Re: Exception: System.NullReferenceException in 0capture

Hi Phil,

thank you for the bug reports. Regarding the two issues you submitted via
the feedback window:

* I've found the bug causing the crash in the "New Feed" Wizard and have
fixed it. I'll push out a 2.8.1 release soon.

* The crash in 0install caused by running the 0caputre feed was caused by
the missing <archive> (because --collect-files did not work). It still
should not have crashed and instead displayed a helpful error message. This
will also be fixed in an upcoming release.


A Zero Install feed needs an archive to extract an implementation from. Zero
Install can treat some installer formats (MSI, certain EXE installers) as
archives, but not all. Unfortunately DocFetcher's setup is not extractable
by Zero Install. For these non-extractable cases there are two solutions:

* Use the installer capture only to get desktop integration information but
then list a ZIP version of the application in the feed to get the actual
binaries. This is what "New Feed" Wizard would have offered if it hadn't
crashed first. ;)

* Create your own ZIP archive from the application's installation directory.
This is what "0capture --collect-files" is intended for; I just haven't
finished implementing it yet. I accidentally added --collect-files to the
public interface before it was ready. 


Looking at DocFetcher's installer I noticed it doesn't perform any desktop
integration like adding file associations. In such cases the best solution
would usually be to use the portable ZIP as the basis for the feed and leave
out the capturing all together. The only problem with this is that the
portable version writes its config and database into its installation
directory while Zero Install expects implementation directories to be
immutable.

With most applications this can be solved by using a <recipe> to remove the
files that tell it to run in portable mode. However in DocFetcher's case the
compiled JARs differ between the portable and non-portable version. In
addition to deleting the "conf" and "indexes" directories,
"net.sourceforge.docfetcher_1.1.14_20150217-2200.jar" from the portable
version needs to be replaced with
"net.sourceforge.docfetcher_1.1.14_20150217-2213.jar" from the installer
version.

I have created a feed that does all this. Additionally, on Windows the feed
bypasses DocFetcher.exe in order to allow Zero Install to provide a Java
implementation from its cache (rather than requiring it to be installed in
"C:\Program Files\Java").
I have uploaded the feed to: http://0install.de/feeds/DocFetcher.xml
Please let me know whether this is a suitable starting point for you. Sorry
that this turned out to be so complicated. Perhaps we can get in touch with
the DocFetcher developers to simplify the process for future releases.

Regards
Bastian


-----Original Message-----
From: [email protected]
[mailto:[email protected]] 
Sent: Dienstag, 12. Mai 2015 16:26
To: [email protected]
Subject: Re: [Zero-install-devel] Exception: System.NullReferenceException
in 0capture

Bastian,
                That fixed the problem, but I found another one or two. 
When the “--collect-files” command line flag was included, a new error was
output.
I also attempted to use the “New Feed” wizard but it also failed. I sent the
debug info for that from the UI.

Input and output

C:\temp\docfetcher>0capture start dockfetcher.snapshot
<ran installer>
C:\temp\docfetcher>0capture finish dockfetcher.snapshot docfetcher.xml
--installation-dir="C:\Program Files (x86)\DocFetcher"
--main-exe=DocFetcher.exe --collect-files
Searching for executable files...
[====================] Complete

Unhandled Exception: System.NotImplementedException: The method or operation
is not implemented.
   at ZeroInstall.Capture.Cli.CaptureCommand.Finish()
   at ZeroInstall.Capture.Cli.Program.Main(String[] args)

Thanks for fixing the original problem, I’ll go write a bug for this one.



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