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<!-- Copyright (C) 2003 Red Hat, Inc. --> <!-- This material may be distributed only subject to the terms --> <!-- and conditions set forth in the Open Publication License, v1.0 --> <!-- or later (the latest version is presently available at --> <!-- http://www.opencontent.org/openpub/). --> <!-- Distribution of the work or derivative of the work in any --> <!-- standard (paper) book form is prohibited unless prior --> <!-- permission is obtained from the copyright holder. --> <HTML ><HEAD ><TITLE >Introduction</TITLE ><meta name="MSSmartTagsPreventParsing" content="TRUE"> <META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="eCos Reference Manual" HREF="ecos-ref.html"><LINK REL="UP" TITLE="File System Support Infrastructure" HREF="fileio.html"><LINK REL="PREVIOUS" TITLE="File System Support Infrastructure" HREF="fileio.html"><LINK REL="NEXT" TITLE="File System Table" HREF="fileio-fstab.html"></HEAD ><BODY CLASS="CHAPTER" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >eCos Reference Manual</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="fileio.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="fileio-fstab.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="CHAPTER" ><H1 ><A NAME="FILEIO-INTRO">Chapter 19. Introduction</H1 ><P >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 <A HREF="posix-standard-support.html" >Chapter 31</A > for details of which parts of the POSIX standard are supported.</P ><P >This document is concerned with the interfaces presented to client filesystems and network protocol stacks.</P ><P >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 <TT CLASS="FUNCTION" >read()</TT >, so long as they are static). The system is also structured to eliminate the need for dynamic memory allocation.</P ><P >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. </P ><P >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.</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="fileio.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ecos-ref.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="fileio-fstab.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >File System Support Infrastructure</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="fileio.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >File System Table</TD ></TR ></TABLE ></DIV ></BODY ></HTML >