wasmparser/readers/core/
globals.rs

1/* Copyright 2018 Mozilla Foundation
2 *
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 *     http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16use crate::{BinaryReader, ConstExpr, FromReader, GlobalType, Result, SectionLimited};
17
18/// Represents a core WebAssembly global.
19#[derive(Debug, Clone)]
20pub struct Global<'a> {
21    /// The global's type.
22    pub ty: GlobalType,
23    /// The global's initialization expression.
24    pub init_expr: ConstExpr<'a>,
25}
26
27/// A reader for the global section of a WebAssembly module.
28pub type GlobalSectionReader<'a> = SectionLimited<'a, Global<'a>>;
29
30impl<'a> FromReader<'a> for Global<'a> {
31    fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> {
32        let ty = reader.read()?;
33        let init_expr = reader.read()?;
34        Ok(Global { ty, init_expr })
35    }
36}
37
38impl<'a> FromReader<'a> for GlobalType {
39    fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> {
40        let content_type = reader.read()?;
41        let flags = reader.read_u8()?;
42        if reader.shared_everything_threads() {
43            if flags > 0b11 {
44                bail!(reader.original_position() - 1, "malformed global flags")
45            }
46        } else {
47            if flags > 0b1 {
48                bail!(
49                    reader.original_position() - 1,
50                    "malformed mutability -- or shared globals \
51                     require the shared-everything-threads proposal"
52                )
53            }
54        }
55        Ok(GlobalType {
56            content_type,
57            mutable: (flags & 0b01) > 0,
58            shared: (flags & 0b10) > 0,
59        })
60    }
61}
wasmparser/readers/core/globals.rs

wasmparser/readers/core/
globals.rs
