Sometimes Blobs (avatars/images) vanish

[Simon-Laux]

I recently had two issues, where core deleted blobs.

• in a bot, where avatars disappeared (may be after upgrade to newer version (2.12), but I haven't tracked the exact time)
• and in the tauri edition of delta chat desktop on macOS, received blobs are not displayed and don't exist, see tauri: GIF, JPEG, and PNG files generate an error message for the recipient deltachat/deltachat-desktop#5211 (this was reproducible at the time, so investigation should start there - it happened to me and to the reporter of the issue)

Because it also happened in the bot, I suspect it is probably a core issue.
Also core had issues about avatar deletion in the past (unfortunately I can't find the exact issue), could be that some edge case remained, whatever it is, it should be investigated.

[Simon-Laux]

First try to reproduce it failed:

• sending message from dc desktop electron 2.11.1 to dc desktop tauri (core 2.15, dev-mode) worked
• sending messages from dc desktop tauri (core 2.15, dev-mode) to another account on the same app did also work.
• sending message from dc desktop electron 2.11.1 to dc desktop tauri (core v1.159.5, dev-mode) worked

But I'm certain that it happened in the past, because in one account there is still an avatar file missing:

[link2xt]

I think it happens when device runs out of space that avatar is unset. The blob fails to be stored, but the error is ignored here:

core/src/mimeparser.rs

Lines 932 to 941 in 1bb966e

	match BlobObject::store_from_base64(context, base64) {
	Ok(path) => Some(AvatarAction::Change(path)),
	Err(err) => {
	warn!(
	context,
	"Could not decode and save avatar to blob file: {:#}", err,
	);
	None
	}
	}

avatar_action_from_header should instead return Result and bubble up the error with ?.

It is safe to bubble up the error all the way up to receive_imf since #7222 is merged.

I don't know however how this can result in missing blob with the avatar still being set.

If this cannot be reproduced, it makes sense to at least stop ignoring blob storage errors and close the issue until the problem appears again with a core that does not ignore errors.