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 the Posix Standard
Support documentation 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.
