Fixes for MPV in macOS

Vendor/mpv/include/stream_cb.h

@@ -0,0 +1,240 @@
+/* Copyright (C) 2017 the mpv developers
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef MPV_CLIENT_API_STREAM_CB_H_
+#define MPV_CLIENT_API_STREAM_CB_H_
+
+#include "client.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Warning: this API is not stable yet.
+ *
+ * Overview
+ * --------
+ *
+ * This API can be used to make mpv read from a stream with a custom
+ * implementation. This interface is inspired by funopen on BSD and
+ * fopencookie on linux. The stream is backed by user-defined callbacks
+ * which can implement customized open, read, seek, size and close behaviors.
+ *
+ * Usage
+ * -----
+ *
+ * Register your stream callbacks with the mpv_stream_cb_add_ro() function. You
+ * have to provide a mpv_stream_cb_open_ro_fn callback to it (open_fn argument).
+ *
+ * Once registered, you can `loadfile myprotocol://myfile`. Your open_fn will be
+ * invoked with the URI and you must fill out the provided mpv_stream_cb_info
+ * struct. This includes your stream callbacks (like read_fn), and an opaque
+ * cookie, which will be passed as the first argument to all the remaining
+ * stream callbacks.
+ *
+ * Note that your custom callbacks must not invoke libmpv APIs as that would
+ * cause a deadlock. (Unless you call a different mpv_handle than the one the
+ * callback was registered for, and the mpv_handles refer to different mpv
+ * instances.)
+ *
+ * Stream lifetime
+ * ---------------
+ *
+ * A stream remains valid until its close callback has been called. It's up to
+ * libmpv to call the close callback, and the libmpv user cannot close it
+ * directly with the stream_cb API.
+ *
+ * For example, if you consider your custom stream to become suddenly invalid
+ * (maybe because the underlying stream died), libmpv will continue using your
+ * stream. All you can do is returning errors from each callback, until libmpv
+ * gives up and closes it.
+ *
+ * Protocol registration and lifetime
+ * ----------------------------------
+ *
+ * Protocols remain registered until the mpv instance is terminated. This means
+ * in particular that it can outlive the mpv_handle that was used to register
+ * it, but once mpv_terminate_destroy() is called, your registered callbacks
+ * will not be called again.
+ *
+ * Protocol unregistration is finished after the mpv core has been destroyed
+ * (e.g. after mpv_terminate_destroy() has returned).
+ *
+ * If you do not call mpv_terminate_destroy() yourself (e.g. plugin-style code),
+ * you will have to deal with the registration or even streams outliving your
+ * code. Here are some possible ways to do this:
+ * - call mpv_terminate_destroy(), which destroys the core, and will make sure
+ *   all streams are closed once this function returns
+ * - you refcount all resources your stream "cookies" reference, so that it
+ *   doesn't matter if streams live longer than expected
+ * - create "cancellation" semantics: after your protocol has been unregistered,
+ *   notify all your streams that are still opened, and make them drop all
+ *   referenced resources - then return errors from the stream callbacks as
+ *   long as the stream is still opened
+ *
+ */
+
+/**
+ * Read callback used to implement a custom stream. The semantics of the
+ * callback match read(2) in blocking mode. Short reads are allowed (you can
+ * return less bytes than requested, and libmpv will retry reading the rest
+ * with another call). If no data can be immediately read, the callback must
+ * block until there is new data. A return of 0 will be interpreted as final
+ * EOF, although libmpv might retry the read, or seek to a different position.
+ *
+ * @param cookie opaque cookie identifying the stream,
+ *               returned from mpv_stream_cb_open_fn
+ * @param buf buffer to read data into
+ * @param size of the buffer
+ * @return number of bytes read into the buffer
+ * @return 0 on EOF
+ * @return -1 on error
+ */
+typedef int64_t (*mpv_stream_cb_read_fn)(void *cookie, char *buf, uint64_t nbytes);
+
+/**
+ * Seek callback used to implement a custom stream.
+ *
+ * Note that mpv will issue a seek to position 0 immediately after opening. This
+ * is used to test whether the stream is seekable (since seekability might
+ * depend on the URI contents, not just the protocol). Return
+ * MPV_ERROR_UNSUPPORTED if seeking is not implemented for this stream. This
+ * seek also serves to establish the fact that streams start at position 0.
+ *
+ * This callback can be NULL, in which it behaves as if always returning
+ * MPV_ERROR_UNSUPPORTED.
+ *
+ * @param cookie opaque cookie identifying the stream,
+ *               returned from mpv_stream_cb_open_fn
+ * @param offset target absolut stream position
+ * @return the resulting offset of the stream
+ *         MPV_ERROR_UNSUPPORTED or MPV_ERROR_GENERIC if the seek failed
+ */
+typedef int64_t (*mpv_stream_cb_seek_fn)(void *cookie, int64_t offset);
+
+/**
+ * Size callback used to implement a custom stream.
+ *
+ * Return MPV_ERROR_UNSUPPORTED if no size is known.
+ *
+ * This callback can be NULL, in which it behaves as if always returning
+ * MPV_ERROR_UNSUPPORTED.
+ *
+ * @param cookie opaque cookie identifying the stream,
+ *               returned from mpv_stream_cb_open_fn
+ * @return the total size in bytes of the stream
+ */
+typedef int64_t (*mpv_stream_cb_size_fn)(void *cookie);
+
+/**
+ * Close callback used to implement a custom stream.
+ *
+ * @param cookie opaque cookie identifying the stream,
+ *               returned from mpv_stream_cb_open_fn
+ */
+typedef void (*mpv_stream_cb_close_fn)(void *cookie);
+
+/**
+ * Cancel callback used to implement a custom stream.
+ *
+ * This callback is used to interrupt any current or future read and seek
+ * operations. It will be called from a separate thread than the demux
+ * thread, and should not block.
+ *
+ * This callback can be NULL.
+ *
+ * Available since API 1.106.
+ *
+ * @param cookie opaque cookie identifying the stream,
+ *               returned from mpv_stream_cb_open_fn
+ */
+typedef void (*mpv_stream_cb_cancel_fn)(void *cookie);
+
+/**
+ * See mpv_stream_cb_open_ro_fn callback.
+ */
+typedef struct mpv_stream_cb_info {
+    /**
+     * Opaque user-provided value, which will be passed to the other callbacks.
+     * The close callback will be called to release the cookie. It is not
+     * interpreted by mpv. It doesn't even need to be a valid pointer.
+     *
+     * The user sets this in the mpv_stream_cb_open_ro_fn callback.
+     */
+    void *cookie;
+
+    /**
+     * Callbacks set by the user in the mpv_stream_cb_open_ro_fn callback. Some
+     * of them are optional, and can be left unset.
+     *
+     * The following callbacks are mandatory: read_fn, close_fn
+     */
+    mpv_stream_cb_read_fn read_fn;
+    mpv_stream_cb_seek_fn seek_fn;
+    mpv_stream_cb_size_fn size_fn;
+    mpv_stream_cb_close_fn close_fn;
+    mpv_stream_cb_cancel_fn cancel_fn; /* since API 1.106 */
+} mpv_stream_cb_info;
+
+/**
+ * Open callback used to implement a custom read-only (ro) stream. The user
+ * must set the callback fields in the passed info struct. The cookie field
+ * also can be set to store state associated to the stream instance.
+ *
+ * Note that the info struct is valid only for the duration of this callback.
+ * You can't change the callbacks or the pointer to the cookie at a later point.
+ *
+ * Each stream instance created by the open callback can have different
+ * callbacks.
+ *
+ * The close_fn callback will terminate the stream instance. The pointers to
+ * your callbacks and cookie will be discarded, and the callbacks will not be
+ * called again.
+ *
+ * @param user_data opaque user data provided via mpv_stream_cb_add()
+ * @param uri name of the stream to be opened (with protocol prefix)
+ * @param info fields which the user should fill
+ * @return 0 on success, MPV_ERROR_LOADING_FAILED if the URI cannot be opened.
+ */
+typedef int (*mpv_stream_cb_open_ro_fn)(void *user_data, char *uri,
+                                        mpv_stream_cb_info *info);
+
+/**
+ * Add a custom stream protocol. This will register a protocol handler under
+ * the given protocol prefix, and invoke the given callbacks if an URI with the
+ * matching protocol prefix is opened.
+ *
+ * The "ro" is for read-only - only read-only streams can be registered with
+ * this function.
+ *
+ * The callback remains registered until the mpv core is registered.
+ *
+ * If a custom stream with the same name is already registered, then the
+ * MPV_ERROR_INVALID_PARAMETER error is returned.
+ *
+ * @param protocol protocol prefix, for example "foo" for "foo://" URIs
+ * @param user_data opaque pointer passed into the mpv_stream_cb_open_fn
+ *                  callback.
+ * @return error code
+ */
+int mpv_stream_cb_add_ro(mpv_handle *ctx, const char *protocol, void *user_data,
+                         mpv_stream_cb_open_ro_fn open_fn);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif