Create CrashReportDatabase interface, a test, and a Mac implementation.

client/crash_report_database_mac.mm

Index: client/crash_report_database_mac.mm
diff --git a/client/crash_report_database_mac.mm b/client/crash_report_database_mac.mm
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+// 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/crash_report_database.h"
+
+#include <fcntl.h>
+#import <Foundation/Foundation.h>
+#include <stdio.h>
+#include <sys/errno.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "base/logging.h"
+#include "base/rand_util.h"
+#include "base/posix/eintr_wrapper.h"
+#include "base/scoped_generic.h"
+#include "base/strings/string_piece.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/sys_string_conversions.h"
+#include "util/mac/xattr.h"
+
+namespace crashpad {
+
+namespace {
+
+const char kDatabaseDirectoryName[] = "Crashpad Database";
+
+const char kWriteDirectory[] = "In Progress";
+
+const char kUploadPendingDirectory[] = "Reports";
+
+const char kUploadedDirectory[] = "Uploaded";
+
+const char kPlaceholderReportFileExtension[] = "placeholder";
+const char kCrashReportFileExtension[] = "dmp";
+
+const char kXattrUUID[] = "uuid";
+const char kXattrCollectorID[] = "id";
+const char kXattrIsUploaded[] = "uploaded";
+const char kXattrLastUploadTime[] = "last_upload_time";
+const char kXattrUploadAttemptCount[] = "upload_count";
+
+const char kXattrDatabaseInitialized[] = "initialized";
+
+struct ScopedFileLockTraits {
+  static int InvalidValue() {
+    return 0;
+  }
+
+  static void Free(int fd) {
+    PCHECK(IGNORE_EINTR(close(fd)) == 0) << "close";
+  }
+};
+
+using ScopedFileLock = base::ScopedGeneric<int, ScopedFileLockTraits>;
+
+void GenerateUUID(UUID* uuid) {
+  uint8_t bytes[sizeof(*uuid)];
+  base::RandBytes(bytes, sizeof(bytes));
+  uuid->InitializeFromBytes(bytes);
+}
+
+class CrashReportDatabaseMac : public CrashReportDatabase {
+ public:
+  explicit CrashReportDatabaseMac(const base::FilePath& path);
+  virtual ~CrashReportDatabaseMac();
+
+  bool Initialize();
+
+  // CrashReportDatabase:
+  OperationStatus PrepareNewCrashReport(Report* report) override;
+  OperationStatus FinishedWritingCrashReport(const UUID& uuid) override;
+  OperationStatus LookUpCrashReport(const UUID& uuid,
+                                    Report* report) override;
+  OperationStatus GetNotUploadedReports(
+      std::vector<const Report>* reports) override;
+  OperationStatus GetUploadedReports(
+      std::vector<const Report>* reports) override;
+  OperationStatus RecordUploadAttempt(const UUID& uuid,
+                                      bool successful,
+                                      const std::string& id) override;
+
+ private:
+  // Locates a crash report by |uuid| in the database and returns the full path
+  // to the report file, or an empty path if it cannot be found.
+  base::FilePath LocateCrashReport(const UUID& uuid);
+
+  // Obtains an advisory lock on the file at |path|. The flock is used to
+  // prevent cross-process concurrent metadata reads or writes. While xattrs
+  // do not observe the lock, if the lock-then-mutate protocol is observed by
+  // all clients of the database, it still enforces synchronization.
+  ScopedFileLock ObtainReportLock(const base::FilePath& path);
+
+  // Reads all the database xattrs from a file at |path| into the |report|. The
+  // flock must be obtained before calling this.
+  bool ReadReportMetadataLocked(const base::FilePath& path,
+                                Report* report);
+
+  // Reads the metadata from all the reports in a database subdirectory.
+  // Invalid reports are skipped.
+  OperationStatus ReportsInDirectory(const base::FilePath& path,
+                                     std::vector<const Report>* reports);
+
+
+  // Creates a database xattr name from the short constant name.
+  static std::string XattrName(const base::StringPiece& name);
+
+  base::FilePath base_dir_;
+
+  DISALLOW_COPY_AND_ASSIGN(CrashReportDatabaseMac);
+};
+
+CrashReportDatabaseMac::CrashReportDatabaseMac(const base::FilePath& path)
+    : CrashReportDatabase(), base_dir_(path) {
+}
+
+CrashReportDatabaseMac::~CrashReportDatabaseMac() {}
+
+bool CrashReportDatabaseMac::Initialize() {
+  const std::string is_initialized_flag = XattrName(kXattrDatabaseInitialized);
+  NSFileManager* file_manager = [NSFileManager defaultManager];
+
+  // Check if the database already exists.
+  BOOL is_dir = NO;
+  if ([file_manager fileExistsAtPath:base::SysUTF8ToNSString(base_dir_.value())
+                         isDirectory:&is_dir]) {
+    if (!is_dir) {
+      LOG(ERROR) << "Database exists at " << base_dir_.value()
+                 << " but is not a directory";
+      return false;
+    }
+
+    // The |base_dir_| path exists and is a directory, make sure it is marked
+    // as initialized. This will also ensure the filesystem has xattr support.
+    bool is_initialized = false;
+    if (ReadXattrBool(base_dir_, is_initialized_flag, &is_initialized) &&
+        is_initialized) {
+      return true;
+    }
+  } else {
+    // The database directory does not exist, so create it.
+    if (mkdir(base_dir_.value().c_str(), S_IRWXU | S_IRWXG)) {
+      PLOG(ERROR) << "mkdir " << base_dir_.value();
+      return false;
+    }
+  }
+
+  // Create the three processing directories for the database.
+  const char* paths[] = {
+    kWriteDirectory,
+    kUploadPendingDirectory,
+    kUploadedDirectory
+  };
+  for (size_t i = 0; i < arraysize(paths); ++i) {
+    base::FilePath path = base_dir_.Append(paths[i]);
+    if (mkdir(path.value().c_str(), S_IRWXU | S_IRWXG)) {
+      PLOG(ERROR) << "mkdir " << path.value();
+      return false;
+    }
+  }
+
+  return WriteXattrBool(base_dir_, is_initialized_flag, true);
+}
+
+CrashReportDatabase::OperationStatus
+CrashReportDatabaseMac::PrepareNewCrashReport(
+    CrashReportDatabase::Report* report) {
+  *report = Report();
+  GenerateUUID(&report->uuid);
+
+  base::FilePath write_dir = base_dir_.Append(kWriteDirectory);
+
+  // Create a placeholder file that will be used to store a record of this
+  // operation. The crash report file is written by a client of this class.
+  base::FilePath placeholder = write_dir.Append(
+      report->uuid.ToString() + "." + kPlaceholderReportFileExtension);
+  NSFileManager* manager = [NSFileManager defaultManager];
+  if (![manager createFileAtPath:base::SysUTF8ToNSString(placeholder.value())
+                        contents:[NSData data]
+                      attributes:nil]) {
+    LOG(ERROR) << "Failed to create report placeholder file "
+               << placeholder.value();
+    return kFileSystemError;
+  }
+
+  report->file_path = write_dir.Append(
+      report->uuid.ToString() + "." + kCrashReportFileExtension);
+
+  return kNoError;
+}
+
+CrashReportDatabase::OperationStatus
+CrashReportDatabaseMac::FinishedWritingCrashReport(const UUID& uuid) {
+  NSFileManager* manager = [NSFileManager defaultManager];
+  base::FilePath write_dir = base_dir_.Append(kWriteDirectory);
+
+  // Look up the placeholder file to ensure this UUID was prepared.
+  base::FilePath placeholder = write_dir.Append(
+      uuid.ToString() + "." + kPlaceholderReportFileExtension);
+  if (![manager fileExistsAtPath:base::SysUTF8ToNSString(placeholder.value())
+                     isDirectory:nullptr]) {
+    LOG(ERROR) << "Failed to find placeholder report " << placeholder.value();
+    return kReportNotFound;
+  }
+
+  // Delete the placeholder.
+  if (unlink(placeholder.value().c_str())) {
+    PLOG(ERROR) << "unlink " << placeholder.value();
+    // While not a good sign, continue processing if possible.
+  }
+
+  // Now make sure the crash report was actually written.
+  base::FilePath report_path = write_dir.Append(
+      uuid.ToString() + "." + kCrashReportFileExtension);
+  if (![manager fileExistsAtPath:base::SysUTF8ToNSString(report_path.value())
+                     isDirectory:nullptr]) {
+    LOG(ERROR) << "Failed to find crash report " << report_path.value();
+    return kReportNotFound;
+  }
+
+  ScopedFileLock lock(ObtainReportLock(report_path));
+
+  // Record the UUID of this crash report.
+  if (!WriteXattr(report_path, XattrName(kXattrUUID), uuid.ToString())) {
+    return kDatabaseError;
+  }
+
+  // Move the report to its new location for uploading.
+  base::FilePath new_path =
+      base_dir_.Append(kUploadPendingDirectory).Append(report_path.BaseName());
+  if (rename(report_path.value().c_str(), new_path.value().c_str())) {
+    PLOG(ERROR) << "rename " << report_path.value() << " to "
+                << new_path.value();
+    return kFileSystemError;
+  }
+
+  return kNoError;
+}
+
+CrashReportDatabase::OperationStatus
+CrashReportDatabaseMac::LookUpCrashReport(const UUID& uuid,
+                                          CrashReportDatabase::Report* report) {
+  base::FilePath path = LocateCrashReport(uuid);
+  if (path.empty())
+    return kReportNotFound;
+
+  ScopedFileLock lock(ObtainReportLock(path));
+
+  *report = Report();
+  report->file_path = path;
+  if (!ReadReportMetadataLocked(path, report)) {
+    LOG(ERROR) << "Failed to look up crash report " << uuid.ToString();
+    return kDatabaseError;
+  }
+  return kNoError;
+}
+
+CrashReportDatabase::OperationStatus
+CrashReportDatabaseMac::GetNotUploadedReports(
+    std::vector<const CrashReportDatabase::Report>* reports) {
+  return ReportsInDirectory(base_dir_.Append(kUploadPendingDirectory), reports);
+}
+
+CrashReportDatabase::OperationStatus
+CrashReportDatabaseMac::GetUploadedReports(
+    std::vector<const CrashReportDatabase::Report>* reports) {
+  return ReportsInDirectory(base_dir_.Append(kUploadedDirectory), reports);
+}
+
+CrashReportDatabase::OperationStatus
+CrashReportDatabaseMac::RecordUploadAttempt(const UUID& uuid,
+                                            bool successful,
+                                            const std::string& id) {
+  DCHECK(successful || id.empty());
+
+  base::FilePath report_path = LocateCrashReport(uuid);
+  if (report_path.empty())
+    return kReportNotFound;
+
+  ScopedFileLock lock(ObtainReportLock(report_path));
+
+  if (successful) {
+    base::FilePath new_path =
+        base_dir_.Append(kUploadedDirectory).Append(report_path.BaseName());
+    if (rename(report_path.value().c_str(), new_path.value().c_str())) {
+      PLOG(ERROR) << "rename " << report_path.value() << " to "
+                  << new_path.value();
+      return kFileSystemError;
+    }
+    report_path = new_path;
+    lock.reset();  // Reset before re-taking.
+    lock.reset(ObtainReportLock(report_path).release());
+  }
+
+  if (!WriteXattrBool(report_path, XattrName(kXattrIsUploaded), successful)) {
+    return kDatabaseError;
+  }
+  if (!WriteXattr(report_path, XattrName(kXattrCollectorID), id)) {
+    return kDatabaseError;
+  }
+
+  int upload_attempts = 0;
+  std::string name = XattrName(kXattrUploadAttemptCount);
+  if (HasXattr(report_path, name) &&
+      !ReadXattrInt(report_path, name, &upload_attempts)) {
+    return kDatabaseError;
+  }
+  if (!WriteXattrInt(report_path, name, ++upload_attempts)) {
+    return kDatabaseError;
+  }
+
+  if (!WriteXattrTimeT(report_path,
+                       XattrName(kXattrLastUploadTime),
+                       time(nullptr))) {
+    return kDatabaseError;
+  }
+
+  return kNoError;
+}
+
+base::FilePath CrashReportDatabaseMac::LocateCrashReport(const UUID& uuid) {
+  const std::string target_uuid = uuid.ToString();
+  NSString* path_ns_string = base::SysUTF8ToNSString(base_dir_.value());
+  NSString* dump_extension =
+      [NSString stringWithUTF8String:kCrashReportFileExtension];
+  NSDirectoryEnumerator* dir_it =
+      [[NSFileManager defaultManager] enumeratorAtPath:path_ns_string];
+  NSString* file = nil;
+  while ((file = [dir_it nextObject])) {
+    if (![[file pathExtension] isEqualToString:dump_extension])
+      continue;
+
+    base::FilePath full_path =
+        base_dir_.Append([file fileSystemRepresentation]);
+
+    ScopedFileLock lock(ObtainReportLock(full_path));
+    std::string uuid_string;
+    if (ReadXattr(full_path, XattrName(kXattrUUID), &uuid_string) &&
+        uuid_string == target_uuid) {
+      return full_path;
+    }
+  }
+  return base::FilePath();
+}
+
+ScopedFileLock CrashReportDatabaseMac::ObtainReportLock(
+    const base::FilePath& path) {
+  int fd = HANDLE_EINTR(open(path.value().c_str(),
+                             O_RDONLY | O_NONBLOCK | O_EXLOCK | O_CLOEXEC));
+  PCHECK(fd >= 0) << "open lock " << path.value();
+  return ScopedFileLock(fd);
+}
+
+bool CrashReportDatabaseMac::ReadReportMetadataLocked(
+    const base::FilePath& path, Report* report) {
+  std::string uuid_string;
+  if (!ReadXattr(path, XattrName(kXattrUUID), &uuid_string) ||
+      !report->uuid.InitializeFromString(uuid_string)) {
+    return false;
+  }
+  if (!HasXattr(path, XattrName(kXattrCollectorID))) {
+    report->id = std::string();
+  } else if (!ReadXattr(path, XattrName(kXattrCollectorID), &report->id)) {
+    return false;
+  }
+  if (!HasXattr(path, XattrName(kXattrIsUploaded))) {
+    report->uploaded = false;
+  } else if (!ReadXattrBool(path, XattrName(kXattrIsUploaded),
+                            &report->uploaded)) {
+    return false;
+  }
+  if (!HasXattr(path, XattrName(kXattrLastUploadTime))) {
+    report->last_upload_attempt_time = 0;
+  } else if (!ReadXattrTimeT(path, XattrName(kXattrLastUploadTime),
+                             &report->last_upload_attempt_time)) {
+    return false;
+  }
+  if (!HasXattr(path, XattrName(kXattrUploadAttemptCount))) {
+    report->upload_attempts = 0;
+  } else if (!ReadXattrInt(path, XattrName(kXattrUploadAttemptCount),
+                           &report->upload_attempts)) {
+    return false;
+  }
+
+  return true;
+}
+
+CrashReportDatabase::OperationStatus
+CrashReportDatabaseMac::ReportsInDirectory(
+    const base::FilePath& path,
+    std::vector<const CrashReportDatabase::Report>* reports) {
+  DCHECK(reports->empty());
+
+  NSError* error = nil;
+  NSArray* paths = [[NSFileManager defaultManager]
+      contentsOfDirectoryAtPath:base::SysUTF8ToNSString(path.value())
+                          error:&error];
+  if (error) {
+    LOG(ERROR) << "Failed to enumerate reports in directory " << path.value()
+               << ": " << [[error description] UTF8String];
+    return kFileSystemError;
+  }
+
+  reports->reserve([paths count]);
+  for (NSString* entry in paths) {
+    base::FilePath report_path = path.Append([entry fileSystemRepresentation]);
+    ScopedFileLock lock(ObtainReportLock(report_path));
+    Report report;
+    if (!ReadReportMetadataLocked(report_path, &report)) {
+      LOG(ERROR) << "Failed to read report metadata for "
+                 << report_path.value();
+      continue;
+    }
+    reports->push_back(report);
+  }
+
+  return kNoError;
+}
+
+std::string CrashReportDatabaseMac::XattrName(const base::StringPiece& name) {
+  return base::StringPrintf("com.google.crashpad.%s", name.data());
+}
+
+}  // namespace
+
+scoped_ptr<CrashReportDatabase> CrashReportDatabase::Initialize(
+    const base::FilePath& path) {
+  scoped_ptr<CrashReportDatabase> database;
+
+  NSFileManager* file_manager = [NSFileManager defaultManager];
+  BOOL is_dir = NO;
+  if ([file_manager fileExistsAtPath:base::SysUTF8ToNSString(path.value())
+                         isDirectory:&is_dir] &&
+      !is_dir) {
+    LOG(ERROR) << "File exists at " << path.value()
+               << " but is not a directory";
+    return database;
+  }
+
+  scoped_ptr<CrashReportDatabaseMac> database_mac(
+      new CrashReportDatabaseMac(path.Append(kDatabaseDirectoryName)));
+  if (!database_mac->Initialize())
+    database_mac.reset();
+
+  database.reset(database_mac.release());
+  return database;
+}
+
+}  // namespace crashpad