[Bf-blender-cvs] [84320976692] greasepencil-object: Fix crash on trying to save files with GP objects

[Joshua Leung]

Commit: 84320976692e1e933b0159b6f3ab15eb6acde583
Author: Joshua Leung
Date:   Sun Nov 5 00:23:02 2017 +1300
Branches: greasepencil-object
https://developer.blender.org/rB84320976692e1e933b0159b6f3ab15eb6acde583

Fix crash on trying to save files with GP objects

Quick fix for context being NULL when the thumbnail renderer gets triggered
while trying to save files.

TODO: We need a better solution here for passing eval_ctx down to GP modifiers

===================================================================

M	source/blender/blenlib/intern/listbase.c
M	source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c

===================================================================

diff --git a/source/blender/blenlib/intern/listbase.c b/source/blender/blenlib/intern/listbase.c
index 0a6d575c7d6..4bfc5218d71 100644
--- a/source/blender/blenlib/intern/listbase.c
+++ b/source/blender/blenlib/intern/listbase.c
@@ -576,6 +576,9 @@ void *BLI_findstring(const ListBase *listbase, const char *id, const int offset)
 	Link *link = NULL;
 	const char *id_iter;
 
+	if (id == NULL)
+		return NULL;
+
 	for (link = listbase->first; link; link = link->next) {
 		id_iter = ((const char *)link) + offset;
 
diff --git a/source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c b/source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c
index 19660781068..4493f830a71 100644
--- a/source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c
+++ b/source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c
@@ -672,8 +672,14 @@ static void gpencil_draw_strokes(GpencilBatchCache *cache, GPENCIL_e_data *e_dat
 	/* Get evaluation context */
 	const DRWContextState *draw_ctx = DRW_context_state_get();
 	const bContext *C = draw_ctx->evil_C;
-	EvaluationContext eval_ctx;
-	CTX_data_eval_ctx(C, &eval_ctx);
+
+	EvaluationContext eval_ctx = {0};
+	if (C) {
+		/* NOTE: We must check if C is valid, otherwise we get crashes when trying to save files
+		 * (i.e. the thumbnail offscreen rendering fails) 
+		 */
+		CTX_data_eval_ctx(C, &eval_ctx);
+	}
 
 	/* get parent matrix and save as static data */
 	ED_gpencil_parent_location(ob, gpd, gpl, viewmatrix);