327 lines
11 KiB
HTML
327 lines
11 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Example: Saving and restoring system-level environment variables" />
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<meta name="abstract" content="This two-part example illustrates how to save the current set of system-level environment variables and restore them later." />
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<meta name="description" content="This two-part example illustrates how to save the current set of system-level environment variables and restore them later." />
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<meta name="DC.Relation" scheme="URI" content="apiexmp.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="apiexsavvar" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Example: Saving and restoring system-level environment variables</title>
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</head>
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<body id="apiexsavvar"><a name="apiexsavvar"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Example: Saving and restoring system-level environment variables</h1>
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<div><p>This two-part example illustrates how to save the current set of
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system-level environment variables and restore them later.</p>
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<div class="section"><div class="note"><span class="notetitle">Note:</span> Read the <a href="codedisclaimer.htm">Code license and disclaimer information</a> for important
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legal information.</div>
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</div>
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<div class="section"><h4 class="sectiontitle">Saving system-level environment variables</h4><p>This program
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stores the system-level environment variables and the associated CCSIDs in
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a file for restoring later.</p>
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<p>Use the Create C Module (CRTCMOD) and the
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Create Program (CRTPGM) commands to create this program.</p>
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<p>Call this program
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with one parameter (the file to store the variable list and the CCSIDs).</p>
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<pre>/******************************************************************/
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/******************************************************************/
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/* */
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/* FUNCTION: Save the system-level environment variable list */
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/* and the CCSIDs in a file */
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/* */
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/* LANGUAGE: ILE C */
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/* */
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/* APIs USED: Qp0zGetAllSysEnv() */
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/* */
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/******************************************************************/
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/******************************************************************/
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#include <fcntl.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <qp0z1170.h>
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int main(int argc, char *argv[])
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{
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int fd, bw, rc;
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int listBufSize, ccsidBufSize, *ccsidBuf;
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char *listBuf;
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int numvar, sl, sc;
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if(argc != 2)
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{
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printf("Usage: call %s <filename>\n",argv[0]);
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printf("Example: call %s '/tmp/sev'\n",argv[0]);
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return -1;
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}
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sl = listBufSize = 1000;
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sc = ccsidBufSize = 1000;
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listBuf = (char *)malloc(listBufSize);
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ccsidBuf = (int *)malloc(ccsidBufSize);
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/* Create a file of specified name */
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/* If it exists, it is cleared out */
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/* Opened for writing */
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fd = open(argv[1], O_CREAT | O_WRONLY | O_TRUNC, S_IRWXU);
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if(fd == -1)
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{
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printf("open() failed. errno = %d\n", errno);
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return -1;
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}
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rc = Qp0zGetAllSysEnv(listBuf, &listBufSize, ccsidBuf,
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&ccsidBufSize, NULL);
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if(rc != 0)
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{
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/* If there are no variables to save, write a */
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/* zero into the file and return success */
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if(rc == ENOENT)
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{
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numvar = 0;
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bw = write(fd, &numvar, sizeof(int));
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close(fd);
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printf("No system-level environment variables to save");
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return 0;
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}
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if(rc != ENOSPC)
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{
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printf("Error using Qp0zGetAllSysEnv(), errno = %d\n", rc);
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return -1;
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}
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/* rc = ENOSPC. size of buffer is not enough */
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/* change buffer size and try again */
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/* If listBuf is not large enough, */
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/* allocate more space */
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if(listBufSize > sl)
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{
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listBuf = (char *)realloc(listBuf, listBufSize);
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}
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/* If ccsidBuf is too small, allocate */
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/* more space */
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if(ccsidBufSize > sc)
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{
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ccsidBuf = (int *)realloc(ccsidBuf, ccsidBufSize);
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}
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rc = Qp0zGetAllSysEnv(listBuf, &listBufSize,
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ccsidBuf, &ccsidBufSize, NULL);
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if(rc != 0)
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{
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printf("Error using Qp0zGetAllSysEnv(), errno = %d\n", rc);
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return -1;
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}
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}
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/* Write the contents of the buffer into the file */
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/* First write the total number of ccsid values */
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/* This is the total number of variables */
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numvar = ccsidBufSize/sizeof(int);
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bw = write(fd, &numvar, sizeof(int));
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if(bw == -1)
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{
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printf("write() of total number of ccsids failed. errno = %d\n", errno);
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return -1;
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}
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/* Next write the ccsid values */
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bw = write(fd, ccsidBuf, ccsidBufSize);
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if(bw == -1)
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{
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printf("write() of ccsid values failed. errno = %d\n", errno);
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return -1;
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}
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/* Now write the size (in bytes) of the listBuf */
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bw = write(fd, &listBufSize, sizeof(int));
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if(bw == -1)
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{
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printf("write() of listBufSize failed. errno = %d\n", errno);
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return -1;
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}
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/* Finally write the listBuf containing the variable strings*/
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bw = write(fd, listBuf, listBufSize);
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if(bw == -1)
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{
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printf("write() of listBuf failed. errno = %d\n", errno);
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return -1;
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}
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/* Close the file */
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rc = close(fd);
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if(rc != 0)
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{
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printf("close() failed. errno = %d\n", errno);
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return -1;
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}
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printf("System-level environment variables saved\n");
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return 0;
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}</pre>
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</div>
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<div class="section"><h4 class="sectiontitle">Restoring system-level environment variables</h4><p>This
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program reads the system-level environment variable list from a file and then
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sets the system-level environment variables.</p>
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<p>Use the Create C Module
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(CRTCMOD) and the Create Program (CRTPGM) commands to create this program.</p>
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<p>Call
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this program with one parameter (the name of the file in which the system-level
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environment variables were stored).</p>
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<pre>/******************************************************************/
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/******************************************************************/
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/* */
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/* FUNCTION: Restore the system-level environment variable list */
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/* and the associated CCSIDs stored in a file */
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/* */
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/* LANGUAGE: ILE C */
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/* */
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/* APIs USED: Qp0zPutSysEnv() */
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/* */
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/******************************************************************/
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/******************************************************************/
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#include <fcntl.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <qp0z1170.h>
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int main(int argc, char *argv[])
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{
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int fd, rc, br, i, numvar;
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int ccsidBufSize = 0, listBufSize = 0, *ccsidBuf;
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char *listBuf;
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if (argc != 2)
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{
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printf("Usage: call %s <filename>\n",argv[0]);
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printf("Example: call %s '/tmp/sev'\n",argv[0]);
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return -1;
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}
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/* Open the file specified */
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fd = open(argv[1], O_RDONLY);
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if(fd == -1)
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{
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printf("open() failed. errno = %d\n", errno);
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return -1;
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}
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/* Get the number of variables */
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br = read(fd, &numvar, sizeof(int));
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if(br == -1)
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{
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printf("read() failed. errno = %d\n", errno);
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return -1;
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}
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/* Could delete the existing system-level environment */
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/* variables and have only the restored values. */
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/* If so desired, could call Qp0zDltSysEnv() to do so */
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/* If there aren't any elements in the file, skip the rest of */
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/* the reads and go to the end */
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if(numvar > 0)
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{
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ccsidBufSize = numvar*sizeof(int);
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ccsidBuf = (int *)malloc(ccsidBufSize);
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/* Read the ccsid values and put it in ccsidBuf */
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br = read(fd, ccsidBuf, ccsidBufSize);
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if(br == -1)
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{
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printf("read() failed. errno = %d\n", errno);
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return -1;
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}
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/* Read the size of the list buffer and put it in listBufSize */
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br = read(fd, &listBufSize, sizeof(int));
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if(br == -1)
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{
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printf("read() failed. errno = %d\n", errno);
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return -1;
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}
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listBuf = (char *)malloc(listBufSize);
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/* Finally read the strings themselves */
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br = read(fd, listBuf, listBufSize);
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if(br == -1)
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{
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printf("read() failed. errno = %d\n", errno);
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return -1;
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}
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}
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/* Walk through the buffer and get the */
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/* name=value strings one by one */
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/* Use Qp0zPutSysEnv() to set the values */
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for(i = 0; i < numvar; i++)
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{
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rc = Qp0zPutSysEnv(listBuf, ccsidBuf[i], NULL);
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if(rc != 0)
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{
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printf("Qp0zPutSysEnv() failed. rc=%d\n",rc);
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return -1;
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}
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listBuf += strlen(listBuf) + 1;
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}
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close(fd);
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printf("System-level environment variables restored\n");
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return 0;
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}</pre>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="apiexmp.htm" title="Contains example programs that use APIs and exit programs.">Examples: APIs</a></div>
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</div>
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</div>
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</body>
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</html>
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