DR 10-0045 - OPC: Consistency of file length records with a ZIP archive

[Alex Brown]

In fact, I think these zero values in question are in the Local File Headers, not the Data Descriptors ... but the issues are the same ...

- Alex.

-----Original Message-----
From: Alex Brown 
Sent: 12 April 2011 14:54
To: 'Chris Rae'; e-SC34-WG4 at ecma-international.org
Subject: RE: DR 10-0045 - OPC: Consistency of file length records with a ZIP archive

Can't we prohibit the 0-length file records instead?

There is certainly one implementation (Office-o-tron) that relies on the removed paragraph about value consistency having force. Are we confident there are no others?

I'm not sure your characterisation of data descriptors as "optional" in OOXML is correct. Annex C states "Data describing files stored in the archive is substantially duplicated in the Local File Headers and Data Descriptors" which sort-of suggests they appear every time (and reinforces the notion that these values be consistent).

And the appnote Itself states: 

"     Immediately following the local header for a file
      is the compressed or stored data for the file. 
      The series of [local file header][file data][data
      descriptor] repeats for each file in the .ZIP archive."

Which seems to imply there is always exactly one data descriptor per compressed item.

Weren't we also concerned in Prague about a possible interrelation between this feature and interleaved stored content - might a de-interleaver require the data descriptor records to be correct?

- Alex.

-----Original Message-----
From: Chris Rae [mailto:Chris.Rae at microsoft.com] 
Sent: 12 April 2011 00:45
To: e-SC34-WG4 at ecma-international.org
Subject: DR 10-0045 - OPC: Consistency of file length records with a ZIP archive

http://cid-c8ba0861dc5e4adc.office.live.com/view.aspx/Public%20Documents/2010/DR-10-0045.docx

This DR covers the various mismatched headers in ZIP archives. 

We marked this DR down as "deferred" in the DR log, but I'm not actually sure that's right. I have in my notes that I was to work out whether removing the offending sentence in C1. I checked with the people who wrote this originally and they say that the C1 sentence wasn't intended to provide any meaning beyond what was already in the rest of the text, so I think we're safe to remove it.

Changes are attached.

Chris

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