From 940811d593bae34fc4da8b909b75ee590880e225 Mon Sep 17 00:00:00 2001
From: Jan Schmidt <jan@centricular.com>
Date: Fri, 14 Oct 2022 06:22:35 +1100
Subject: [PATCH] adaptivedemux2/downloadrequest: Add new methods

Add download_request_take_buffer_range() and
download_request_get_bytes_available() methods.

download_request_take_buffer_range() takes bytes from the front of the request
that satisfy the requested start/end byterange, and puts any remaining bytes
back into the DownloadRequest

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3883>
---
 .../ext/adaptivedemux2/downloadrequest.c      | 72 +++++++++++++++++++
 .../ext/adaptivedemux2/downloadrequest.h      |  2 +
 2 files changed, 74 insertions(+)

diff --git a/subprojects/gst-plugins-good/ext/adaptivedemux2/downloadrequest.c b/subprojects/gst-plugins-good/ext/adaptivedemux2/downloadrequest.c
index 496325111b..62454c8ecc 100644
--- a/subprojects/gst-plugins-good/ext/adaptivedemux2/downloadrequest.c
+++ b/subprojects/gst-plugins-good/ext/adaptivedemux2/downloadrequest.c
@@ -235,6 +235,78 @@ download_request_take_buffer (DownloadRequest * request)
   return buffer;
 }
 
+GstBuffer *
+download_request_take_buffer_range (DownloadRequest * request,
+    gint64 target_range_start, gint64 target_range_end)
+{
+  DownloadRequestPrivate *priv = DOWNLOAD_REQUEST_PRIVATE (request);
+  GstBuffer *buffer = NULL;
+  GstBuffer *input_buffer = NULL;
+
+  g_return_val_if_fail (request != NULL, NULL);
+
+  g_rec_mutex_lock (&priv->lock);
+
+  if (request->state != DOWNLOAD_REQUEST_STATE_LOADING
+      && request->state != DOWNLOAD_REQUEST_STATE_COMPLETE) {
+    g_rec_mutex_unlock (&priv->lock);
+    return NULL;
+  }
+
+  input_buffer = priv->buffer;
+  priv->buffer = NULL;
+  if (input_buffer == NULL)
+    goto out;
+
+  /* Figure out how much of the available data (if any) belongs to
+   * the target range */
+  gint64 avail_start = GST_BUFFER_OFFSET (input_buffer);
+  gint64 avail_end = avail_start + gst_buffer_get_size (input_buffer) - 1;
+
+  if (target_range_start <= avail_end) {
+    /* There's at least 1 byte available that belongs to this target request, but
+     * does this buffer need splitting in two? */
+    if (target_range_end != -1 && target_range_end < avail_end) {
+      /* Yes, it does. Cut off the front of the buffer */
+      buffer =
+          gst_buffer_copy_region (input_buffer, GST_BUFFER_COPY_MEMORY, 0,
+          target_range_end - avail_start);
+      GST_BUFFER_OFFSET (buffer) = GST_BUFFER_OFFSET (input_buffer);
+
+      /* Put the rest of the buffer back */
+      priv->buffer =
+          gst_buffer_copy_region (input_buffer, GST_BUFFER_COPY_MEMORY,
+          target_range_end - avail_start, -1);
+
+      /* Release the original buffer. The sub-buffers are holding their own refs as needed */
+      gst_buffer_unref (input_buffer);
+    } else {
+      /* No, return the entire buffer */
+      buffer = input_buffer;
+    }
+  }
+
+out:
+  g_rec_mutex_unlock (&priv->lock);
+  return buffer;
+}
+
+guint64
+download_request_get_bytes_available (DownloadRequest * request)
+{
+  DownloadRequestPrivate *priv = DOWNLOAD_REQUEST_PRIVATE (request);
+  guint64 ret = 0;
+
+  g_rec_mutex_lock (&priv->lock);
+
+  if (priv->buffer != NULL)
+    ret = gst_buffer_get_size (priv->buffer);
+
+  g_rec_mutex_unlock (&priv->lock);
+
+  return ret;
+}
+
 void
 download_request_set_uri (DownloadRequest * request, const gchar * uri,
     gint64 range_start, gint64 range_end)
diff --git a/subprojects/gst-plugins-good/ext/adaptivedemux2/downloadrequest.h b/subprojects/gst-plugins-good/ext/adaptivedemux2/downloadrequest.h
index b814d921b3..13827d6fbf 100644
--- a/subprojects/gst-plugins-good/ext/adaptivedemux2/downloadrequest.h
+++ b/subprojects/gst-plugins-good/ext/adaptivedemux2/downloadrequest.h
@@ -85,6 +85,8 @@ GstCaps * download_request_get_caps (DownloadRequest * request);
 
 void download_request_add_buffer (DownloadRequest *request, GstBuffer *buffer);
 GstBuffer * download_request_take_buffer (DownloadRequest *request);
+GstBuffer * download_request_take_buffer_range (DownloadRequest *request, gint64 range_start, gint64 range_end);
+guint64 download_request_get_bytes_available (DownloadRequest *request);
 
 DownloadRequest * download_request_new (void);
 DownloadRequest * download_request_new_uri (const gchar * uri);