[daemon] init method runs as downgraded user when the -user option is used with jsvc

[AGRO AGRO <ag...@hotmail.com>]

I've pretty much resigned to the fact that jsvc doesn't work as documented, specifically:

Daemon : Java Service
Downgrading user
On Linux setuid()/setgid() + capabilities are used. On other unix setgid/initgroups are used. We have something like:
/* as root */
init_JVM().
load_service. /*  java_load() calls the load method */
downgrade user (set_caps() or set_user_group())
/* as the user $USER (from -user $USER parameter) */
umask()
start_service. /* java_start() calls the start method */
http://commons.apache.org/proper/commons-daemon/jsvc.html

This document should probably read:

Downgrading user
On Linux setuid()/setgid() + capabilities are used. On other unix setgid/initgroups are used. We have something like:
/* as root */
downgrade user (set_caps() or set_user_group())
/* as the user $USER (from -user $USER parameter) */
init_JVM().
load_service. /*  java_load() calls the init method */
umask()
start_service. /* java_start() calls the start method */

The only avenue I wasn't able to exhaustively evaluate was loading the capability module. From what I can tell, this module was removed from a kernel version around 2.6.x and, since I'm using 3.10.x, I wasn't able to locate and load this module, which I'm not confident would have resulted in jsvc operating according to its documentation anyway.

To: user@commons.apache.org
Subject: [daemon]
Date: Fri, 7 Mar 2014 20:35:35 +1100

Hi,
    I'm using Daemon in a Java program on Linux using jsvc and find that, when using the -user option, the init method runs as the specified user rather than the user that launched jsvc, which according to the documentation and in my case is root. I have tried implementing this by implementing the Daemon interface and also the Direct way. If I understand the documentation correctly, when using the -user option, the init method is supposed to run as the calling user and then the process is forked and setuid is used to downgrade the process at which point the start method is called and runs as the non-privileged user specified by the user option, but this is not the behaviour I'm experiencing. I've compiled jsvc version 1.0.15 and am using Sun Java 1.7.0_45. When I run jsvc with the debug option, the output indicates it has changed the user to the non-privileged user before initialising the JVM. If I remove the -user option and run jsvc as root the code executed by the start method has elevated privilidges i.e. those of the root account. Is this expected behaviour, a bug or something I'm doing wrong?