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From Justin Erenkrantz <jus...@erenkrantz.com>
Subject Re: should input filter return the exact amount of bytes asked for?
Date Fri, 14 Nov 2003 08:48:09 GMT
--On Thursday, November 13, 2003 11:01 AM -0800 Stas Bekman <stas@stason.org> 
wrote:

> Should we add an explicit explanation to AP_MODE_READBYTES: return at most
> readbytes data. Can't return 0 with APR_BLOCK_READ. Can't return more than
> readbytes data.

I'd say the first and last one are equivalent statements.  And, that 
APR_BLOCK_READ description belongs with the definition of APR_BLOCK_READ not 
AP_MODE_READBYTES.

> Also while we are at it I have a few more questions:
>
>      /** The filter should return at most one line of CRLF data.
>       *  (If a potential line is too long or no CRLF is found, the
>       *   filter may return partial data).
>       */
>      AP_MODE_GETLINE,
>
> does it mean that the filter should ignore the readbytes argument in this
> mode?

I think so, yes.

>      /** The filter should implicitly eat any CRLF pairs that it sees. */
>      AP_MODE_EATCRLF,
>
> does it mean that it should do the same as AP_MODE_GETLINE but kill CRLF? If
> not how much data is it supposed to read? Or is it a mode that never goes on
> its own and should be OR'ed with some definitive mode, e.g.:
> AP_MODE_GETLINE|AP_MODE_EATCRLF and AP_MODE_READBYTES|AP_MODE_EATCRLF?

It's meant to be called right before we read the next pipelined request on the 
connection.  Old (really old) Netscape clients added spurious CRLFs between 
requests.  I don't see a clear rationale why it'd have to be 'combined' with 
other ap_get_brigade() modes.  The only one that'd make sense (to me) is 
AP_MODE_GETLINE.  Note that AP_MODE_EATCRLF doesn't necessarily return 
anything.  It's wildly HTTP specific...

> Though it'd be nice to add a note re: APR_BLOCK_READ in the
> AP_MODE_READBYTES doc above. Or I guess may be it belongs to some filters
> tutorial...

I'll note that I wrote an article on describing httpd-2.x's filters for some 
Linux magazine recently.  I bet you can find back issues.  As an aside, I 
never actually saw the final copy or the printed copy.  So, don't blame me if 
it doesn't help.  ;-)  -- justin

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