extern int _SysCopyFD(int srcfd, int dstfd);
extern int _SysFDFlags(int fd, int mask, int newflags);
extern size_t _SysRead(int fd, void *buffer, size_t length);
+extern size_t _SysReadAt(int fd, uint64_t offset, size_t length, void *buffer);
extern int _SysClose(int fd);
extern int _SysFDCtl(int fd, int option, ...);
extern size_t _SysWrite(int fd, const void *buffer, size_t length);
+extern size_t _SysWriteAt(int fd, uint64_t offset, size_t length, const void *buffer);
extern int _SysSeek(int fd, int64_t offset, int whence);
extern uint64_t _SysTell(int fd);
extern int _SysIOCtl(int fd, int id, void *data);