📄 fileio-sockets.html
字号:
<!-- 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>Sockets</TITLE><meta name="MSSmartTagsPreventParsing" content="TRUE"><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+"><LINKREL="HOME"TITLE="eCos Reference Manual"HREF="ecos-ref.html"><LINKREL="UP"TITLE="File System Support Infrastructure"HREF="fileio.html"><LINKREL="PREVIOUS"TITLE="Initialization and Mounting"HREF="fileio-mounting.html"><LINKREL="NEXT"TITLE="Select"HREF="fileio-select.html"></HEAD><BODYCLASS="CHAPTER"BGCOLOR="#FFFFFF"TEXT="#000000"LINK="#0000FF"VLINK="#840084"ALINK="#0000FF"><DIVCLASS="NAVHEADER"><TABLESUMMARY="Header navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">eCos Reference Manual</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><AHREF="fileio-mounting.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom"></TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="fileio-select.html"ACCESSKEY="N">Next</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="CHAPTER"><H1><ANAME="FILEIO-SOCKETS">Chapter 26. Sockets</H1><P>If a network stack is present, then the FILEIO infrastructure alsoprovides access to the standard BSD socket calls.</P><P>The netstack table contains entries which describe the networkprotocol stacks that are in the system image. Each resident stackshould export an entry to this table using the<TTCLASS="LITERAL">NSTAB_ENTRY()</TT> macro.</P><P>Each table entry has the following structure:</P><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">struct cyg_nstab_entry{ cyg_bool valid; // true if stack initialized cyg_uint32 syncmode; // synchronization protocol char *name; // stack name char *devname; // hardware device name CYG_ADDRWORD data; // private data value int (*init)( cyg_nstab_entry *nste ); int (*socket)( cyg_nstab_entry *nste, int domain, int type, int protocol, cyg_file *file );};</PRE></TD></TR></TABLE><P>This table is analogous to a combination of the filesystem and mounttables.</P><P>The <TTCLASS="STRUCTFIELD"><I>valid</I></TT> field is set<TTCLASS="LITERAL">true</TT> if the stack's <TTCLASS="FUNCTION">init()</TT>function returned successfully and the<TTCLASS="STRUCTFIELD"><I>syncmode</I></TT> field contains the<TTCLASS="LITERAL">CYG_SYNCMODE_SOCK_*</TT> bits described above.</P><P>The <TTCLASS="STRUCTFIELD"><I>name</I></TT> field contains the name of theprotocol stack.</P><P>The <TTCLASS="STRUCTFIELD"><I>devname</I></TT> field names the device that the stack is using. This mayreference a device under "/dev", or may be a name that is onlymeaningful to the stack itself.</P><P>The <TTCLASS="FUNCTION">init()</TT> function pointer is called duringsystem initialization to start the protocol stack running. If itreturns non-zero the <TTCLASS="STRUCTFIELD"><I>valid</I></TT> field is setfalse and the stack will be ignored subsequently.</P><P>The <TTCLASS="FUNCTION">socket()</TT> function is called to attempt to create a socket in thestack. When the <TTCLASS="FUNCTION">socket()</TT> API function is called the netstack table isscanned and for each valid entry the <TTCLASS="FUNCTION">socket()</TT>function pointer is called. Ifthis returns non-zero then the scan continues to the next valid stack,or terminates with an error if the end of the table is reached.</P><P>The result of a successful socket call is an initialized file objectwith the <TTCLASS="STRUCTFIELD"><I>f_xops</I></TT> field pointing to thefollowing structure:</P><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">struct cyg_sock_ops{ int (*bind) ( cyg_file *fp, const sockaddr *sa, socklen_t len ); int (*connect) ( cyg_file *fp, const sockaddr *sa, socklen_t len ); int (*accept) ( cyg_file *fp, cyg_file *new_fp, struct sockaddr *name, socklen_t *anamelen ); int (*listen) ( cyg_file *fp, int len ); int (*getname) ( cyg_file *fp, sockaddr *sa, socklen_t *len, int peer ); int (*shutdown) ( cyg_file *fp, int flags ); int (*getsockopt)( cyg_file *fp, int level, int optname, void *optval, socklen_t *optlen); int (*setsockopt)( cyg_file *fp, int level, int optname, const void *optval, socklen_t optlen); int (*sendmsg) ( cyg_file *fp, const struct msghdr *m, int flags, ssize_t *retsize ); int (*recvmsg) ( cyg_file *fp, struct msghdr *m, socklen_t *namelen, ssize_t *retsize );};</PRE></TD></TR></TABLE><P>It should be obvious from the names of these functions which API callsthey provide support for. The <TTCLASS="FUNCTION">getname()</TT> functionpointer provides support for both <TTCLASS="FUNCTION">getsockname()</TT>and <TTCLASS="FUNCTION">getpeername()</TT> while the<TTCLASS="FUNCTION">sendmsg()</TT> and <TTCLASS="FUNCTION">recvmsg()</TT>function pointers provide support for <TTCLASS="FUNCTION">send()</TT>,<TTCLASS="FUNCTION">sendto()</TT>, <TTCLASS="FUNCTION">sendmsg()</TT>,<TTCLASS="FUNCTION">recv()</TT>, <TTCLASS="FUNCTION">recvfrom()</TT> and<TTCLASS="FUNCTION">recvmsg()</TT> as appropriate.</P></DIV><DIVCLASS="NAVFOOTER"><HRALIGN="LEFT"WIDTH="100%"><TABLESUMMARY="Footer navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top"><AHREF="fileio-mounting.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="ecos-ref.html"ACCESSKEY="H">Home</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top"><AHREF="fileio-select.html"ACCESSKEY="N">Next</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Initialization and Mounting</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="fileio.html"ACCESSKEY="U">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">Select</TD></TR></TABLE></DIV></BODY></HTML>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -