win: Add open equivalent

util/file/file_writer.h

Index: util/file/file_writer.h
diff --git a/util/file/file_writer.h b/util/file/file_writer.h
index 54c59c923378f58f9e8bffe5a8207e9ae764b0c4..1fe46cb56a33cc7c95e7461a261945fbed4f6429 100644
--- a/util/file/file_writer.h
+++ b/util/file/file_writer.h
@@ -16,9 +16,8 @@
 #define CRASHPAD_UTIL_FILE_FILE_WRITER_H_
 
 #include <fcntl.h>
+#include <inttypes.h>
 #include <stddef.h>
-#include <sys/uio.h>
-#include <unistd.h>
 
 #include <string>
 #include <vector>
@@ -26,6 +25,16 @@
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_file.h"
+#include "build/build_config.h"
+
+#if defined(OS_POSIX)
+#include <sys/uio.h>
+#include <unistd.h>
+using FileOffset = off_t;
+#elif defined(OS_WIN)
+#include "util/win/scoped_handle.h"
+using FileOffset = int64_t;
+#endif
 
 namespace crashpad {
 
@@ -34,7 +43,7 @@ namespace crashpad {
 //! This structure is intended to be used for write operations.
 //
 // Type compatibility with iovec is tested with static assertions in the
-// implementation file.
+// POSIX implementation file.
 struct WritableIoVec {
   //! \brief The base address of a memory region for output.
   const void* iov_base;
@@ -47,9 +56,10 @@ struct WritableIoVec {
 //!     semantics.
 class FileWriterInterface {
  public:
-  //! \brief Wraps `write()` or provides an alternate implementation with
-  //!     identical semantics. This method will write the entire buffer,
-  //!     continuing after a short write or after being interrupted.
+  //! \brief Wraps `write()` or `WriteFile()` or provides an alternate
+  //!     implementation with identical semantics. This method will write the
+  //!     entire buffer, continuing after a short write or after being
+  //!     interrupted.
   //!
   //! \return `true` if the operation succeeded, `false` if it failed, with an
   //!     error message logged.
@@ -65,12 +75,12 @@ class FileWriterInterface {
   //! \note The contents of \a iovecs are undefined when this method returns.
   virtual bool WriteIoVec(std::vector<WritableIoVec>* iovecs) = 0;
 
-  //! \brief Wraps `lseek()` or provides an alternate implementation with
-  //!     identical semantics.
+  //! \brief Wraps `lseek()` or `SetFilePointer` or provides an alternate
+  //!     implementation with identical semantics.
   //!
-  //! \return The return value of `lseek()`. `-1` on failure, with an error
-  //!     message logged.
-  virtual off_t Seek(off_t offset, int whence) = 0;
+  //! \return The return value of the underlying function. `-1` on failure,
+  //!     with an error message logged.
+  virtual FileOffset Seek(FileOffset offset, int whence) = 0;
 
  protected:
   ~FileWriterInterface() {}
@@ -83,16 +93,16 @@ class FileWriter : public FileWriterInterface {
   FileWriter();
   ~FileWriter();
 
-  //! \brief Wraps `open()`.
+  //! \brief Wraps `open()` or `CreateFile()`.
   //!
   //! \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, int oflag, mode_t mode);
+  bool Open(const base::FilePath& path, int oflag, uint32_t mode);
 
-  //! \brief Wraps `close().`
+  //! \brief Wraps `close()` or `CloseHandle()`.
   //!
   //! \note It is only valid to call this method on an object that has had a
   //!     successful Open() that has not yet been matched by a subsequent call
@@ -117,10 +127,14 @@ class FileWriter : public FileWriterInterface {
   //!
   //! \note It is only valid to call this method between a successful Open() and
   //!     a Close().
-  off_t Seek(off_t offset, int whence) override;
+  FileOffset Seek(FileOffset offset, int whence) override;
 
  private:
-  base::ScopedFD fd_;
+#if defined(OS_POSIX)
+  base::ScopedFD file_;
+#else
+  win::ScopedFileHandle file_;
+#endif
 
   DISALLOW_COPY_AND_ASSIGN(FileWriter);
 };