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.
//     * 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.
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//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// 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,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>

// module.h: Define google_breakpad::Module. A Module holds debugging
// information, and can write that information out as a Breakpad
// symbol file.

#ifndef COMMON_LINUX_MODULE_H__
#define COMMON_LINUX_MODULE_H__

#include <iostream>
#include <map>
#include <set>
#include <string>
#include <vector>

#include "common/symbol_data.h"
#include "common/using_std_string.h"
#include "google_breakpad/common/breakpad_types.h"

namespace google_breakpad {

using std::set;
using std::vector;
using std::map;

// A Module represents the contents of a module, and supports methods
// for adding information produced by parsing STABS or DWARF data
// --- possibly both from the same file --- and then writing out the
// unified contents as a Breakpad-format symbol file.
class Module {
 public:
  // The type of addresses and sizes in a symbol table.
  typedef uint64_t Address;
  struct File;
  struct Function;
  struct Line;
  struct Extern;

  // Addresses appearing in File, Function, and Line structures are
  // absolute, not relative to the the module's load address.  That
  // is, if the module were loaded at its nominal load address, the
  // addresses would be correct.

  // A source file.
  struct File {
    explicit File(const string &name_input) : name(name_input), source_id(0) {}

    // The name of the source file.
    const string name;

    // The file's source id.  The Write member function clears this
    // field and assigns source ids a fresh, so any value placed here
    // before calling Write will be lost.
    int source_id;
  };

  // A function.
  struct Function {
    Function(const string &name_input, const Address &address_input) :
        name(name_input), address(address_input), size(0), parameter_size(0) {}

    // For sorting by address.  (Not style-guide compliant, but it's
    // stupid not to put this in the struct.)
    static bool CompareByAddress(const Function *x, const Function *y) {
      return x->address < y->address;
    }

    // The function's name.
    const string name;

    // The start address and length of the function's code.
    const Address address;
    Address size;

    // The function's parameter size.
    Address parameter_size;

    // Source lines belonging to this function, sorted by increasing
    // address.
    vector<Line> lines;
  };

  // A source line.
  struct Line {
    // For sorting by address.  (Not style-guide compliant, but it's
    // stupid not to put this in the struct.)
    static bool CompareByAddress(const Module::Line &x, const Module::Line &y) {
      return x.address < y.address;
    }

    Address address, size;    // The address and size of the line's code.
    File *file;                // The source file.
    int number;                // The source line number.
  };

  // An exported symbol.
  struct Extern {
    explicit Extern(const Address &address_input) : address(address_input) {}
    const Address address;
    string name;
  };

  // A map from register names to postfix expressions that recover
  // their their values. This can represent a complete set of rules to
  // follow at some address, or a set of changes to be applied to an
  // extant set of rules.
  typedef map<string, string> RuleMap;

  // A map from addresses to RuleMaps, representing changes that take
  // effect at given addresses.
  typedef map<Address, RuleMap> RuleChangeMap;

  // A range of 'STACK CFI' stack walking information. An instance of
  // this structure corresponds to a 'STACK CFI INIT' record and the
  // subsequent 'STACK CFI' records that fall within its range.
  struct StackFrameEntry {
    // The starting address and number of bytes of machine code this
    // entry covers.
    Address address, size;

    // The initial register recovery rules, in force at the starting
    // address.
    RuleMap initial_rules;

    // A map from addresses to rule changes. To find the rules in
    // force at a given address, start with initial_rules, and then
    // apply the changes given in this map for all addresses up to and
    // including the address you're interested in.
    RuleChangeMap rule_changes;
  };

  struct FunctionCompare {
    bool operator() (const Function *lhs,
                     const Function *rhs) const {
      if (lhs->address == rhs->address)
        return lhs->name < rhs->name;
      return lhs->address < rhs->address;
    }
  };

  struct ExternCompare {
    bool operator() (const Extern *lhs,
                     const Extern *rhs) const {
      return lhs->address < rhs->address;
    }
  };

  // Create a new module with the given name, operating system,
  // architecture, and ID string.
  Module(const string &name, const string &os, const string &architecture,
         const string &id, const string &code_id = "");
  ~Module();

  // Set the module's load address to LOAD_ADDRESS; addresses given
  // for functions and lines will be written to the Breakpad symbol
  // file as offsets from this address.  Construction initializes this
  // module's load address to zero: addresses written to the symbol
  // file will be the same as they appear in the Function, Line, and
  // StackFrameEntry structures.
  //
  // Note that this member function has no effect on addresses stored
  // in the data added to this module; the Write member function
  // simply subtracts off the load address from addresses before it
  // prints them. Only the last load address given before calling
  // Write is used.
  void SetLoadAddress(Address load_address);

  // Add FUNCTION to the module. FUNCTION's name must not be empty.
  // This module owns all Function objects added with this function:
  // destroying the module destroys them as well.
  void AddFunction(Function *function);

  // Add all the functions in [BEGIN,END) to the module.
  // This module owns all Function objects added with this function:
  // destroying the module destroys them as well.
  void AddFunctions(vector<Function *>::iterator begin,
                    vector<Function *>::iterator end);

  // Add STACK_FRAME_ENTRY to the module.
  // This module owns all StackFrameEntry objects added with this
  // function: destroying the module destroys them as well.
  void AddStackFrameEntry(StackFrameEntry *stack_frame_entry);

  // Add PUBLIC to the module.
  // This module owns all Extern objects added with this function:
  // destroying the module destroys them as well.
  void AddExtern(Extern *ext);

  // If this module has a file named NAME, return a pointer to it. If
  // it has none, then create one and return a pointer to the new
  // file. This module owns all File objects created using these
  // functions; destroying the module destroys them as well.
  File *FindFile(const string &name);
  File *FindFile(const char *name);

  // If this module has a file named NAME, return a pointer to it.
  // Otherwise, return NULL.
  File *FindExistingFile(const string &name);

  // Insert pointers to the functions added to this module at I in
  // VEC. The pointed-to Functions are still owned by this module.
  // (Since this is effectively a copy of the function list, this is
  // mostly useful for testing; other uses should probably get a more
  // appropriate interface.)
  void GetFunctions(vector<Function *> *vec, vector<Function *>::iterator i);

  // Insert pointers to the externs added to this module at I in
  // VEC. The pointed-to Externs are still owned by this module.
  // (Since this is effectively a copy of the extern list, this is
  // mostly useful for testing; other uses should probably get a more
  // appropriate interface.)
  void GetExterns(vector<Extern *> *vec, vector<Extern *>::iterator i);

  // Clear VEC and fill it with pointers to the Files added to this
  // module, sorted by name. The pointed-to Files are still owned by
  // this module. (Since this is effectively a copy of the file list,
  // this is mostly useful for testing; other uses should probably get
  // a more appropriate interface.)
  void GetFiles(vector<File *> *vec);

  // Clear VEC and fill it with pointers to the StackFrameEntry
  // objects that have been added to this module. (Since this is
  // effectively a copy of the stack frame entry list, this is mostly
  // useful for testing; other uses should probably get
  // a more appropriate interface.)
  void GetStackFrameEntries(vector<StackFrameEntry *> *vec) const;

  // Find those files in this module that are actually referred to by
  // functions' line number data, and assign them source id numbers.
  // Set the source id numbers for all other files --- unused by the
  // source line data --- to -1.  We do this before writing out the
  // symbol file, at which point we omit any unused files.
  void AssignSourceIds();

  // Call AssignSourceIds, and write this module to STREAM in the
  // breakpad symbol format. Return true if all goes well, or false if
  // an error occurs. This method writes out:
  // - a header based on the values given to the constructor,
  // If symbol_data is not ONLY_CFI then:
  // - the source files added via FindFile,
  // - the functions added via AddFunctions, each with its lines,
  // - all public records,
  // If symbol_data is not NO_CFI then:
  // - all CFI records.
  // Addresses in the output are all relative to the load address
  // established by SetLoadAddress.
  bool Write(std::ostream &stream, SymbolData symbol_data);

  string name() const { return name_; }
  string os() const { return os_; }
  string architecture() const { return architecture_; }
  string identifier() const { return id_; }
  string code_identifier() const { return code_id_; }

 private:
  // Report an error that has occurred writing the symbol file, using
  // errno to find the appropriate cause.  Return false.
  static bool ReportError();

  // Write RULE_MAP to STREAM, in the form appropriate for 'STACK CFI'
  // records, without a final newline. Return true if all goes well;
  // if an error occurs, return false, and leave errno set.
  static bool WriteRuleMap(const RuleMap &rule_map, std::ostream &stream);

  // Module header entries.
  string name_, os_, architecture_, id_, code_id_;

  // The module's nominal load address.  Addresses for functions and
  // lines are absolute, assuming the module is loaded at this
  // address.
  Address load_address_;

  // Relation for maps whose keys are strings shared with some other
  // structure.
  struct CompareStringPtrs {
    bool operator()(const string *x, const string *y) const { return *x < *y; }
  };

  // A map from filenames to File structures.  The map's keys are
  // pointers to the Files' names.
  typedef map<const string *, File *, CompareStringPtrs> FileByNameMap;

  // A set containing Function structures, sorted by address.
  typedef set<Function *, FunctionCompare> FunctionSet;

  // A set containing Extern structures, sorted by address.
  typedef set<Extern *, ExternCompare> ExternSet;

  // The module owns all the files and functions that have been added
  // to it; destroying the module frees the Files and Functions these
  // point to.
  FileByNameMap files_;    // This module's source files.
  FunctionSet functions_;  // This module's functions.

  // The module owns all the call frame info entries that have been
  // added to it.
  vector<StackFrameEntry *> stack_frame_entries_;

  // The module owns all the externs that have been added to it;
  // destroying the module frees the Externs these point to.
  ExternSet externs_;
};

}  // namespace google_breakpad

#endif  // COMMON_LINUX_MODULE_H__