[Webkit-unassigned] [Bug 82672] [Mac] XHR range requests are broken; affects pdf.js (Test failure: http/tests/xmlhttprequest/range-test.html)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=82672


Paolo Martini <mrtnpaolo at gmail.com> changed:

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                 CC|                            |mrtnpaolo at gmail.com




--- Comment #7 from Paolo Martini <mrtnpaolo at gmail.com>  2014-02-26 15:33:15 PST ---
I've just finished a long debugging session on a product that uses XHR range requests to fetch particular files from zip archives hosted on the server. I found a new work-around for the Safari bug. It has been tested and verified working on:

- OS X Mountain Lion - Safari Version 6.0.5 (8536.30.1)
- OS X Mavericks - Safari Version 7.0.1 (9537.73.11)
- iOS 7.0.6 (11B651)

The problem: the second request to the same file for a different range returns the same contents as the first one. Safari wrongly reports "Cached: no" in the relevant line of the network tab of the developer tools. It also ignores "pragma=no-cache" headers, if added.

The solution: I succeeded in making it throw away the old request by making each request unique. I accomplished this by generating a random string and adding the following header: If-None-Match: "<random string>".

After this change Safari began returning the right contents from the new specified range of the file.

This should let the web developers deploy a new and better work-around for their products instead of resorting to disabling range requests altogether. I also hope it can help the webkit developers in pin-pointing where this problem stems from.

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