DescriptorStructure can occur inside an ImageResourcesBlock

[joedevivo]

Inside read_resource_block, some resource_ids like 3000 expect the value to be a Descriptor. I actually encountered this because when it is a Descriptor, I'm not sure what the deal is with data_len, but it is way off. This caused an Index out of bounds error, as it was trying to read the cursor way too far.

I tried to reverse engineer the binary, along with reading from the PSD file spec, but there's still just some bits in there I can't figure out, especially at the beginning with the data length.

I think something similar to what you're doing in read_slice_block could work, but I'm not quite sure how to set that up properly in read_resource_block

[chinedufn]

Hey, thanks for reporting this issue.

Can you create a minimal PSD that can be used to reproduce this issue?

Here are some examples https://github.com/chinedufn/psd/tree/master/tests/fixtures

Then we'd add a test to the image resources section. Here's an example test

psd/tests/image_resources_section.rs

Lines 8 to 32 in 3d4c196

	fn image_check_1x1p_bound_field() {
	let psd = include_bytes!("./fixtures/two-layers-red-green-1x1.psd");
	let psd = Psd::from_bytes(psd).unwrap();
	let descriptors = match &psd.resources()[0] {
	ImageResource::Slices(s) => s.descriptors(),
	};
	let descriptor = descriptors.get(0).unwrap();
	let bounds = descriptor.fields.get("bounds").unwrap();
	if let DescriptorField::Descriptor(d) = bounds {
	match d.fields.get("Rght").unwrap() {
	DescriptorField::Integer(v) => assert_eq!(*v, 1),
	_ => panic!("expected integer"),
	}
	match d.fields.get("Btom").unwrap() {
	DescriptorField::Integer(v) => assert_eq!(*v, 1),
	_ => panic!("expected integer"),
	}
	} else {
	panic!("expected descriptor");
	}
	}

From there we can figure out how to get the test passing.