Add MinidumpContext (X86 and AMD64 variants) and their writers

minidump/minidump_context_writer.h

Index: minidump/minidump_context_writer.h
diff --git a/minidump/minidump_context_writer.h b/minidump/minidump_context_writer.h
new file mode 100644
index 0000000000000000000000000000000000000000..c01c1f5ed25cdd2350d47423f4f7276cc33bd3c5
--- /dev/null
+++ b/minidump/minidump_context_writer.h
@@ -0,0 +1,113 @@
+// 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_MINIDUMP_MINIDUMP_CONTEXT_WRITER_H_
+#define CRASHPAD_MINIDUMP_MINIDUMP_CONTEXT_WRITER_H_
+
+#include <sys/types.h>
+
+#include "base/basictypes.h"
+#include "minidump/minidump_context.h"
+#include "minidump/minidump_writable.h"
+#include "util/file/file_writer.h"
+
+namespace crashpad {
+
+//! \brief The base class for writers of CPU context structures in minidump
+//!     files.
+class MinidumpContextWriter : public internal::MinidumpWritable {
+ public:
+  virtual ~MinidumpContextWriter();
+
+ protected:
+  MinidumpContextWriter() : MinidumpWritable() {}
+
+  //! \brief Returns the size of the context structure that this object will
+  //!     write.
+  //!
+  //! \note This method will only be called in #kStateFrozen or a subsequent
+  //!     state.
+  virtual size_t ContextSize() const = 0;

[Robert Sesek, 2014/09/24 15:42:15]

Why require this instead of just use SizeOfObject()? 

[Mark Mentovai, 2014/09/24 16:58:28]

rsesek wrote:
SizeOfObject is protected, but code that comes across a MinidumpContextWriter
might want to know this.

This follows the same design that I used for MinidumpMemory, where we have
MemoryRangeSize().

+
+  // MinidumpWritable:
+  virtual size_t SizeOfObject() override final;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MinidumpContextWriter);
+};
+
+//! \brief The writer for a MinidumpContextX86 structure in a minidump file.
+class MinidumpContextX86Writer final : public MinidumpContextWriter {
+ public:
+  MinidumpContextX86Writer();
+  virtual ~MinidumpContextX86Writer();
+
+  //! \brief Returns a pointer to the context structure that this object will
+  //!     write.
+  //!
+  //! \attention This returns a non-`const` pointer to this object’s private
+  //!     data so that a caller can populate the context structure directly.
+  //!     This is done because providing setter interfaces to each field in the
+  //!     context structure would be unwieldy and cumbersome. Care must be taken
+  //!     to populate the context structure correctly. The context structure
+  //!     must only be modified while this object is in the #kStateMutable state.

[Robert Sesek, 2014/09/24 15:42:15]

nit: 80cols

+  MinidumpContextX86* context() { return &context_; }
+
+ protected:
+  // MinidumpWritable:
+  virtual bool WriteObject(FileWriterInterface* file_writer) override;
+
+  // MinidumpContextWriter:
+  virtual size_t ContextSize() const override;
+
+ private:
+  MinidumpContextX86 context_;
+
+  DISALLOW_COPY_AND_ASSIGN(MinidumpContextX86Writer);
+};
+
+//! \brief The writer for a MinidumpContextAMD64 structure in a minidump file.
+class MinidumpContextAMD64Writer final : public MinidumpContextWriter {
+ public:
+  MinidumpContextAMD64Writer();
+  virtual ~MinidumpContextAMD64Writer();
+
+  //! \brief Returns a pointer to the context structure that this object will
+  //!     write.
+  //!
+  //! \attention This returns a non-`const` pointer to this object’s private
+  //!     data so that a caller can populate the context structure directly.
+  //!     This is done because providing setter interfaces to each field in the
+  //!     context structure would be unwieldy and cumbersome. Care must be taken
+  //!     to populate the context structure correctly. The context structure
+  //!     must only be modified while this object is in the #kStateMutable state.
+  MinidumpContextAMD64* context() { return &context_; }
+
+ protected:
+  // MinidumpWritable:
+  virtual size_t Alignment() override;
+  virtual bool WriteObject(FileWriterInterface* file_writer) override;
+
+  // MinidumpContextWriter:
+  virtual size_t ContextSize() const override;
+
+ private:
+  MinidumpContextAMD64 context_;
+
+  DISALLOW_COPY_AND_ASSIGN(MinidumpContextAMD64Writer);
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_MINIDUMP_MINIDUMP_CONTEXT_WRITER_H_