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[mono-project.git] / mcs / class / Mono.CompilerServices.SymbolWriter / MonoSymbolTable.cs

//
// Mono.CSharp.Debugger/MonoSymbolTable.cs
//
// Author:
//   Martin Baulig (martin@ximian.com)
//
// (C) 2002 Ximian, Inc.  http://www.ximian.com
//

//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Security.Cryptography;
using System.Collections.Generic;
using System.Text;
using System.IO;

//
// Parts which are actually written into the symbol file are marked with
//
//         #region This is actually written to the symbol file
//         #endregion
//
// Please do not modify these regions without previously talking to me.
//
// All changes to the file format must be synchronized in several places:
//
// a) The fields in these regions (and their order) must match the actual
//    contents of the symbol file.
//
//    This helps people to understand the symbol file format without reading
//    too much source code, ie. you look at the appropriate region and then
//    you know what's actually in the file.
//
//    It is also required to help me enforce b).
//
// b) The regions must be kept in sync with the unmanaged code in
//    mono/metadata/debug-mono-symfile.h
//
// When making changes to the file format, you must also increase two version
// numbers:
//
// i)  OffsetTable.Version in this file.
// ii) MONO_SYMBOL_FILE_VERSION in mono/metadata/debug-mono-symfile.h
//
// After doing so, recompile everything, including the debugger.  Symbol files
// with different versions are incompatible to each other and the debugger and
// the runtime enfore this, so you need to recompile all your assemblies after
// changing the file format.
//

namespace Mono.CompilerServices.SymbolWriter
{
        public class OffsetTable
        {
                public const int  MajorVersion = 50;
                public const int  MinorVersion = 0;
                public const long Magic        = 0x45e82623fd7fa614;

                #region This is actually written to the symbol file
                public int TotalFileSize;
                public int DataSectionOffset;
                public int DataSectionSize;
                public int CompileUnitCount;
                public int CompileUnitTableOffset;
                public int CompileUnitTableSize;
                public int SourceCount;
                public int SourceTableOffset;
                public int SourceTableSize;
                public int MethodCount;
                public int MethodTableOffset;
                public int MethodTableSize;
                public int TypeCount;
                public int AnonymousScopeCount;
                public int AnonymousScopeTableOffset;
                public int AnonymousScopeTableSize;

                [Flags]
                public enum Flags
                {
                        IsAspxSource            = 1,
                        WindowsFileNames        = 2
                }

                public Flags FileFlags;

                public int LineNumberTable_LineBase = LineNumberTable.Default_LineBase;
                public int LineNumberTable_LineRange = LineNumberTable.Default_LineRange;
                public int LineNumberTable_OpcodeBase = LineNumberTable.Default_OpcodeBase;
                #endregion

                internal OffsetTable ()
                {
                        int platform = (int) Environment.OSVersion.Platform;
                        if ((platform != 4) && (platform != 128))
                                FileFlags |= Flags.WindowsFileNames;
                }

                internal OffsetTable (BinaryReader reader, int major_version, int minor_version)
                {
                        TotalFileSize = reader.ReadInt32 ();
                        DataSectionOffset = reader.ReadInt32 ();
                        DataSectionSize = reader.ReadInt32 ();
                        CompileUnitCount = reader.ReadInt32 ();
                        CompileUnitTableOffset = reader.ReadInt32 ();
                        CompileUnitTableSize = reader.ReadInt32 ();
                        SourceCount = reader.ReadInt32 ();
                        SourceTableOffset = reader.ReadInt32 ();
                        SourceTableSize = reader.ReadInt32 ();
                        MethodCount = reader.ReadInt32 ();
                        MethodTableOffset = reader.ReadInt32 ();
                        MethodTableSize = reader.ReadInt32 ();
                        TypeCount = reader.ReadInt32 ();

                        AnonymousScopeCount = reader.ReadInt32 ();
                        AnonymousScopeTableOffset = reader.ReadInt32 ();
                        AnonymousScopeTableSize = reader.ReadInt32 ();

                        LineNumberTable_LineBase = reader.ReadInt32 ();
                        LineNumberTable_LineRange = reader.ReadInt32 ();
                        LineNumberTable_OpcodeBase = reader.ReadInt32 ();

                        FileFlags = (Flags) reader.ReadInt32 ();
                }

                internal void Write (BinaryWriter bw, int major_version, int minor_version)
                {
                        bw.Write (TotalFileSize);
                        bw.Write (DataSectionOffset);
                        bw.Write (DataSectionSize);
                        bw.Write (CompileUnitCount);
                        bw.Write (CompileUnitTableOffset);
                        bw.Write (CompileUnitTableSize);
                        bw.Write (SourceCount);
                        bw.Write (SourceTableOffset);
                        bw.Write (SourceTableSize);
                        bw.Write (MethodCount);
                        bw.Write (MethodTableOffset);
                        bw.Write (MethodTableSize);
                        bw.Write (TypeCount);

                        bw.Write (AnonymousScopeCount);
                        bw.Write (AnonymousScopeTableOffset);
                        bw.Write (AnonymousScopeTableSize);

                        bw.Write (LineNumberTable_LineBase);
                        bw.Write (LineNumberTable_LineRange);
                        bw.Write (LineNumberTable_OpcodeBase);

                        bw.Write ((int) FileFlags);
                }

                public override string ToString ()
                {
                        return String.Format (
                                "OffsetTable [{0} - {1}:{2} - {3}:{4}:{5} - {6}:{7}:{8} - {9}]",
                                TotalFileSize, DataSectionOffset, DataSectionSize, SourceCount,
                                SourceTableOffset, SourceTableSize, MethodCount, MethodTableOffset,
                                MethodTableSize, TypeCount);
                }
        }

        public class LineNumberEntry
        {
                #region This is actually written to the symbol file
                public readonly int Row;
                public int Column;
                public int EndRow, EndColumn;
                public readonly int File;
                public readonly int Offset;
                public readonly bool IsHidden;  // Obsolete is never used
                #endregion

                public sealed class LocationComparer : IComparer<LineNumberEntry>
                {
                        public static readonly LocationComparer Default = new LocationComparer ();

                        public int Compare (LineNumberEntry l1, LineNumberEntry l2)
                        {
                                return l1.Row == l2.Row ?
                                        l1.Column.CompareTo (l2.Column) :
                                        l1.Row.CompareTo (l2.Row);
                        }
                }

                public static readonly LineNumberEntry Null = new LineNumberEntry (0, 0, 0, 0);

                public LineNumberEntry (int file, int row, int column, int offset)
                        : this (file, row, column, offset, false)
                {
                }

                public LineNumberEntry (int file, int row, int offset)
                        : this (file, row, -1, offset, false)
                {
                }

                public LineNumberEntry (int file, int row, int column, int offset, bool is_hidden)
                : this (file, row, column, -1, -1, offset, is_hidden)
                {
                }

                public LineNumberEntry (int file, int row, int column, int end_row, int end_column, int offset, bool is_hidden)
                {
                        this.File = file;
                        this.Row = row;
                        this.Column = column;
                        this.EndRow = end_row;
                        this.EndColumn = end_column;
                        this.Offset = offset;
                        this.IsHidden = is_hidden;
                }

                public override string ToString ()
                {
                        return String.Format ("[Line {0}:{1,2}-{3,4}:{5}]", File, Row, Column, EndRow, EndColumn, Offset);
                }
        }

        public class CodeBlockEntry
        {
                public int Index;
                #region This is actually written to the symbol file
                public int Parent;
                public Type BlockType;
                public int StartOffset;
                public int EndOffset;
                #endregion

                public enum Type {
                        Lexical                 = 1,
                        CompilerGenerated       = 2,
                        IteratorBody            = 3,
                        IteratorDispatcher      = 4
                }

                public CodeBlockEntry (int index, int parent, Type type, int start_offset)
                {
                        this.Index = index;
                        this.Parent = parent;
                        this.BlockType = type;
                        this.StartOffset = start_offset;
                }

                internal CodeBlockEntry (int index, MyBinaryReader reader)
                {
                        this.Index = index;
                        int type_flag = reader.ReadLeb128 ();
                        BlockType = (Type) (type_flag & 0x3f);
                        this.Parent = reader.ReadLeb128 ();
                        this.StartOffset = reader.ReadLeb128 ();
                        this.EndOffset = reader.ReadLeb128 ();

                        /* Reserved for future extensions. */
                        if ((type_flag & 0x40) != 0) {
                                int data_size = reader.ReadInt16 ();
                                reader.BaseStream.Position += data_size;
                        }                               
                }

                public void Close (int end_offset)
                {
                        this.EndOffset = end_offset;
                }

                internal void Write (MyBinaryWriter bw)
                {
                        bw.WriteLeb128 ((int) BlockType);
                        bw.WriteLeb128 (Parent);
                        bw.WriteLeb128 (StartOffset);
                        bw.WriteLeb128 (EndOffset);
                }

                public override string ToString ()
                {
                        return String.Format ("[CodeBlock {0}:{1}:{2}:{3}:{4}]",
                                              Index, Parent, BlockType, StartOffset, EndOffset);
                }
        }

        public struct LocalVariableEntry
        {
                #region This is actually written to the symbol file
                public readonly int Index;
                public readonly string Name;
                public readonly int BlockIndex;
                #endregion

                public LocalVariableEntry (int index, string name, int block)
                {
                        this.Index = index;
                        this.Name = name;
                        this.BlockIndex = block;
                }

                internal LocalVariableEntry (MonoSymbolFile file, MyBinaryReader reader)
                {
                        Index = reader.ReadLeb128 ();
                        Name = reader.ReadString ();
                        BlockIndex = reader.ReadLeb128 ();
                }

                internal void Write (MonoSymbolFile file, MyBinaryWriter bw)
                {
                        bw.WriteLeb128 (Index);
                        bw.Write (Name);
                        bw.WriteLeb128 (BlockIndex);
                }

                public override string ToString ()
                {
                        return String.Format ("[LocalVariable {0}:{1}:{2}]",
                                              Name, Index, BlockIndex - 1);
                }
        }

        public struct CapturedVariable
        {
                #region This is actually written to the symbol file
                public readonly string Name;
                public readonly string CapturedName;
                public readonly CapturedKind Kind;
                #endregion

                public enum CapturedKind : byte
                {
                        Local,
                        Parameter,
                        This
                }

                public CapturedVariable (string name, string captured_name,
                                         CapturedKind kind)
                {
                        this.Name = name;
                        this.CapturedName = captured_name;
                        this.Kind = kind;
                }

                internal CapturedVariable (MyBinaryReader reader)
                {
                        Name = reader.ReadString ();
                        CapturedName = reader.ReadString ();
                        Kind = (CapturedKind) reader.ReadByte ();
                }

                internal void Write (MyBinaryWriter bw)
                {
                        bw.Write (Name);
                        bw.Write (CapturedName);
                        bw.Write ((byte) Kind);
                }

                public override string ToString ()
                {
                        return String.Format ("[CapturedVariable {0}:{1}:{2}]",
                                              Name, CapturedName, Kind);
                }
        }

        public struct CapturedScope
        {
                #region This is actually written to the symbol file
                public readonly int Scope;
                public readonly string CapturedName;
                #endregion

                public CapturedScope (int scope, string captured_name)
                {
                        this.Scope = scope;
                        this.CapturedName = captured_name;
                }

                internal CapturedScope (MyBinaryReader reader)
                {
                        Scope = reader.ReadLeb128 ();
                        CapturedName = reader.ReadString ();
                }

                internal void Write (MyBinaryWriter bw)
                {
                        bw.WriteLeb128 (Scope);
                        bw.Write (CapturedName);
                }

                public override string ToString ()
                {
                        return String.Format ("[CapturedScope {0}:{1}]",
                                              Scope, CapturedName);
                }
        }

        public struct ScopeVariable
        {
                #region This is actually written to the symbol file
                public readonly int Scope;
                public readonly int Index;
                #endregion

                public ScopeVariable (int scope, int index)
                {
                        this.Scope = scope;
                        this.Index = index;
                }

                internal ScopeVariable (MyBinaryReader reader)
                {
                        Scope = reader.ReadLeb128 ();
                        Index = reader.ReadLeb128 ();
                }

                internal void Write (MyBinaryWriter bw)
                {
                        bw.WriteLeb128 (Scope);
                        bw.WriteLeb128 (Index);
                }

                public override string ToString ()
                {
                        return String.Format ("[ScopeVariable {0}:{1}]", Scope, Index);
                }
        }

        public class AnonymousScopeEntry
        {
                #region This is actually written to the symbol file
                public readonly int ID;
                #endregion

                List<CapturedVariable> captured_vars = new List<CapturedVariable> ();
                List<CapturedScope> captured_scopes = new List<CapturedScope> ();

                public AnonymousScopeEntry (int id)
                {
                        this.ID = id;
                }

                internal AnonymousScopeEntry (MyBinaryReader reader)
                {
                        ID = reader.ReadLeb128 ();

                        int num_captured_vars = reader.ReadLeb128 ();
                        for (int i = 0; i < num_captured_vars; i++)
                                captured_vars.Add (new CapturedVariable (reader));

                        int num_captured_scopes = reader.ReadLeb128 ();
                        for (int i = 0; i < num_captured_scopes; i++)
                                captured_scopes.Add (new CapturedScope (reader));
                }

                internal void AddCapturedVariable (string name, string captured_name,
                                                   CapturedVariable.CapturedKind kind)
                {
                        captured_vars.Add (new CapturedVariable (name, captured_name, kind));
                }

                public CapturedVariable[] CapturedVariables {
                        get {
                                CapturedVariable[] retval = new CapturedVariable [captured_vars.Count];
                                captured_vars.CopyTo (retval, 0);
                                return retval;
                        }
                }

                internal void AddCapturedScope (int scope, string captured_name)
                {
                        captured_scopes.Add (new CapturedScope (scope, captured_name));
                }

                public CapturedScope[] CapturedScopes {
                        get {
                                CapturedScope[] retval = new CapturedScope [captured_scopes.Count];
                                captured_scopes.CopyTo (retval, 0);
                                return retval;
                        }
                }

                internal void Write (MyBinaryWriter bw)
                {
                        bw.WriteLeb128 (ID);

                        bw.WriteLeb128 (captured_vars.Count);
                        foreach (CapturedVariable cv in captured_vars)
                                cv.Write (bw);

                        bw.WriteLeb128 (captured_scopes.Count);
                        foreach (CapturedScope cs in captured_scopes)
                                cs.Write (bw);
                }

                public override string ToString ()
                {
                        return String.Format ("[AnonymousScope {0}]", ID);
                }
        }

        public class CompileUnitEntry : ICompileUnit
        {
                #region This is actually written to the symbol file
                public readonly int Index;
                int DataOffset;
                #endregion

                MonoSymbolFile file;
                SourceFileEntry source;
                List<SourceFileEntry> include_files;
                List<NamespaceEntry> namespaces;

                bool creating;

                public static int Size {
                        get { return 8; }
                }

                CompileUnitEntry ICompileUnit.Entry {
                        get { return this; }
                }

                public CompileUnitEntry (MonoSymbolFile file, SourceFileEntry source)
                {
                        this.file = file;
                        this.source = source;

                        this.Index = file.AddCompileUnit (this);

                        creating = true;
                        namespaces = new List<NamespaceEntry> ();
                }

                public void AddFile (SourceFileEntry file)
                {
                        if (!creating)
                                throw new InvalidOperationException ();

                        if (include_files == null)
                                include_files = new List<SourceFileEntry> ();

                        include_files.Add (file);
                }

                public SourceFileEntry SourceFile {
                        get {
                                if (creating)
                                        return source;

                                ReadData ();
                                return source;
                        }
                }

                public int DefineNamespace (string name, string[] using_clauses, int parent)
                {
                        if (!creating)
                                throw new InvalidOperationException ();

                        int index = file.GetNextNamespaceIndex ();
                        NamespaceEntry ns = new NamespaceEntry (name, index, using_clauses, parent);
                        namespaces.Add (ns);
                        return index;
                }

                internal void WriteData (MyBinaryWriter bw)
                {
                        DataOffset = (int) bw.BaseStream.Position;
                        bw.WriteLeb128 (source.Index);

                        int count_includes = include_files != null ? include_files.Count : 0;
                        bw.WriteLeb128 (count_includes);
                        if (include_files != null) {
                                foreach (SourceFileEntry entry in include_files)
                                        bw.WriteLeb128 (entry.Index);
                        }

                        bw.WriteLeb128 (namespaces.Count);
                        foreach (NamespaceEntry ns in namespaces)
                                ns.Write (file, bw);
                }

                internal void Write (BinaryWriter bw)
                {
                        bw.Write (Index);
                        bw.Write (DataOffset);
                }

                internal CompileUnitEntry (MonoSymbolFile file, MyBinaryReader reader)
                {
                        this.file = file;

                        Index = reader.ReadInt32 ();
                        DataOffset = reader.ReadInt32 ();
                }

                public void ReadAll ()
                {
                        ReadData ();
                }

                void ReadData ()
                {
                        if (creating)
                                throw new InvalidOperationException ();

                        lock (file) {
                                if (namespaces != null)
                                        return;

                                MyBinaryReader reader = file.BinaryReader;
                                int old_pos = (int) reader.BaseStream.Position;

                                reader.BaseStream.Position = DataOffset;

                                int source_idx = reader.ReadLeb128 ();
                                source = file.GetSourceFile (source_idx);

                                int count_includes = reader.ReadLeb128 ();
                                if (count_includes > 0) {
                                        include_files = new List<SourceFileEntry> ();
                                        for (int i = 0; i < count_includes; i++)
                                                include_files.Add (file.GetSourceFile (reader.ReadLeb128 ()));
                                }

                                int count_ns = reader.ReadLeb128 ();
                                namespaces = new List<NamespaceEntry> ();
                                for (int i = 0; i < count_ns; i ++)
                                        namespaces.Add (new NamespaceEntry (file, reader));

                                reader.BaseStream.Position = old_pos;
                        }
                }

                public NamespaceEntry[] Namespaces {
                        get {
                                ReadData ();
                                NamespaceEntry[] retval = new NamespaceEntry [namespaces.Count];
                                namespaces.CopyTo (retval, 0);
                                return retval;
                        }
                }

                public SourceFileEntry[] IncludeFiles {
                        get {
                                ReadData ();
                                if (include_files == null)
                                        return new SourceFileEntry [0];

                                SourceFileEntry[] retval = new SourceFileEntry [include_files.Count];
                                include_files.CopyTo (retval, 0);
                                return retval;
                        }
                }
        }

        public class SourceFileEntry
        {
                #region This is actually written to the symbol file
                public readonly int Index;
                int DataOffset;
                #endregion

                MonoSymbolFile file;
                string file_name;
                byte[] guid;
                byte[] hash;
                bool creating;
                bool auto_generated;
                readonly string sourceFile;

                public static int Size {
                        get { return 8; }
                }

                public SourceFileEntry (MonoSymbolFile file, string file_name)
                {
                        this.file = file;
                        this.file_name = file_name;
                        this.Index = file.AddSource (this);

                        creating = true;
                }

                public SourceFileEntry (MonoSymbolFile file, string sourceFile, byte [] guid, byte [] checksum)
                        : this (file, sourceFile, sourceFile, guid, checksum)
                {
                }

                public SourceFileEntry (MonoSymbolFile file, string fileName, string sourceFile, byte[] guid, byte[] checksum)
                        : this (file, fileName)
                {
                        this.guid = guid;
                        this.hash = checksum;
                        this.sourceFile = sourceFile;
                }

                public byte[] Checksum {
                        get {
                                return hash;
                        }
                }

                internal void WriteData (MyBinaryWriter bw)
                {
                        DataOffset = (int) bw.BaseStream.Position;
                        bw.Write (file_name);

                        if (guid == null)
                                guid = new byte[16];

                        if (hash == null) {
                                try {
                                    using (FileStream fs = new FileStream (sourceFile, FileMode.Open, FileAccess.Read)) {
                                        MD5 md5 = MD5.Create ();
                                        hash = md5.ComputeHash (fs);
                                    }
                                } catch {
                                        hash = new byte [16];
                                }
                        }

                        bw.Write (guid);
                        bw.Write (hash);
                        bw.Write ((byte) (auto_generated ? 1 : 0));
                }

                internal void Write (BinaryWriter bw)
                {
                        bw.Write (Index);
                        bw.Write (DataOffset);
                }

                internal SourceFileEntry (MonoSymbolFile file, MyBinaryReader reader)
                {
                        this.file = file;

                        Index = reader.ReadInt32 ();
                        DataOffset = reader.ReadInt32 ();

                        int old_pos = (int) reader.BaseStream.Position;
                        reader.BaseStream.Position = DataOffset;

                        sourceFile = file_name = reader.ReadString ();
                        guid = reader.ReadBytes (16);
                        hash = reader.ReadBytes (16);
                        auto_generated = reader.ReadByte () == 1;

                        reader.BaseStream.Position = old_pos;
                }

                public string FileName {
                        get { return file_name; }
                        set { file_name = value; }
                }

                public bool AutoGenerated {
                        get { return auto_generated; }
                }

                public void SetAutoGenerated ()
                {
                        if (!creating)
                                throw new InvalidOperationException ();

                        auto_generated = true;
                        file.OffsetTable.FileFlags |= OffsetTable.Flags.IsAspxSource;
                }

                public bool CheckChecksum ()
                {
                        try {
                                using (FileStream fs = new FileStream (sourceFile, FileMode.Open)) {
                                        MD5 md5 = MD5.Create ();
                                        byte[] data = md5.ComputeHash (fs);
                                        for (int i = 0; i < 16; i++)
                                                if (data [i] != hash [i])
                                                        return false;
                                        return true;
                                }
                        } catch {
                                return false;
                        }
                }

                public override string ToString ()
                {
                        return String.Format ("SourceFileEntry ({0}:{1})", Index, DataOffset);
                }
        }

        public class LineNumberTable
        {
                protected LineNumberEntry[] _line_numbers;
                public LineNumberEntry[] LineNumbers {
                        get { return _line_numbers; }
                }

                public readonly int LineBase;
                public readonly int LineRange;
                public readonly byte OpcodeBase;
                public readonly int MaxAddressIncrement;

#region Configurable constants
                public const int Default_LineBase = -1;
                public const int Default_LineRange = 8;
                public const byte Default_OpcodeBase = 9;

#endregion

                public const byte DW_LNS_copy = 1;
                public const byte DW_LNS_advance_pc = 2;
                public const byte DW_LNS_advance_line = 3;
                public const byte DW_LNS_set_file = 4;
                public const byte DW_LNS_const_add_pc = 8;

                public const byte DW_LNE_end_sequence = 1;

                // MONO extensions.
                public const byte DW_LNE_MONO_negate_is_hidden = 0x40;

                internal const byte DW_LNE_MONO__extensions_start = 0x40;
                internal const byte DW_LNE_MONO__extensions_end   = 0x7f;

                protected LineNumberTable (MonoSymbolFile file)
                {
                        this.LineBase = file.OffsetTable.LineNumberTable_LineBase;
                        this.LineRange = file.OffsetTable.LineNumberTable_LineRange;
                        this.OpcodeBase = (byte) file.OffsetTable.LineNumberTable_OpcodeBase;
                        this.MaxAddressIncrement = (255 - OpcodeBase) / LineRange;
                }

                internal LineNumberTable (MonoSymbolFile file, LineNumberEntry[] lines)
                        : this (file)
                {
                        this._line_numbers = lines;
                }

                internal void Write (MonoSymbolFile file, MyBinaryWriter bw, bool hasColumnsInfo, bool hasEndInfo)
                {
                        int start = (int) bw.BaseStream.Position;

                        bool last_is_hidden = false;
                        int last_line = 1, last_offset = 0, last_file = 1;
                        for (int i = 0; i < LineNumbers.Length; i++) {
                                int line_inc = LineNumbers [i].Row - last_line;
                                int offset_inc = LineNumbers [i].Offset - last_offset;

                                if (LineNumbers [i].File != last_file) {
                                        bw.Write (DW_LNS_set_file);
                                        bw.WriteLeb128 (LineNumbers [i].File);
                                        last_file = LineNumbers [i].File;
                                }

                                if (LineNumbers [i].IsHidden != last_is_hidden) {
                                        bw.Write ((byte) 0);
                                        bw.Write ((byte) 1);
                                        bw.Write (DW_LNE_MONO_negate_is_hidden);
                                        last_is_hidden = LineNumbers [i].IsHidden;
                                }

                                if (offset_inc >= MaxAddressIncrement) {
                                        if (offset_inc < 2 * MaxAddressIncrement) {
                                                bw.Write (DW_LNS_const_add_pc);
                                                offset_inc -= MaxAddressIncrement;
                                        } else {
                                                bw.Write (DW_LNS_advance_pc);
                                                bw.WriteLeb128 (offset_inc);
                                                offset_inc = 0;
                                        }
                                }

                                if ((line_inc < LineBase) || (line_inc >= LineBase + LineRange)) {
                                        bw.Write (DW_LNS_advance_line);
                                        bw.WriteLeb128 (line_inc);
                                        if (offset_inc != 0) {
                                                bw.Write (DW_LNS_advance_pc);
                                                bw.WriteLeb128 (offset_inc);
                                        }
                                        bw.Write (DW_LNS_copy);
                                } else {
                                        byte opcode;
                                        opcode = (byte) (line_inc - LineBase + (LineRange * offset_inc) +
                                                         OpcodeBase);
                                        bw.Write (opcode);
                                }

                                last_line = LineNumbers [i].Row;
                                last_offset = LineNumbers [i].Offset;
                        }

                        bw.Write ((byte) 0);
                        bw.Write ((byte) 1);
                        bw.Write (DW_LNE_end_sequence);

                        if (hasColumnsInfo) {
                                for (int i = 0; i < LineNumbers.Length; i++) {
                                        var ln = LineNumbers [i];
                                        if (ln.Row >= 0)
                                                bw.WriteLeb128 (ln.Column);
                                }
                        }

                        if (hasEndInfo) {
                                for (int i = 0; i < LineNumbers.Length; i++) {
                                        var ln = LineNumbers [i];
                                        if (ln.EndRow == -1 || ln.EndColumn == -1 || ln.Row > ln.EndRow) {
                                                bw.WriteLeb128 (0xffffff);
                                        } else {
                                                bw.WriteLeb128 (ln.EndRow - ln.Row);
                                                bw.WriteLeb128 (ln.EndColumn);
                                        }
                                }
                        }

                        file.ExtendedLineNumberSize += (int) bw.BaseStream.Position - start;
                }

                internal static LineNumberTable Read (MonoSymbolFile file, MyBinaryReader br, bool readColumnsInfo, bool readEndInfo)
                {
                        LineNumberTable lnt = new LineNumberTable (file);
                        lnt.DoRead (file, br, readColumnsInfo, readEndInfo);
                        return lnt;
                }

                void DoRead (MonoSymbolFile file, MyBinaryReader br, bool includesColumns, bool includesEnds)
                {
                        var lines = new List<LineNumberEntry> ();

                        bool is_hidden = false, modified = false;
                        int stm_line = 1, stm_offset = 0, stm_file = 1;
                        while (true) {
                                byte opcode = br.ReadByte ();

                                if (opcode == 0) {
                                        byte size = br.ReadByte ();
                                        long end_pos = br.BaseStream.Position + size;
                                        opcode = br.ReadByte ();

                                        if (opcode == DW_LNE_end_sequence) {
                                                if (modified)
                                                        lines.Add (new LineNumberEntry (
                                                                stm_file, stm_line, -1, stm_offset, is_hidden));
                                                break;
                                        } else if (opcode == DW_LNE_MONO_negate_is_hidden) {
                                                is_hidden = !is_hidden;
                                                modified = true;
                                        } else if ((opcode >= DW_LNE_MONO__extensions_start) &&
                                                   (opcode <= DW_LNE_MONO__extensions_end)) {
                                                ; // reserved for future extensions
                                        } else {
                                                throw new MonoSymbolFileException ("Unknown extended opcode {0:x}", opcode);
                                        }

                                        br.BaseStream.Position = end_pos;
                                        continue;
                                } else if (opcode < OpcodeBase) {
                                        switch (opcode) {
                                        case DW_LNS_copy:
                                                lines.Add (new LineNumberEntry (
                                                        stm_file, stm_line, -1, stm_offset, is_hidden));
                                                modified = false;
                                                break;
                                        case DW_LNS_advance_pc:
                                                stm_offset += br.ReadLeb128 ();
                                                modified = true;
                                                break;
                                        case DW_LNS_advance_line:
                                                stm_line += br.ReadLeb128 ();
                                                modified = true;
                                                break;
                                        case DW_LNS_set_file:
                                                stm_file = br.ReadLeb128 ();
                                                modified = true;
                                                break;
                                        case DW_LNS_const_add_pc:
                                                stm_offset += MaxAddressIncrement;
                                                modified = true;
                                                break;
                                        default:
                                                throw new MonoSymbolFileException (
                                                        "Unknown standard opcode {0:x} in LNT",
                                                        opcode);
                                        }
                                } else {
                                        opcode -= OpcodeBase;

                                        stm_offset += opcode / LineRange;
                                        stm_line += LineBase + (opcode % LineRange);
                                        lines.Add (new LineNumberEntry (
                                                stm_file, stm_line, -1, stm_offset, is_hidden));
                                        modified = false;
                                }
                        }

                        _line_numbers = lines.ToArray ();

                        if (includesColumns) {
                                for (int i = 0; i < _line_numbers.Length; ++i) {
                                        var ln = _line_numbers[i];
                                        if (ln.Row >= 0)
                                                ln.Column = br.ReadLeb128 ();
                                }
                        }
                        if (includesEnds) {
                                for (int i = 0; i < _line_numbers.Length; ++i) {
                                        var ln = _line_numbers[i];

                                        int row = br.ReadLeb128 ();
                                        if (row == 0xffffff) {
                                                ln.EndRow = -1;
                                                ln.EndColumn = -1;
                                        } else {
                                                ln.EndRow = ln.Row + row;
                                                ln.EndColumn = br.ReadLeb128 ();
                                        }
                                }
                        }
                }

                public bool GetMethodBounds (out LineNumberEntry start, out LineNumberEntry end)
                {
                        if (_line_numbers.Length > 1) {
                                start = _line_numbers [0];
                                end = _line_numbers [_line_numbers.Length - 1];
                                return true;
                        }

                        start = LineNumberEntry.Null;
                        end = LineNumberEntry.Null;
                        return false;
                }
        }

        public class MethodEntry : IComparable
        {
                #region This is actually written to the symbol file
                public readonly int CompileUnitIndex;
                public readonly int Token;
                public readonly int NamespaceID;

                int DataOffset;
                int LocalVariableTableOffset;
                int LineNumberTableOffset;
                int CodeBlockTableOffset;
                int ScopeVariableTableOffset;
                int RealNameOffset;
                Flags flags;
                #endregion

                int index;

                public Flags MethodFlags {
                        get { return flags; }
                }

                public readonly CompileUnitEntry CompileUnit;

                LocalVariableEntry[] locals;
                CodeBlockEntry[] code_blocks;
                ScopeVariable[] scope_vars;
                LineNumberTable lnt;
                string real_name;

                public readonly MonoSymbolFile SymbolFile;

                public int Index {
                        get { return index; }
                        set { index = value; }
                }

                [Flags]
                public enum Flags
                {
                        LocalNamesAmbiguous     = 1,
                        ColumnsInfoIncluded = 1 << 1,
                        EndInfoIncluded = 1 << 2
                }

                public const int Size = 12;

                internal MethodEntry (MonoSymbolFile file, MyBinaryReader reader, int index)
                {
                        this.SymbolFile = file;
                        this.index = index;

                        Token = reader.ReadInt32 ();
                        DataOffset = reader.ReadInt32 ();
                        LineNumberTableOffset = reader.ReadInt32 ();

                        long old_pos = reader.BaseStream.Position;
                        reader.BaseStream.Position = DataOffset;

                        CompileUnitIndex = reader.ReadLeb128 ();
                        LocalVariableTableOffset = reader.ReadLeb128 ();
                        NamespaceID = reader.ReadLeb128 ();

                        CodeBlockTableOffset = reader.ReadLeb128 ();
                        ScopeVariableTableOffset = reader.ReadLeb128 ();

                        RealNameOffset = reader.ReadLeb128 ();

                        flags = (Flags) reader.ReadLeb128 ();

                        reader.BaseStream.Position = old_pos;

                        CompileUnit = file.GetCompileUnit (CompileUnitIndex);
                }

                internal MethodEntry (MonoSymbolFile file, CompileUnitEntry comp_unit,
                                      int token, ScopeVariable[] scope_vars,
                                      LocalVariableEntry[] locals, LineNumberEntry[] lines,
                                      CodeBlockEntry[] code_blocks, string real_name,
                                      Flags flags, int namespace_id)
                {
                        this.SymbolFile = file;
                        this.real_name = real_name;
                        this.locals = locals;
                        this.code_blocks = code_blocks;
                        this.scope_vars = scope_vars;
                        this.flags = flags;

                        index = -1;

                        Token = token;
                        CompileUnitIndex = comp_unit.Index;
                        CompileUnit = comp_unit;
                        NamespaceID = namespace_id;

                        CheckLineNumberTable (lines);
                        lnt = new LineNumberTable (file, lines);
                        file.NumLineNumbers += lines.Length;

                        int num_locals = locals != null ? locals.Length : 0;

                        if (num_locals <= 32) {
                                // Most of the time, the O(n^2) factor is actually
                                // less than the cost of allocating the hash table,
                                // 32 is a rough number obtained through some testing.
                                
                                for (int i = 0; i < num_locals; i ++) {
                                        string nm = locals [i].Name;
                                        
                                        for (int j = i + 1; j < num_locals; j ++) {
                                                if (locals [j].Name == nm) {
                                                        flags |= Flags.LocalNamesAmbiguous;
                                                        goto locals_check_done;
                                                }
                                        }
                                }
                        locals_check_done :
                                ;
                        } else {
                                var local_names = new Dictionary<string, LocalVariableEntry> ();
                                foreach (LocalVariableEntry local in locals) {
                                        if (local_names.ContainsKey (local.Name)) {
                                                flags |= Flags.LocalNamesAmbiguous;
                                                break;
                                        }
                                        local_names.Add (local.Name, local);
                                }
                        }
                }
                
                static void CheckLineNumberTable (LineNumberEntry[] line_numbers)
                {
                        int last_offset = -1;
                        int last_row = -1;

                        if (line_numbers == null)
                                return;
                        
                        for (int i = 0; i < line_numbers.Length; i++) {
                                LineNumberEntry line = line_numbers [i];

                                if (line.Equals (LineNumberEntry.Null))
                                        throw new MonoSymbolFileException ();

                                if (line.Offset < last_offset)
                                        throw new MonoSymbolFileException ();

                                if (line.Offset > last_offset) {
                                        last_row = line.Row;
                                        last_offset = line.Offset;
                                } else if (line.Row > last_row) {
                                        last_row = line.Row;
                                }
                        }
                }

                internal void Write (MyBinaryWriter bw)
                {
                        if ((index <= 0) || (DataOffset == 0))
                                throw new InvalidOperationException ();

                        bw.Write (Token);
                        bw.Write (DataOffset);
                        bw.Write (LineNumberTableOffset);
                }

                internal void WriteData (MonoSymbolFile file, MyBinaryWriter bw)
                {
                        if (index <= 0)
                                throw new InvalidOperationException ();

                        LocalVariableTableOffset = (int) bw.BaseStream.Position;
                        int num_locals = locals != null ? locals.Length : 0;
                        bw.WriteLeb128 (num_locals);
                        for (int i = 0; i < num_locals; i++)
                                locals [i].Write (file, bw);
                        file.LocalCount += num_locals;

                        CodeBlockTableOffset = (int) bw.BaseStream.Position;
                        int num_code_blocks = code_blocks != null ? code_blocks.Length : 0;
                        bw.WriteLeb128 (num_code_blocks);
                        for (int i = 0; i < num_code_blocks; i++)
                                code_blocks [i].Write (bw);

                        ScopeVariableTableOffset = (int) bw.BaseStream.Position;
                        int num_scope_vars = scope_vars != null ? scope_vars.Length : 0;
                        bw.WriteLeb128 (num_scope_vars);
                        for (int i = 0; i < num_scope_vars; i++)
                                scope_vars [i].Write (bw);

                        if (real_name != null) {
                                RealNameOffset = (int) bw.BaseStream.Position;
                                bw.Write (real_name);
                        }

                        foreach (var lne in lnt.LineNumbers) {
                                if (lne.EndRow != -1 || lne.EndColumn != -1)
                                        flags |= Flags.EndInfoIncluded;
                        }

                        LineNumberTableOffset = (int) bw.BaseStream.Position;
                        lnt.Write (file, bw, (flags & Flags.ColumnsInfoIncluded) != 0, (flags & Flags.EndInfoIncluded) != 0);

                        DataOffset = (int) bw.BaseStream.Position;

                        bw.WriteLeb128 (CompileUnitIndex);
                        bw.WriteLeb128 (LocalVariableTableOffset);
                        bw.WriteLeb128 (NamespaceID);

                        bw.WriteLeb128 (CodeBlockTableOffset);
                        bw.WriteLeb128 (ScopeVariableTableOffset);

                        bw.WriteLeb128 (RealNameOffset);
                        bw.WriteLeb128 ((int) flags);
                }

                public void ReadAll ()
                {
                        GetLineNumberTable ();
                        GetLocals ();
                        GetCodeBlocks ();
                        GetScopeVariables ();
                        GetRealName ();
                }

                public LineNumberTable GetLineNumberTable ()
                {
                        lock (SymbolFile) {
                                if (lnt != null)
                                        return lnt;

                                if (LineNumberTableOffset == 0)
                                        return null;

                                MyBinaryReader reader = SymbolFile.BinaryReader;
                                long old_pos = reader.BaseStream.Position;
                                reader.BaseStream.Position = LineNumberTableOffset;

                                lnt = LineNumberTable.Read (SymbolFile, reader, (flags & Flags.ColumnsInfoIncluded) != 0, (flags & Flags.EndInfoIncluded) != 0);

                                reader.BaseStream.Position = old_pos;
                                return lnt;
                        }
                }

                public LocalVariableEntry[] GetLocals ()
                {
                        lock (SymbolFile) {
                                if (locals != null)
                                        return locals;

                                if (LocalVariableTableOffset == 0)
                                        return null;

                                MyBinaryReader reader = SymbolFile.BinaryReader;
                                long old_pos = reader.BaseStream.Position;
                                reader.BaseStream.Position = LocalVariableTableOffset;

                                int num_locals = reader.ReadLeb128 ();
                                locals = new LocalVariableEntry [num_locals];

                                for (int i = 0; i < num_locals; i++)
                                        locals [i] = new LocalVariableEntry (SymbolFile, reader);

                                reader.BaseStream.Position = old_pos;
                                return locals;
                        }
                }

                public CodeBlockEntry[] GetCodeBlocks ()
                {
                        lock (SymbolFile) {
                                if (code_blocks != null)
                                        return code_blocks;

                                if (CodeBlockTableOffset == 0)
                                        return null;

                                MyBinaryReader reader = SymbolFile.BinaryReader;
                                long old_pos = reader.BaseStream.Position;
                                reader.BaseStream.Position = CodeBlockTableOffset;

                                int num_code_blocks = reader.ReadLeb128 ();
                                code_blocks = new CodeBlockEntry [num_code_blocks];

                                for (int i = 0; i < num_code_blocks; i++)
                                        code_blocks [i] = new CodeBlockEntry (i, reader);

                                reader.BaseStream.Position = old_pos;
                                return code_blocks;
                        }
                }

                public ScopeVariable[] GetScopeVariables ()
                {
                        lock (SymbolFile) {
                                if (scope_vars != null)
                                        return scope_vars;

                                if (ScopeVariableTableOffset == 0)
                                        return null;

                                MyBinaryReader reader = SymbolFile.BinaryReader;
                                long old_pos = reader.BaseStream.Position;
                                reader.BaseStream.Position = ScopeVariableTableOffset;

                                int num_scope_vars = reader.ReadLeb128 ();
                                scope_vars = new ScopeVariable [num_scope_vars];

                                for (int i = 0; i < num_scope_vars; i++)
                                        scope_vars [i] = new ScopeVariable (reader);

                                reader.BaseStream.Position = old_pos;
                                return scope_vars;
                        }
                }

                public string GetRealName ()
                {
                        lock (SymbolFile) {
                                if (real_name != null)
                                        return real_name;

                                if (RealNameOffset == 0)
                                        return null;

                                real_name = SymbolFile.BinaryReader.ReadString (RealNameOffset);
                                return real_name;
                        }
                }

                public int CompareTo (object obj)
                {
                        MethodEntry method = (MethodEntry) obj;

                        if (method.Token < Token)
                                return 1;
                        else if (method.Token > Token)
                                return -1;
                        else
                                return 0;
                }

                public override string ToString ()
                {
                        return String.Format ("[Method {0}:{1:x}:{2}:{3}]",
                                              index, Token, CompileUnitIndex, CompileUnit);
                }
        }

        public struct NamespaceEntry
        {
                #region This is actually written to the symbol file
                public readonly string Name;
                public readonly int Index;
                public readonly int Parent;
                public readonly string[] UsingClauses;
                #endregion

                public NamespaceEntry (string name, int index, string[] using_clauses, int parent)
                {
                        this.Name = name;
                        this.Index = index;
                        this.Parent = parent;
                        this.UsingClauses = using_clauses != null ? using_clauses : new string [0];
                }

                internal NamespaceEntry (MonoSymbolFile file, MyBinaryReader reader)
                {
                        Name = reader.ReadString ();
                        Index = reader.ReadLeb128 ();
                        Parent = reader.ReadLeb128 ();

                        int count = reader.ReadLeb128 ();
                        UsingClauses = new string [count];
                        for (int i = 0; i < count; i++)
                                UsingClauses [i] = reader.ReadString ();
                }

                internal void Write (MonoSymbolFile file, MyBinaryWriter bw)
                {
                        bw.Write (Name);
                        bw.WriteLeb128 (Index);
                        bw.WriteLeb128 (Parent);
                        bw.WriteLeb128 (UsingClauses.Length);
                        foreach (string uc in UsingClauses)
                                bw.Write (uc);
                }

                public override string ToString ()
                {
                        return String.Format ("[Namespace {0}:{1}:{2}]", Name, Index, Parent);
                }
        }
}