[Cgicc-help] [help-cgicc] File upload memory usage

[Martin Oberhuber]

Hello Dries, dear cgicc users and maintainers -

Like others before [1][2][3], I have also found cgicc to require

an unreasonable amount of main memory when processing

uploaded files. In my case (cgicc-3.2.16, gcc-4.8.1, ARM Linux)

a 100MB uploaded file required 300MB main memory.

I debugged the case and noticed that parseMIME() can

easily avoid one of the two string::substring() usages,

thus cutting down memory usage to 200MB. 

I didn't pursue it further than that, though I found Dries'

arguments about  copy-on-write in the string class very interesting.

I suppose that c++17 string_view would also be interesting.

I believe that my patch (attached) is simple, safe and

fully portable and solves at least part of the problem.

Could it be considered for a future cgicc release?

Thanks,

Martin

[1] https://lists.gnu.org/archive/html/help-cgicc/2018-03/msg00000.html

[2] https://lists.gnu.org/archive/html/help-cgicc/2015-10/msg00000.html

[3] https://lists.gnu.org/archive/html/help-cgicc/2010-09/msg00000.html

cgicc-3.2.16-memopt.patch
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