path: root/src/common/dwarf_cu_to_module.h

// -*- mode: c++ -*-

// Copyright (c) 2010 Google Inc.
// All rights reserved.
//
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// 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.
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// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>

// Add DWARF debugging information to a Breakpad symbol file. This
// file defines the DwarfCUToModule class, which accepts parsed DWARF
// data and populates a google_breakpad::Module with the results; the
// Module can then write its contents as a Breakpad symbol file.

#ifndef COMMON_LINUX_DWARF_CU_TO_MODULE_H__
#define COMMON_LINUX_DWARF_CU_TO_MODULE_H__

#include <string>

#include <elf.h>
#include <link.h>
#include "common/language.h"
#include "common/module.h"
#include "common/dwarf/bytereader.h"
#include "common/dwarf/dwarf2diehandler.h"
#include "common/dwarf/dwarf2reader.h"

namespace google_breakpad {

using dwarf2reader::AttributeList;
using dwarf2reader::DwarfAttribute;
using dwarf2reader::DwarfForm;
using dwarf2reader::DwarfLanguage;
using dwarf2reader::DwarfTag;

// Populate a google_breakpad::Module with DWARF debugging information.
//
// An instance of this class can be provided as a handler to a
// dwarf2reader::CompilationUnit DWARF parser. The handler uses the
// results of parsing to populate a google_breakpad::Module with
// source file, function, and source line information.
class DwarfCUToModule: public dwarf2reader::RootDIEHandler {
  struct FilePrivate;
 public:

  // Information global to the DWARF-bearing file we are processing,
  // for use by DwarfCUToModule. Each DwarfCUToModule instance deals
  // with a single compilation unit within the file, but information
  // global to the whole file is held here. The client is responsible
  // for filling it in appropriately (except for the 'file_private'
  // field, which the constructor and destructor take care of), and
  // then providing it to the DwarfCUToModule instance for each
  // compilation unit we process in that file.
  struct FileContext {
    FileContext(const string &filename_arg, Module *module_arg);
    ~FileContext();

    // The name of this file, for use in error messages.
    string filename;

    // A map of this file's sections, used for finding other DWARF
    // sections that the .debug_info section may refer to.
    dwarf2reader::SectionMap section_map;

    // The Module to which we're contributing definitions.
    Module *module;

    // Inter-compilation unit data used internally by the handlers.
    FilePrivate *file_private;
  };

  // An abstract base class for functors that handle DWARF line data
  // for DwarfCUToModule. DwarfCUToModule could certainly just use
  // dwarf2reader::LineInfo itself directly, but decoupling things
  // this way makes unit testing a little easier.
  class LineToModuleFunctor {
   public:
    LineToModuleFunctor() { }
    virtual ~LineToModuleFunctor() { }

    // Populate MODULE and LINES with source file names and code/line
    // mappings, given a pointer to some DWARF line number data
    // PROGRAM, and an overestimate of its size. Add no zero-length
    // lines to LINES.
    virtual void operator()(const char *program, uint64 length,
                            Module *module, vector<Module::Line> *lines) = 0;
  };

  // The interface DwarfCUToModule uses to report warnings. The member
  // function definitions for this class write messages to stderr, but
  // you can override them if you'd like to detect or report these
  // conditions yourself.
  class WarningReporter {
   public:
    // Warn about problems in the DWARF file FILENAME, in the
    // compilation unit at OFFSET.
    WarningReporter(const string &filename, uint64 cu_offset)
        : filename_(filename), cu_offset_(cu_offset), printed_cu_header_(false),
          printed_unpaired_header_(false),
          uncovered_warnings_enabled_(false) { }
    virtual ~WarningReporter() { }

    // Set the name of the compilation unit we're processing to NAME.
    virtual void SetCUName(const string &name) { cu_name_ = name; }

    // Accessor and setter for uncovered_warnings_enabled_.
    // UncoveredFunction and UncoveredLine only report a problem if that is
    // true. By default, these warnings are disabled, because those
    // conditions occur occasionally in healthy code.
    virtual bool uncovered_warnings_enabled() const {
      return uncovered_warnings_enabled_;
    }
    virtual void set_uncovered_warnings_enabled(bool value) {
      uncovered_warnings_enabled_ = value;
    }

    // A DW_AT_specification in the DIE at OFFSET refers to a DIE we
    // haven't processed yet, or that wasn't marked as a declaration,
    // at TARGET.
    virtual void UnknownSpecification(uint64 offset, uint64 target);

    // A DW_AT_abstract_origin in the DIE at OFFSET refers to a DIE we
    // haven't processed yet, or that wasn't marked as inline, at TARGET.
    virtual void UnknownAbstractOrigin(uint64 offset, uint64 target);

    // We were unable to find the DWARF section named SECTION_NAME.
    virtual void MissingSection(const string &section_name);

    // The CU's DW_AT_stmt_list offset OFFSET is bogus.
    virtual void BadLineInfoOffset(uint64 offset);

    // FUNCTION includes code covered by no line number data.
    virtual void UncoveredFunction(const Module::Function &function);

    // Line number NUMBER in LINE_FILE, of length LENGTH, includes code
    // covered by no function.
    virtual void UncoveredLine(const Module::Line &line);

   protected:
    string filename_;
    uint64 cu_offset_;
    string cu_name_;
    bool printed_cu_header_;
    bool printed_unpaired_header_;
    bool uncovered_warnings_enabled_;

   private:
    // Print a per-CU heading, once.
    void CUHeading();
    // Print an unpaired function/line heading, once.
    void UncoveredHeading();
  };

  // Create a DWARF debugging info handler for a compilation unit
  // within FILE_CONTEXT. This uses information received from the
  // dwarf2reader::CompilationUnit DWARF parser to populate
  // FILE_CONTEXT->module. Use LINE_READER to handle the compilation
  // unit's line number data. Use REPORTER to report problems with the
  // data we find.
  DwarfCUToModule(FileContext *file_context,
                  LineToModuleFunctor *line_reader,
                  WarningReporter *reporter);
  ~DwarfCUToModule();

  void ProcessAttributeSigned(enum DwarfAttribute attr,
                              enum DwarfForm form,
                              int64 data);
  void ProcessAttributeUnsigned(enum DwarfAttribute attr,
                                enum DwarfForm form,
                                uint64 data);
  void ProcessAttributeString(enum DwarfAttribute attr,
                              enum DwarfForm form,
                              const string &data);
  bool EndAttributes();
  DIEHandler *FindChildHandler(uint64 offset, enum DwarfTag tag,
                               const AttributeList &attrs);

  // Assign all our source Lines to the Functions that cover their
  // addresses, and then add them to module_.
  void Finish();

  bool StartCompilationUnit(uint64 offset, uint8 address_size,
                            uint8 offset_size, uint64 cu_length,
                            uint8 dwarf_version);
  bool StartRootDIE(uint64 offset, enum DwarfTag tag,
                    const AttributeList& attrs);

 private:

  // Used internally by the handler. Full definitions are in
  // dwarf_cu_to_module.cc.
  struct FilePrivate;
  struct Specification;
  struct CUContext;
  struct DIEContext;
  class GenericDIEHandler;
  class FuncHandler;
  class NamedScopeHandler;

  // A map from section offsets to specifications.
  typedef map<uint64, Specification> SpecificationByOffset;

  // Set this compilation unit's source language to LANGUAGE.
  void SetLanguage(DwarfLanguage language);
  
  // Read source line information at OFFSET in the .debug_line
  // section.  Record source files in module_, but record source lines
  // in lines_; we apportion them to functions in
  // AssignLinesToFunctions.
  void ReadSourceLines(uint64 offset);

  // Assign the lines in lines_ to the individual line lists of the
  // functions in functions_.  (DWARF line information maps an entire
  // compilation unit at a time, and gives no indication of which
  // lines belong to which functions, beyond their addresses.)
  void AssignLinesToFunctions();

  // The only reason cu_context_ and child_context_ are pointers is
  // that we want to keep their definitions private to
  // dwarf_cu_to_module.cc, instead of listing them all here. They are
  // owned by this DwarfCUToModule: the constructor sets them, and the
  // destructor deletes them.

  // The functor to use to handle line number data.
  LineToModuleFunctor *line_reader_;

  // This compilation unit's context.
  CUContext *cu_context_;

  // A context for our children.
  DIEContext *child_context_;

  // True if this compilation unit has source line information.
  bool has_source_line_info_;

  // The offset of this compilation unit's line number information in
  // the .debug_line section.
  uint64 source_line_offset_;

  // The line numbers we have seen thus far.  We accumulate these here
  // during parsing.  Then, in Finish, we call AssignLinesToFunctions
  // to dole them out to the appropriate functions.
  vector<Module::Line> lines_;
};

} // namespace google_breakpad

#endif  // COMMON_LINUX_DWARF_CU_TO_MODULE_H__