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| 1 | +/* |
| 2 | +Copyright 2025 The Hyperlight Authors. |
| 3 | +
|
| 4 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | +you may not use this file except in compliance with the License. |
| 6 | +You may obtain a copy of the License at |
| 7 | +
|
| 8 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | +
|
| 10 | +Unless required by applicable law or agreed to in writing, software |
| 11 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | +See the License for the specific language governing permissions and |
| 14 | +limitations under the License. |
| 15 | + */ |
| 16 | + |
| 17 | +//! Just enough component parsing support to get at the actual types |
| 18 | +
|
| 19 | +use wasmparser::Payload::{ |
| 20 | + ComponentAliasSection, ComponentExportSection, ComponentTypeSection, Version, |
| 21 | +}; |
| 22 | +use wasmparser::{ |
| 23 | + ComponentAlias, ComponentExternalKind, ComponentOuterAliasKind, ComponentType, |
| 24 | + ComponentTypeRef, Payload, |
| 25 | +}; |
| 26 | + |
| 27 | +use crate::etypes::{Component, Ctx, Defined}; |
| 28 | + |
| 29 | +/// From [`wasmparser::ComponentExport`], elaborate a deftype_e as per |
| 30 | +/// the specification. |
| 31 | +fn raw_type_export_type<'p, 'a, 'c>( |
| 32 | + ctx: &'c Ctx<'p, 'a>, |
| 33 | + ce: &'c wasmparser::ComponentExport<'a>, |
| 34 | +) -> &'c Defined<'a> { |
| 35 | + match ce.ty { |
| 36 | + Some(ComponentTypeRef::Component(n)) => match ctx.types.get(n as usize) { |
| 37 | + Some(t) => t, |
| 38 | + None => { |
| 39 | + panic!("malformed component type export: ascription does not refer to a type"); |
| 40 | + } |
| 41 | + }, |
| 42 | + Some(_) => { |
| 43 | + panic!( |
| 44 | + "malformed component type export: ascription does not refer to a component type" |
| 45 | + ); |
| 46 | + } |
| 47 | + None => match ctx.types.get(ce.index as usize) { |
| 48 | + Some(t) => t, |
| 49 | + None => { |
| 50 | + panic!("malformed component type export: does not refer to a type"); |
| 51 | + } |
| 52 | + }, |
| 53 | + } |
| 54 | +} |
| 55 | + |
| 56 | +/// Find the last exported type in a component, since in wasm-encoded |
| 57 | +/// WIT this is typically the main world to use. This is a very |
| 58 | +/// special case that just lets us pull a type out of a value-level |
| 59 | +/// |
| 60 | +/// Precondition: The given iterator is |
| 61 | +/// - a component, whose |
| 62 | +/// - encoding version is 0xd exactly, and who |
| 63 | +/// - does not contain any value-level aliases, and whose |
| 64 | +/// - final export is a component type |
| 65 | +/// |
| 66 | +/// Anything that is a "binary-encoded WIT" produced by a recent |
| 67 | +/// toolchain should satisfy this. On violation, this function will |
| 68 | +/// panic with an error message. |
| 69 | +/// |
| 70 | +/// The reason we look for the last export is that the WIT binary |
| 71 | +/// encoding encodes any instance type imported/exported from the main |
| 72 | +/// component (a/k/a WIT world) as a type export, followed by a final |
| 73 | +/// type export for the type of the main component/world. |
| 74 | +/// |
| 75 | +/// TODO: Allow the user to specify a specific export to use (or a WIT |
| 76 | +/// world name), since current WIT tooling can generate encoded |
| 77 | +/// packages with multiple component types in them. |
| 78 | +/// |
| 79 | +/// TODO: Encode even more assumptions about WIT package structure |
| 80 | +/// (which are already there in rtypes/host/guest) and allow looking |
| 81 | +/// for a specific named world, instead of simply grabbing the last |
| 82 | +/// export. |
| 83 | +pub fn read_component_single_exported_type<'a>( |
| 84 | + items: impl Iterator<Item = wasmparser::Result<Payload<'a>>>, |
| 85 | +) -> Component<'a> { |
| 86 | + let mut ctx = Ctx::new(None, false); |
| 87 | + let mut last_idx = None; |
| 88 | + for x in items { |
| 89 | + match x { |
| 90 | + Ok(Version { num, encoding, .. }) => { |
| 91 | + if encoding != wasmparser::Encoding::Component { |
| 92 | + panic!("wasm file is not a component") |
| 93 | + } |
| 94 | + if num != 0xd { |
| 95 | + panic!("unknown component encoding version 0x{:x}\n", num); |
| 96 | + } |
| 97 | + } |
| 98 | + Ok(ComponentTypeSection(ts)) => { |
| 99 | + for t in ts { |
| 100 | + match t { |
| 101 | + Ok(ComponentType::Component(ct)) => { |
| 102 | + let ct_ = ctx.elab_component(&ct); |
| 103 | + ctx.types.push(Defined::Component(ct_.unwrap())); |
| 104 | + } |
| 105 | + _ => panic!("non-component type"), |
| 106 | + } |
| 107 | + } |
| 108 | + } |
| 109 | + Ok(ComponentExportSection(es)) => { |
| 110 | + for e in es { |
| 111 | + match e { |
| 112 | + Err(_) => panic!("invalid export section"), |
| 113 | + Ok(ce) => { |
| 114 | + if ce.kind == ComponentExternalKind::Type { |
| 115 | + last_idx = Some(ctx.types.len()); |
| 116 | + ctx.types.push(raw_type_export_type(&ctx, &ce).clone()); |
| 117 | + } |
| 118 | + } |
| 119 | + } |
| 120 | + } |
| 121 | + } |
| 122 | + Ok(ComponentAliasSection(r#as)) => { |
| 123 | + for a in r#as { |
| 124 | + match a { |
| 125 | + Ok(ComponentAlias::InstanceExport { |
| 126 | + kind: ComponentExternalKind::Type, |
| 127 | + .. |
| 128 | + }) |
| 129 | + | Ok(ComponentAlias::Outer { |
| 130 | + kind: ComponentOuterAliasKind::Type, |
| 131 | + .. |
| 132 | + }) => { |
| 133 | + panic!("Component outer type aliases are not supported") |
| 134 | + } |
| 135 | + // Anything else doesn't affect the index |
| 136 | + // space that we are interested in, so we can |
| 137 | + // safely ignore |
| 138 | + _ => {} |
| 139 | + } |
| 140 | + } |
| 141 | + } |
| 142 | + |
| 143 | + // No other component section should be terribly relevant |
| 144 | + // for us. We would not generally expect to find them in |
| 145 | + // a file that just represents a type like this, but it |
| 146 | + // seems like there are/may be a whole bunch of debugging |
| 147 | + // custom sections, etc that might show up, so for now |
| 148 | + // let's just ignore anything. |
| 149 | + _ => {} |
| 150 | + } |
| 151 | + } |
| 152 | + match last_idx { |
| 153 | + None => panic!("no exported type"), |
| 154 | + Some(n) => match ctx.types.into_iter().nth(n) { |
| 155 | + Some(Defined::Component(c)) => c, |
| 156 | + _ => panic!("final export is not component"), |
| 157 | + }, |
| 158 | + } |
| 159 | +} |
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