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From Jeff Trawick <>
Subject Re: Question re mod_proxy_fcgi.c and mod_authnz_fcgi.c
Date Thu, 12 Dec 2013 21:11:06 GMT
On Thu, Dec 12, 2013 at 3:54 PM, Kean Johnston <>wrote:

> On 12/12/2013 10:11 PM, Jeff Trawick wrote:
>> There's nothing magic about it, and there is indeed the potential for a
>> problem with the environment variable limitation.  Generally I preferred
>> to
>> have a lower per-request memory use even if it takes another write to send
>> all the envars to the application.
> But if I am reading the code correctly, increasing that number wont
> increase the per-request size at all, unless the environment is huge. If
> the total environment only took say 2K, that's all that would be allocated.
> All I can see from that limit I mentioned is limiting the size of 1
> individual environment entry. Admittedly not something you'd run into every
> day but I can see no downside to making that be AP_FCGI_MAX_CONTENT_LEN.
> Just my $0.02. I'm a complete Apache neophyte and you're a commiter so I
> won't argue :)

Making it AP_FCGI_MAX_CONTENT_LEN (64K) is certainly not going to make any
difference in most configurations, and in addition support the largest
possible envvar...

I'm sure I was coming at it from this angle:  The original code wouldn't
allow more than 64K *total* in envvar space; how could I allow a mostly
arbitrary collection of envvars to be sent, though keeping small-ish I/O
(as httpd does on the client side) buffers while sending large collections.
 One possibility was a more complex API for packing the buffers; another
possibility was placing a limitation on the size that any particular envvar
could take up.

There's a happy medium -- generally using smaller buffers but making an
exception for a huge envvar.  The need for this would be triggered by the
length calculation stopping before the end (like the warning message
currently).  Is this overkill?  Probably so :)

Born in Roswell... married an alien...

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