master(3.0): Blender crashes in onLoad Addon handler #91192

New Issue

Gaia Clary · 2021-09-05T10:31:16+02:00

Gaia Clary commented

2021-09-05 10:31:16 +02:00

System Information
Operating system: windows-10

Blender Version
Broken: master (3.0)

Short description of error

When i add an on load handler, in which i touch bpy.context, then Blender crashes

def after_load(scene):
    if bpy.context:
        ctx = bpy.context.copy() # <== Crash is here

Exact steps for others to reproduce the error

This is a minimal demo Addon: testit.zip

Start Blender
load Factory settings
install/enable the addon
load a file into Blender <== crash in the on-load handler
restart Blender <== crash instantly

The only way i could get Blender back to live is by manually removing the addon from its installation folder.

This is a related crash dump file: testit.crash.txt

**System Information** Operating system: windows-10 **Blender Version** Broken: master (3.0) **Short description of error** When i add an on load handler, in which i touch bpy.context, then Blender crashes ``` def after_load(scene): if bpy.context: ctx = bpy.context.copy() # <== Crash is here ``` **Exact steps for others to reproduce the error** This is a minimal demo Addon: [testit.zip](https://archive.blender.org/developer/F10378575/testit.zip) - Start Blender - load Factory settings - install/enable the addon - load a file into Blender <== crash in the on-load handler - restart Blender <== crash instantly The only way i could get Blender back to live is by manually removing the addon from its installation folder. This is a related crash dump file: [testit.crash.txt](https://archive.blender.org/developer/F10378578/testit.crash.txt)

Gaia Clary commented

2021-09-05 10:31:16 +02:00

Added subscriber: @GaiaClary

Ryan Inch commented

2021-09-07 08:39:32 +02:00

Added subscriber: @Imaginer

Germano Cavalcante commented

2021-09-08 16:35:39 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-09-08 16:35:39 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Germano Cavalcante commented

2021-09-08 16:35:39 +02:00

Thanks for the report, I can confirm.
The handler can be simplified and the problem reduced to "Crash accessing context.ui_list when there is no ARegion".
This is the handler I used:

def after_load(scene):
    print(bpy.context.ui_list)

Thanks for the report, I can confirm. The handler can be simplified and the problem reduced to "Crash accessing `context.ui_list` when there is no `ARegion`". This is the handler I used: ``` def after_load(scene): print(bpy.context.ui_list) ```

Dalai Felinto commented

2021-09-14 18:06:32 +02:00

Added subscriber: @dfelinto

Dalai Felinto commented

2021-09-14 18:06:32 +02:00

I usually don't copy bpy.context. I instead pass the parameters I need to change:

@bpy.app.handlers.persistent
def setup_fullscreen(dummy):
    for area in bpy.context.screen.areas:
        if area.type == 'VIEW_3D':
            override = {}
            override["area"] = area
            bpy.ops.screen.screen_full_area(override, use_hide_panels=True)
            break

I usually don't copy bpy.context. I instead pass the parameters I need to change: ``` @bpy.app.handlers.persistent def setup_fullscreen(dummy): for area in bpy.context.screen.areas: if area.type == 'VIEW_3D': override = {} override["area"] = area bpy.ops.screen.screen_full_area(override, use_hide_panels=True) break ```

Gaia Clary commented

2021-09-14 18:42:19 +02:00

@dfelinto Thank you for the hint, i did not know this is possible. However when accessing the context (or the ui_list as @mano-wii mentioned) shouldn't this be working in first place? Or if this is not possible, shouldn't Blender then report an error instead of crashing? And finally if this is a total nogo thing, then shouldn't this be mentioned somewhere (in the python documentation) ? It is not obvious that accessing bpy.context is an issue here ...

blender-admin commented

2021-09-24 13:10:02 +02:00

This issue was referenced by 2b5733ff01

This issue was referenced by 2b5733ff0122859b713ad9199d715add496c1608

Campbell Barton commented

2021-09-24 13:10:24 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Campbell Barton closed this issue

2021-09-24 13:10:24 +02:00

Campbell Barton self-assigned this 2021-09-24 13:10:24 +02:00

Erik Abrahamsson commented

2021-09-24 13:11:40 +02:00

Added subscriber: @erik85

Erik Abrahamsson commented

2021-09-24 13:11:40 +02:00

What if a not null-check would be added to screen_ctx_ui_list like this?

static eContextResult screen_ctx_ui_list(const bContext *C, bContextDataResult *result)
{
  wmWindow *win = CTX_wm_window(C);
  ARegion *region = CTX_wm_region(C);

  if (region) {
    uiList *list = UI_list_find_mouse_over(region, win->eventstate);
    CTX_data_pointer_set(result, NULL, &RNA_UIList, list);
    return CTX_RESULT_OK;
  }
  return CTX_RESULT_NO_DATA;
}

edit: hehe too slow.

What if a not null-check would be added to `screen_ctx_ui_list` like this? ``` static eContextResult screen_ctx_ui_list(const bContext *C, bContextDataResult *result) { wmWindow *win = CTX_wm_window(C); ARegion *region = CTX_wm_region(C); if (region) { uiList *list = UI_list_find_mouse_over(region, win->eventstate); CTX_data_pointer_set(result, NULL, &RNA_UIList, list); return CTX_RESULT_OK; } return CTX_RESULT_NO_DATA; } ``` edit: hehe too slow.

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master(3.0): Blender crashes in onLoad Addon handler #91192