Add LoggingSeekFile

util/file/file_io.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,
@@ skipping 12 matching lines @@
 #include <windows.h>
 #endif
 
 namespace base {
 class FilePath;
 }  // namespace base
 
 namespace crashpad {
 
 #if defined(OS_POSIX) || DOXYGEN
+
 //! \brief Platform-specific alias for a low-level file handle.
 using FileHandle = int;
+
+//! \brief Platform-specific alias for a position in an open file.
+using FileOffset = off_t;
+
 #elif defined(OS_WIN)
+
 using FileHandle = HANDLE;
+using FileOffset = LONGLONG;
+
 #endif
 
 //! \brief Determines the mode that LoggingOpenFileForWrite() uses.
 enum class FileWriteMode {
   //! \brief Opens the file if it exists, or creates a new file.
   kReuseOrCreate,
 
   //! \brief Creates a new file. If the file already exists, it will be
   //!     overwritten.
   kTruncateOrCreate,
@@ skipping 112 matching lines @@
 //!
 //! \return The newly opened FileHandle, or an invalid FileHandle on failure.
 //!
 //! \sa FileWriteMode
 //! \sa ScopedFD
 //! \sa ScopedFileHANDLE
 FileHandle LoggingOpenFileForWrite(const base::FilePath& path,
                                    FileWriteMode write_mode,
                                    bool world_readable);
 
+//! \brief Wraps `lseek()` or `SetFilePointerEx()`. Logs an error if the
+//!     operation fails.
+//!
+//! Repositions the offset of the open \a file to the specified \a offset,
+//! relative to \a whence. \a whence must be one of `SEEK_SET`, `SEEK_CUR`, or
+//! `SEEK_END`, and is interpreted in the usual way.
+//!
+//! \return The resulting offset in bytes from the beginning of the file, or
+//!     `-1` on failure.
+FileOffset LoggingSeekFile(FileHandle file, FileOffset offset, int whence);
+
 //! \brief Wraps `close()` or `CloseHandle()`, logging an error if the operation
 //!     fails.
 //!
 //! \return On success, `true` is returned. On failure, an error is logged and
 //!     `false` is returned.
 bool LoggingCloseFile(FileHandle file);
 
 //! \brief Wraps `close()` or `CloseHandle()`, ensuring that it succeeds.
 //!
 //! If the underlying function fails, this function causes execution to
 //! terminate without returning.
 void CheckedCloseFile(FileHandle file);
 
 }  // namespace crashpad
 
 #endif  // CRASHPAD_UTIL_FILE_FILE_IO_H_