Added a utility to set the ssl library's MT hooks.

[jimfcarroll]

This should fix the MT problems with libraries that use SSL. Namely, libcurl. It sets openssl and/or gcrypt locking hooks. It expects gcrypt to be used only on LINUX like machines.

Currently the Windows implementation is missing (at least) the openssl header file(s).

@wiso, can you let me know what I need to do to get openssl/crypto.h installed on windows? We apparently already have the dll.

[jimfcarroll]

WiSo, sorry about the miss-ping (if you check).

@wsoltys is who I meant. ^^

[wsoltys]

hehe, WiSo = wsoltys so you pinged me twice ;)
We're using a precompiled libcurl from here http://www.gknw.de/mirror/curl/win32/old_releases/. Problem is every third party lib can ship it's own version of ssl. If we just have an eye on curl we can take the dev package of the version used by libcurl and put it in our dependency lib. We just have to take this version in future too if we need ssl somewhere else and want to use our dependency system (or bump it if we bump libcurl).
Let me see if I can cook something together today or tomorrow.

[wsoltys]

I've added the missing headers but getting unresolved external symbols for _CRYPTO_set_locking_callback and _CRYPTO_set_id_callback. To resolve them I would need the ssl import lib which fits to the ssl dll used by the third party build of libcurl which we don't have.
Do we have the curl locking in windows as well or can we skip this implementation?

[elupus]

Worth, noting: http://thread.gmane.org/gmane.comp.video.ffmpeg.cvs/43425

[wsoltys]

so we don't need any changes on win32. If worth I can change to a newer version of libcurl which uses openssl 1.0.0

[jimfcarroll]

If that's the case I'm going to simply add a destructor to clean up the locks then check this in. Is everyone Ok with that?

[ghost]

what a bloody mess. pull is fine with me.

[elupus]

We should do as done in that ffmpeg commit, only set the thread id for older versions.

[arnova]

I'm fine with this. Are you sure this works properly with libcurl-gnutls? I'm not that familar with the internals of this...

[jimfcarroll]

@arnova, I copied the code from an example and on my system HAVE_GCRYPT is true and it executes. I'm not sure how else to verify it since it's used indirectly anyway.

[davilla]

status on this pull/req ? I've been seeing reports of hangs and bt logs that point to

libcrypto.0.9.8.dylib 0x0276a6b8 lh_insert + 152

[jimfcarroll]

I have a code change that includes a simplification and cleanup (previous to this the locks don't get cleaned up) I didn't get a chance to check in this weekend. I'll do it shortly.

[jimfcarroll]

Ok, one more review would help.

[jimfcarroll]

Ok, I'm putting this in. Please let me know if it addresses the problems we've been seeing.