Add FileReaderInterface. Move StringFileWriter to StringFile and

util/file/file_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_UTIL_FILE_FILE_WRITER_H_
 #define CRASHPAD_UTIL_FILE_FILE_WRITER_H_
 
-#include <fcntl.h>
-#include <stddef.h>
+#include <sys/types.h>
 
-#include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
-#include "build/build_config.h"
 #include "util/file/file_io.h"
+#include "util/file/file_seeker.h"
 
 namespace crashpad {
 
 //! \brief A version of `iovec` with a `const` #iov_base field.
 //!
 //! This structure is intended to be used for write operations.
 //
 // Type compatibility with iovec is tested with static assertions in the
 // implementation file.
 struct WritableIoVec {
   //! \brief The base address of a memory region for output.
   const void* iov_base;
 
   //! \brief The size of the memory pointed to by #iov_base.
   size_t iov_len;
 };
 
 //! \brief An interface to write to files and other file-like objects with
 //!     semantics matching the underlying platform (POSIX or Windows).
-class FileWriterInterface {
+class FileWriterInterface : public FileSeekerInterface {
  public:
-  //! \brief Wraps WriteFile(), or provides an implementation with identical
-  //!     semantics.
+  //! \brief Wraps LoggingWriteFile(), or provides an implementation with
+  //!     identical semantics.
   //!
   //! \return `true` if the operation succeeded, `false` if it failed, with an
   //!     error message logged.
   virtual bool Write(const void* data, size_t size) = 0;
 
   //! \brief Wraps `writev()` on POSIX or provides an alternate implementation
   //!     with identical semantics. This method will write entire buffers,
   //!     continuing after a short write or after being interrupted. On
   //!     non-POSIX this is a simple wrapper around Write().
   //!
   //! \return `true` if the operation succeeded, `false` if it failed, with an
   //!     error message logged.
   //!
   //! \note The contents of \a iovecs are undefined when this method returns.
   virtual bool WriteIoVec(std::vector<WritableIoVec>* iovecs) = 0;
 
-  //! \brief Wraps LoggingFileSeek() or provides an alternate implementation
-  //!     with identical semantics.
-  //!
-  //! \return The return value of LoggingFileSeek(). `-1` on failure,
-  //!     with an error message logged.
-  virtual FileOffset Seek(FileOffset offset, int whence) = 0;
-
  protected:
   ~FileWriterInterface() {}
 };
 
 //! \brief A file writer backed by a FileHandle.
 //!
 //! FileWriter requires users to provide a FilePath to open, but this class
 //! accepts an already-open FileHandle instead. Like FileWriter, this class may
 //! write to a filesystem-based file, but unlike FileWriter, this class is not
 //! responsible for creating or closing the file. Users of this class must
 //! ensure that the file handle is closed appropriately elsewhere. Objects of
 //! this class may be used to write to file handles not associated with
 //! filesystem-based files, although special attention should be paid to the
 //! Seek() method, which may not function on file handles that do not refer to
 //! disk-based files.
 //!
 //! This class is expected to be used when other code is responsible for
 //! creating files and already provides file handles.
 class WeakFileHandleFileWriter : public FileWriterInterface {
  public:
   explicit WeakFileHandleFileWriter(FileHandle file_handle);
   ~WeakFileHandleFileWriter();
 
   // FileWriterInterface:
   bool Write(const void* data, size_t size) override;
   bool WriteIoVec(std::vector<WritableIoVec>* iovecs) override;
 
+  // FileSeekerInterface:
+
   //! \copydoc FileWriterInterface::Seek()
   //!
   //! \note This method is only guaranteed to function on file handles referring
   //!     to disk-based files.
   FileOffset Seek(FileOffset offset, int whence) override;
 
  private:
   void set_file_handle(FileHandle file_handle) { file_handle_ = file_handle; }
 
   FileHandle file_handle_;  // weak
 
   // FileWriter uses this class as its internal implementation, and it needs to
-  // be able to call set_file_handle(). FileWriter cannot initialize an
+  // be able to call set_file_handle(). FileWriter cannot initialize a
   // WeakFileHandleFileWriter with a correct file descriptor at the time of
   // construction because no file descriptor will be available until
   // FileWriter::Open() is called.
   friend class FileWriter;
 
   DISALLOW_COPY_AND_ASSIGN(WeakFileHandleFileWriter);
 };
 
 //! \brief A file writer implementation that wraps traditional system file
 //!     operations on files accessed through the filesystem.
 class FileWriter : public FileWriterInterface {
  public:
   FileWriter();
   ~FileWriter();
 
+  // FileWriterInterface:
+
   //! \brief Wraps LoggingOpenFileForWrite().
   //!
   //! \return `true` if the operation succeeded, `false` if it failed, with an
   //!     error message logged.
   //!
   //! \note After a successful call, this method cannot be called again until
   //!     after Close().
   bool Open(const base::FilePath& path,
             FileWriteMode write_mode,
             FilePermissions permissions);
@@ skipping 12 matching lines @@
   //! \note It is only valid to call this method between a successful Open() and
   //!     a Close().
   bool Write(const void* data, size_t size) override;
 
   //! \copydoc FileWriterInterface::WriteIoVec()
   //!
   //! \note It is only valid to call this method between a successful Open() and
   //!     a Close().
   bool WriteIoVec(std::vector<WritableIoVec>* iovecs) override;
 
+  // FileSeekerInterface:
+
   //! \copydoc FileWriterInterface::Seek()
   //!
   //! \note It is only valid to call this method between a successful Open() and
   //!     a Close().
   FileOffset Seek(FileOffset offset, int whence) override;
 
  private:
   ScopedFileHandle file_;
   WeakFileHandleFileWriter weak_file_handle_file_writer_;
 
   DISALLOW_COPY_AND_ASSIGN(FileWriter);
 };
 
 }  // namespace crashpad
 
 #endif  // CRASHPAD_UTIL_FILE_FILE_WRITER_H_