Need help opening printer spool shadow file (.SHD) that is locked

Question

I'm interested in some information inside a shadow file (.shd) located inside the windows print spooling directory "C:\Windows\System32\spool\PRINTERS". Every time a print job is started, a spool file (.spl) and a shadow file (.shd) are created in that directory. So far I have been successful in detecting when a print job has started, and have been able to pause that print job. If you don't pause the job, the files eventually make their way to the printer and then are deleted by windows.

My problem is. I cannot open the .SHD files because they are locked in such a way that you can not read them while they are open by the sprint spooler. I've even tried going to the file in windows explorer and simply copying the file to another file, and that didn't work either. The .SPL spool files I can open though. I simply wait, and fairly quickly the spooler release that file. For the shadow file though, it permanently holds on to this file. Unfortunately, its the one I need.

The line of code I'm using specifically to open the file is as follows:

m_spoolJobStream = new FileStream(spoolFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

The IOException I get is:

The process cannot access the file 'C:\Windows\system32\spool\PRINTERS\FP00083.SHD' because it is being used by another process.

So yes, it is being used by another process. Its being used by the window's print spooler service. But I don't think there is anything I can do about that. All I want to do is read the file. I don't want to make any changes to it. Is there anything I can do here or am I just screwed?

Answer 1

Well, I did not find a way around this problem. I suspect there is no solution for this and it is by design. However I did find another way to get the information I wanted (at least it seems so thus far).

I'm using the FindNextPrinterChangeNotification() routine out of the winspool.drv library. This guy returns a pointer to a PRINTER_NOTIFY_INFO structure, which in turn contains an array of PRINTER_NOTIFY_INFO_DATA structures. Within that array, there is an element with its "Field" member marked as "JOB_NOTIFY_FIELD_DEVMODE". This element contains a fairly large structure of type DEVMODE. The structure is explained by M$ here http://msdn.microsoft.com/en-us/library/dd183565%28v=vs.85%29.aspx . This structure looks like it contains what I'm looking for and apparently is wrapped up in the .SHD file anyways according to this page http://www.undocprint.org/formats/winspool/shd. I'd like to know what else is in that .SHD file, but I still can't open it because its locked while the job is paused, and I suspect that it stays locked until the job is complete. Oh well, I think my new solution is more elegant anyways.

Answer 2

Check the option: "Keep printed documents" (if you have HP printer) and then see your spool file folder, both shadow and spool files would be there.

Answer 3

Just make sure you pause the job in the spool on BOTH your box and the server, then you should be able to copy/open/move the shd file just like you can the spl file. Worked for me, anyway...

Answer 4

This works for me:
- Hang your printer (e.g. jam the paper)
- Print and observe .SHD and .SPL being created
- Stop Print Spooler
- Open the file

Answer 5

The problem might be the FileShare.ReadWrite parameter. You're asking to read and write on the file and maybe that's why you get an error. You should try asking for read-only permission.