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+// Copyright 2006 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.
+
+// This file contains definitions related to the DWARF2/3 reader and
+// it's handler interfaces.
+// The DWARF2/3 specification can be found at
+// http://dwarf.freestandards.org and should be considered required
+// reading if you wish to modify the implementation.
+// Only a cursory attempt is made to explain terminology that is
+// used here, as it is much better explained in the standard documents
+#ifndef COMMON_DWARF_DWARF2READER_H__
+#define COMMON_DWARF_DWARF2READER_H__
+
+#include <list>
+#include <map>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "common/dwarf/dwarf2enums.h"
+#include "common/dwarf/types.h"
+
+using namespace std;
+
+namespace dwarf2reader {
+struct LineStateMachine;
+class ByteReader;
+class Dwarf2Handler;
+class LineInfoHandler;
+
+// This maps from a string naming a section to a pair containing a
+// the data for the section, and the size of the section.
+typedef map<string, pair<const char*, uint64> > SectionMap;
+typedef list<pair<enum DwarfAttribute, enum DwarfForm> > AttributeList;
+typedef AttributeList::iterator AttributeIterator;
+typedef AttributeList::const_iterator ConstAttributeIterator;
+
+struct LineInfoHeader {
+  uint64 total_length;
+  uint16 version;
+  uint64 prologue_length;
+  uint8 min_insn_length; // insn stands for instructin
+  bool default_is_stmt; // stmt stands for statement
+  int8 line_base;
+  uint8 line_range;
+  uint8 opcode_base;
+  // Use a pointer so that signalsafe_addr2line is able to use this structure
+  // without heap allocation problem.
+  vector<unsigned char> *std_opcode_lengths;
+};
+
+class LineInfo {
+ public:
+
+  // Initializes a .debug_line reader. Buffer and buffer length point
+  // to the beginning and length of the line information to read.
+  // Reader is a ByteReader class that has the endianness set
+  // properly.
+  LineInfo(const char* buffer_, uint64 buffer_length,
+           ByteReader* reader, LineInfoHandler* handler);
+
+  virtual ~LineInfo() {
+    if (header_.std_opcode_lengths) {
+      delete header_.std_opcode_lengths;
+    }
+  }
+
+  // Start processing line info, and calling callbacks in the handler.
+  // Consumes the line number information for a single compilation unit.
+  // Returns the number of bytes processed.
+  uint64 Start();
+
+  // Process a single line info opcode at START using the state
+  // machine at LSM.  Return true if we should define a line using the
+  // current state of the line state machine.  Place the length of the
+  // opcode in LEN.
+  // If LSM_PASSES_PC is non-NULL, this function also checks if the lsm
+  // passes the address of PC. In other words, LSM_PASSES_PC will be
+  // set to true, if the following condition is met.
+  //
+  // lsm's old address < PC <= lsm's new address
+  static bool ProcessOneOpcode(ByteReader* reader,
+                               LineInfoHandler* handler,
+                               const struct LineInfoHeader &header,
+                               const char* start,
+                               struct LineStateMachine* lsm,
+                               size_t* len,
+                               uintptr_t pc,
+                               bool *lsm_passes_pc);
+
+ private:
+  // Reads the DWARF2/3 header for this line info.
+  void ReadHeader();
+
+  // Reads the DWARF2/3 line information
+  void ReadLines();
+
+  // The associated handler to call processing functions in
+  LineInfoHandler* handler_;
+
+  // The associated ByteReader that handles endianness issues for us
+  ByteReader* reader_;
+
+  // A DWARF2/3 line info header.  This is not the same size as
+  // in the actual file, as the one in the file may have a 32 bit or
+  // 64 bit lengths
+
+  struct LineInfoHeader header_;
+
+  // buffer is the buffer for our line info, starting at exactly where
+  // the line info to read is.  after_header is the place right after
+  // the end of the line information header.
+  const char* buffer_;
+  uint64 buffer_length_;
+  const char* after_header_;
+};
+
+// This class is the main interface between the line info reader and
+// the client.  The virtual functions inside this get called for
+// interesting events that happen during line info reading.  The
+// default implementation does nothing
+
+class LineInfoHandler {
+ public:
+  LineInfoHandler() { }
+
+  virtual ~LineInfoHandler() { }
+
+  // Called when we define a directory.  NAME is the directory name,
+  // DIR_NUM is the directory number
+  virtual void DefineDir(const string& name, uint32 dir_num) { }
+
+  // Called when we define a filename. NAME is the filename, FILE_NUM
+  // is the file number which is -1 if the file index is the next
+  // index after the last numbered index (this happens when files are
+  // dynamically defined by the line program), DIR_NUM is the
+  // directory index for the directory name of this file, MOD_TIME is
+  // the modification time of the file, and LENGTH is the length of
+  // the file
+  virtual void DefineFile(const string& name, int32 file_num,
+                          uint32 dir_num, uint64 mod_time,
+                          uint64 length) { }
+
+  // Called when the line info reader has a new line, address pair
+  // ready for us.  ADDRESS is the address of the code, FILE_NUM is
+  // the file number containing the code, LINE_NUM is the line number in
+  // that file for the code, and COLUMN_NUM is the column number the code
+  // starts at, if we know it (0 otherwise).
+  virtual void AddLine(uint64 address, uint32 file_num, uint32 line_num,
+                       uint32 column_num) { }
+};
+
+// The base of DWARF2/3 debug info is a DIE (Debugging Information
+// Entry.
+// DWARF groups DIE's into a tree and calls the root of this tree a
+// "compilation unit".  Most of the time, their is one compilation
+// unit in the .debug_info section for each file that had debug info
+// generated.
+// Each DIE consists of
+
+// 1. a tag specifying a thing that is being described (ie
+// DW_TAG_subprogram for functions, DW_TAG_variable for variables, etc
+// 2. attributes (such as DW_AT_location for location in memory,
+// DW_AT_name for name), and data for each attribute.
+// 3. A flag saying whether the DIE has children or not
+
+// In order to gain some amount of compression, the format of
+// each DIE (tag name, attributes and data forms for the attributes)
+// are stored in a separate table called the "abbreviation table".
+// This is done because a large number of DIEs have the exact same tag
+// and list of attributes, but different data for those attributes.
+// As a result, the .debug_info section is just a stream of data, and
+// requires reading of the .debug_abbrev section to say what the data
+// means.
+
+// As a warning to the user, it should be noted that the reason for
+// using absolute offsets from the beginning of .debug_info is that
+// DWARF2/3 support referencing DIE's from other DIE's by their offset
+// from either the current compilation unit start, *or* the beginning
+// of the .debug_info section.  This means it is possible to reference
+// a DIE in one compilation unit from a DIE in another compilation
+// unit.  This style of reference is usually used to eliminate
+// duplicated information that occurs across compilation
+// units, such as base types, etc.  GCC 3.4+ support this with
+// -feliminate-dwarf2-dups.  Other toolchains will sometimes do
+// duplicate elimination in the linker.
+
+class CompilationUnit {
+ public:
+
+  // Initialize a compilation unit.  This requires a map of sections,
+  // the offset of this compilation unit in the debug_info section, a
+  // ByteReader, and a Dwarf2Handler class to call callbacks in.
+  CompilationUnit(const SectionMap& sections, uint64 offset,
+                  ByteReader* reader, Dwarf2Handler* handler);
+  virtual ~CompilationUnit() {
+    if (abbrevs_) delete abbrevs_;
+  }
+
+  // Begin reading a Dwarf2 compilation unit, and calling the
+  // callbacks in the Dwarf2Handler
+  // Return the offset of the end of the compilation unit - the passed
+  // in offset.
+  uint64 Start();
+
+ private:
+
+  // This struct represents a single DWARF2/3 abbreviation
+  // The abbreviation tells how to read a DWARF2/3 DIE, and consist of a
+  // tag and a list of attributes, as well as the data form of each attribute.
+  struct Abbrev {
+    uint32 number;
+    enum DwarfTag tag;
+    bool has_children;
+    AttributeList attributes;
+  };
+
+  // A DWARF2/3 compilation unit header.  This is not the same size as
+  // in the actual file, as the one in the file may have a 32 bit or
+  // 64 bit length.
+  struct CompilationUnitHeader {
+    uint64 length;
+    uint16 version;
+    uint64 abbrev_offset;
+    uint8 address_size;
+  } header_;
+
+  // Reads the DWARF2/3 header for this compilation unit.
+  void ReadHeader();
+
+  // Reads the DWARF2/3 abbreviations for this compilation unit
+  void ReadAbbrevs();
+
+  // Processes a single DIE for this compilation unit and return a new
+  // pointer just past the end of it
+  const char* ProcessDIE(uint64 dieoffset,
+                                  const char* start,
+                                  const Abbrev& abbrev);
+
+  // Processes a single attribute and return a new pointer just past the
+  // end of it
+  const char* ProcessAttribute(uint64 dieoffset,
+                                        const char* start,
+                                        enum DwarfAttribute attr,
+                                        enum DwarfForm form);
+
+  // Processes all DIEs for this compilation unit
+  void ProcessDIEs();
+
+  // Skips the die with attributes specified in ABBREV starting at
+  // START, and return the new place to position the stream to.
+  const char* SkipDIE(const char* start,
+                               const Abbrev& abbrev);
+
+  // Skips the attribute starting at START, with FORM, and return the
+  // new place to position the stream to.
+  const char* SkipAttribute(const char* start,
+                                     enum DwarfForm form);
+
+  // Offset from section start is the offset of this compilation unit
+  // from the beginning of the .debug_info section.
+  uint64 offset_from_section_start_;
+
+  // buffer is the buffer for our CU, starting at .debug_info + offset
+  // passed in from constructor.
+  // after_header points to right after the compilation unit header.
+  const char* buffer_;
+  uint64 buffer_length_;
+  const char* after_header_;
+
+  // The associated ByteReader that handles endianness issues for us
+  ByteReader* reader_;
+
+  // The map of sections in our file to buffers containing their data
+  const SectionMap& sections_;
+
+  // The associated handler to call processing functions in
+  Dwarf2Handler* handler_;
+
+  // Set of DWARF2/3 abbreviations for this compilation unit.  Indexed
+  // by abbreviation number, which means that abbrevs_[0] is not
+  // valid.
+  vector<Abbrev>* abbrevs_;
+
+  // String section buffer and length, if we have a string section.
+  // This is here to avoid doing a section lookup for strings in
+  // ProcessAttribute, which is in the hot path for DWARF2 reading.
+  const char* string_buffer_;
+  uint64 string_buffer_length_;
+};
+
+// This class is the main interface between the reader and the
+// client.  The virtual functions inside this get called for
+// interesting events that happen during DWARF2 reading.
+// The default implementation skips everything.
+
+class Dwarf2Handler {
+ public:
+  Dwarf2Handler() { }
+
+  virtual ~Dwarf2Handler() { }
+
+  // Start to process a compilation unit at OFFSET from the beginning of the
+  // debug_info section.  Return false if you would like
+  // to skip this compilation unit.
+  virtual bool StartCompilationUnit(uint64 offset, uint8 address_size,
+                                    uint8 offset_size, uint64 cu_length,
+                                    uint8 dwarf_version) { return false; }
+
+  // Start to process a DIE at OFFSET from the beginning of the
+  // debug_info section.  Return false if you would like to skip this
+  // DIE.
+  virtual bool StartDIE(uint64 offset, enum DwarfTag tag,
+                        const AttributeList& attrs) { return false; }
+
+  // Called when we have an attribute with unsigned data to give to
+  // our handler.  The attribute is for the DIE at OFFSET from the
+  // beginning of compilation unit, has a name of ATTR, a form of
+  // FORM, and the actual data of the attribute is in DATA.
+  virtual void ProcessAttributeUnsigned(uint64 offset,
+                                        enum DwarfAttribute attr,
+                                        enum DwarfForm form,
+                                        uint64 data) { }
+
+  // Called when we have an attribute with signed data to give to
+  // our handler.  The attribute is for the DIE at OFFSET from the
+  // beginning of compilation unit, has a name of ATTR, a form of
+  // FORM, and the actual data of the attribute is in DATA.
+  virtual void ProcessAttributeSigned(uint64 offset,
+                                      enum DwarfAttribute attr,
+                                      enum DwarfForm form,
+                                      int64 data) { }
+
+  // Called when we have an attribute with a buffer of data to give to
+  // our handler.  The attribute is for the DIE at OFFSET from the
+  // beginning of compilation unit, has a name of ATTR, a form of
+  // FORM, and the actual data of the attribute is in DATA, and the
+  // length of the buffer is LENGTH.  The buffer is owned by the
+  // caller, not the callee, and may not persist for very long.  If
+  // you want the data to be available later, it needs to be copied.
+  virtual void ProcessAttributeBuffer(uint64 offset,
+                                      enum DwarfAttribute attr,
+                                      enum DwarfForm form,
+                                      const char* data,
+                                      uint64 len) { }
+
+  // Called when we have an attribute with string data to give to
+  // our handler.  The attribute is for the DIE at OFFSET from the
+  // beginning of compilation unit, has a name of ATTR, a form of
+  // FORM, and the actual data of the attribute is in DATA.
+  virtual void ProcessAttributeString(uint64 offset,
+                                      enum DwarfAttribute attr,
+                                      enum DwarfForm form,
+                                      const string& data) { }
+
+  // Called when finished processing the DIE at OFFSET.
+  // Because DWARF2/3 specifies a tree of DIEs, you may get starts
+  // before ends of the previous DIE, as we process children before
+  // ending the parent.
+  virtual void EndDIE(uint64 offset) { }
+
+};
+
+
+}  // namespace dwarf2reader
+
+#endif  // UTIL_DEBUGINFO_DWARF2READER_H__