[webkit-dev] localStorage quota limit

Darin Fisher darin at chromium.org
Wed Dec 2 21:07:49 PST 2009

On Wed, Dec 2, 2009 at 8:44 PM, Maciej Stachowiak <mjs at apple.com> wrote:

> On Dec 2, 2009, at 8:14 PM, Darin Fisher wrote:
> What about Maciej's comment.  JS strings are often use to store binary
> values.  Obviously, if people stick to octets, then it should be fine, but
> perhaps some folks leverage all 16 bits?
> I think some people do use JavaScript strings this way, though not
> necessarily with LocalStorage. This kind of use will probably become
> obsolete when we add a proper way to store binary data from the platform.
> Most Web-related APIs are fully accepting of JavaScript strings that are
> not proper UTF-16. I don't see a strong reason to make LocalStorage an
> exception. It does make sense for WebSocket to be an exception, since in
> that case charset transcoding is required by the protocol, and since it is
> desirable in that case to prevent any funny business that may trip up the
> server..
> Also, looking at UTF-16 more closely, it seems like all UTF-16 can be
> transcoded to UTF-8 and round-tripped if one is willing to allow technically
> invalid UTF-8 that encodes unpaired characters in the surrogate range as if
> they were characters. It's not clear to me why Firefox or IE choose to
> reject instead of doing this. This also removes my original objection to
> storing strings as UTF-8.
I think it is typical for UTF-16 to UTF-8 conversion to involve the
intermediate step of forming a Unicode code point.  If that cannot be done,
then conversion fails.  This may actually be a security thing.  If something
expects UTF-8, it is safer to ensure that it gets valid UTF-8 (even if that
involves loss of information).


> Regards,
> Maciej
> -Darin
> On Wed, Dec 2, 2009 at 5:03 PM, Ian Hickson <ian at hixie.ch> wrote:
>> On Wed, 2 Dec 2009, Michael Nordman wrote:
>> >
>> > Arguably, seems like a bug that invalid string values are let thru the
>> > door to start with?
>> Yeah, I should make the spec through SYNTAX_ERR if there are any unpaired
>> surrogates, the same way WebSocket does. I'll file a bug.
>> --
>> Ian Hickson               U+1047E                )\._.,--....,'``.    fL
>> http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
>> Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
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