Add the Snapshot interface

snapshot/process_snapshot.h

Index: snapshot/process_snapshot.h
diff --git a/snapshot/process_snapshot.h b/snapshot/process_snapshot.h
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+// Copyright 2014 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.
+
+#ifndef CRASHPAD_SNAPSHOT_PROCESS_SNAPSHOT_H_
+#define CRASHPAD_SNAPSHOT_PROCESS_SNAPSHOT_H_
+
+#include <sys/time.h>
+#include <sys/types.h>
+
+#include <vector>
+
+namespace crashpad {
+
+class ExceptionSnapshot;
+class ModuleSnapshot;
+class SystemSnapshot;
+class ThreadSnapshot;
+
+//! \brief An abstract interface to a snapshot representing the state of a
+//!     process.
+//!
+//! This is the top-level object in a family of Snapshot objects, because it
+//! gives access to a SystemSnapshot, vectors of ModuleSnapshot and
+//! ThreadSnapshot objects, and possibly an ExceptionSnapshot. In turn,
+//! ThreadSnapshot and ExceptionSnapshot objects both give access to CPUContext
+//! objects, and ThreadSnapshot objects also give access to MemorySnapshot
+//! objects corresponding to thread stacks.
+class ProcessSnapshot {
+ public:
+  //! \brief Returns the snapshot process’ process ID.
+  virtual pid_t ProcessID() const = 0;
+
+  //! \brief Returns the snapshot process’ parent process’ process ID.
+  virtual pid_t ParentProcessID() const = 0;
+
+  //! \brief Returns the time that the snapshot was taken in \a snapshot_time.
+  //!
+  //! \param[out] snapshot_time The time that the snapshot was taken. This is
+  //!     distinct from the time that a ProcessSnapshot object was created or
+  //!     initialized, although it may be that time for ProcessSnapshot objects
+  //!     representing live or recently-crashed process state.
+  virtual void SnapshotTime(timeval* snapshot_time) const = 0;
+
+  //! \brief Returns the time that the snapshot process was started in \a
+  //!     start_time.
+  //!
+  //! Normally, process uptime in wall clock time can be computed as
+  //! SnapshotTime() − ProcessStartTime(), but this cannot be guaranteed in
+  //! cases where the real-time clock has been set during the snapshot process’
+  //! lifetime.
+  //!
+  //! \param[out] start_time The time that the process was started.
+  virtual void ProcessStartTime(timeval* start_time) const = 0;
+
+  //! \brief Returns the snapshot process’ CPU usage times in \a user_time and
+  //!     \a system_time.
+  //!
+  //! \param[out] user_time The time that the process has spent executing in
+  //!     user mode.
+  //! \param[out] system_time The time that the process has spent executing in
+  //!     system (kernel) mode.
+  virtual void ProcessCPUTimes(timeval* user_time,
+                               timeval* system_time) const = 0;
+
+  //! \brief Returns a SystemSnapshot reflecting the characteristics of the
+  //!     system that ran the snapshot process at the time of the snapshot.
+  //!
+  //! \return A SystemSnapshot object. The caller does not take ownership of
+  //!     this object, it is scoped to the lifetime of the ProcessSnapshot
+  //!     object that it was obtained from.
+  virtual const SystemSnapshot* System() const = 0;
+
+  //! \brief Returns ModuleSnapshot objects reflecting the code modules (binary
+  //!     images) loaded into the snapshot process at the time of the snapshot.
+  //!
+  //! \return A vector of ModuleSnapshot objects. The caller does not take
+  //!     ownership of these objects, they are scoped to the lifetime of the
+  //!     ProcessSnapshot object that they were obtained from.
+  virtual std::vector<const ModuleSnapshot*> Modules() const = 0;
+
+  //! \brief Returns ThreadSnapshot objects reflecting the threads (lightweight
+  //!     processes) existing in the snapshot process at the time of the
+  //!     snapshot.
+  //!
+  //! \return A vector of ThreadSnapshot objects. The caller does not take
+  //!     ownership of these objects, they are scoped to the lifetime of the
+  //!     ProcessSnapshot object that they were obtained from.
+  virtual std::vector<const ThreadSnapshot*> Threads() const = 0;
+
+  //! \brief Returns an ExceptionSnapshot reflecting the exception that the
+  //!     snapshot process sustained to trigger the snapshot being taken.
+  //!
+  //! \return An ExceptionSnapshot object. The caller does not take ownership of
+  //!     this object, it is scoped to the lifetime of the ProcessSnapshot
+  //!     object that it was obtained from. If the snapshot is not a result of
+  //!     an exception, returns `NULL`.
+  virtual const ExceptionSnapshot* Exception() const = 0;
+
+ protected:
+  ~ProcessSnapshot() {}
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_SNAPSHOT_PROCESS_SNAPSHOT_H_