Differential updates for components.

chrome/browser/component_updater/component_patcher.cc

+// Copyright (c) 2013 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.
+
+#include "chrome/browser/component_updater/component_patcher.h"
+
+#include <string>
+#include <vector>
+
+#include "base/file_util.h"
+#include "base/files/memory_mapped_file.h"
+#include "base/json/json_file_value_serializer.h"
+#include "base/memory/scoped_handle.h"
+#include "base/path_service.h"
+#include "base/strings/string_number_conversions.h"
+#include "chrome/browser/component_updater/component_patcher_internal.h"
+#include "chrome/browser/component_updater/component_updater_service.h"
+#include "chrome/common/extensions/extension_constants.h"
+#include "crypto/secure_hash.h"
+#include "crypto/sha2.h"
+#include "crypto/signature_verifier.h"
+#include "extensions/common/crx_file.h"
+#include "third_party/zlib/google/zip.h"
+
+using crypto::SecureHash;
+
+namespace {
+
+const char kInput[] = "input";
+const char kOp[] = "op";
+const char kOutput[] = "output";
+const char kPatch[] = "patch";
+const char kSha256[] = "sha256";
+
+DeltaUpdateOp* CreateDeltaUpdateOp(base::DictionaryValue* command) {
+  std::string operation;
+  if (!command->GetString(kOp, &operation))
+    return NULL;
+  if (operation == "copy")
+    return new DeltaUpdateOpCopy();
+  else if (operation == "create")
+    return new DeltaUpdateOpCreate();
+  else if (operation == "bsdiff")
+    return new DeltaUpdateOpPatchBsdiff();
+  else if (operation == "courgette")
+    return new DeltaUpdateOpPatchCourgette();
+  return NULL;
+}
+
+// Deserialize the commands file (present in delta update packages). The top
+// level must be a list.
+base::ListValue* ReadCommands(const base::FilePath& unpack_path) {
+  const base::FilePath commands =
+      unpack_path.Append(FILE_PATH_LITERAL("commands.json"));
+  if (!file_util::PathExists(commands))
+    return NULL;
+  JSONFileValueSerializer serializer(commands);
+  std::string error;

[robertshield, 2013/06/17 17:47:00]

error isn't used, pass NULL to Deserialize instead

[Sorin Jianu, 2013/06/17 22:21:09]

Done.

+  scoped_ptr<base::Value> root(serializer.Deserialize(NULL, &error));
+  if (!root.get())
+    return NULL;
+  if (!root->IsType(base::Value::TYPE_LIST))
+    return NULL;
+  return static_cast<base::ListValue*>(root.release());

[robertshield, 2013/06/17 17:47:00]

Could shorten the last five lines to:

return (root.get() && root->IsType(base::Value::TYPE_LIST)) ?
    static_cast<base::ListValue*>(root.release()) : NULL;

[Sorin Jianu, 2013/06/17 22:21:09]

I prefer to keep it as is instead of the terse expression. Seems easier to read
but I can change it if needed.

[robertshield, 2013/06/18 13:27:07]

How about a compromise:

if (!root.get()) || !root->IsType(base::Value::TYPE_LIST))
  return NULL;
return static_cast<base::ListValue*>(root.release());

The repeated "return NULL;" statements looked odd to me. Or you can leave it as
is, don't really mind :-)

[Sorin Jianu, 2013/06/18 17:00:11]

Thank you Robert. Given the choice, I decided to follow your first suggestion
and used the ?: operator.

+}
+
+}  // namespace.
+
+
+// The patching support is not cross-platform at the moment.
+ComponentPatcherCrossPlatform::ComponentPatcherCrossPlatform() {}
+
+ComponentUnpacker::Error ComponentPatcherCrossPlatform::Patch(
+    PatchType patch_type,
+    const base::FilePath& input_file,
+    const base::FilePath& patch_file,
+    const base::FilePath& output_file,
+    int* error) {
+  return ComponentUnpacker::kDeltaOperationFailure;

[cpu_(ooo_6.6-7.5), 2013/06/14 23:25:28]

return kDeltaOperationUnsuported ?

[waffles, 2013/06/15 00:01:37]

Done; will be in the next patch set.

+}
+
+DeltaUpdateOp::~DeltaUpdateOp() {}
+
+DeltaUpdateOp::DeltaUpdateOp() {}

[robertshield, 2013/06/17 17:47:00]

This is a relatively unconventional file structure for Chrome code. Typically
method definitions for a class defined in foo.h will be found in foo.cc.

This isn't universally true, but is so often enough that it should only be
deviated from if there's a strong reason (per-platform definitions, etc.).

Unless there's a good reason, please move the definitions of the classes
declared in component_patcher_internal.h to component_patcher_internal.cc. Also,
consider naming those files component_patcher_operations.[h|cc].

[Sorin Jianu, 2013/06/18 03:05:14]

Done. Introduced component_patcher_operation.[h|cc]

+
+ComponentUnpacker::Error DeltaUpdateOp::Run(base::DictionaryValue* command_args,
+                                            const base::FilePath& input_dir,
+                                            const base::FilePath& unpack_dir,
+                                            ComponentPatcher* patcher,
+                                            ComponentInstaller* installer,
+                                            int* error) {

[cpu_(ooo_6.6-7.5), 2013/06/17 20:27:01]

After trying to like the int* error (and its friend extended_error_), I was
unable to. I am back to my comment in the initial CL I don't see it adding any
value and yet being present, passed about or assigned zero in almost all the new
code. Cognitive noise if you will. I strongly suggest you go without it on the
first release.

Is the only real place used in the return value of setup.exe?

[Sorin Jianu, 2013/06/17 22:21:09]

The component patcher can give us valuable error information regarding why
deltas can fail, either due to Courgette or bsdiff errors. I know it sux to have
it but at the same time we also want to get a detailed understanding of
patching. Even though in the future we will change the way we run Courgette, we
would still want the errors in the pings. Part of the issue here is that we have
overlapping error ranges, so we use a category and an extended error
information, which is this error which I agree, it is hard to fall in love with
it. 

+  std::string output_rel_path;
+  if (!command_args->GetString(kOutput, &output_rel_path) ||
+      !command_args->GetString(kSha256, &output_sha256_))
+    return ComponentUnpacker::kDeltaBadCommands;
+  output_abs_path_ = unpack_dir.Append(
+      base::FilePath::FromUTF8Unsafe(output_rel_path));
+  ComponentUnpacker::Error parse_result = DoParseArguments(
+      command_args, input_dir, installer);
+  if (parse_result != ComponentUnpacker::kNone)
+    return parse_result;
+
+  const base::FilePath parent = output_abs_path_.DirName();
+  if (!file_util::DirectoryExists(parent)) {
+    if (!file_util::CreateDirectory(parent))
+      return ComponentUnpacker::kIoError;
+  }
+
+  ComponentUnpacker::Error run_result = DoRun(patcher, error);
+  if (run_result != ComponentUnpacker::kNone)
+    return run_result;
+  return CheckHash();
+}
+
+// Uses the hash as a checksum to confirm that the file now residing in the
+// output directory probably has the contents it should.
+ComponentUnpacker::Error DeltaUpdateOp::CheckHash() {
+  std::vector<uint8> expected_hash(0);

[robertshield, 2013/06/17 17:47:00]

remove the (0), it is redundant

[Sorin Jianu, 2013/06/17 22:21:09]

Done.

+  if (!base::HexStringToBytes(output_sha256_, &expected_hash) ||
+      expected_hash.size() != crypto::kSHA256Length)
+    return ComponentUnpacker::kDeltaVerificationFailure;

[robertshield, 2013/06/17 17:47:00]

nit: I find this code a little too dense, and would prefer a blank line after
each return statement (except the last). If you disagree vigorously, let me know
:-)

[Sorin Jianu, 2013/06/17 22:21:09]

Done.

+  uint8 actual_hash[crypto::kSHA256Length] = {0};
+  base::MemoryMappedFile output_file_mmapped;
+  if (!output_file_mmapped.Initialize(output_abs_path_))
+    return ComponentUnpacker::kDeltaVerificationFailure;
+  const scoped_ptr<SecureHash> hasher(SecureHash::Create(SecureHash::SHA256));
+  hasher->Update(output_file_mmapped.data(), output_file_mmapped.length());
+  hasher->Finish(actual_hash, sizeof(actual_hash));
+  if (memcmp(actual_hash, &expected_hash[0], crypto::kSHA256Length))

[robertshield, 2013/06/17 17:47:00]

crypto::kSHA256Length -> arraysize(actual_hash)

[Sorin Jianu, 2013/06/17 22:21:09]

replaced it with sizeof since we are doing a byte-wise memcmp.

+    return ComponentUnpacker::kDeltaVerificationFailure;
+  return ComponentUnpacker::kNone;
+}
+
+DeltaUpdateOpCopy::DeltaUpdateOpCopy() {}
+
+ComponentUnpacker::Error DeltaUpdateOpCopy::DoParseArguments(
+    base::DictionaryValue* command_args,
+    const base::FilePath& input_dir,
+    ComponentInstaller* installer) {
+  std::string input_rel_path;
+  if (!command_args->GetString(kInput, &input_rel_path))
+    return ComponentUnpacker::kDeltaBadCommands;
+  if (!installer->GetInstalledFile(input_rel_path, &input_abs_path_))
+    return ComponentUnpacker::kDeltaMissingExistingFile;
+  return ComponentUnpacker::kNone;
+}
+
+ComponentUnpacker::Error DeltaUpdateOpCopy::DoRun(ComponentPatcher*,
+                                                  int* error) {
+  *error = 0;
+  if (!file_util::CopyFile(input_abs_path_, output_abs_path_))
+    return ComponentUnpacker::kDeltaOperationFailure;
+  return ComponentUnpacker::kNone;
+}
+
+DeltaUpdateOpCreate::DeltaUpdateOpCreate() {}
+
+ComponentUnpacker::Error DeltaUpdateOpCreate::DoParseArguments(
+    base::DictionaryValue* command_args,
+    const base::FilePath& input_dir,
+    ComponentInstaller* installer) {
+  std::string patch_rel_path;
+  if (!command_args->GetString(kPatch, &patch_rel_path))
+    return ComponentUnpacker::kDeltaBadCommands;
+  patch_abs_path_ = input_dir.Append(
+      base::FilePath::FromUTF8Unsafe(patch_rel_path));
+  return ComponentUnpacker::kNone;
+}
+
+ComponentUnpacker::Error DeltaUpdateOpCreate::DoRun(ComponentPatcher*,
+                                                    int* error) {
+  *error = 0;
+  if (!file_util::Move(patch_abs_path_, output_abs_path_))
+    return ComponentUnpacker::kDeltaOperationFailure;
+  return ComponentUnpacker::kNone;
+}
+
+DeltaUpdateOpPatchBsdiff::DeltaUpdateOpPatchBsdiff() {}
+
+ComponentUnpacker::Error DeltaUpdateOpPatchBsdiff::DoParseArguments(
+    base::DictionaryValue* command_args,
+    const base::FilePath& input_dir,
+    ComponentInstaller* installer) {
+  std::string patch_rel_path;
+  std::string input_rel_path;
+  if (!command_args->GetString(kPatch, &patch_rel_path) ||
+      !command_args->GetString(kInput, &input_rel_path))
+    return ComponentUnpacker::kDeltaBadCommands;
+  if (!installer->GetInstalledFile(input_rel_path, &input_abs_path_))
+    return ComponentUnpacker::kDeltaMissingExistingFile;
+  patch_abs_path_ = input_dir.Append(
+      base::FilePath::FromUTF8Unsafe(patch_rel_path));
+  return ComponentUnpacker::kNone;
+}
+
+ComponentUnpacker::Error DeltaUpdateOpPatchBsdiff::DoRun(
+    ComponentPatcher* patcher,
+    int* error) {
+  *error = 0;
+  return patcher->Patch(kPatchTypeBsdiff,
+                        input_abs_path_,
+                        patch_abs_path_,
+                        output_abs_path_,
+                        error);
+}
+
+DeltaUpdateOpPatchCourgette::DeltaUpdateOpPatchCourgette() {}
+
+ComponentUnpacker::Error DeltaUpdateOpPatchCourgette::DoParseArguments(
+    base::DictionaryValue* command_args,
+    const base::FilePath& input_dir,
+    ComponentInstaller* installer) {
+  std::string patch_rel_path;
+  std::string input_rel_path;
+  if (!command_args->GetString(kPatch, &patch_rel_path) ||
+      !command_args->GetString(kInput, &input_rel_path))
+    return ComponentUnpacker::kDeltaBadCommands;
+  if (!installer->GetInstalledFile(input_rel_path, &input_abs_path_))
+    return ComponentUnpacker::kDeltaMissingExistingFile;
+  patch_abs_path_ = input_dir.Append(
+      base::FilePath::FromUTF8Unsafe(patch_rel_path));
+  return ComponentUnpacker::kNone;
+}
+
+ComponentUnpacker::Error DeltaUpdateOpPatchCourgette::DoRun(
+    ComponentPatcher* patcher,
+    int* error) {
+  *error = 0;
+  return patcher->Patch(kPatchTypeCourgette,
+                        input_abs_path_,
+                        patch_abs_path_,
+                        output_abs_path_,
+                        error);
+}
+
+// Takes the contents of a differential component update in input_dir
+// and produces the contents of a full component update in unpack_dir
+// using input_abs_path_ files that the installer knows about.
+ComponentUnpacker::Error DifferentialUpdatePatch(
+    const base::FilePath& input_dir,
+    const base::FilePath& unpack_dir,
+    ComponentPatcher* patcher,
+    ComponentInstaller* installer,
+    int* error) {
+  *error = 0;
+  scoped_ptr<base::ListValue> commands(ReadCommands(input_dir));
+  if (!commands.get())
+    return ComponentUnpacker::kDeltaBadCommands;
+  for (base::ValueVector::const_iterator command = commands->begin(),
+      end = commands->end(); command != end; command++) {
+    if (!(*command)->IsType(base::Value::TYPE_DICTIONARY))
+      return ComponentUnpacker::kDeltaBadCommands;
+    base::DictionaryValue* command_args =
+        static_cast<base::DictionaryValue*>(*command);
+    scoped_ptr<DeltaUpdateOp> operation(CreateDeltaUpdateOp(command_args));
+    if (!operation)
+      return ComponentUnpacker::kDeltaUnsupportedCommand;
+    ComponentUnpacker::Error result = operation->Run(
+        command_args, input_dir, unpack_dir, patcher, installer, error);
+    if (result != ComponentUnpacker::kNone)
+      return result;
+  }
+  return ComponentUnpacker::kNone;
+}
+