| /* Copyright 2018 Mozilla Foundation |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| use crate::{BinaryReader, FromReader, MemoryType, Result, SectionLimited}; |
| |
| /// A reader for the memory section of a WebAssembly module. |
| pub type MemorySectionReader<'a> = SectionLimited<'a, MemoryType>; |
| |
| impl<'a> FromReader<'a> for MemoryType { |
| fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> { |
| let pos = reader.original_position(); |
| let flags = reader.read_u8()?; |
| if (flags & !0b111) != 0 { |
| bail!(pos, "invalid memory limits flags"); |
| } |
| |
| let memory64 = flags & 0b100 != 0; |
| let shared = flags & 0b010 != 0; |
| let has_max = flags & 0b001 != 0; |
| Ok(MemoryType { |
| memory64, |
| shared, |
| // FIXME(WebAssembly/memory64#21) as currently specified if the |
| // `shared` flag is set we should be reading a 32-bit limits field |
| // here. That seems a bit odd to me at the time of this writing so |
| // I've taken the liberty of reading a 64-bit limits field in those |
| // situations. I suspect that this is a typo in the spec, but if not |
| // we'll need to update this to read a 32-bit limits field when the |
| // shared flag is set. |
| initial: if memory64 { |
| reader.read_var_u64()? |
| } else { |
| reader.read_var_u32()?.into() |
| }, |
| maximum: if !has_max { |
| None |
| } else if memory64 { |
| Some(reader.read_var_u64()?) |
| } else { |
| Some(reader.read_var_u32()?.into()) |
| }, |
| }) |
| } |
| } |