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From "Daniel John Debrunner (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-668) SysInfo does not print the right information when Derby is not loaded through the classpath.
Date Tue, 28 Feb 2006 02:12:57 GMT
    [ http://issues.apache.org/jira/browse/DERBY-668?page=comments#action_12368063 ] 

Daniel John Debrunner commented on DERBY-668:
---------------------------------------------

Minor comments on the code

 -  would be good to make the comment for the new method getFileWhichLoadedClass a javadoc
method (use /** ... */) show that it shows up in the generated javadoc and IDE's.

- why check getProtectionDomain() for a null return when the javadoc does not indicate it
can return null?
  I personally don't like this coding style as it add code for no value, should we check all
methods that return references
   for null, even ones like String.trim()?  It can make the reader have to look to the javadoc
to see in what situations the method
can return null, to understand the code, only to find out it can't.

I'm trying to think through the ramifications of using getProtectionDomain() and hence possibly
needing the associated permission in the policy file. One issue is that this permission might
be needed for all derby jar files, since sysinfo is in all jars.
It probably comes down to what situations would we expect sysinfo to be executed with a security
manager present,
in those situations how likely is the policy file going to be configured to support sysinfo?
Since sysinfo is really meant to
be a quick check of the classpath, not an integral part of an application.



> SysInfo does not print the right information when Derby is not loaded through the classpath.
> --------------------------------------------------------------------------------------------
>
>          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
>     Assignee: Bryan Pendleton
>     Priority: Critical
>  Attachments: Derby-668.diff, derby-668-2.diff, derby-668-3.diff, derby-668-4.diff, sysinfo_Feb27_2006.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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