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Posted to derby-dev@db.apache.org by "Bryan Pendleton (JIRA)" <de...@db.apache.org> on 2005/11/06 19:37:20 UTC
[jira] Updated: (DERBY-668) SysInfo can give misleading information when JDBC jars are loaded from jre/lib/ext
[ http://issues.apache.org/jira/browse/DERBY-668?page=all ]
Bryan Pendleton updated DERBY-668:
----------------------------------
Attachment: Derby-668.diff
Here is a fix. The fix uses two techniques to detect the case where the DB2Driver class did not come from the expected jar file in the classpath, but rather was loaded from some location (e.g., JAVA_HOME/jre/lib/ext):
1) Using the JavaWorld Tip 105 technique, we ask the DB2Driver classfile itself for the location from which it was loaded, and we print that location, rather than just assuming that the class was loaded from the db2jcc.jar in the application class path.
2) If the DB2Driver class has a different class loader than the sysinfo Main class's class loader, we print a warning.
To see the effects of this patch, you can run the following experiment:
a) First, run sysinfo with db2jcc.jar in your classpath as normal.
b) Second, copy db2jcc.jar into JAVA_HOME/jre/lib/ext and re-run sysinfo with the same classpath. Note that it detects where DB2Driver was *really* loaded from, and displays that information.
> SysInfo can give misleading information when JDBC jars are loaded from jre/lib/ext
> ----------------------------------------------------------------------------------
>
> Key: DERBY-668
> URL: http://issues.apache.org/jira/browse/DERBY-668
> Project: Derby
> Type: Bug
> Components: Build tools
> Versions: 10.1.1.0
> Reporter: Bryan Pendleton
> Priority: Minor
> Attachments: Derby-668.diff
>
> There is a section in the SysInfo tool's output titled "Derby Information", which prints location and version information for the major Derby jars. Here is an example of that output:
> --------- Derby Information --------
> JRE - JDBC: J2SE 1.4.2 - JDBC 3.0
> [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derby.jar] 10.2.0.0 alpha - (315052M)
> [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbytools.jar] 10.2.0.0 alpha - (315052M)
> [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbynet.jar] 10.2.0.0 alpha - (315052M)
> [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbyclient.jar] 10.2.0.0 alpha - (315052M)
> [/home/bpendleton/downloads/derby/db2jcc/lib/db2jcc.jar] 2.4 - (17)
> [/home/bpendleton/downloads/derby/db2jcc/lib/db2jcc_license_c.jar] 2.4 - (17)
> Unfortunately, this tool can be fooled if you arrange for one of these jar files to be loaded from a magic location like $JAVA_HOME/jre/lib/ext.
> For example, I had (accidentally) placed an old version of db2jcc.jar into $JAVA_HOME/jre/lib/ext. When I ran SysInfo, it printed out:
> --------- Derby Information --------
> JRE - JDBC: J2SE 1.4.2 - JDBC 3.0
> [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derby.jar] 10.2.0.0 alpha - (315052M)
> [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbytools.jar] 10.2.0.0 alpha - (315052M)
> [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbynet.jar] 10.2.0.0 alpha - (315052M)
> [/home/bpendleton/src/derby-subversion/trunk/jars/insane/derbyclient.jar] 10.2.0.0 alpha - (315052M)
> [/home/bpendleton/downloads/derby/db2jcc/lib/db2jcc.jar] 1.0 - (581)
> [/home/bpendleton/downloads/derby/db2jcc/lib/db2jcc_license_c.jar] 1.0 - (581)
> However, the "1.0 (581)" information actually came from $JAVA_HOME/jre/lib/ext/db2jcc.jar, NOT from
> /home/bpendleton/downloads/derby/db2jcc/lib/db2jcc.jar.
> It would be nice if SysInfo could detect the difference between a jar file being loaded via the application class loader using $CLASSPATH, and a jar file being loaded via the system class loader using JDK library extensions.
> To reproduce the problem, simply:
> 1) Place an older version of db2jcc.jar into $JAVA_HOME/jre/lib/ext
> 2) Place a newer version of db2jcc.jar into your $CLASSPATH
> 3) Run SysInfo. You will see that it prints the name of the jarfile from $CLASSPATH, but the version info from the JDK copy.
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