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, FromReader, MemoryType, Result, SectionLimited};
17
18/// A reader for the memory section of a WebAssembly module.
19pub type MemorySectionReader<'a> = SectionLimited<'a, MemoryType>;
20
21impl<'a> FromReader<'a> for MemoryType {
22 fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> {
23 let pos = reader.original_position();
24 let flags = reader.read_u8()?;
25
26 if (flags & !0b1111) != 0 {
27 bail!(pos, "invalid memory limits flags");
28 }
29
30 let memory64 = flags & 0b0100 != 0;
31 let shared = flags & 0b0010 != 0;
32 let has_max = flags & 0b0001 != 0;
33 let has_page_size = flags & 0b1000 != 0;
34
35 Ok(MemoryType {
36 memory64,
37 shared,
38 initial: if memory64 {
39 reader.read_var_u64()?
40 } else {
41 reader.read_var_u32()?.into()
42 },
43 maximum: if !has_max {
44 None
45 } else if memory64 {
46 Some(reader.read_var_u64()?)
47 } else {
48 Some(reader.read_var_u32()?.into())
49 },
50 page_size_log2: if has_page_size {
51 Some(reader.read_var_u32()?)
52 } else {
53 None
54 },
55 })
56 }
57}
58