This document describes the filesystem infrastructure provided in +eCos. This is implemented by the FILEIO package and provides POSIX +compliant file and IO operations together with the BSD socket +API. These APIs are described in the relevant standards and original +documentation and will not be described here. See Chapter 31 for details of which parts of the +POSIX standard are supported.
This document is concerned with the interfaces presented to client +filesystems and network protocol stacks.
The FILEIO infrastructure consist mainly of a set of tables containing +pointers to the primary interface functions of a file system. This +approach avoids problems of namespace pollution (for example several +filesystems can have a function called read(), so long as they are +static). The system is also structured to eliminate the need for +dynamic memory allocation.
New filesystems can be written directly to the interfaces described +here. Existing filesystems can be ported very easily by the +introduction of a thin veneer porting layer that translates FILEIO +calls into native filesystem calls.
The term filesystem should be read fairly loosely in this +document. Object accessed through these interfaces could equally be +network protocol sockets, device drivers, fifos, message queues or any +other object that can present a file-like interface.