path: root/src/processor/synth_minidump.h

// -*- mode: C++ -*-

// Copyright (c) 2010, Google Inc.
// All rights reserved.
//
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// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>

// synth_minidump.h: Interface to SynthMinidump: fake minidump generator.
//
// We treat a minidump file as the concatenation of a bunch of
// TestAssembler::Sections. The file header, stream directory,
// streams, memory regions, strings, and so on --- each is a Section
// that eventually gets appended to the minidump. Dump, Memory,
// Context, Thread, and so on all inherit from TestAssembler::Section.
// For example:
//
//    using google_breakpad::TestAssembler::kLittleEndian;
//    using google_breakpad::SynthMinidump::Context;
//    using google_breakpad::SynthMinidump::Dump;
//    using google_breakpad::SynthMinidump::Memory;
//    using google_breakpad::SynthMinidump::Thread;
//    
//    Dump minidump(MD_NORMAL, kLittleEndian);
//    
//    Memory stack1(minidump, 0x569eb0a9);
//    ... build contents of stack1 with TestAssembler::Section functions ...
//    
//    MDRawContextX86 x86_context1;
//    x86_context1.context_flags = MD_CONTEXT_X86;
//    x86_context1.eip = 0x7c90eb94;
//    x86_context1.esp = 0x569eb0a9;
//    x86_context1.ebp = x86_context1.esp + something appropriate;
//    Context context1(minidump, x86_context1);
//    
//    Thread thread1(minidump, 0xe4a4821d, stack1, context1);
//    
//    minidump.Add(&stack1);
//    minidump.Add(&context1);
//    minidump.Add(&thread1);
//    minidump.Finish();
//    
//    string contents;
//    EXPECT_TRUE(minidump.GetContents(&contents));
//    // contents now holds the bytes of a minidump file
//
// Because the TestAssembler classes let us write Label references to
// sections before the Labels' values are known, this gives us
// flexibility in how we put the dump together: minidump pieces can
// hold the file offsets of other minidump pieces before the
// referents' positions have been decided. As long as everything has
// been placed by the time we call dump.GetContents to obtain the
// bytes, all the Labels' values will be known, and everything will
// get patched up appropriately.
//   
// The dump.Add(thing) functions append THINGS's contents to the
// minidump, but they also do two other things:
//
// - dump.Add(thing) invokes thing->Finish, which tells *thing the
//   offset within the file at which it was placed, and allows *thing
//   to do any final content generation.
//
// - If THING is something which should receive an entry in some sort
//   of list or directory, then dump.Add(THING) automatically creates
//   the appropriate directory or list entry. Streams must appear in
//   the stream directory; memory ranges should be listed in the
//   memory list; threads should be placed in the thread list; and so
//   on.
//
// By convention, Section subclass constructors that take references
// to other Sections do not take care of 'Add'ing their arguments to
// the dump. For example, although the Thread constructor takes
// references to a Memory and a Context, it does not add them to the
// dump on the caller's behalf. Rather, the caller is responsible for
// 'Add'ing every section they create. This allows Sections to be
// cited from more than one place; for example, Memory ranges are
// cited both from Thread objects (as their stack contents) and by the
// memory list stream.
//
// If you forget to Add some Section, the Dump::GetContents call will
// fail, as the TestAssembler::Labels used to cite the Section's
// contents from elsewhere will still be undefined.
#ifndef PROCESSOR_SYNTH_MINIDUMP_H_
#define PROCESSOR_SYNTH_MINIDUMP_H_

#include <cassert>
#include <iostream>
#include <string>

#include "common/test_assembler.h"
#include "google_breakpad/common/breakpad_types.h"
#include "google_breakpad/common/minidump_format.h"

namespace google_breakpad {

namespace SynthMinidump {

using std::string;
using TestAssembler::Endianness;
using TestAssembler::kBigEndian;
using TestAssembler::kLittleEndian;
using TestAssembler::kUnsetEndian;
using TestAssembler::Label;

class Dump;
class Memory;
class String;

// A TestAssembler::Section which will be appended to a minidump.
class Section: public TestAssembler::Section {
 public:
  explicit Section(const Dump &dump);

  // Append an MDLocationDescriptor referring to this section to SECTION.
  // If 'this' is NULL, append a descriptor with a zero length and MDRVA.
  //
  // (I couldn't find the language in the C++ standard that says that
  // invoking member functions of a NULL pointer to a class type is
  // bad, if such language exists. Having this function handle NULL
  // 'this' is convenient, but if it causes trouble, it's not hard to
  // do differently.)
  void CiteLocationIn(TestAssembler::Section *section) const;

  // Note that this section's contents are complete, and that it has
  // been placed in the minidump file at OFFSET. The 'Add' member
  // functions call the Finish member function of the object being
  // added for you; if you are 'Add'ing this section, you needn't Finish it.
  virtual void Finish(const Label &offset) { 
    file_offset_ = offset; size_ = Size();
  }

 protected:
  // This section's size and offset within the minidump file.
  Label file_offset_, size_;
};

// A stream within a minidump file. 'Add'ing a stream to a minidump
// creates an entry for it in the minidump's stream directory.
class Stream: public Section {
 public:
  // Create a stream of type TYPE.  You can append whatever contents
  // you like to this stream using the TestAssembler::Section methods.
  Stream(const Dump &dump, u_int32_t type) : Section(dump), type_(type) { }

  // Append an MDRawDirectory referring to this stream to SECTION.
  void CiteStreamIn(TestAssembler::Section *section) const;

 private:
  // The type of this stream.
  u_int32_t type_;
};

class SystemInfo: public Stream {
 public:
  // Create an MD_SYSTEM_INFO_STREAM stream belonging to DUMP holding
  // an MDRawSystem info structure initialized with the values from
  // SYSTEM_INFO, except that the csd_version field is replaced with
  // the file offset of the string CSD_VERSION, which can be 'Add'ed
  // to the dump at the desired location.
  // 
  // Remember that you are still responsible for 'Add'ing CSD_VERSION
  // to the dump yourself.
  SystemInfo(const Dump &dump,
             const MDRawSystemInfo &system_info,
             const String &csd_version);

  // Stock MDRawSystemInfo information and associated strings, for
  // writing tests.
  static const MDRawSystemInfo windows_x86;
  static const string windows_x86_csd_version;
};

// An MDString: a string predeced by a 32-bit length.
class String: public Section {
 public:
  String(const Dump &dump, const string &value);

  // Append an MDRVA referring to this string to SECTION.
  void CiteStringIn(TestAssembler::Section *section) const;
};

// A range of memory contents. 'Add'ing a memory range to a minidump
// creates n entry for it in the minidump's memory list. By
// convention, the 'start', 'Here', and 'Mark' member functions refer
// to memory addresses.
class Memory: public Section {
 public:
  Memory(const Dump &dump, u_int64_t address)
      : Section(dump), address_(address) { start() = address; }

  // Append an MDMemoryDescriptor referring to this memory range to SECTION.
  void CiteMemoryIn(TestAssembler::Section *section) const;

 private:
  // The process address from which these memory contents were taken.
  // Shouldn't this be a Label?
  u_int64_t address_;
};

class Context: public Section {
 public:
  // Create a context belonging to DUMP whose contents are a copy of CONTEXT.
  Context(const Dump &dump, const MDRawContextX86 &context);
  // Add constructors for other architectures here. Remember to byteswap.
};

class Thread: public Section {
 public:
  // Create a thread belonging to DUMP with the given values, citing
  // STACK and CONTEXT (which you must Add to the dump separately).
  Thread(const Dump &dump,
         u_int32_t thread_id,
         const Memory &stack,
         const Context &context,
         u_int32_t suspend_count = 0,
         u_int32_t priority_class = 0,
         u_int32_t priority = 0,
         u_int64_t teb = 0);
};

class Module: public Section {
 public:
  // Create a module with the given values. Note that CV_RECORD and
  // MISC_RECORD can be NULL, in which case the corresponding location
  // descriptior in the minidump will have a length of zero.
  Module(const Dump &dump,
         u_int64_t base_of_image,
         u_int32_t size_of_image,
         const String &name,
         u_int32_t time_date_stamp = 1262805309,
         u_int32_t checksum = 0,
         const MDVSFixedFileInfo &version_info = Module::stock_version_info,
         const Section *cv_record = NULL,
         const Section *misc_record = NULL);

 private:
  // A standard MDVSFixedFileInfo structure to use as a default for
  // minidumps.  There's no reason to make users write out all this crap
  // over and over.
  static const MDVSFixedFileInfo stock_version_info;
};

// A list of entries starting with a 32-bit count, like a memory list
// or a thread list.
template<typename Element>
class List: public Stream {
 public:
  List(const Dump &dump, u_int32_t type) : Stream(dump, type), count_(0) {
    D32(count_label_);
  }

  // Add ELEMENT to this list.
  void Add(Element *element) {
    element->Finish(file_offset_ + Size());
    Append(*element);
    count_++;
  }

  // Return true if this List is empty, false otherwise.
  bool Empty() { return count_ == 0; }

  // Finish up the contents of this section, mark it as having been
  // placed at OFFSET.
  virtual void Finish(const Label &offset) {
    Stream::Finish(offset);
    count_label_ = count_;
  }

 private:
  size_t count_;
  Label count_label_;
};

class Dump: public TestAssembler::Section {
 public:

  // Create a TestAssembler::Section containing a minidump file whose
  // header uses the given values. ENDIANNESS determines the
  // endianness of the signature; we set this section's default
  // endianness by this.
  Dump(u_int64_t flags,
       Endianness endianness = kLittleEndian,
       u_int32_t version = MD_HEADER_VERSION,
       u_int32_t date_time_stamp = 1262805309);

  // The following functions call OBJECT->Finish(), and append the
  // contents of OBJECT to this minidump. They also record OBJECT in
  // whatever directory or list is appropriate for its type. The
  // stream directory, memory list, thread list, and module list are
  // accumulated this way.
  Dump &Add(SynthMinidump::Section *object); // simply append data
  Dump &Add(Stream *object); // append, record in stream directory
  Dump &Add(Memory *object); // append, record in memory list
  Dump &Add(Thread *object); // append, record in thread list
  Dump &Add(Module *object); // append, record in module list

  // Complete the construction of the minidump, given the Add calls
  // we've seen up to this point. After this call, this Dump's
  // contents are complete, all labels should be defined if everything
  // Cited has been Added, and you may call GetContents on it.
  void Finish();

 private:
  // A label representing the start of the minidump file.
  Label file_start_;

  // The stream directory.  We construct this incrementally from
  // Add(Stream *) calls.
  SynthMinidump::Section stream_directory_; // The directory's contents.
  size_t stream_count_;                 // The number of streams so far.
  Label stream_count_label_;            // Cited in file header.
  Label stream_directory_rva_;          // The directory's file offset.

  // This minidump's thread list. We construct this incrementally from
  // Add(Thread *) calls.
  List<Thread> thread_list_;

  // This minidump's module list. We construct this incrementally from
  // Add(Module *) calls.
  List<Module> module_list_;

  // This minidump's memory list. We construct this incrementally from
  // Add(Memory *) calls. This is actually a list of MDMemoryDescriptors,
  // not memory ranges --- thus the odd type.
  List<SynthMinidump::Section> memory_list_;
};

} // namespace SynthMinidump

} // namespace google_breakpad

#endif  // PROCESSOR_SYNTH_MINIDUMP_H_