avio: add avio_open2, taking an interrupt callback and options

The interrupt callback has to be passed in during opening (setting it
after opening isn't enough), since a blocking open couldn't be
interrupted otherwise.

Options are passed down to procotols and also need to be available
during open() in most cases.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavformat/avio.c

@@ -73,7 +73,7 @@ static const AVClass *urlcontext_child_class_next(const AVClass *prev)
 }
 
 static const AVOption options[] = {{NULL}};
-static const AVClass urlcontext_class = {
+const AVClass ffurl_context_class = {
     .class_name     = "URLContext",
     .item_name      = urlcontext_to_name,
     .option         = options,
@@ -135,7 +135,7 @@ static int url_alloc_for_protocol (URLContext **puc, struct URLProtocol *up,
         err = AVERROR(ENOMEM);
         goto fail;
     }
-    uc->av_class = &urlcontext_class;
+    uc->av_class = &ffurl_context_class;
     uc->filename = (char *) &uc[1];
     strcpy(uc->filename, filename);
     uc->prot = up;

libavformat/avio.h

@@ -28,6 +28,7 @@
 #include <stdint.h>
 
 #include "libavutil/common.h"
+#include "libavutil/dict.h"
 #include "libavutil/log.h"
 
 #include "libavformat/version.h"
@@ -64,6 +65,21 @@ typedef struct {
  *       function pointers specified in avio_alloc_context()
  */
 typedef struct {
+#if !FF_API_OLD_AVIO
+    /**
+     * A class for private options.
+     *
+     * If this AVIOContext is created by avio_open2(), av_class is set and
+     * passes the options down to protocols.
+     *
+     * If this AVIOContext is manually allocated, then av_class may be set by
+     * the caller.
+     *
+     * warning -- this field can be NULL, be sure to not pass this AVIOContext
+     * to any av_opt_* functions in that case.
+     */
+    AVClass *av_class;
+#endif
     unsigned char *buffer;  /**< Start of the buffer. */
     int buffer_size;        /**< Maximum buffer size */
     unsigned char *buf_ptr; /**< Current position in the buffer */
@@ -573,6 +589,26 @@ int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
  */
 int avio_open(AVIOContext **s, const char *url, int flags);
 
+/**
+ * Create and initialize a AVIOContext for accessing the
+ * resource indicated by url.
+ * @note When the resource indicated by url has been opened in
+ * read+write mode, the AVIOContext can be used only for writing.
+ *
+ * @param s Used to return the pointer to the created AVIOContext.
+ * In case of failure the pointed to value is set to NULL.
+ * @param flags flags which control how the resource indicated by url
+ * is to be opened
+ * @param int_cb an interrupt callback to be used at the protocols level
+ * @param options  A dictionary filled with protocol-private options. On return
+ * this parameter will be destroyed and replaced with a dict containing options
+ * that were not found. May be NULL.
+ * @return 0 in case of success, a negative value corresponding to an
+ * AVERROR code in case of failure
+ */
+int avio_open2(AVIOContext **s, const char *url, int flags,
+               const AVIOInterruptCB *int_cb, AVDictionary **options);
+
 /**
  * Close the resource accessed by the AVIOContext s and free it.
  * This function can only be used if s was opened by avio_open().

libavformat/avio_internal.h

@@ -23,6 +23,10 @@
 #include "avio.h"
 #include "url.h"
 
+#include "libavutil/log.h"
+
+extern const AVClass ffio_url_class;
+
 int ffio_init_context(AVIOContext *s,
                   unsigned char *buffer,
                   int buffer_size,

libavformat/aviobuf.c

@@ -20,7 +20,10 @@
  */
 
 #include "libavutil/crc.h"
+#include "libavutil/dict.h"
 #include "libavutil/intreadwrite.h"
+#include "libavutil/log.h"
+#include "libavutil/opt.h"
 #include "avformat.h"
 #include "avio.h"
 #include "avio_internal.h"
@@ -37,6 +40,31 @@
  */
 #define SHORT_SEEK_THRESHOLD 4096
 
+#if !FF_API_OLD_AVIO
+static void *ffio_url_child_next(void *obj, void *prev)
+{
+    AVIOContext *s = obj;
+    return prev ? NULL : s->opaque;
+}
+
+static const AVClass *ffio_url_child_class_next(const AVClass *prev)
+{
+    return prev ? NULL : &ffurl_context_class;
+}
+
+static const AVOption ffio_url_options[] = {
+    { NULL },
+};
+
+const AVClass ffio_url_class = {
+    .class_name = "AVIOContext",
+    .item_name  = av_default_item_name,
+    .version    = LIBAVUTIL_VERSION_INT,
+    .option     = ffio_url_options,
+    .child_next = ffio_url_child_next,
+    .child_class_next = ffio_url_child_class_next,
+};
+#endif
 static void fill_buffer(AVIOContext *s);
 static int url_resetbuf(AVIOContext *s, int flags);
 
@@ -856,6 +884,9 @@ int ffio_fdopen(AVIOContext **s, URLContext *h)
         (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
         (*s)->read_seek  = (int64_t (*)(void *, int, int64_t, int))h->prot->url_read_seek;
     }
+#if !FF_API_OLD_AVIO
+    (*s)->av_class = &ffio_url_class;
+#endif
     return 0;
 }
 
@@ -928,11 +959,17 @@ int ffio_rewind_with_probe_data(AVIOContext *s, unsigned char *buf, int buf_size
 }
 
 int avio_open(AVIOContext **s, const char *filename, int flags)
+{
+    return avio_open2(s, filename, flags, NULL, NULL);
+}
+
+int avio_open2(AVIOContext **s, const char *filename, int flags,
+               const AVIOInterruptCB *int_cb, AVDictionary **options)
 {
     URLContext *h;
     int err;
 
-    err = ffurl_open(&h, filename, flags, NULL, NULL);
+    err = ffurl_open(&h, filename, flags, int_cb, options);
     if (err < 0)
         return err;
     err = ffio_fdopen(s, h);

libavformat/url.h

@@ -29,12 +29,15 @@
 #include "libavformat/version.h"
 
 #include "libavutil/dict.h"
+#include "libavutil/log.h"
 
 #if !FF_API_OLD_AVIO
 #define URL_PROTOCOL_FLAG_NESTED_SCHEME 1 /*< The protocol name can be the first part of a nested protocol scheme */
 
 extern int (*url_interrupt_cb)(void);
 
+extern const AVClass ffurl_context_class;
+
 typedef struct URLContext {
     const AVClass *av_class;    /**< information for av_log(). Set by url_open(). */
     struct URLProtocol *prot;