avformat: add parent AVFormatContext to URLContext

Add a URLContext.fmt_ctx back-reference, set by io_open_default before
url_open() runs. Will be used to access shared resources per avfc.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>

libavformat/avio.c

@@ -365,16 +365,17 @@ int ffurl_alloc(URLContext **puc, const char *filename, int flags,
     return AVERROR_PROTOCOL_NOT_FOUND;
 }
 
-int ffurl_open_whitelist(URLContext **puc, const char *filename, int flags,
-                         const AVIOInterruptCB *int_cb, AVDictionary **options,
-                         const char *whitelist, const char* blacklist,
-                         URLContext *parent)
+static int url_open_whitelist(URLContext **puc, const char *filename, int flags,
+                              const AVIOInterruptCB *int_cb, AVDictionary **options,
+                              const char *whitelist, const char* blacklist,
+                              URLContext *parent, AVFormatContext *avfc)
 {
     AVDictionary *tmp_opts = NULL;
     AVDictionaryEntry *e;
     int ret = ffurl_alloc(puc, filename, flags, int_cb);
     if (ret < 0)
         return ret;
+    (*puc)->avfc = avfc;
     if (parent) {
         ret = av_opt_copy(*puc, parent);
         if (ret < 0)
@@ -415,6 +416,15 @@ fail:
     return ret;
 }
 
+int ffurl_open_whitelist(URLContext **puc, const char *filename, int flags,
+                         const AVIOInterruptCB *int_cb, AVDictionary **options,
+                         const char *whitelist, const char* blacklist,
+                         URLContext *parent)
+{
+    return url_open_whitelist(puc, filename, flags, int_cb, options,
+                              whitelist, blacklist, parent, NULL);
+}
+
 int ffio_fdopen(AVIOContext **sp, URLContext *h)
 {
     AVIOContext *s;
@@ -474,16 +484,18 @@ int ffio_fdopen(AVIOContext **sp, URLContext *h)
     return 0;
 }
 
-int ffio_open_whitelist(AVIOContext **s, const char *filename, int flags,
-                        const AVIOInterruptCB *int_cb, AVDictionary **options,
-                        const char *whitelist, const char *blacklist)
+int ffio_open_whitelist2(AVIOContext **s, const char *filename, int flags,
+                         const AVIOInterruptCB *int_cb, AVDictionary **options,
+                         const char *whitelist, const char *blacklist,
+                         AVFormatContext *avfc)
 {
     URLContext *h;
     int err;
 
     *s = NULL;
 
-    err = ffurl_open_whitelist(&h, filename, flags, int_cb, options, whitelist, blacklist, NULL);
+    err = url_open_whitelist(&h, filename, flags, int_cb, options, whitelist,
+                             blacklist, NULL, avfc);
     if (err < 0)
         return err;
     err = ffio_fdopen(s, h);
@@ -494,6 +506,14 @@ int ffio_open_whitelist(AVIOContext **s, const char *filename, int flags,
     return 0;
 }
 
+int ffio_open_whitelist(AVIOContext **s, const char *filename, int flags,
+                        const AVIOInterruptCB *int_cb, AVDictionary **options,
+                        const char *whitelist, const char *blacklist)
+{
+    return ffio_open_whitelist2(s, filename, flags, int_cb, options,
+                                whitelist, blacklist, NULL);
+}
+
 int avio_open2(AVIOContext **s, const char *filename, int flags,
                const AVIOInterruptCB *int_cb, AVDictionary **options)
 {

libavformat/avio_internal.h

@@ -23,6 +23,8 @@
 
 #include "libavutil/log.h"
 
+typedef struct AVFormatContext AVFormatContext;
+
 extern const AVClass ff_avio_class;
 
 typedef struct FFIOContext {
@@ -255,6 +257,16 @@ int ffio_open_whitelist(AVIOContext **s, const char *url, int flags,
                          const AVIOInterruptCB *int_cb, AVDictionary **options,
                          const char *whitelist, const char *blacklist);
 
+/**
+ * Like ffio_open_whitelist(), but additionally records @p avfc on the
+ * underlying URLContext before it is connected, so protocols can use shared
+ * per-format resource. Pass NULL for standalone use.
+ */
+int ffio_open_whitelist2(AVIOContext **s, const char *url, int flags,
+                         const AVIOInterruptCB *int_cb, AVDictionary **options,
+                         const char *whitelist, const char *blacklist,
+                         AVFormatContext *avfc);
+
 /**
  * Close a null buffer.
  *

libavformat/internal.h

@@ -23,6 +23,8 @@
 
 #include <stdint.h>
 
+#include "config_components.h"
+
 #include "packet_internal.h"
 
 #include "avformat.h"

libavformat/options.c

@@ -153,7 +153,8 @@ static int io_open_default(AVFormatContext *s, AVIOContext **pb,
 
     av_log(s, loglevel, "Opening \'%s\' for %s\n", url, flags & AVIO_FLAG_WRITE ? "writing" : "reading");
 
-    return ffio_open_whitelist(pb, url, flags, &s->interrupt_callback, options, s->protocol_whitelist, s->protocol_blacklist);
+    return ffio_open_whitelist2(pb, url, flags, &s->interrupt_callback, options,
+                                s->protocol_whitelist, s->protocol_blacklist, s);
 }
 
 static int io_close2_default(AVFormatContext *s, AVIOContext *pb)

libavformat/url.h

@@ -46,6 +46,7 @@ typedef struct URLContext {
     const char *protocol_whitelist;
     const char *protocol_blacklist;
     int min_packet_size;        /**< if non zero, the stream is packetized with this min packet size */
+    struct AVFormatContext *avfc; /**< the AVFormatContext that opened this URLContext, or NULL for standalone use */
 } URLContext;
 
 typedef struct URLProtocol {