From a1b3effd55f775643e99b17865e36c506e9bdc90 Mon Sep 17 00:00:00 2001
From: Richard Antalik <richardantalik@gmail.com>
Date: Sun, 10 May 2020 07:50:09 +0200
Subject: Fix T71300: Crash on rendering scene recursively from sequencer

Adding recursive scenes has been disabled, but old files still can be opened.

Add check if scene will render itself.
Opening such file will produce warning on open and error on running render.

Reviewed By: campbellbarton

Differential Revision: https://developer.blender.org/D7562
---
 source/blender/blenkernel/intern/sequencer.c | 66 ++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

(limited to 'source/blender/blenkernel/intern/sequencer.c')

diff --git a/source/blender/blenkernel/intern/sequencer.c b/source/blender/blenkernel/intern/sequencer.c
index d3d885fccd9..46edcea26c0 100644
--- a/source/blender/blenkernel/intern/sequencer.c
+++ b/source/blender/blenkernel/intern/sequencer.c
@@ -39,6 +39,7 @@
 #include "DNA_sequence_types.h"
 #include "DNA_sound_types.h"
 #include "DNA_space_types.h"
+#include "DNA_windowmanager_types.h"
 
 #include "BLI_fileops.h"
 #include "BLI_linklist.h"
@@ -69,6 +70,7 @@
 #include "BKE_main.h"
 #include "BKE_mask.h"
 #include "BKE_movieclip.h"
+#include "BKE_report.h"
 #include "BKE_scene.h"
 #include "BKE_sequencer.h"
 #include "BKE_sequencer_offscreen.h"
@@ -3462,6 +3464,11 @@ static ImBuf *seq_render_scene_strip(const SeqRenderData *context,
     return NULL;
   }
 
+  /* Prevent rendering scene recursively. */
+  if (seq->scene == context->scene) {
+    return NULL;
+  }
+
   scene = seq->scene;
   frame = (double)scene->r.sfra + (double)nr + (double)seq->anim_startofs;
 
@@ -5970,3 +5977,62 @@ void BKE_sequencer_all_free_anim_ibufs(Scene *scene, int cfra)
   sequencer_all_free_anim_ibufs(&ed->seqbase, cfra);
   BKE_sequencer_cache_cleanup(scene);
 }
+
+static bool sequencer_seq_generates_image(Sequence *seq)
+{
+  switch (seq->type) {
+    case SEQ_TYPE_IMAGE:
+    case SEQ_TYPE_SCENE:
+    case SEQ_TYPE_MOVIE:
+    case SEQ_TYPE_MOVIECLIP:
+    case SEQ_TYPE_MASK:
+    case SEQ_TYPE_COLOR:
+    case SEQ_TYPE_TEXT:
+      return true;
+  }
+  return false;
+}
+
+static Sequence *sequencer_check_scene_recursion(Scene *scene, ListBase *seqbase)
+{
+  LISTBASE_FOREACH (Sequence *, seq, seqbase) {
+    if (seq->type == SEQ_TYPE_SCENE && seq->scene == scene) {
+      return seq;
+    }
+
+    if (seq->type == SEQ_TYPE_META && sequencer_check_scene_recursion(scene, &seq->seqbase)) {
+      return seq;
+    }
+  }
+
+  return NULL;
+}
+
+bool BKE_sequencer_check_scene_recursion(Scene *scene, ReportList *reports)
+{
+  Editing *ed = BKE_sequencer_editing_get(scene, false);
+  if (ed == NULL) {
+    return false;
+  }
+
+  Sequence *recursive_seq = sequencer_check_scene_recursion(scene, &ed->seqbase);
+
+  if (recursive_seq != NULL) {
+    BKE_reportf(reports,
+                RPT_WARNING,
+                "Recursion detected in video sequencer. Strip %s at frame %d will not be rendered",
+                recursive_seq->name + 2,
+                recursive_seq->startdisp);
+
+    LISTBASE_FOREACH (Sequence *, seq, &ed->seqbase) {
+      if (seq->type != SEQ_TYPE_SCENE && sequencer_seq_generates_image(seq)) {
+        /* There are other strips to render, so render them. */
+        return false;
+      }
+    }
+    /* No other strips to render - cancel operator. */
+    return true;
+  }
+
+  return false;
+}
-- 
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