On Tue, 15 Sep 2015, David Chapman wrote:

  If you're using libcurl as a win32 DLL, you MUST use the
  CURLOPT_WRITEFUNCTION if you set this option or you will experience
  crashes.

Due to how ownership of that FILE pointer is handled.

I don't think the wording here is at all clear. Are you saying that when cURL is used as a Win32 DLL, fwrite is not a valid CURLOPT_WRITEFUNCTION even if passed in explicitly?

Hm, yes I guess that is the logical conclusion and it is a good question. I'm not sure, maybe our way of using it makes it different? The problem has something to do with the FILE * being owned by the application and it can't pass it on to the DLL to be accessed from there, but the flow isn't 100% clear to me.

Or are you saying that use of NULL as a CURLOPT_WRITEFUNCTION is not valid when cURL is used as a Win32 DLL, and that a pointer to fwrite must be passed in (or else the call should be skipped)?

The regular way we've phrased it, is that you need to implement a write callback. I'm not sure what happens if you just put fopen there.

All this is just info I've gathered and learned from other libcurl users, I am myself not an experienced wanderer in the world of Windows memory setups and concepts.

In either case, the documentation in the CURLOPT_WRITEFUNCTION page should have the same warning. You don't want pages to be inconsistent with each other.

Agreed!

--

 / daniel.haxx.se
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