Add FileReaderInterface. Move StringFileWriter to StringFile and

util/file/string_file.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_UTIL_FILE_STRING_FILE_WRITER_H_
-#define CRASHPAD_UTIL_FILE_STRING_FILE_WRITER_H_
+#ifndef CRASHPAD_UTIL_FILE_STRING_FILE_H_
+#define CRASHPAD_UTIL_FILE_STRING_FILE_H_
 
 #include <sys/types.h>
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/numerics/safe_math.h"
+#include "util/file/file_reader.h"
 #include "util/file/file_writer.h"
 
 namespace crashpad {
 
-//! \brief A file writer backed by a virtual file, as opposed to a file on disk
-//!     or other operating system file descriptor-based file.
+//! \brief A file reader and writer backed by a virtual file, as opposed to a
+//!     file on disk or other operating system file descriptor-based file.
 //!
 //! The virtual file is a buffer in memory. This class is convenient for use
-//! with other code that normally expects to write files, when it is impractical
-//! or inconvenient to write a file. It is expected that tests, in particular,
-//! will benefit from using this class.
-class StringFileWriter : public FileWriterInterface {
+//! with other code that normally expects to read or write files, when it is
+//! impractical or inconvenient to read or write a file. It is expected that
+//! tests, in particular, will benefit from using this class.
+class StringFile : public FileReaderInterface, public FileWriterInterface {
  public:
-  StringFileWriter();
-  ~StringFileWriter();
+  StringFile();
+  ~StringFile();
 
   //! \brief Returns a string containing the virtual file’s contents.
   const std::string& string() const { return string_; }
 
+  //! \brief Sets the virtual file’s contents to \a string, and resets its file
+  //!     position to `0`.
+  void SetString(const std::string& string);
+
   //! \brief Resets the virtual file’s contents to be empty, and resets its file
   //!     position to `0`.
   void Reset();
 
+  // FileReaderInterface:
+  ssize_t Read(void* data, size_t size) override;
+
   // FileWriterInterface:
   bool Write(const void* data, size_t size) override;
   bool WriteIoVec(std::vector<WritableIoVec>* iovecs) override;
+
+  // FileSeekerInterface:
   FileOffset Seek(FileOffset offset, int whence) override;
 
  private:
   //! \brief The virtual file’s contents.
   std::string string_;
 
   //! \brief The file offset of the virtual file.
   //!
   //! \note This is stored in a `size_t` to match the characteristics of
   //!     #string_, the `std::string` used to store the virtual file’s contents.
   //!     This type will have different characteristics than the `off_t` used to
   //!     report file offsets. The implementation must take care when converting
   //!     between these distinct types.
   base::CheckedNumeric<size_t> offset_;
 
-  DISALLOW_COPY_AND_ASSIGN(StringFileWriter);
+  DISALLOW_COPY_AND_ASSIGN(StringFile);
 };
 
 }  // namespace crashpad
 
-#endif  // CRASHPAD_UTIL_FILE_STRING_FILE_WRITER_H_
+#endif  // CRASHPAD_UTIL_FILE_STRING_FILE_H_