Add MinidumpContextWriter::CreateFromSnapshot(), everything downstream, and its test

minidump/minidump_context_writer.h

 // 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 "base/memory/scoped_ptr.h"
 #include "minidump/minidump_context.h"
 #include "minidump/minidump_writable.h"
 
 namespace crashpad {
 
+struct CPUContext;
+struct CPUContextX86;
+struct CPUContextX86_64;
+
 //! \brief The base class for writers of CPU context structures in minidump
 //!     files.
 class MinidumpContextWriter : public internal::MinidumpWritable {
  public:
   ~MinidumpContextWriter() override;
 
+  //! \brief Creates a MinidumpContextWriter based on \a context_snapshot.
+  //!
+  //! \param[in] context_snapshot The context snapshot to use as source data.
+  //!
+  //! \return A MinidumpContextWriter subclass, such as MinidumpContextWriterX86
+  //!     or MinidumpContextWriterAMD64, appropriate to the CPU type of \a
+  //!     context_snapshot. The returned object is initialized using the source
+  //!     data in \a context_snapshot. If \a context_snapshot is an unknown CPU
+  //!     type’s context, logs a message and returns `nullptr`.
+  static scoped_ptr<MinidumpContextWriter> CreateFromSnapshot(
+      const CPUContext* context_snapshot);
+
  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;
 
   // MinidumpWritable:
   size_t SizeOfObject() 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();
   ~MinidumpContextX86Writer() override;
 
+  //! \brief Initializes the MinidumpContextX86 based on \a context_snapshot.
+  //!
+  //! \param[in] context_snapshot The context snapshot to use as source data.
+  //!
+  //! \note Valid in #kStateMutable. No mutation of context() may be done before
+  //!     calling this method, and it is not normally necessary to alter
+  //!     context() after calling this method.
+  void InitializeFromSnapshot(const CPUContextX86* context_snapshot);
+
   //! \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.
@@ skipping 11 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(MinidumpContextX86Writer);
 };
 
 //! \brief The writer for a MinidumpContextAMD64 structure in a minidump file.
 class MinidumpContextAMD64Writer final : public MinidumpContextWriter {
  public:
   MinidumpContextAMD64Writer();
   ~MinidumpContextAMD64Writer() override;
 
+  //! \brief Initializes the MinidumpContextAMD64 based on \a context_snapshot.
+  //!
+  //! \param[in] context_snapshot The context snapshot to use as source data.
+  //!
+  //! \note Valid in #kStateMutable. No mutation of context() may be done before
+  //!     calling this method, and it is not normally necessary to alter
+  //!     context() after calling this method.
+  void InitializeFromSnapshot(const CPUContextX86_64* context_snapshot);
+
   //! \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:
   size_t Alignment() override;
   bool WriteObject(FileWriterInterface* file_writer) override;
 
   // MinidumpContextWriter:
   size_t ContextSize() const override;
 
  private:
   MinidumpContextAMD64 context_;
 
   DISALLOW_COPY_AND_ASSIGN(MinidumpContextAMD64Writer);
 };
 
 }  // namespace crashpad
 
 #endif  // CRASHPAD_MINIDUMP_MINIDUMP_CONTEXT_WRITER_H_