A simple minidump writer for postmortem stability reports.

components/browser_watcher/postmortem_minidump_writer_win.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// Note: aside from using windows headers to obtain the definitions of minidump
+//     structures, nothing here is windows specific. This seems like the best
+//     approach given this code is for temporary experimentation on Windows.
+//     Longer term, Crashpad will take over the minidump writing in this case as
+//     well.
+
+#include "components/browser_watcher/postmortem_minidump_writer.h"
+
+#include <windows.h>  // NOLINT
+#include <dbghelp.h>
+
+#include <map>
+#include <type_traits>
+#include <vector>
+
+#include "base/files/file_util.h"
+#include "base/macros.h"
+#include "base/numerics/safe_math.h"
+#include "base/strings/string_piece.h"
+#include "third_party/crashpad/crashpad/minidump/minidump_extensions.h"
+
+namespace browser_watcher {
+
+namespace {
+
+// The stream type assigned to the minidump stream that holds the serialized
+// stability report.
+// Note: the value was obtained by adding 1 to the stream type used for holding
+// the SyzyAsan proto.
+// TODO(manzagop): centralize the stream type definitions to avoid issues.
+const uint32_t kStabilityReportStreamType = 0x4B6B0002;
+
+int64_t GetFileOffset(base::File* file) {
+  DCHECK(file);
+  return file->Seek(base::File::FROM_CURRENT, 0LL);
+}
+
+// Returns true if the file is empty, and false if the file is not empty or if
+// there is an error.
+bool IsFileEmpty(base::File* file) {
+  DCHECK(file);
+  int64_t end = file->Seek(base::File::FROM_END, 0LL);

[Sigurður Ásgeirsson, 2016/09/14 15:11:48]

nit: this is GetFileOffset?

[manzagop (departed), 2016/09/14 15:43:49]

No because we seek relative to the end instead of the current location. 
This made me notice a signed/unsigned mismatch though.

+  return end == 0ULL;
+}
+
+// A class with functionality for writing minimal minidump containers to wrap
+// postmortem stability reports.
+// TODO(manzagop): remove this class once Crashpad takes over writing postmortem
+//     minidumps.
+// TODO(manzagop): revisit where the module information should be transported,
+//     in the protocol buffer or in a module stream.
+class PostmortemMinidumpWriter {
+ public:
+  PostmortemMinidumpWriter();
+  ~PostmortemMinidumpWriter() = default;

[Sigurður Ásgeirsson, 2016/09/14 15:11:48]

nit: DCHECK_EQ(nullptr, minidump_file_) in destructor?

[manzagop (departed), 2016/09/14 15:43:49]

Done.

+
+  // Write to |minidump_file| a minimal minidump that wraps |report|. Returns
+  // true on success, false otherwise.
+  // Note: the caller owns |minidump_file| and is responsible for keeping it
+  // valid for this object's lifetime. |minidump_file| is expected to be empty
+  // and a binary stream.
+  bool WriteDump(base::PlatformFile minidump_file,
+                 const StabilityReport& report,
+                 const MinidumpInfo& minidump_info);
+
+ private:
+  // An offset within a minidump file. Note: using this type to avoid including
+  // windows.h and relying on the RVA type.
+  using FilePosition = uint32_t;
+
+  // The minidump header is always located at the head.
+  static const FilePosition kHeaderPos = 0U;
+
+  bool WriteDumpImpl(const StabilityReport& report,
+                     const MinidumpInfo& minidump_info);
+
+  bool AppendCrashpadInfo(const crashpad::UUID& client_id,
+                          const crashpad::UUID& report_id,
+                          const std::map<std::string, std::string>& crash_keys);
+
+  bool AppendCrashpadDictionaryEntry(
+      const std::string& key,
+      const std::string& value,
+      std::vector<crashpad::MinidumpSimpleStringDictionaryEntry>* entries);
+
+  // Allocate |size_bytes| within the minidump. On success, |pos| contains the
+  // location of the allocation. Returns true on success, false otherwise.
+  bool Allocate(size_t size_bytes, FilePosition* pos);
+
+  // Seeks |cursor_|. The seek operation is kept separate from the write in
+  // order to make the call explicit. Seek operations can be costly and should
+  // be avoided.
+  bool SeekCursor(FilePosition destination);
+
+  // Write to pre-allocated space.
+  // Note: |pos| must match |cursor_|.
+  template <class DataType>
+  bool Write(FilePosition pos, const DataType& data);
+  bool WriteBytes(FilePosition pos, size_t size_bytes, const char* data);
+
+  // Allocate space for and write the contents of |data|. On success, |pos|
+  // contains the location of the write. Returns true on success, false
+  // otherwise.
+  template <class DataType>
+  bool Append(const DataType& data, FilePosition* pos);
+  template <class DataType>
+  bool AppendVec(const std::vector<DataType>& data, FilePosition* pos);
+  bool AppendUtf8String(base::StringPiece data, FilePosition* pos);
+  bool AppendBytes(base::StringPiece data, FilePosition* pos);
+
+  void RegisterDirectoryEntry(uint32_t stream_type,
+                              FilePosition pos,
+                              uint32_t size);
+
+  // The next allocatable FilePosition.
+  FilePosition next_available_byte_;
+
+  // Storage for the directory during writes.
+  std::vector<MINIDUMP_DIRECTORY> directory_;
+
+  // The file to write to. Only valid within the scope of a call to WriteDump.
+  base::File* minidump_file_;
+
+  DISALLOW_COPY_AND_ASSIGN(PostmortemMinidumpWriter);
+};
+
+PostmortemMinidumpWriter::PostmortemMinidumpWriter()
+    : next_available_byte_(0U), minidump_file_(nullptr) {}
+
+bool PostmortemMinidumpWriter::WriteDump(
+    base::PlatformFile minidump_platform_file,
+    const StabilityReport& report,
+    const MinidumpInfo& minidump_info) {
+  DCHECK_NE(base::kInvalidPlatformFile, minidump_platform_file);
+
+  DCHECK_EQ(0U, next_available_byte_);
+  DCHECK(directory_.empty());
+  DCHECK_EQ(nullptr, minidump_file_);
+
+  // We do not own |minidump_platform_file|, but we want to rely on base::File's
+  // API, and so we need to duplicate it.
+  HANDLE duplicated_handle;
+  BOOL duplicate_success = ::DuplicateHandle(
+      ::GetCurrentProcess(), minidump_platform_file, ::GetCurrentProcess(),
+      &duplicated_handle, 0, FALSE, DUPLICATE_SAME_ACCESS);
+  if (!duplicate_success)
+    return false;
+  base::File minidump_file(duplicated_handle);
+  DCHECK(minidump_file.IsValid());
+  minidump_file_ = &minidump_file;
+  DCHECK_EQ(0LL, GetFileOffset(minidump_file_));
+  DCHECK(IsFileEmpty(minidump_file_));
+
+  // Write the minidump, then reset members.
+  bool success = WriteDumpImpl(report, minidump_info);
+  next_available_byte_ = 0U;
+  directory_.clear();
+  minidump_file_ = nullptr;
+
+  return success;
+}
+
+bool PostmortemMinidumpWriter::WriteDumpImpl(
+    const StabilityReport& report,
+    const MinidumpInfo& minidump_info) {
+  // Allocate space for the header and seek the cursor.
+  FilePosition pos = 0U;
+  if (!Allocate(sizeof(MINIDUMP_HEADER), &pos))
+    return false;
+  if (!SeekCursor(sizeof(MINIDUMP_HEADER)))
+    return false;
+  DCHECK_EQ(kHeaderPos, pos);
+
+  // Write the proto to the file.
+  std::string serialized_report;
+  if (!report.SerializeToString(&serialized_report))
+    return false;
+  FilePosition report_pos = 0U;
+  if (!AppendBytes(serialized_report, &report_pos))
+    return false;
+
+  // The directory entry for the stability report's stream.
+  RegisterDirectoryEntry(kStabilityReportStreamType, report_pos,
+                         serialized_report.length());
+
+  // Write mandatory crash keys. These will be read by crashpad and used as
+  // http request parameters for the upload. Keys and values should match
+  // server side configuration.
+  // TODO(manzagop): use product and version from the stability report. The
+  // current executable's values are an (imperfect) proxy.
+  std::map<std::string, std::string> crash_keys = {
+      {"product", minidump_info.product_name + "_Postmortem"},
+      {"version", minidump_info.version_number}};
+  if (!AppendCrashpadInfo(minidump_info.client_id, minidump_info.report_id,
+                          crash_keys))
+    return false;
+
+  // Write the directory.
+  FilePosition directory_pos = 0U;
+  if (!AppendVec(directory_, &directory_pos))
+    return false;
+
+  // Write the header.
+  MINIDUMP_HEADER header;
+  header.Signature = MINIDUMP_SIGNATURE;
+  header.Version = MINIDUMP_VERSION;
+  header.NumberOfStreams = directory_.size();
+  header.StreamDirectoryRva = directory_pos;
+  if (!SeekCursor(0U))
+    return false;
+  return Write(kHeaderPos, header);
+}
+
+bool PostmortemMinidumpWriter::AppendCrashpadInfo(
+    const crashpad::UUID& client_id,
+    const crashpad::UUID& report_id,
+    const std::map<std::string, std::string>& crash_keys) {
+  // Write the crash keys as the contents of a crashpad dictionary.
+  std::vector<crashpad::MinidumpSimpleStringDictionaryEntry> entries;
+  for (const auto& crash_key : crash_keys) {
+    if (!AppendCrashpadDictionaryEntry(crash_key.first, crash_key.second,
+                                       &entries)) {
+      return false;
+    }
+  }
+
+  // Write the dictionary's index.
+  FilePosition dict_pos = 0U;
+  uint32_t entry_count = entries.size();
+  if (entry_count > 0) {
+    if (!Append(entry_count, &dict_pos))
+      return false;
+    FilePosition unused_pos = 0U;
+    if (!AppendVec(entries, &unused_pos))
+      return false;
+  }
+
+  MINIDUMP_LOCATION_DESCRIPTOR simple_annotations = {0};
+  simple_annotations.DataSize = 0U;
+  if (entry_count > 0)
+    simple_annotations.DataSize = next_available_byte_ - dict_pos;
+  // Note: an RVA of 0 indicates the absence of a dictionary.
+  simple_annotations.Rva = dict_pos;
+
+  // Write the crashpad info.
+  crashpad::MinidumpCrashpadInfo crashpad_info;
+  crashpad_info.version = crashpad::MinidumpCrashpadInfo::kVersion;
+  crashpad_info.report_id = report_id;
+  crashpad_info.client_id = client_id;
+  crashpad_info.simple_annotations = simple_annotations;
+  // Note: module_list is left at 0, which means none.
+
+  FilePosition crashpad_pos = 0U;
+  if (!Append(crashpad_info, &crashpad_pos))
+    return false;
+
+  // Append a directory entry for the crashpad info stream.
+  RegisterDirectoryEntry(crashpad::kMinidumpStreamTypeCrashpadInfo,
+                         crashpad_pos, sizeof(crashpad::MinidumpCrashpadInfo));
+
+  return true;
+}
+
+bool PostmortemMinidumpWriter::AppendCrashpadDictionaryEntry(
+    const std::string& key,
+    const std::string& value,
+    std::vector<crashpad::MinidumpSimpleStringDictionaryEntry>* entries) {
+  DCHECK_NE(nullptr, entries);
+
+  FilePosition key_pos = 0U;
+  if (!AppendUtf8String(key, &key_pos))
+    return false;
+  FilePosition value_pos = 0U;
+  if (!AppendUtf8String(value, &value_pos))
+    return false;
+
+  crashpad::MinidumpSimpleStringDictionaryEntry entry = {0};
+  entry.key = key_pos;
+  entry.value = value_pos;
+  entries->push_back(entry);
+
+  return true;
+}
+
+bool PostmortemMinidumpWriter::Allocate(size_t size_bytes, FilePosition* pos) {
+  DCHECK(pos);
+  *pos = next_available_byte_;
+
+  base::CheckedNumeric<FilePosition> next = next_available_byte_;
+  next += size_bytes;
+  if (!next.IsValid())
+    return false;
+
+  next_available_byte_ += size_bytes;
+  return true;
+}
+
+bool PostmortemMinidumpWriter::SeekCursor(FilePosition destination) {
+  DCHECK_NE(nullptr, minidump_file_);
+  DCHECK(minidump_file_->IsValid());
+
+  // Validate the write does not extend past the allocated space.
+  if (destination > next_available_byte_)
+    return false;
+
+  int64_t new_pos = minidump_file_->Seek(base::File::FROM_BEGIN,
+                                         static_cast<int64_t>(destination));
+  return new_pos != -1;
+}
+
+template <class DataType>
+bool PostmortemMinidumpWriter::Write(FilePosition pos, const DataType& data) {
+  static_assert(std::is_trivially_copyable<DataType>::value,
+                "restricted to trivially copyable");
+  return WriteBytes(pos, sizeof(data), reinterpret_cast<const char*>(&data));
+}
+
+bool PostmortemMinidumpWriter::WriteBytes(FilePosition pos,
+                                          size_t size_bytes,
+                                          const char* data) {
+  DCHECK(data);
+  DCHECK_NE(nullptr, minidump_file_);
+  DCHECK(minidump_file_->IsValid());
+  DCHECK_EQ(static_cast<int64_t>(pos), GetFileOffset(minidump_file_));
+
+  // Validate the write does not extend past the next available byte.
+  base::CheckedNumeric<FilePosition> pos_end = pos;
+  pos_end += size_bytes;
+  if (!pos_end.IsValid() || pos_end.ValueOrDie() > next_available_byte_)
+    return false;
+
+  int size_bytes_signed = static_cast<int>(size_bytes);
+  CHECK_LE(0, size_bytes_signed);
+
+  int written_bytes =
+      minidump_file_->WriteAtCurrentPos(data, size_bytes_signed);
+  if (written_bytes < 0)
+    return false;
+  return static_cast<size_t>(written_bytes) == size_bytes;
+}
+
+template <class DataType>
+bool PostmortemMinidumpWriter::Append(const DataType& data, FilePosition* pos) {
+  static_assert(std::is_trivially_copyable<DataType>::value,
+                "restricted to trivially copyable");
+  DCHECK(pos);
+  if (!Allocate(sizeof(data), pos))
+    return false;
+  return Write(*pos, data);
+}
+
+template <class DataType>
+bool PostmortemMinidumpWriter::AppendVec(const std::vector<DataType>& data,
+                                         FilePosition* pos) {
+  static_assert(std::is_trivially_copyable<DataType>::value,
+                "restricted to trivially copyable");
+  DCHECK(!data.empty());
+  DCHECK(pos);
+
+  size_t size_bytes = sizeof(DataType) * data.size();
+  if (!Allocate(size_bytes, pos))
+    return false;
+  return WriteBytes(*pos, size_bytes,
+                    reinterpret_cast<const char*>(&data.at(0)));
+}
+
+bool PostmortemMinidumpWriter::AppendUtf8String(base::StringPiece data,
+                                                FilePosition* pos) {
+  DCHECK(pos);
+  uint32_t string_size = data.size();
+  if (!Append(string_size, pos))
+    return false;
+
+  FilePosition unused_pos = 0U;
+  return AppendBytes(data, &unused_pos);
+}
+
+bool PostmortemMinidumpWriter::AppendBytes(base::StringPiece data,
+                                           FilePosition* pos) {
+  DCHECK(pos);
+  if (!Allocate(data.length(), pos))
+    return false;
+  return WriteBytes(*pos, data.length(), data.data());
+}
+
+void PostmortemMinidumpWriter::RegisterDirectoryEntry(uint32_t stream_type,
+                                                      FilePosition pos,
+                                                      uint32_t size) {
+  MINIDUMP_DIRECTORY entry = {0};
+  entry.StreamType = stream_type;
+  entry.Location.Rva = pos;
+  entry.Location.DataSize = size;
+  directory_.push_back(entry);
+}
+
+}  // namespace
+
+bool WritePostmortemDump(base::PlatformFile minidump_file,
+                         const StabilityReport& report,
+                         const MinidumpInfo& minidump_info) {
+  PostmortemMinidumpWriter writer;
+  return writer.WriteDump(minidump_file, report, minidump_info);
+}
+
+}  // namespace browser_watcher