Add the Snapshot interface

snapshot/exception_snapshot.h

Index: snapshot/exception_snapshot.h
diff --git a/snapshot/exception_snapshot.h b/snapshot/exception_snapshot.h
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+++ b/snapshot/exception_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_EXCEPTION_SNAPSHOT_H_
+#define CRASHPAD_SNAPSHOT_EXCEPTION_SNAPSHOT_H_
+
+#include <stdint.h>
+
+#include <vector>
+
+namespace crashpad {
+
+struct CPUContext;
+
+//! \brief An abstract interface to a snapshot representing an exception that a
+//!     snapshot process sustained and triggered the snapshot being taken.
+class ExceptionSnapshot {
+ public:
+  //! \brief Returns a CPUContext object corresponding to the exception thread’s
+  //!     CPU context at the time of the exception.
+  //!
+  //! The caller does not take ownership of this object, it is scoped to the
+  //! lifetime of the ThreadSnapshot object that it was obtained from.
+  virtual const CPUContext* Context() const = 0;
+
+  //! \brief Returns the thread identifier of the thread that triggered the
+  //!     exception.
+  //!
+  //! This value can be compared to ThreadSnapshot::ThreadID() to associate an
+  //! ExceptionSnapshot object with the ThreadSnapshot that contains a snapshot
+  //! of the thread that triggered the exception.
+  virtual uint64_t ThreadID() const = 0;
+
+  //! \brief Returns the top-level exception code identifying the exception.
+  //!
+  //! This is an operating system-specific value.
+  //!
+  //! For Mac OS X, this will be an \ref EXC_x "EXC_*" exception type, such as
+  //! `EXC_BAD_ACCESS`. `EXC_CRASH` will not appear here for exceptions
+  //! processed as `EXC_CRASH` when generated from another preceding exception:
+  //! the original exception code will appear instead. The exception type as it
+  //! was received will appear at index 0 of Codes().
+  virtual uint32_t Exception() const = 0;
+
+  //! \brief Returns the second-level exception code identifying the exception.
+  //!
+  //! This is an operating system-specific value.
+  //!
+  //! For Mac OS X, this will be the value of the exception code at index 0 as
+  //! received by a Mach exception handler. For `EXC_CRASH` exceptions generated
+  //! from another preceding exception, the original exception code will appear
+  //! here, not the code as received by the Mach exception handler. The code as
+  //! it was received will appear at index 1 of Codes().
+  virtual uint32_t ExceptionInfo() const = 0;
+
+  //! \brief Returns the address that triggered the exception.
+  //!
+  //! This may be the address that caused a fault on data access, or it may be
+  //! the instruction pointer that contained an offending instruction. For
+  //! exceptions where this value cannot be determined, it will be `0`.
+  //!
+  //! For Mac OS X, this will be the value of the exception code at index 1 as
+  //! received by a Mach exception handler.
+  virtual uint64_t ExceptionAddress() const = 0;
+
+  //! \brief Returns a series of operating system-specific exception codes.
+  //!
+  //! The precise interpretation of these codes is specific to the snapshot
+  //! operating system. These codes may provide a duplicate of information
+  //! available elsewhere, they may extend information available elsewhere, or
+  //! they may not be present at all. In this case, an empty vector will be
+  //! returned.
+  //!
+  //! For Mac OS X, this will be a vector containing the original exception type
+  //! and the values of `code[0]` and `code[1]` as received by a Mach exception
+  //! handler.
+  virtual const std::vector<uint64_t>& Codes() const = 0;
+
+ protected:
+  ~ExceptionSnapshot() {}
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_SNAPSHOT_EXCEPTION_SNAPSHOT_H_