Merge commit '0a75d1da'

* commit '0a75d1da':
  options_table: refs option is not snow-only
  random_seed: Support using CryptGenRandom on windows
  doc: update the faq entry about custom I/O

Conflicts:
	doc/faq.texi
	libavcodec/options_table.h
Merged-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -1281,6 +1281,7 @@ HAVE_LIST="
     closesocket
     cmov
     cpunop
+    CryptGenRandom
     dcbzl
     dev_bktr_ioctl_bt848_h
     dev_bktr_ioctl_meteor_h
@@ -3540,6 +3541,7 @@ check_func_headers windows.h PeekNamedPipe
 check_func_headers io.h setmode
 check_func_headers lzo/lzo1x.h lzo1x_999_compress
 check_lib2 "windows.h shellapi.h" CommandLineToArgvW -lshell32
+check_lib2 "windows.h wincrypt.h" CryptGenRandom -ladvapi32
 check_lib2 "windows.h psapi.h" GetProcessMemoryInfo -lpsapi
 check_func_headers windows.h GetProcessAffinityMask
 check_func_headers windows.h GetProcessTimes

doc/faq.texi

@@ -467,8 +467,8 @@ to use them you have to append -D__STDC_CONSTANT_MACROS to your CXXFLAGS
 
 @section I have a file in memory / a API different from *open/*read/ libc how do I use it with libavformat?
 
-You have to implement a URLProtocol, see @file{libavformat/file.c} in
-FFmpeg and @file{libmpdemux/demux_lavf.c} in MPlayer sources.
+You have to create a custom AVIOContext using @code{avio_alloc_context},
+see @file{libavformat/aviobuf.c} in FFmpeg and @file{libmpdemux/demux_lavf.c} in MPlayer or MPlayer2 sources.
 
 @section Where can I find libav* headers for Pascal/Delphi?
 

libavutil/random_seed.c

@@ -23,6 +23,10 @@
 #if HAVE_UNISTD_H
 #include <unistd.h>
 #endif
+#if HAVE_CRYPTGENRANDOM
+#include <windows.h>
+#include <wincrypt.h>
+#endif
 #include <fcntl.h>
 #include <math.h>
 #include <time.h>
@@ -102,6 +106,17 @@ uint32_t av_get_random_seed(void)
 {
     uint32_t seed;
 
+#if HAVE_CRYPTGENRANDOM
+    HCRYPTPROV provider;
+    if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
+                            CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
+        BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed);
+        CryptReleaseContext(provider, 0);
+        if (ret)
+            return seed;
+    }
+#endif
+
     if (read_random(&seed, "/dev/urandom") == sizeof(seed))
         return seed;
     if (read_random(&seed, "/dev/random")  == sizeof(seed))