Re: [Aglets-users] Fwd: Urgent need help! Problem with file access permissions-Aglets

[shruti n. <shr...@gm...>]

Hi Thomas,

Thank you for the prompt reply. I think I understood what you're trying to
say, I still have one doubt, there are 3 codebase sections in the
aglets.policy file (atp, http, file), to which should I give
the necessary permissions.


Thanks again!

Regards
Shruti

On Sun, Apr 1, 2012 at 12:27 AM, Thomas Herlea <
max...@us...> wrote:

> (Forgot to send this to the list)
>
>
> ---------- Forwarded message ----------
> From: Thomas Herlea <max...@us...>
> Date: Sat, Mar 31, 2012 at 19:23
> Subject: Re: Urgent need help! Problem with file access permissions-Aglets
> To: shruti nagani <shr...@gm...>
>
>
> Dear Shruti,
>
> The security exception you got does not mean the aglet is prevented
> from accessing the file, but that it is prevented from finding out
> what the current directory is. That is what the 'user.dir' property
> stores. See
> http://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html
> for a list of system properties. Perhaps you are using a relative path
> to your file in your code and therefore at some point the method for
> accessing the file has to first look up the current directory, at
> which point it throws the exception.
>
> You can use the AccessControlException messages to guide you in adding
> the required permission to the 'aglets.policy' file. It mentions the
> missing permission type, 'java.util.PropertyPermission', so you should
> look it up to see how it is granted
> (
> http://docs.oracle.com/javase/7/docs/technotes/guides/security/permissions.html#PropertyPermission
> ).
>  You will discover the parameters available when granting it. These
> parameters are specific to the permission type, so you really need to
> look in yhe documentation. For PropertyPermission you specify a
> pattern to match one or more properties, in your case 'user.dir' or
> something with wildcards which covers 'user.dir', too. Then you
> provide in the grant of a PropertyPermission an action about the
> property or properties matching the first parameter. In your case
> 'read' is needed, but you also can grant a 'write' permission or both,
> using the list syntax specified in the documentation.
>
> I think it is an interesting problem to determine during development
> which permissions an aglet may need. Does anyone know a more automated
> method than looking up in the API documentation which
> AccessControlExceptions every method call might throw? The guide
> linked to above does have a section "Methods and the Permissions They
> Require", but if the method listed there is called internally by
> another standard library method which you call, I don't know if it is
> easy to determine what exceptions may be thrown indirectly like that.
>
> Good luck!
>
> Thomas
>
>
>
> On Sat, Mar 31, 2012 at 16:28, shruti nagani <shr...@gm...>
> wrote:
> >
> > Hi,
> >
> > I am accessing a file on my system from an aglet whose code is also on
> my system
> > I am getting the following exception:
> >
> > java.security.AccessControlException:access denied
> ("java.util.PropertyPermission" "user.dir" "read")
> >
> > at java.security...etc etc
> >
> >
> > I edited the aglets.policy in $HOME/.aglets/security and appended the
> following line
> >
> > permission java.io.FilePermission
>  "C:\\Users\\new\\Documents\\arffs\\bayes_labeled.arff", "read";
> >
> > to all 3 sections, (atp, http and file)
> >
> > bayes_labeled.arff is the file I need to read
> >
> > I am still getting the same exception. Please someone tell what am I
> doing wrong here?
> >
> > I'll be very grateful! Have been stuck on this for the past week.
> >
> > Thanks a tonne in advance!!
> >
> > Shruti
>
>
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