Why are there zero-length files included in the downloads?

Why are there zero-length files included in the downloads?

Postby newton51 » 23.05.2017, 22:14

As per Windows WSUS service, this shouldn't occur (at least anymore):
https://blogs.technet.microsoft.com/wsu ... xport-bug/

Can anyone at this service comment on why these files are occurring?
newton51
 
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Re: Why are there zero-length files included in the download

Postby boco » 23.05.2017, 22:57

WSUS Offline Update is completely unrelated to the WSUS provided by Microsoft. We only make use of the same catalog.
Microsoft update catalog: http://catalog.update.microsoft.com/v7/site/
Windows Install media download: https://support.microsoft.com/en-us/help/15088/windows-create-installation-media
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Re: Why are there zero-length files included in the download

Postby newton51 » 24.05.2017, 17:12

Thanks for the follow up.

I guess I could have been more overt with my questioning. What is the need for these zero-length files? Do they really serve a purpose for the updates?

Case in point, I did not enable any Office updates, but these zero-length files (among others) are downloaded:
./wsusoffline/client/static/StaticUpdateIds-o2k10.txt
./wsusoffline/client/static/StaticUpdateIds-o2k13.txt
./wsusoffline/client/static/StaticUpdateIds-o2k16.txt
./wsusoffline/client/static/StaticUpdateIds-o2k7.txt
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Re: Why are there zero-length files included in the download

Postby boco » 24.05.2017, 21:08

Ah, yes, those. Placeholders. WOU uses commandline downloaders (like wget) to get the files. It refreshes the static definitions by downloading them from this site. That prevents the need to release a new version, every time static links change.
The important thing to know is: wget can only download, it cannot delete. So, the only way to effectively kill a file (that previously might have had contents that are now obsolete) is to download an empty file over it.
Otherwise, no file or zero-Byte file makes no difference.

Note that all static definitions will be refreshed, independent from your actual OS selection.


Follow-up: There's also a historical reason for placeholder files in archives: Some unpackers won't restore empty directories unless there is at least one file inside it. So, if restoring the directory structure is important, placeholders will ensure all directories are extracted.
Microsoft update catalog: http://catalog.update.microsoft.com/v7/site/
Windows Install media download: https://support.microsoft.com/en-us/help/15088/windows-create-installation-media
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