avformat: make avformat_network_init() explicitly optional

It was sort of optional before - if you didn't call it, networking was
initialized on demand, and an ugly warning was logged. Also, the doxygen
comments threatened that it would be made strictly required one day.

Make it explicitly optional. I would prefer to deprecate it fully, but
there might still be legitimate reasons to use this. But the average
user won't need it.

This is needed only for two reasons: to initialize TLS libraries like
OpenSSL and GnuTLS, and winsock.

OpenSSL and GnuTLS were already silently initialized on demand if the
global network init function was not called. They also have various
thread-safety acrobatics, which make concurrent initialization within
libavformat safe. In addition, the libraries are moving towards making
their global init functions safe, which removes all need for central
global init. In particular, GnuTLS 3.5.16 and OpenSSL 1.1.0g have been
found to have safe init functions. In all cases, they use internal
reference counters to avoid that the global uninit functions interfere
with concurrent uses of the library by other API users who called global
init.

winsock should be thread-safe as well, and maintains an internal
reference counter as well.

Since we still support ancient TLS libraries, which do not have this
fixed, and since it's unknown whether winsock and GnuTLS
reinitialization is costly in any way, don't deprecate the libavformat
functions yet.

1 files changed, 0 insertions, 9 deletions

diff --git a/libavformat/network.c b/libavformat/network.c
index e9eb4b443a..d5c82e9ab9 100644
--- a/libavformat/network.c
+++ b/libavformat/network.c
@@ -54,20 +54,11 @@ void ff_tls_deinit(void)
 #endif
 }
 
-int ff_network_inited_globally;
-
 int ff_network_init(void)
 {
 #if HAVE_WINSOCK2_H
     WSADATA wsaData;
-#endif
 
-    if (!ff_network_inited_globally)
-        av_log(NULL, AV_LOG_WARNING, "Using network protocols without global "
-                                     "network initialization. Please use "
-                                     "avformat_network_init(), this will "
-                                     "become mandatory later.\n");
-#if HAVE_WINSOCK2_H
     if (WSAStartup(MAKEWORD(1,1), &wsaData))
         return 0;
 #endif