Use LockFile/UnlockFile for Settings to port to Windows

client/settings.cc

 // Copyright 2015 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #include "client/settings.h"
 
 #include <limits>
 
-#include <fcntl.h>
-#include <unistd.h>
-#include <uuid/uuid.h>
-
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/posix/eintr_wrapper.h"
 #include "util/numeric/in_range_cast.h"
 
 namespace crashpad {
 
 struct ALIGNAS(4) Settings::Data {
   static const uint32_t kSettingsMagic = 'CPds';
   static const uint32_t kSettingsVersion = 1;
@@ skipping 21 matching lines @@
     : file_path_(file_path),
       initialized_() {
 }
 
 Settings::~Settings() {
 }
 
 bool Settings::Initialize() {
   INITIALIZATION_STATE_SET_INITIALIZING(initialized_);
 
-  ScopedFileHandle handle(HANDLE_EINTR(
-      open(file_path().value().c_str(),
-           O_CREAT | O_EXCL | O_WRONLY | O_EXLOCK,
-           0644)));
-
-  // The file was created, so this is a new database that needs to be
-  // initialized with a client ID.
-  if (handle.is_valid()) {
-    bool initialized = InitializeSettings(handle.get());
-    if (initialized)
-      INITIALIZATION_STATE_SET_VALID(initialized_);
-    return initialized;
-  }
-
-  // The file wasn't created, try opening it for a write operation. If the file
-  // needs to be recovered, writing is necessary. This also ensures that the
-  // process has permission to write the file.
   Data settings;
   if (!OpenForWritingAndReadSettings(&settings).is_valid())
     return false;
 
   INITIALIZATION_STATE_SET_VALID(initialized_);
   return true;
 }
 
 bool Settings::GetClientID(UUID* client_id) {
   INITIALIZATION_STATE_DCHECK_VALID(initialized_);
@@ skipping 14 matching lines @@
     return false;
 
   *enabled = (settings.options & Data::Options::kUploadsEnabled) != 0;
   return true;
 }
 
 bool Settings::SetUploadsEnabled(bool enabled) {
   INITIALIZATION_STATE_DCHECK_VALID(initialized_);
 
   Data settings;
-  ScopedFileHandle handle = OpenForWritingAndReadSettings(&settings);
+  ScopedLockedFileHandle handle = OpenForWritingAndReadSettings(&settings);
   if (!handle.is_valid())
     return false;
 
   if (enabled)
     settings.options |= Data::Options::kUploadsEnabled;
   else
     settings.options &= ~Data::Options::kUploadsEnabled;
 
   return WriteSettings(handle.get(), settings);
 }
 
 bool Settings::GetLastUploadAttemptTime(time_t* time) {
   INITIALIZATION_STATE_DCHECK_VALID(initialized_);
 
   Data settings;
   if (!OpenAndReadSettings(&settings))
     return false;
 
   *time = InRangeCast<time_t>(settings.last_upload_attempt_time,
                               std::numeric_limits<time_t>::max());
   return true;
 }
 
 bool Settings::SetLastUploadAttemptTime(time_t time) {
   INITIALIZATION_STATE_DCHECK_VALID(initialized_);
 
   Data settings;
-  ScopedFileHandle handle = OpenForWritingAndReadSettings(&settings);
+  ScopedLockedFileHandle handle = OpenForWritingAndReadSettings(&settings);
   if (!handle.is_valid())
     return false;
 
   settings.last_upload_attempt_time = InRangeCast<uint64_t>(time, 0);
 
   return WriteSettings(handle.get(), settings);
 }
 
-ScopedFileHandle Settings::OpenForReading() {
-  ScopedFileHandle handle(HANDLE_EINTR(
-      open(file_path().value().c_str(), O_RDONLY | O_SHLOCK)));
-  PLOG_IF(ERROR, !handle.is_valid()) << "open for reading";
+Settings::ScopedLockedFileHandle::ScopedLockedFileHandle() : handle_() {
+}
+
+Settings::ScopedLockedFileHandle::ScopedLockedFileHandle(FileHandle file,
+                                                         FileLocking locking)
+    : handle_(file) {
+  if (handle_.is_valid()) {
+    if (!LoggingLockFile(handle_.get(), locking))
+      handle_.reset();
+  }
+}
+
+Settings::ScopedLockedFileHandle::~ScopedLockedFileHandle() {
+  FreeIfNecessary();
+}
+
+Settings::ScopedLockedFileHandle Settings::OpenForReading() {
+  ScopedLockedFileHandle handle(LoggingOpenFileForRead(file_path()),
+                                FileLocking::kShared);
   return handle.Pass();
 }
 
-ScopedFileHandle Settings::OpenForReadingAndWriting() {
-  ScopedFileHandle handle(HANDLE_EINTR(
-      open(file_path().value().c_str(), O_RDWR | O_EXLOCK | O_CREAT, 0644)));
-  PLOG_IF(ERROR, !handle.is_valid()) << "open for writing";
+Settings::ScopedLockedFileHandle Settings::OpenForReadingAndWriting() {
+  ScopedLockedFileHandle handle(
+      LoggingOpenFileForReadAndWrite(file_path(),
+                                     FileWriteMode::kReuseOrCreate,
+                                     FilePermissions::kWorldReadable),
+      FileLocking::kExclusive);
   return handle.Pass();
 }
 
+void Settings::ScopedLockedFileHandle::reset() {

[Robert Sesek, 2015/04/01 15:08:26]

nit: Implementation order should match header order.

[scottmg, 2015/04/01 19:32:10]

Removed.

+  FreeIfNecessary();
+  handle_.reset();
+}
+
+void Settings::ScopedLockedFileHandle::FreeIfNecessary() {
+  if (is_valid())
+    LoggingUnlockFile(handle_.get());
+}
+
 bool Settings::OpenAndReadSettings(Data* out_data) {
-  ScopedFileHandle handle = OpenForReading();
+  ScopedLockedFileHandle handle = OpenForReading();
   if (!handle.is_valid())
     return false;
 
   if (ReadSettings(handle.get(), out_data))
     return true;
 
   // The settings file is corrupt, so reinitialize it.
   handle.reset();
 
   // The settings failed to be read, so re-initialize them.
   return RecoverSettings(kInvalidFileHandle, out_data);
 }
 
-ScopedFileHandle Settings::OpenForWritingAndReadSettings(Data* out_data) {
-  ScopedFileHandle handle = OpenForReadingAndWriting();
+Settings::ScopedLockedFileHandle Settings::OpenForWritingAndReadSettings(
+    Data* out_data) {
+  ScopedLockedFileHandle handle = OpenForReadingAndWriting();
   if (!handle.is_valid())
-    return ScopedFileHandle();
+    return ScopedLockedFileHandle();
 
   if (!ReadSettings(handle.get(), out_data)) {
     if (!RecoverSettings(handle.get(), out_data))
-      return ScopedFileHandle();
+      return ScopedLockedFileHandle();
   }
 
   return handle.Pass();
 }
 
 bool Settings::ReadSettings(FileHandle handle, Data* out_data) {
   if (LoggingSeekFile(handle, 0, SEEK_SET) != 0)
     return false;
 
   if (!LoggingReadFile(handle, out_data, sizeof(*out_data)))
     return false;
 
   if (out_data->magic != Data::kSettingsMagic) {
     LOG(ERROR) << "Settings magic is not " << Data::kSettingsMagic;
     return false;
   }
 
   if (out_data->version != Data::kSettingsVersion) {
     LOG(ERROR) << "Settings version is not " << Data::kSettingsVersion;
     return false;
   }
 
   return true;
 }
 
 bool Settings::WriteSettings(FileHandle handle, const Data& data) {
   if (LoggingSeekFile(handle, 0, SEEK_SET) != 0)
     return false;
 
-  if (HANDLE_EINTR(ftruncate(handle, 0)) != 0) {
-    PLOG(ERROR) << "ftruncate settings file";
+  if (!LoggingTruncateFile(handle))
     return false;
-  }
 
   return LoggingWriteFile(handle, &data, sizeof(Data));
 }
 
 bool Settings::RecoverSettings(FileHandle handle, Data* out_data) {
-  ScopedFileHandle scoped_handle;
+  ScopedLockedFileHandle scoped_handle;
   if (handle == kInvalidFileHandle) {
     scoped_handle = OpenForReadingAndWriting();
     handle = scoped_handle.get();
 
     // Test if the file has already been recovered now that the exclusive lock
     // is held.
     if (ReadSettings(handle, out_data))
       return true;
   }
 
-  LOG(INFO) << "Recovering settings file " << file_path().value();
+  LOG(INFO) << "Recovering settings file " << file_path().value().c_str();
 
   if (handle == kInvalidFileHandle) {
     LOG(ERROR) << "Invalid file handle";
     return false;
   }
 
   if (!InitializeSettings(handle))
     return false;
 
   return ReadSettings(handle, out_data);
 }
 
 bool Settings::InitializeSettings(FileHandle handle) {
-  uuid_t uuid;
-  uuid_generate(uuid);
-
   Data settings;
-  settings.client_id.InitializeFromBytes(uuid);
+  if (!UUID::GenerateFromSystem(&settings.client_id))
+    return false;
 
   return WriteSettings(handle, settings);
 }
 
 }  // namespace crashpad