size() {
	return entryCount;
	}
	};
	}

	public abstract class Symbol {
	protected final int offset;
	public Symbol(int offset) { this.offset = offset; }
	@Nonnull public abstract String getName();
	public abstract long getValue();
	public abstract int getSize();
	public abstract int getSectionIndex();

	public int getFileOffset() {
	SectionHeader sectionHeader;
	try {
	sectionHeader = getSections().get(getSectionIndex());
	} catch (IndexOutOfBoundsException ex) {
	throw new InvalidOatFileException("Section index for symbol is out of bounds");
	}

	long sectionAddress = sectionHeader.getAddress();
	int sectionOffset = sectionHeader.getOffset();
	int sectionSize = sectionHeader.getSize();

	long symbolAddress = getValue();

	if (symbolAddress < sectionAddress \|\| symbolAddress >= sectionAddress + sectionSize) {
	throw new InvalidOatFileException("symbol address lies outside it's associated section");
	}

	long fileOffset = (sectionOffset + (getValue() - sectionAddress));
	assert fileOffset <= Integer.MAX_VALUE;
	return (int)fileOffset;
	}
	}

	public class Symbol32 extends Symbol {
	public Symbol32(int offset) { super(offset); }

	@Nonnull
	public String getName() { return stringTable.getString(readSmallUint(offset)); }
	public long getValue() { return readSmallUint(offset + 4); }
	public int getSize() { return readSmallUint(offset + 8); }
	public int getSectionIndex() { return readUshort(offset + 14); }
	}

	public class Symbol64 extends Symbol {
	public Symbol64(int offset) { super(offset); }

	@Nonnull
	public String getName() { return stringTable.getString(readSmallUint(offset)); }
	public long getValue() { return readLong(offset + 8); }
	public int getSize() { return readLongAsSmallUint(offset + 16); }
	public int getSectionIndex() { return readUshort(offset + 6); }
	}
	}

	private class StringTable {
	private final int offset;
	private final int size;

	public StringTable(@Nonnull SectionHeader header) {
	this.offset = header.getOffset();
	this.size = header.getSize();

	if (offset + size > buf.length) {
	throw new InvalidOatFileException("String table extends past end of file");
	}
	}

	@Nonnull
	public String getString(int index) {
	if (index >= size) {
	throw new InvalidOatFileException("String index is out of bounds");
	}

	int start = offset + index;
	int end = start;
	while (buf[end] != 0) {
	end++;
	if (end >= offset + size) {
	throw new InvalidOatFileException("String extends past end of string table");
	}
	}

	return new String(buf, start, end-start, Charset.forName("US-ASCII"));
	}

	}

	public static class InvalidOatFileException extends RuntimeException {
	public InvalidOatFileException(String message) {
	super(message);
	}
	}

	public static class NotAnOatFileException extends RuntimeException {
	public NotAnOatFileException() {}
	}
	}