259 lines
7.2 KiB
HTML
259 lines
7.2 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>Qp0zPipe()--Create Interprocess Channel with Sockets</title>
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</head>
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<body>
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<script language="Javascript" src="../rzahg/synch.js" type="text/javascript">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>Qp0zPipe()--Create Interprocess Channel with Sockets</h2>
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<div class="box" style="width: 60%;">
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<br>
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Syntax<br>
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<pre>
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#include <spawn.h>
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int Qp0zPipe(int <em>fildes[2]</em>);
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</pre>
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Service Program Name: QP0ZSPWN<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>Qp0zPipe()</strong> function creates a data pipe that can be
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used by two processes. One end of the pipe is represented by the file
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descriptor returned in <em>fildes[0]</em>. The other end of the pipe is
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represented by the file descriptor returned in <em>fildes[1]</em>. Data that is
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written to one end of the pipe can be read from the other end of the pipe in a
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first-in-first-out basis. Both ends of the pipe are open for reading and
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writing.</p>
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<p>The <strong>Qp0zPipe()</strong> function is often used with the <strong>
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spawn()</strong> function to allow the parent and child processes to send data
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to each other.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong><em>fildes[2]</em></strong></dt>
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<dd>(Input) An integer array of size 2 that will contain the pipe
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descriptors.</dd>
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</dl>
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<br>
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<h3>Authorities</h3>
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<p>None.</p>
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<br>
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<h3>Return Value</h3>
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<table cellpadding="5">
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<!-- cols="5 95" -->
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<tr>
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<td align="left" valign="top"><em>0</em></td>
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<td align="left" valign="top"><strong>Qp0zPipe()</strong> was successful.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>-1</em></td>
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<td align="left" valign="top"><strong>Qp0zPipe()</strong> was not successful.
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The <em>errno</em> variable is set to indicate the error.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>Qp0zPipe()</strong> is not successful, <em>errno</em> usually
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indicates one of the following errors. Under some conditions, <em>errno</em>
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could indicate an error other than those listed here.</p>
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<table cellpadding="5">
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<!-- cols="25 75" -->
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<tr>
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<th align="left" valign="bottom">Error condition</th>
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<th align="left" valign="bottom">Additional information</th>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EFAULT">EFAULT</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EINVAL">EINVAL</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EIO">EIO</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EMFILE">EMFILE</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENFILE">ENFILE</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOBUFS">ENOBUFS</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[<a href="unix14.htm#EOPNOTSUPP">EOPNOTSUPP</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EUNKNOWN">EUNKNOWN</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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</table>
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<br>
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<h3><a name="USAGE_NOTES">Usage Notes</a></h3>
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<p>The i5/OS implementation of the <strong>Qp0zPipe()</strong>function is
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based on sockets rather than pipes and, therefore, uses socket descriptors.
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There are several differences:</p>
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<ol>
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<li><p>After calling the <strong>fstat()</strong> function using one of the file
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descriptors returned on a Qp0zPipe() call, when the <samp>st_mode</samp> from
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the <samp>stat</samp> structure is passed to the S_ISFIFO() macro, the return
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value indicates FALSE. When the <samp>st_mode</samp> from the <samp>stat</samp>
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structure is passed to S_ISSOCK(), the return value indicates TRUE.</p></li>
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<li><p>The file descriptors returned <strong>on a Qp0zPipe()</strong> call can be
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used with the <strong>send()</strong>, <strong>recv()</strong>, <strong>
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sendto()</strong>, <strong>recvfrom()</strong>, <strong>sendmsg()</strong>, and
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<strong>recvmsg()</strong> functions.</p></li>
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<li>If this function is called
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by a thread executing one of the scan-related exit programs (or any of its
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created threads), the descriptors that are returned are scan descriptors. See
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<a href="ifsopenexit.htm">Integrated File System Scan on Open Exit Programs</a>
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and <a href="ifscloseexit.htm">Integrated File System Scan on Close Exit
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Programs</a> for more information. If a process is spawned, these scan
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descriptors are not inherited by the spawned process and therefore cannot be
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used in that spawned process. Therefore, in this case, the descriptors returned
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by <strong>Qp0zPipe()</strong> function will only work within the same process.
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</li>
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</ol>
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<p>If you want to use the traditional implementation of pipes, in which the
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descriptors returned are pipe descriptors instead of socket descriptors, use
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the <strong>pipe()</strong> function.</p>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>spawn.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)
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</li>
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<li><a href="fstat.htm">fstat()</a>--Get File Information by Descriptor
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</li>
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<li><a href="pipe2.htm">pipe()</a>--Create an Interprocess Channel
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</li>
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<li><a href="spawn.htm">spawn()</a>--Spawn Process
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</li>
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<li><a href="socketp.htm">socketpair()</a>--Create a Pair of Sockets
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</li>
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<li><a href="stat.htm">stat()</a>--Get File Information</li>
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</ul>
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<br>
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<hr>
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API introduced: V4R1
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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