From d98df47e534459bec3c51c8c0e5d53a47e569f2c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
Date: Mon, 5 May 2025 11:08:51 +0300
Subject: [PATCH] qtdemux: Add qtdemux_tree_get_child_by_index_full() helper
 function

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8929>
---
 .../gst/isomp4/qtdemux_tree.c                 | 24 +++++++++++++++++++
 .../gst/isomp4/qtdemux_tree.h                 |  2 ++
 2 files changed, 26 insertions(+)

diff --git a/subprojects/gst-plugins-good/gst/isomp4/qtdemux_tree.c b/subprojects/gst-plugins-good/gst/isomp4/qtdemux_tree.c
index e27dc45a39..14ba2214ab 100644
--- a/subprojects/gst-plugins-good/gst/isomp4/qtdemux_tree.c
+++ b/subprojects/gst-plugins-good/gst/isomp4/qtdemux_tree.c
@@ -87,6 +87,30 @@ qtdemux_tree_get_child_by_index (GNode * node, guint index)
   return g_node_nth_child (node, index);
 }
 
+GNode *
+qtdemux_tree_get_child_by_index_full (GNode * node, guint index,
+    GstByteReader * parser)
+{
+  GNode *child;
+  guint8 *buffer;
+  guint32 child_len;
+
+  child = g_node_nth_child (node, index);
+  if (child) {
+    buffer = (guint8 *) child->data;
+
+    if (parser) {
+      child_len = QT_UINT32 (buffer);
+      if (G_UNLIKELY (child_len < (4 + 4)))
+        return NULL;
+      /* FIXME: must verify if atom length < parent atom length */
+      gst_byte_reader_init (parser, buffer + (4 + 4), child_len - (4 + 4));
+    }
+    return child;
+  }
+  return NULL;
+}
+
 GNode *
 qtdemux_tree_get_sibling_by_type_full (GNode * node, guint32 fourcc,
     GstByteReader * parser)
diff --git a/subprojects/gst-plugins-good/gst/isomp4/qtdemux_tree.h b/subprojects/gst-plugins-good/gst/isomp4/qtdemux_tree.h
index 14381815ae..c8775f14da 100644
--- a/subprojects/gst-plugins-good/gst/isomp4/qtdemux_tree.h
+++ b/subprojects/gst-plugins-good/gst/isomp4/qtdemux_tree.h
@@ -41,6 +41,8 @@ GNode *qtdemux_tree_get_sibling_by_type (GNode * node, guint32 fourcc);
 GNode *qtdemux_tree_get_sibling_by_type_full (GNode * node,
     guint32 fourcc, GstByteReader * parser);
 GNode *qtdemux_tree_get_child_by_index (GNode * node, guint index);
+GNode *qtdemux_tree_get_child_by_index_full (GNode * node, guint index,
+    GstByteReader * parser);
 
 G_END_DECLS