[help-cgicc] File upload memory usage

[Dries Deschout]

Hello,

While upgrading compilers from GCC 4.7 to GCC 7.2 on an embedded device, I noticed a substantial increase in memory usage while parsing a file upload request.

This seems to be caused by changed behavior in std::string. As GCC 4.7 was using copy-on-write and refcounting for std::string, a string copy did not cause a copy of the data. Now with GCC 7.2, a string copy also copies the data. For some large (+30MB) requests, this now makes our application go out-of-memory on a embedded device with only 128MB of RAM.

To bring memory usage back to the GCC 4.7 values, I patched Cgicc::parseMIME to std::move the data to the FormFile and FormEntry (see attached patch).

As this patch is using some C++ 11 features, I was wondering if you do accept patches that (conditionally) use C++ 11 (or higher) features?

I could rework the patch to only use those features when supported by the __cplusplus version.

Best Regards,

Dries

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01-move-form-data.patch
Description: 01-move-form-data.patch