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NAME="FILEIO-INTRO">Chapter 19. Introduction</H1
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NAME="FILEIO-INTRO">Chapter 19. Introduction</H1
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><P
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><P
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>This document describes the filesystem infrastructure provided in
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>This document describes the filesystem infrastructure provided in
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eCos. This is implemented by the FILEIO package and provides POSIX
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eCos. This is implemented by the FILEIO package and provides POSIX
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compliant file and IO operations together with the BSD socket
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compliant file and IO operations together with the BSD socket
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API. These APIs are described in the relevant standards and original
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API. These APIs are described in the relevant standards and original
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documentation and will not be described here. See <A
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documentation and will not be described here. See <A
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>Chapter 31</A
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>Chapter 31</A
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> for details of which parts of the
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> for details of which parts of the
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POSIX standard are supported.</P
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POSIX standard are supported.</P
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><P
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><P
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>This document is concerned with the interfaces presented to client
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>This document is concerned with the interfaces presented to client
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filesystems and network protocol stacks.</P
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filesystems and network protocol stacks.</P
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><P
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><P
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>The FILEIO infrastructure consist mainly of a set of tables containing
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>The FILEIO infrastructure consist mainly of a set of tables containing
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pointers to the primary interface functions of a file system. This
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pointers to the primary interface functions of a file system. This
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approach avoids problems of namespace pollution (for example several
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approach avoids problems of namespace pollution (for example several
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filesystems can have a function called <TT
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filesystems can have a function called <TT
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CLASS="FUNCTION"
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CLASS="FUNCTION"
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>read()</TT
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>read()</TT
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>, so long as they are
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>, so long as they are
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static). The system is also structured to eliminate the need for
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static). The system is also structured to eliminate the need for
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dynamic memory allocation.</P
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dynamic memory allocation.</P
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><P
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><P
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>New filesystems can be written directly to the interfaces described
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>New filesystems can be written directly to the interfaces described
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here. Existing filesystems can be ported very easily by the
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here. Existing filesystems can be ported very easily by the
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introduction of a thin veneer porting layer that translates FILEIO
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introduction of a thin veneer porting layer that translates FILEIO
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calls into native filesystem calls. </P
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calls into native filesystem calls. </P
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><P
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><P
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>The term filesystem should be read fairly loosely in this
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>The term filesystem should be read fairly loosely in this
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document. Object accessed through these interfaces could equally be
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document. Object accessed through these interfaces could equally be
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network protocol sockets, device drivers, fifos, message queues or any
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network protocol sockets, device drivers, fifos, message queues or any
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other object that can present a file-like interface.</P
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other object that can present a file-like interface.</P
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