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Re: Clipboard API: remove dangerous formats from mandatory data types

From: Chaals McCathie Nevile <chaals@yandex-team.ru>
Date: Tue, 28 Jul 2015 11:40:22 -0400
To: "Hallvord Reiar Michaelsen Steen" <hsteen@mozilla.com>
Cc: "Daniel Cheng" <dcheng@google.com>, public-webapps <public-webapps@w3.org>
Message-ID: <op.x2hptkr3s7agh9@widsith.local>
On Tue, 28 Jul 2015 08:24:17 -0400, Hallvord Reiar Michaelsen Steen  
<hsteen@mozilla.com> wrote:

> On Tue, Jul 28, 2015 at 1:08 PM, Chaals McCathie Nevile <
> chaals@yandex-team.ru> wrote:
>> I'm just thinking out loud here, but this problem is similar to one
>> already faced by email clients, especially those which are web-based...
>> On Mon, 27 Jul 2015 15:03:40 -0400, Hallvord Reiar Michaelsen Steen <
>> hsteen@mozilla.com> wrote:
>>  So PNG, JPG et al go in the "support
>>> reading from clipboard" list, and the "support writing" starts out with
>>> text/plain, text/html and text/uri-list - although it would be nice if
>>> CSV was also considered safe enough.
>> I'm not sure you should directly read image formats from the clipboard,
>> especially if you don't know how they got there.
> What are your concerns exactly? As Wez mentioned we may have to add some
> transcoding - but if there's a chunk of binary data labelled as JPEG on  
> the clipboard, and the user wants to paste this into her blog editor,
> how would we do that if web content "shouldn't" read image formats from
> the clipboard?

Essentially only certain things would be delivered from the clipboard - a  
picture in the desired format, and hopefully a certain amount of metadata.  
But we would be pretty explicit that unexpected stuff may well be dropped  
- and probably *should* in various cases like images

(I think we might actually agree in practice, and be looking for words)


>> You shouldn't write stuff there that can be dangerous, but you really
>> shouldn't read it direct. So maybe what happens is that when stuff gets
>> written, it goes through a process like painting it onto a canvas, and  
>> then being scraped back off as coloured pixels and "safe" metadata.
> Indeed, if that's what it takes.. like the addImageFromCanvas()  
> suggestion below. Regarding that suggestion you asked:
>> Is it more than syntactic sugar?
> If we allow adding image data as blobs, the "normal" way with
> clipboardData.items.add() it would be just a convenience method. Since
> Daniel Cheng has serious concerns and good arguments against allowing  
> that, something like addImageFromCanvas() might be a workaround that
> would let users put images on the clipboard in a safe way.. If we have
> neither, I guess we'll see data:image/jpeg URLs placed on the clipboard
> as plain text.
> -Hallvord R.

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Received on Tuesday, 28 July 2015 15:40:55 UTC

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