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use crate::binary_reader::WASM_MAGIC_NUMBER;
use crate::prelude::*;
#[cfg(feature = "features")]
use crate::WasmFeatures;
#[cfg(feature = "component-model")]
use crate::{
limits::MAX_WASM_MODULE_SIZE, ComponentCanonicalSectionReader, ComponentExportSectionReader,
ComponentImportSectionReader, ComponentInstanceSectionReader, ComponentStartFunction,
ComponentTypeSectionReader, CoreTypeSectionReader, InstanceSectionReader, SectionLimited,
};
use crate::{
BinaryReader, BinaryReaderError, CustomSectionReader, DataSectionReader, ElementSectionReader,
ExportSectionReader, FromReader, FunctionBody, FunctionSectionReader, GlobalSectionReader,
ImportSectionReader, MemorySectionReader, Result, TableSectionReader, TagSectionReader,
TypeSectionReader,
};
use core::fmt;
use core::iter;
use core::ops::Range;
pub(crate) const WASM_MODULE_VERSION: u16 = 0x1;
// Note that this started at `0xa` and we're incrementing up from there. When
// the component model is stabilized this will become 0x1. The changes here are:
//
// * [????-??-??] 0xa - original version
// * [2023-01-05] 0xb - `export` introduces an alias
// * [2023-02-06] 0xc - `export` has an optional type ascribed to it
// * [2023-05-10] 0xd - imports/exports drop URLs, new discriminator byte which
// allows for `(import (interface "...") ...)` syntax.
pub(crate) const WASM_COMPONENT_VERSION: u16 = 0xd;
const KIND_MODULE: u16 = 0x00;
const KIND_COMPONENT: u16 = 0x01;
/// The supported encoding formats for the parser.
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum Encoding {
/// The encoding format is a WebAssembly module.
Module,
/// The encoding format is a WebAssembly component.
Component,
}
/// An incremental parser of a binary WebAssembly module or component.
///
/// This type is intended to be used to incrementally parse a WebAssembly module
/// or component as bytes become available for the module. This can also be used
/// to parse modules or components that are already entirely resident within memory.
///
/// This primary function for a parser is the [`Parser::parse`] function which
/// will incrementally consume input. You can also use the [`Parser::parse_all`]
/// function to parse a module or component that is entirely resident in memory.
#[derive(Debug, Clone)]
pub struct Parser {
state: State,
offset: u64,
max_size: u64,
encoding: Encoding,
#[cfg(feature = "features")]
features: WasmFeatures,
}
#[derive(Debug, Clone)]
enum State {
Header,
SectionStart,
FunctionBody { remaining: u32, len: u32 },
}
/// A successful return payload from [`Parser::parse`].
///
/// On success one of two possible values can be returned, either that more data
/// is needed to continue parsing or a chunk of the input was parsed, indicating
/// how much of it was parsed.
#[derive(Debug)]
pub enum Chunk<'a> {
/// This can be returned at any time and indicates that more data is needed
/// to proceed with parsing. Zero bytes were consumed from the input to
/// [`Parser::parse`]. The `u64` value here is a hint as to how many more
/// bytes are needed to continue parsing.
NeedMoreData(u64),
/// A chunk was successfully parsed.
Parsed {
/// This many bytes of the `data` input to [`Parser::parse`] were
/// consumed to produce `payload`.
consumed: usize,
/// The value that we actually parsed.
payload: Payload<'a>,
},
}
/// Values that can be parsed from a WebAssembly module or component.
///
/// This enumeration is all possible chunks of pieces that can be parsed by a
/// [`Parser`] from a binary WebAssembly module or component. Note that for many
/// sections the entire section is parsed all at once, whereas other functions,
/// like the code section, are parsed incrementally. This is a distinction where some
/// sections, like the type section, are required to be fully resident in memory
/// (fully downloaded) before proceeding. Other sections, like the code section,
/// can be processed in a streaming fashion where each function is extracted
/// individually so it can possibly be shipped to another thread while you wait
/// for more functions to get downloaded.
///
/// Note that payloads, when returned, do not indicate that the module or component
/// is valid. For example when you receive a `Payload::TypeSection` the type
/// section itself has not yet actually been parsed. The reader returned will be
/// able to parse it, but you'll have to actually iterate the reader to do the
/// full parse. Each payload returned is intended to be a *window* into the
/// original `data` passed to [`Parser::parse`] which can be further processed
/// if necessary.
#[non_exhaustive]
pub enum Payload<'a> {
/// Indicates the header of a WebAssembly module or component.
Version {
/// The version number found in the header.
num: u16,
/// The encoding format being parsed.
encoding: Encoding,
/// The range of bytes that were parsed to consume the header of the
/// module or component. Note that this range is relative to the start
/// of the byte stream.
range: Range<usize>,
},
/// A module type section was received and the provided reader can be
/// used to parse the contents of the type section.
TypeSection(TypeSectionReader<'a>),
/// A module import section was received and the provided reader can be
/// used to parse the contents of the import section.
ImportSection(ImportSectionReader<'a>),
/// A module function section was received and the provided reader can be
/// used to parse the contents of the function section.
FunctionSection(FunctionSectionReader<'a>),
/// A module table section was received and the provided reader can be
/// used to parse the contents of the table section.
TableSection(TableSectionReader<'a>),
/// A module memory section was received and the provided reader can be
/// used to parse the contents of the memory section.
MemorySection(MemorySectionReader<'a>),
/// A module tag section was received, and the provided reader can be
/// used to parse the contents of the tag section.
TagSection(TagSectionReader<'a>),
/// A module global section was received and the provided reader can be
/// used to parse the contents of the global section.
GlobalSection(GlobalSectionReader<'a>),
/// A module export section was received, and the provided reader can be
/// used to parse the contents of the export section.
ExportSection(ExportSectionReader<'a>),
/// A module start section was received.
StartSection {
/// The start function index
func: u32,
/// The range of bytes that specify the `func` field, specified in
/// offsets relative to the start of the byte stream.
range: Range<usize>,
},
/// A module element section was received and the provided reader can be
/// used to parse the contents of the element section.
ElementSection(ElementSectionReader<'a>),
/// A module data count section was received.
DataCountSection {
/// The number of data segments.
count: u32,
/// The range of bytes that specify the `count` field, specified in
/// offsets relative to the start of the byte stream.
range: Range<usize>,
},
/// A module data section was received and the provided reader can be
/// used to parse the contents of the data section.
DataSection(DataSectionReader<'a>),
/// Indicator of the start of the code section of a WebAssembly module.
///
/// This entry is returned whenever the code section starts. The `count`
/// field indicates how many entries are in this code section. After
/// receiving this start marker you're guaranteed that the next `count`
/// items will be either `CodeSectionEntry` or an error will be returned.
///
/// This, unlike other sections, is intended to be used for streaming the
/// contents of the code section. The code section is not required to be
/// fully resident in memory when we parse it. Instead a [`Parser`] is
/// capable of parsing piece-by-piece of a code section.
CodeSectionStart {
/// The number of functions in this section.
count: u32,
/// The range of bytes that represent this section, specified in
/// offsets relative to the start of the byte stream.
range: Range<usize>,
/// The size, in bytes, of the remaining contents of this section.
///
/// This can be used in combination with [`Parser::skip_section`]
/// where the caller will know how many bytes to skip before feeding
/// bytes into `Parser` again.
size: u32,
},
/// An entry of the code section, a function, was parsed from a WebAssembly
/// module.
///
/// This entry indicates that a function was successfully received from the
/// code section, and the payload here is the window into the original input
/// where the function resides. Note that the function itself has not been
/// parsed, it's only been outlined. You'll need to process the
/// `FunctionBody` provided to test whether it parses and/or is valid.
CodeSectionEntry(FunctionBody<'a>),
/// A core module section was received and the provided parser can be
/// used to parse the nested module.
///
/// This variant is special in that it returns a sub-`Parser`. Upon
/// receiving a `ModuleSection` it is expected that the returned
/// `Parser` will be used instead of the parent `Parser` until the parse has
/// finished. You'll need to feed data into the `Parser` returned until it
/// returns `Payload::End`. After that you'll switch back to the parent
/// parser to resume parsing the rest of the current component.
///
/// Note that binaries will not be parsed correctly if you feed the data for
/// a nested module into the parent [`Parser`].
#[cfg(feature = "component-model")]
ModuleSection {
/// The parser for the nested module.
parser: Parser,
/// The range of bytes that represent the nested module in the
/// original byte stream.
///
/// Note that, to better support streaming parsing and validation, the
/// validator does *not* check that this range is in bounds.
unchecked_range: Range<usize>,
},
/// A core instance section was received and the provided parser can be
/// used to parse the contents of the core instance section.
///
/// Currently this section is only parsed in a component.
#[cfg(feature = "component-model")]
InstanceSection(InstanceSectionReader<'a>),
/// A core type section was received and the provided parser can be
/// used to parse the contents of the core type section.
///
/// Currently this section is only parsed in a component.
#[cfg(feature = "component-model")]
CoreTypeSection(CoreTypeSectionReader<'a>),
/// A component section from a WebAssembly component was received and the
/// provided parser can be used to parse the nested component.
///
/// This variant is special in that it returns a sub-`Parser`. Upon
/// receiving a `ComponentSection` it is expected that the returned
/// `Parser` will be used instead of the parent `Parser` until the parse has
/// finished. You'll need to feed data into the `Parser` returned until it
/// returns `Payload::End`. After that you'll switch back to the parent
/// parser to resume parsing the rest of the current component.
///
/// Note that binaries will not be parsed correctly if you feed the data for
/// a nested component into the parent [`Parser`].
#[cfg(feature = "component-model")]
ComponentSection {
/// The parser for the nested component.
parser: Parser,
/// The range of bytes that represent the nested component in the
/// original byte stream.
///
/// Note that, to better support streaming parsing and validation, the
/// validator does *not* check that this range is in bounds.
unchecked_range: Range<usize>,
},
/// A component instance section was received and the provided reader can be
/// used to parse the contents of the component instance section.
#[cfg(feature = "component-model")]
ComponentInstanceSection(ComponentInstanceSectionReader<'a>),
/// A component alias section was received and the provided reader can be
/// used to parse the contents of the component alias section.
#[cfg(feature = "component-model")]
ComponentAliasSection(SectionLimited<'a, crate::ComponentAlias<'a>>),
/// A component type section was received and the provided reader can be
/// used to parse the contents of the component type section.
#[cfg(feature = "component-model")]
ComponentTypeSection(ComponentTypeSectionReader<'a>),
/// A component canonical section was received and the provided reader can be
/// used to parse the contents of the component canonical section.
#[cfg(feature = "component-model")]
ComponentCanonicalSection(ComponentCanonicalSectionReader<'a>),
/// A component start section was received.
#[cfg(feature = "component-model")]
ComponentStartSection {
/// The start function description.
start: ComponentStartFunction,
/// The range of bytes that specify the `start` field.
range: Range<usize>,
},
/// A component import section was received and the provided reader can be
/// used to parse the contents of the component import section.
#[cfg(feature = "component-model")]
ComponentImportSection(ComponentImportSectionReader<'a>),
/// A component export section was received, and the provided reader can be
/// used to parse the contents of the component export section.
#[cfg(feature = "component-model")]
ComponentExportSection(ComponentExportSectionReader<'a>),
/// A module or component custom section was received.
CustomSection(CustomSectionReader<'a>),
/// An unknown section was found.
///
/// This variant is returned for all unknown sections encountered. This
/// likely wants to be interpreted as an error by consumers of the parser,
/// but this can also be used to parse sections currently unsupported by
/// the parser.
UnknownSection {
/// The 8-bit identifier for this section.
id: u8,
/// The contents of this section.
contents: &'a [u8],
/// The range of bytes, relative to the start of the original data
/// stream, that the contents of this section reside in.
range: Range<usize>,
},
/// The end of the WebAssembly module or component was reached.
///
/// The value is the offset in the input byte stream where the end
/// was reached.
End(usize),
}
const CUSTOM_SECTION: u8 = 0;
const TYPE_SECTION: u8 = 1;
const IMPORT_SECTION: u8 = 2;
const FUNCTION_SECTION: u8 = 3;
const TABLE_SECTION: u8 = 4;
const MEMORY_SECTION: u8 = 5;
const GLOBAL_SECTION: u8 = 6;
const EXPORT_SECTION: u8 = 7;
const START_SECTION: u8 = 8;
const ELEMENT_SECTION: u8 = 9;
const CODE_SECTION: u8 = 10;
const DATA_SECTION: u8 = 11;
const DATA_COUNT_SECTION: u8 = 12;
const TAG_SECTION: u8 = 13;
#[cfg(feature = "component-model")]
const COMPONENT_MODULE_SECTION: u8 = 1;
#[cfg(feature = "component-model")]
const COMPONENT_CORE_INSTANCE_SECTION: u8 = 2;
#[cfg(feature = "component-model")]
const COMPONENT_CORE_TYPE_SECTION: u8 = 3;
#[cfg(feature = "component-model")]
const COMPONENT_SECTION: u8 = 4;
#[cfg(feature = "component-model")]
const COMPONENT_INSTANCE_SECTION: u8 = 5;
#[cfg(feature = "component-model")]
const COMPONENT_ALIAS_SECTION: u8 = 6;
#[cfg(feature = "component-model")]
const COMPONENT_TYPE_SECTION: u8 = 7;
#[cfg(feature = "component-model")]
const COMPONENT_CANONICAL_SECTION: u8 = 8;
#[cfg(feature = "component-model")]
const COMPONENT_START_SECTION: u8 = 9;
#[cfg(feature = "component-model")]
const COMPONENT_IMPORT_SECTION: u8 = 10;
#[cfg(feature = "component-model")]
const COMPONENT_EXPORT_SECTION: u8 = 11;
impl Parser {
/// Creates a new parser.
///
/// Reports errors and ranges relative to `offset` provided, where `offset`
/// is some logical offset within the input stream that we're parsing.
pub fn new(offset: u64) -> Parser {
Parser {
state: State::Header,
offset,
max_size: u64::MAX,
// Assume the encoding is a module until we know otherwise
encoding: Encoding::Module,
#[cfg(feature = "features")]
features: WasmFeatures::all(),
}
}
/// Tests whether `bytes` looks like a core WebAssembly module.
///
/// This will inspect the first 8 bytes of `bytes` and return `true` if it
/// starts with the standard core WebAssembly header.
pub fn is_core_wasm(bytes: &[u8]) -> bool {
const HEADER: [u8; 8] = [
WASM_MAGIC_NUMBER[0],
WASM_MAGIC_NUMBER[1],
WASM_MAGIC_NUMBER[2],
WASM_MAGIC_NUMBER[3],
WASM_MODULE_VERSION.to_le_bytes()[0],
WASM_MODULE_VERSION.to_le_bytes()[1],
KIND_MODULE.to_le_bytes()[0],
KIND_MODULE.to_le_bytes()[1],
];
bytes.starts_with(&HEADER)
}
/// Tests whether `bytes` looks like a WebAssembly component.
///
/// This will inspect the first 8 bytes of `bytes` and return `true` if it
/// starts with the standard WebAssembly component header.
pub fn is_component(bytes: &[u8]) -> bool {
const HEADER: [u8; 8] = [
WASM_MAGIC_NUMBER[0],
WASM_MAGIC_NUMBER[1],
WASM_MAGIC_NUMBER[2],
WASM_MAGIC_NUMBER[3],
WASM_COMPONENT_VERSION.to_le_bytes()[0],
WASM_COMPONENT_VERSION.to_le_bytes()[1],
KIND_COMPONENT.to_le_bytes()[0],
KIND_COMPONENT.to_le_bytes()[1],
];
bytes.starts_with(&HEADER)
}
/// Returns the currently active set of wasm features that this parser is
/// using while parsing.
///
/// The default set of features is [`WasmFeatures::all()`] for new parsers.
///
/// For more information see [`BinaryReader::new`].
#[cfg(feature = "features")]
pub fn features(&self) -> WasmFeatures {
self.features
}
/// Sets the wasm features active while parsing to the `features` specified.
///
/// The default set of features is [`WasmFeatures::all()`] for new parsers.
///
/// For more information see [`BinaryReader::new`].
#[cfg(feature = "features")]
pub fn set_features(&mut self, features: WasmFeatures) {
self.features = features;
}
/// Returns the original offset that this parser is currently at.
pub fn offset(&self) -> u64 {
self.offset
}
/// Attempts to parse a chunk of data.
///
/// This method will attempt to parse the next incremental portion of a
/// WebAssembly binary. Data available for the module or component is
/// provided as `data`, and the data can be incomplete if more data has yet
/// to arrive. The `eof` flag indicates whether more data will ever be received.
///
/// There are two ways parsing can succeed with this method:
///
/// * `Chunk::NeedMoreData` - this indicates that there is not enough bytes
/// in `data` to parse a payload. The caller needs to wait for more data to
/// be available in this situation before calling this method again. It is
/// guaranteed that this is only returned if `eof` is `false`.
///
/// * `Chunk::Parsed` - this indicates that a chunk of the input was
/// successfully parsed. The payload is available in this variant of what
/// was parsed, and this also indicates how many bytes of `data` was
/// consumed. It's expected that the caller will not provide these bytes
/// back to the [`Parser`] again.
///
/// Note that all `Chunk` return values are connected, with a lifetime, to
/// the input buffer. Each parsed chunk borrows the input buffer and is a
/// view into it for successfully parsed chunks.
///
/// It is expected that you'll call this method until `Payload::End` is
/// reached, at which point you're guaranteed that the parse has completed.
/// Note that complete parsing, for the top-level module or component,
/// implies that `data` is empty and `eof` is `true`.
///
/// # Errors
///
/// Parse errors are returned as an `Err`. Errors can happen when the
/// structure of the data is unexpected or if sections are too large for
/// example. Note that errors are not returned for malformed *contents* of
/// sections here. Sections are generally not individually parsed and each
/// returned [`Payload`] needs to be iterated over further to detect all
/// errors.
///
/// # Examples
///
/// An example of reading a wasm file from a stream (`std::io::Read`) and
/// incrementally parsing it.
///
/// ```
/// use std::io::Read;
/// use anyhow::Result;
/// use wasmparser::{Parser, Chunk, Payload::*};
///
/// fn parse(mut reader: impl Read) -> Result<()> {
/// let mut buf = Vec::new();
/// let mut cur = Parser::new(0);
/// let mut eof = false;
/// let mut stack = Vec::new();
///
/// loop {
/// let (payload, consumed) = match cur.parse(&buf, eof)? {
/// Chunk::NeedMoreData(hint) => {
/// assert!(!eof); // otherwise an error would be returned
///
/// // Use the hint to preallocate more space, then read
/// // some more data into our buffer.
/// //
/// // Note that the buffer management here is not ideal,
/// // but it's compact enough to fit in an example!
/// let len = buf.len();
/// buf.extend((0..hint).map(|_| 0u8));
/// let n = reader.read(&mut buf[len..])?;
/// buf.truncate(len + n);
/// eof = n == 0;
/// continue;
/// }
///
/// Chunk::Parsed { consumed, payload } => (payload, consumed),
/// };
///
/// match payload {
/// // Sections for WebAssembly modules
/// Version { .. } => { /* ... */ }
/// TypeSection(_) => { /* ... */ }
/// ImportSection(_) => { /* ... */ }
/// FunctionSection(_) => { /* ... */ }
/// TableSection(_) => { /* ... */ }
/// MemorySection(_) => { /* ... */ }
/// TagSection(_) => { /* ... */ }
/// GlobalSection(_) => { /* ... */ }
/// ExportSection(_) => { /* ... */ }
/// StartSection { .. } => { /* ... */ }
/// ElementSection(_) => { /* ... */ }
/// DataCountSection { .. } => { /* ... */ }
/// DataSection(_) => { /* ... */ }
///
/// // Here we know how many functions we'll be receiving as
/// // `CodeSectionEntry`, so we can prepare for that, and
/// // afterwards we can parse and handle each function
/// // individually.
/// CodeSectionStart { .. } => { /* ... */ }
/// CodeSectionEntry(body) => {
/// // here we can iterate over `body` to parse the function
/// // and its locals
/// }
///
/// // Sections for WebAssembly components
/// InstanceSection(_) => { /* ... */ }
/// CoreTypeSection(_) => { /* ... */ }
/// ComponentInstanceSection(_) => { /* ... */ }
/// ComponentAliasSection(_) => { /* ... */ }
/// ComponentTypeSection(_) => { /* ... */ }
/// ComponentCanonicalSection(_) => { /* ... */ }
/// ComponentStartSection { .. } => { /* ... */ }
/// ComponentImportSection(_) => { /* ... */ }
/// ComponentExportSection(_) => { /* ... */ }
///
/// ModuleSection { parser, .. }
/// | ComponentSection { parser, .. } => {
/// stack.push(cur.clone());
/// cur = parser.clone();
/// }
///
/// CustomSection(_) => { /* ... */ }
///
/// // Once we've reached the end of a parser we either resume
/// // at the parent parser or we break out of the loop because
/// // we're done.
/// End(_) => {
/// if let Some(parent_parser) = stack.pop() {
/// cur = parent_parser;
/// } else {
/// break;
/// }
/// }
///
/// // most likely you'd return an error here
/// _ => { /* ... */ }
/// }
///
/// // once we're done processing the payload we can forget the
/// // original.
/// buf.drain(..consumed);
/// }
///
/// Ok(())
/// }
///
/// # parse(&b"\0asm\x01\0\0\0"[..]).unwrap();
/// ```
pub fn parse<'a>(&mut self, data: &'a [u8], eof: bool) -> Result<Chunk<'a>> {
let (data, eof) = if usize_to_u64(data.len()) > self.max_size {
(&data[..(self.max_size as usize)], true)
} else {
(data, eof)
};
// TODO: thread through `offset: u64` to `BinaryReader`, remove
// the cast here.
let starting_offset = self.offset as usize;
let mut reader = BinaryReader::new(data, starting_offset);
#[cfg(feature = "features")]
{
reader.set_features(self.features);
}
match self.parse_reader(&mut reader, eof) {
Ok(payload) => {
// Be sure to update our offset with how far we got in the
// reader
let consumed = reader.original_position() - starting_offset;
self.offset += usize_to_u64(consumed);
self.max_size -= usize_to_u64(consumed);
Ok(Chunk::Parsed {
consumed: consumed,
payload,
})
}
Err(e) => {
// If we're at EOF then there's no way we can recover from any
// error, so continue to propagate it.
if eof {
return Err(e);
}
// If our error doesn't look like it can be resolved with more
// data being pulled down, then propagate it, otherwise switch
// the error to "feed me please"
match e.inner.needed_hint {
Some(hint) => Ok(Chunk::NeedMoreData(usize_to_u64(hint))),
None => Err(e),
}
}
}
}
fn parse_reader<'a>(
&mut self,
reader: &mut BinaryReader<'a>,
eof: bool,
) -> Result<Payload<'a>> {
use Payload::*;
match self.state {
State::Header => {
let start = reader.original_position();
let header_version = reader.read_header_version()?;
self.encoding = match (header_version >> 16) as u16 {
KIND_MODULE => Encoding::Module,
KIND_COMPONENT => Encoding::Component,
_ => bail!(start + 4, "unknown binary version: {header_version:#10x}"),
};
let num = header_version as u16;
self.state = State::SectionStart;
Ok(Version {
num,
encoding: self.encoding,
range: start..reader.original_position(),
})
}
State::SectionStart => {
// If we're at eof and there are no bytes in our buffer, then
// that means we reached the end of the data since it's
// just a bunch of sections concatenated after the header.
if eof && reader.bytes_remaining() == 0 {
return Ok(Payload::End(reader.original_position()));
}
let id_pos = reader.original_position();
let id = reader.read_u8()?;
if id & 0x80 != 0 {
return Err(BinaryReaderError::new("malformed section id", id_pos));
}
let len_pos = reader.original_position();
let mut len = reader.read_var_u32()?;
// Test to make sure that this section actually fits within
// `Parser::max_size`. This doesn't matter for top-level modules
// but it is required for nested modules/components to correctly ensure
// that all sections live entirely within their section of the
// file.
let consumed = reader.original_position() - id_pos;
let section_overflow = self
.max_size
.checked_sub(usize_to_u64(consumed))
.and_then(|s| s.checked_sub(len.into()))
.is_none();
if section_overflow {
return Err(BinaryReaderError::new("section too large", len_pos));
}
match (self.encoding, id) {
// Sections for both modules and components.
(_, 0) => section(reader, len, CustomSectionReader::new, CustomSection),
// Module sections
(Encoding::Module, TYPE_SECTION) => {
section(reader, len, TypeSectionReader::new, TypeSection)
}
(Encoding::Module, IMPORT_SECTION) => {
section(reader, len, ImportSectionReader::new, ImportSection)
}
(Encoding::Module, FUNCTION_SECTION) => {
section(reader, len, FunctionSectionReader::new, FunctionSection)
}
(Encoding::Module, TABLE_SECTION) => {
section(reader, len, TableSectionReader::new, TableSection)
}
(Encoding::Module, MEMORY_SECTION) => {
section(reader, len, MemorySectionReader::new, MemorySection)
}
(Encoding::Module, GLOBAL_SECTION) => {
section(reader, len, GlobalSectionReader::new, GlobalSection)
}
(Encoding::Module, EXPORT_SECTION) => {
section(reader, len, ExportSectionReader::new, ExportSection)
}
(Encoding::Module, START_SECTION) => {
let (func, range) = single_item(reader, len, "start")?;
Ok(StartSection { func, range })
}
(Encoding::Module, ELEMENT_SECTION) => {
section(reader, len, ElementSectionReader::new, ElementSection)
}
(Encoding::Module, CODE_SECTION) => {
let start = reader.original_position();
let count = delimited(reader, &mut len, |r| r.read_var_u32())?;
let range = start..reader.original_position() + len as usize;
self.state = State::FunctionBody {
remaining: count,
len,
};
Ok(CodeSectionStart {
count,
range,
size: len,
})
}
(Encoding::Module, DATA_SECTION) => {
section(reader, len, DataSectionReader::new, DataSection)
}
(Encoding::Module, DATA_COUNT_SECTION) => {
let (count, range) = single_item(reader, len, "data count")?;
Ok(DataCountSection { count, range })
}
(Encoding::Module, TAG_SECTION) => {
section(reader, len, TagSectionReader::new, TagSection)
}
// Component sections
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_MODULE_SECTION)
| (Encoding::Component, COMPONENT_SECTION) => {
if len as usize > MAX_WASM_MODULE_SIZE {
bail!(
len_pos,
"{} section is too large",
if id == 1 { "module" } else { "component " }
);
}
let range = reader.original_position()
..reader.original_position() + usize::try_from(len).unwrap();
self.max_size -= u64::from(len);
self.offset += u64::from(len);
let mut parser = Parser::new(usize_to_u64(reader.original_position()));
#[cfg(feature = "features")]
{
parser.features = self.features;
}
parser.max_size = u64::from(len);
Ok(match id {
1 => ModuleSection {
parser,
unchecked_range: range,
},
4 => ComponentSection {
parser,
unchecked_range: range,
},
_ => unreachable!(),
})
}
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_CORE_INSTANCE_SECTION) => {
section(reader, len, InstanceSectionReader::new, InstanceSection)
}
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_CORE_TYPE_SECTION) => {
section(reader, len, CoreTypeSectionReader::new, CoreTypeSection)
}
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_INSTANCE_SECTION) => section(
reader,
len,
ComponentInstanceSectionReader::new,
ComponentInstanceSection,
),
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_ALIAS_SECTION) => {
section(reader, len, SectionLimited::new, ComponentAliasSection)
}
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_TYPE_SECTION) => section(
reader,
len,
ComponentTypeSectionReader::new,
ComponentTypeSection,
),
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_CANONICAL_SECTION) => section(
reader,
len,
ComponentCanonicalSectionReader::new,
ComponentCanonicalSection,
),
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_START_SECTION) => {
let (start, range) = single_item(reader, len, "component start")?;
Ok(ComponentStartSection { start, range })
}
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_IMPORT_SECTION) => section(
reader,
len,
ComponentImportSectionReader::new,
ComponentImportSection,
),
#[cfg(feature = "component-model")]
(Encoding::Component, COMPONENT_EXPORT_SECTION) => section(
reader,
len,
ComponentExportSectionReader::new,
ComponentExportSection,
),
(_, id) => {
let offset = reader.original_position();
let contents = reader.read_bytes(len as usize)?;
let range = offset..offset + len as usize;
Ok(UnknownSection {
id,
contents,
range,
})
}
}
}
// Once we hit 0 remaining incrementally parsed items, with 0
// remaining bytes in each section, we're done and can switch back
// to parsing sections.
State::FunctionBody {
remaining: 0,
len: 0,
} => {
self.state = State::SectionStart;
self.parse_reader(reader, eof)
}
// ... otherwise trailing bytes with no remaining entries in these
// sections indicates an error.
State::FunctionBody { remaining: 0, len } => {
debug_assert!(len > 0);
let offset = reader.original_position();
Err(BinaryReaderError::new(
"trailing bytes at end of section",
offset,
))
}
// Functions are relatively easy to parse when we know there's at
// least one remaining and at least one byte available to read
// things.
//
// We use the remaining length try to read a u32 size of the
// function, and using that size we require the entire function be
// resident in memory. This means that we're reading whole chunks of
// functions at a time.
//
// Limiting via `Parser::max_size` (nested parsing) happens above in
// `fn parse`, and limiting by our section size happens via
// `delimited`. Actual parsing of the function body is delegated to
// the caller to iterate over the `FunctionBody` structure.
State::FunctionBody { remaining, mut len } => {
let body = delimited(reader, &mut len, |r| {
Ok(FunctionBody::new(r.read_reader()?))
})?;
self.state = State::FunctionBody {
remaining: remaining - 1,
len,
};
Ok(CodeSectionEntry(body))
}
}
}
/// Convenience function that can be used to parse a module or component
/// that is entirely resident in memory.
///
/// This function will parse the `data` provided as a WebAssembly module
/// or component.
///
/// Note that when this function yields sections that provide parsers,
/// no further action is required for those sections as payloads from
/// those parsers will be automatically returned.
///
/// # Examples
///
/// An example of reading a wasm file from a stream (`std::io::Read`) into
/// a buffer and then parsing it.
///
/// ```
/// use std::io::Read;
/// use anyhow::Result;
/// use wasmparser::{Parser, Chunk, Payload::*};
///
/// fn parse(mut reader: impl Read) -> Result<()> {
/// let mut buf = Vec::new();
/// reader.read_to_end(&mut buf)?;
/// let parser = Parser::new(0);
///
/// for payload in parser.parse_all(&buf) {
/// match payload? {
/// // Sections for WebAssembly modules
/// Version { .. } => { /* ... */ }
/// TypeSection(_) => { /* ... */ }
/// ImportSection(_) => { /* ... */ }
/// FunctionSection(_) => { /* ... */ }
/// TableSection(_) => { /* ... */ }
/// MemorySection(_) => { /* ... */ }
/// TagSection(_) => { /* ... */ }
/// GlobalSection(_) => { /* ... */ }
/// ExportSection(_) => { /* ... */ }
/// StartSection { .. } => { /* ... */ }
/// ElementSection(_) => { /* ... */ }
/// DataCountSection { .. } => { /* ... */ }
/// DataSection(_) => { /* ... */ }
///
/// // Here we know how many functions we'll be receiving as
/// // `CodeSectionEntry`, so we can prepare for that, and
/// // afterwards we can parse and handle each function
/// // individually.
/// CodeSectionStart { .. } => { /* ... */ }
/// CodeSectionEntry(body) => {
/// // here we can iterate over `body` to parse the function
/// // and its locals
/// }
///
/// // Sections for WebAssembly components
/// ModuleSection { .. } => { /* ... */ }
/// InstanceSection(_) => { /* ... */ }
/// CoreTypeSection(_) => { /* ... */ }
/// ComponentSection { .. } => { /* ... */ }
/// ComponentInstanceSection(_) => { /* ... */ }
/// ComponentAliasSection(_) => { /* ... */ }
/// ComponentTypeSection(_) => { /* ... */ }
/// ComponentCanonicalSection(_) => { /* ... */ }
/// ComponentStartSection { .. } => { /* ... */ }
/// ComponentImportSection(_) => { /* ... */ }
/// ComponentExportSection(_) => { /* ... */ }
///
/// CustomSection(_) => { /* ... */ }
///
/// // Once we've reached the end of a parser we either resume
/// // at the parent parser or the payload iterator is at its
/// // end and we're done.
/// End(_) => {}
///
/// // most likely you'd return an error here, but if you want
/// // you can also inspect the raw contents of unknown sections
/// other => {
/// match other.as_section() {
/// Some((id, range)) => { /* ... */ }
/// None => { /* ... */ }
/// }
/// }
/// }
/// }
///
/// Ok(())
/// }
///
/// # parse(&b"\0asm\x01\0\0\0"[..]).unwrap();
/// ```
pub fn parse_all(self, mut data: &[u8]) -> impl Iterator<Item = Result<Payload>> {
let mut stack = Vec::new();
let mut cur = self;
let mut done = false;
iter::from_fn(move || {
if done {
return None;
}
let payload = match cur.parse(data, true) {
// Propagate all errors
Err(e) => {
done = true;
return Some(Err(e));
}
// This isn't possible because `eof` is always true.
Ok(Chunk::NeedMoreData(_)) => unreachable!(),
Ok(Chunk::Parsed { payload, consumed }) => {
data = &data[consumed..];
payload
}
};
match &payload {
#[cfg(feature = "component-model")]
Payload::ModuleSection { parser, .. }
| Payload::ComponentSection { parser, .. } => {
stack.push(cur.clone());
cur = parser.clone();
}
Payload::End(_) => match stack.pop() {
Some(p) => cur = p,
None => done = true,
},
_ => {}
}
Some(Ok(payload))
})
}
/// Skip parsing the code section entirely.
///
/// This function can be used to indicate, after receiving
/// `CodeSectionStart`, that the section will not be parsed.
///
/// The caller will be responsible for skipping `size` bytes (found in the
/// `CodeSectionStart` payload). Bytes should only be fed into `parse`
/// after the `size` bytes have been skipped.
///
/// # Panics
///
/// This function will panic if the parser is not in a state where it's
/// parsing the code section.
///
/// # Examples
///
/// ```
/// use wasmparser::{Result, Parser, Chunk, Payload::*};
/// use core::ops::Range;
///
/// fn objdump_headers(mut wasm: &[u8]) -> Result<()> {
/// let mut parser = Parser::new(0);
/// loop {
/// let payload = match parser.parse(wasm, true)? {
/// Chunk::Parsed { consumed, payload } => {
/// wasm = &wasm[consumed..];
/// payload
/// }
/// // this state isn't possible with `eof = true`
/// Chunk::NeedMoreData(_) => unreachable!(),
/// };
/// match payload {
/// TypeSection(s) => print_range("type section", &s.range()),
/// ImportSection(s) => print_range("import section", &s.range()),
/// // .. other sections
///
/// // Print the range of the code section we see, but don't
/// // actually iterate over each individual function.
/// CodeSectionStart { range, size, .. } => {
/// print_range("code section", &range);
/// parser.skip_section();
/// wasm = &wasm[size as usize..];
/// }
/// End(_) => break,
/// _ => {}
/// }
/// }
/// Ok(())
/// }
///
/// fn print_range(section: &str, range: &Range<usize>) {
/// println!("{:>40}: {:#010x} - {:#010x}", section, range.start, range.end);
/// }
/// ```
pub fn skip_section(&mut self) {
let skip = match self.state {
State::FunctionBody { remaining: _, len } => len,
_ => panic!("wrong state to call `skip_section`"),
};
self.offset += u64::from(skip);
self.max_size -= u64::from(skip);
self.state = State::SectionStart;
}
}
fn usize_to_u64(a: usize) -> u64 {
a.try_into().unwrap()
}
/// Parses an entire section resident in memory into a `Payload`.
///
/// Requires that `len` bytes are resident in `reader` and uses `ctor`/`variant`
/// to construct the section to return.
fn section<'a, T>(
reader: &mut BinaryReader<'a>,
len: u32,
ctor: fn(BinaryReader<'a>) -> Result<T>,
variant: fn(T) -> Payload<'a>,
) -> Result<Payload<'a>> {
let reader = reader.skip(|r| {
r.read_bytes(len as usize)?;
Ok(())
})?;
// clear the hint for "need this many more bytes" here because we already
// read all the bytes, so it's not possible to read more bytes if this
// fails.
let reader = ctor(reader).map_err(clear_hint)?;
Ok(variant(reader))
}
/// Reads a section that is represented by a single uleb-encoded `u32`.
fn single_item<'a, T>(
reader: &mut BinaryReader<'a>,
len: u32,
desc: &str,
) -> Result<(T, Range<usize>)>
where
T: FromReader<'a>,
{
let range = reader.original_position()..reader.original_position() + len as usize;
let mut content = reader.skip(|r| {
r.read_bytes(len as usize)?;
Ok(())
})?;
// We can't recover from "unexpected eof" here because our entire section is
// already resident in memory, so clear the hint for how many more bytes are
// expected.
let ret = content.read().map_err(clear_hint)?;
if !content.eof() {
bail!(
content.original_position(),
"unexpected content in the {desc} section",
);
}
Ok((ret, range))
}
/// Attempts to parse using `f`.
///
/// This will update `*len` with the number of bytes consumed, and it will cause
/// a failure to be returned instead of the number of bytes consumed exceeds
/// what `*len` currently is.
fn delimited<'a, T>(
reader: &mut BinaryReader<'a>,
len: &mut u32,
f: impl FnOnce(&mut BinaryReader<'a>) -> Result<T>,
) -> Result<T> {
let start = reader.original_position();
let ret = f(reader)?;
*len = match (reader.original_position() - start)
.try_into()
.ok()
.and_then(|i| len.checked_sub(i))
{
Some(i) => i,
None => return Err(BinaryReaderError::new("unexpected end-of-file", start)),
};
Ok(ret)
}
impl Default for Parser {
fn default() -> Parser {
Parser::new(0)
}
}
impl Payload<'_> {
/// If this `Payload` represents a section in the original wasm module then
/// the section's id and range within the original wasm binary are returned.
///
/// Not all payloads refer to entire sections, such as the `Version` and
/// `CodeSectionEntry` variants. These variants will return `None` from this
/// function.
///
/// Otherwise this function will return `Some` where the first element is
/// the byte identifier for the section and the second element is the range
/// of the contents of the section within the original wasm binary.
///
/// The purpose of this method is to enable tools to easily iterate over
/// entire sections if necessary and handle sections uniformly, for example
/// dropping custom sections while preserving all other sections.
pub fn as_section(&self) -> Option<(u8, Range<usize>)> {
use Payload::*;
match self {
Version { .. } => None,
TypeSection(s) => Some((TYPE_SECTION, s.range())),
ImportSection(s) => Some((IMPORT_SECTION, s.range())),
FunctionSection(s) => Some((FUNCTION_SECTION, s.range())),
TableSection(s) => Some((TABLE_SECTION, s.range())),
MemorySection(s) => Some((MEMORY_SECTION, s.range())),
TagSection(s) => Some((TAG_SECTION, s.range())),
GlobalSection(s) => Some((GLOBAL_SECTION, s.range())),
ExportSection(s) => Some((EXPORT_SECTION, s.range())),
ElementSection(s) => Some((ELEMENT_SECTION, s.range())),
DataSection(s) => Some((DATA_SECTION, s.range())),
StartSection { range, .. } => Some((START_SECTION, range.clone())),
DataCountSection { range, .. } => Some((DATA_COUNT_SECTION, range.clone())),
CodeSectionStart { range, .. } => Some((CODE_SECTION, range.clone())),
CodeSectionEntry(_) => None,
#[cfg(feature = "component-model")]
ModuleSection {
unchecked_range: range,
..
} => Some((COMPONENT_MODULE_SECTION, range.clone())),
#[cfg(feature = "component-model")]
InstanceSection(s) => Some((COMPONENT_CORE_INSTANCE_SECTION, s.range())),
#[cfg(feature = "component-model")]
CoreTypeSection(s) => Some((COMPONENT_CORE_TYPE_SECTION, s.range())),
#[cfg(feature = "component-model")]
ComponentSection {
unchecked_range: range,
..
} => Some((COMPONENT_SECTION, range.clone())),
#[cfg(feature = "component-model")]
ComponentInstanceSection(s) => Some((COMPONENT_INSTANCE_SECTION, s.range())),
#[cfg(feature = "component-model")]
ComponentAliasSection(s) => Some((COMPONENT_ALIAS_SECTION, s.range())),
#[cfg(feature = "component-model")]
ComponentTypeSection(s) => Some((COMPONENT_TYPE_SECTION, s.range())),
#[cfg(feature = "component-model")]
ComponentCanonicalSection(s) => Some((COMPONENT_CANONICAL_SECTION, s.range())),
#[cfg(feature = "component-model")]
ComponentStartSection { range, .. } => Some((COMPONENT_START_SECTION, range.clone())),
#[cfg(feature = "component-model")]
ComponentImportSection(s) => Some((COMPONENT_IMPORT_SECTION, s.range())),
#[cfg(feature = "component-model")]
ComponentExportSection(s) => Some((COMPONENT_EXPORT_SECTION, s.range())),
CustomSection(c) => Some((CUSTOM_SECTION, c.range())),
UnknownSection { id, range, .. } => Some((*id, range.clone())),
End(_) => None,
}
}
}
impl fmt::Debug for Payload<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use Payload::*;
match self {
Version {
num,
encoding,
range,
} => f
.debug_struct("Version")
.field("num", num)
.field("encoding", encoding)
.field("range", range)
.finish(),
// Module sections
TypeSection(_) => f.debug_tuple("TypeSection").field(&"...").finish(),
ImportSection(_) => f.debug_tuple("ImportSection").field(&"...").finish(),
FunctionSection(_) => f.debug_tuple("FunctionSection").field(&"...").finish(),
TableSection(_) => f.debug_tuple("TableSection").field(&"...").finish(),
MemorySection(_) => f.debug_tuple("MemorySection").field(&"...").finish(),
TagSection(_) => f.debug_tuple("TagSection").field(&"...").finish(),
GlobalSection(_) => f.debug_tuple("GlobalSection").field(&"...").finish(),
ExportSection(_) => f.debug_tuple("ExportSection").field(&"...").finish(),
ElementSection(_) => f.debug_tuple("ElementSection").field(&"...").finish(),
DataSection(_) => f.debug_tuple("DataSection").field(&"...").finish(),
StartSection { func, range } => f
.debug_struct("StartSection")
.field("func", func)
.field("range", range)
.finish(),
DataCountSection { count, range } => f
.debug_struct("DataCountSection")
.field("count", count)
.field("range", range)
.finish(),
CodeSectionStart { count, range, size } => f
.debug_struct("CodeSectionStart")
.field("count", count)
.field("range", range)
.field("size", size)
.finish(),
CodeSectionEntry(_) => f.debug_tuple("CodeSectionEntry").field(&"...").finish(),
// Component sections
#[cfg(feature = "component-model")]
ModuleSection {
parser: _,
unchecked_range: range,
} => f
.debug_struct("ModuleSection")
.field("range", range)
.finish(),
#[cfg(feature = "component-model")]
InstanceSection(_) => f.debug_tuple("InstanceSection").field(&"...").finish(),
#[cfg(feature = "component-model")]
CoreTypeSection(_) => f.debug_tuple("CoreTypeSection").field(&"...").finish(),
#[cfg(feature = "component-model")]
ComponentSection {
parser: _,
unchecked_range: range,
} => f
.debug_struct("ComponentSection")
.field("range", range)
.finish(),
#[cfg(feature = "component-model")]
ComponentInstanceSection(_) => f
.debug_tuple("ComponentInstanceSection")
.field(&"...")
.finish(),
#[cfg(feature = "component-model")]
ComponentAliasSection(_) => f
.debug_tuple("ComponentAliasSection")
.field(&"...")
.finish(),
#[cfg(feature = "component-model")]
ComponentTypeSection(_) => f.debug_tuple("ComponentTypeSection").field(&"...").finish(),
#[cfg(feature = "component-model")]
ComponentCanonicalSection(_) => f
.debug_tuple("ComponentCanonicalSection")
.field(&"...")
.finish(),
#[cfg(feature = "component-model")]
ComponentStartSection { .. } => f
.debug_tuple("ComponentStartSection")
.field(&"...")
.finish(),
#[cfg(feature = "component-model")]
ComponentImportSection(_) => f
.debug_tuple("ComponentImportSection")
.field(&"...")
.finish(),
#[cfg(feature = "component-model")]
ComponentExportSection(_) => f
.debug_tuple("ComponentExportSection")
.field(&"...")
.finish(),
CustomSection(c) => f.debug_tuple("CustomSection").field(c).finish(),
UnknownSection { id, range, .. } => f
.debug_struct("UnknownSection")
.field("id", id)
.field("range", range)
.finish(),
End(offset) => f.debug_tuple("End").field(offset).finish(),
}
}
}
fn clear_hint(mut err: BinaryReaderError) -> BinaryReaderError {
err.inner.needed_hint = None;
err
}
#[cfg(test)]
mod tests {
use super::*;
macro_rules! assert_matches {
($a:expr, $b:pat $(,)?) => {
match $a {
$b => {}
a => panic!("`{:?}` doesn't match `{}`", a, stringify!($b)),
}
};
}
#[test]
fn header() {
assert!(Parser::default().parse(&[], true).is_err());
assert_matches!(
Parser::default().parse(&[], false),
Ok(Chunk::NeedMoreData(4)),
);
assert_matches!(
Parser::default().parse(b"\0", false),
Ok(Chunk::NeedMoreData(3)),
);
assert_matches!(
Parser::default().parse(b"\0asm", false),
Ok(Chunk::NeedMoreData(4)),
);
assert_matches!(
Parser::default().parse(b"\0asm\x01\0\0\0", false),
Ok(Chunk::Parsed {
consumed: 8,
payload: Payload::Version { num: 1, .. },
}),
);
}
#[test]
fn header_iter() {
for _ in Parser::default().parse_all(&[]) {}
for _ in Parser::default().parse_all(b"\0") {}
for _ in Parser::default().parse_all(b"\0asm") {}
for _ in Parser::default().parse_all(b"\0asm\x01\x01\x01\x01") {}
}
fn parser_after_header() -> Parser {
let mut p = Parser::default();
assert_matches!(
p.parse(b"\0asm\x01\0\0\0", false),
Ok(Chunk::Parsed {
consumed: 8,
payload: Payload::Version {
num: WASM_MODULE_VERSION,
encoding: Encoding::Module,
..
},
}),
);
p
}
fn parser_after_component_header() -> Parser {
let mut p = Parser::default();
assert_matches!(
p.parse(b"\0asm\x0d\0\x01\0", false),
Ok(Chunk::Parsed {
consumed: 8,
payload: Payload::Version {
num: WASM_COMPONENT_VERSION,
encoding: Encoding::Component,
..
},
}),
);
p
}
#[test]
fn start_section() {
assert_matches!(
parser_after_header().parse(&[], false),
Ok(Chunk::NeedMoreData(1)),
);
assert!(parser_after_header().parse(&[8], true).is_err());
assert!(parser_after_header().parse(&[8, 1], true).is_err());
assert!(parser_after_header().parse(&[8, 2], true).is_err());
assert_matches!(
parser_after_header().parse(&[8], false),
Ok(Chunk::NeedMoreData(1)),
);
assert_matches!(
parser_after_header().parse(&[8, 1], false),
Ok(Chunk::NeedMoreData(1)),
);
assert_matches!(
parser_after_header().parse(&[8, 2], false),
Ok(Chunk::NeedMoreData(2)),
);
assert_matches!(
parser_after_header().parse(&[8, 1, 1], false),
Ok(Chunk::Parsed {
consumed: 3,
payload: Payload::StartSection { func: 1, .. },
}),
);
assert!(parser_after_header().parse(&[8, 2, 1, 1], false).is_err());
assert!(parser_after_header().parse(&[8, 0], false).is_err());
}
#[test]
fn end_works() {
assert_matches!(
parser_after_header().parse(&[], true),
Ok(Chunk::Parsed {
consumed: 0,
payload: Payload::End(8),
}),
);
}
#[test]
fn type_section() {
assert!(parser_after_header().parse(&[1], true).is_err());
assert!(parser_after_header().parse(&[1, 0], false).is_err());
assert!(parser_after_header().parse(&[8, 2], true).is_err());
assert_matches!(
parser_after_header().parse(&[1], false),
Ok(Chunk::NeedMoreData(1)),
);
assert_matches!(
parser_after_header().parse(&[1, 1], false),
Ok(Chunk::NeedMoreData(1)),
);
assert_matches!(
parser_after_header().parse(&[1, 1, 1], false),
Ok(Chunk::Parsed {
consumed: 3,
payload: Payload::TypeSection(_),
}),
);
assert_matches!(
parser_after_header().parse(&[1, 1, 1, 2, 3, 4], false),
Ok(Chunk::Parsed {
consumed: 3,
payload: Payload::TypeSection(_),
}),
);
}
#[test]
fn custom_section() {
assert!(parser_after_header().parse(&[0], true).is_err());
assert!(parser_after_header().parse(&[0, 0], false).is_err());
assert!(parser_after_header().parse(&[0, 1, 1], false).is_err());
assert_matches!(
parser_after_header().parse(&[0, 2, 1], false),
Ok(Chunk::NeedMoreData(1)),
);
assert_custom(
parser_after_header().parse(&[0, 1, 0], false).unwrap(),
3,
"",
11,
b"",
Range { start: 10, end: 11 },
);
assert_custom(
parser_after_header()
.parse(&[0, 2, 1, b'a'], false)
.unwrap(),
4,
"a",
12,
b"",
Range { start: 10, end: 12 },
);
assert_custom(
parser_after_header()
.parse(&[0, 2, 0, b'a'], false)
.unwrap(),
4,
"",
11,
b"a",
Range { start: 10, end: 12 },
);
}
fn assert_custom(
chunk: Chunk<'_>,
expected_consumed: usize,
expected_name: &str,
expected_data_offset: usize,
expected_data: &[u8],
expected_range: Range<usize>,
) {
let (consumed, s) = match chunk {
Chunk::Parsed {
consumed,
payload: Payload::CustomSection(s),
} => (consumed, s),
_ => panic!("not a custom section payload"),
};
assert_eq!(consumed, expected_consumed);
assert_eq!(s.name(), expected_name);
assert_eq!(s.data_offset(), expected_data_offset);
assert_eq!(s.data(), expected_data);
assert_eq!(s.range(), expected_range);
}
#[test]
fn function_section() {
assert!(parser_after_header().parse(&[10], true).is_err());
assert!(parser_after_header().parse(&[10, 0], true).is_err());
assert!(parser_after_header().parse(&[10, 1], true).is_err());
assert_matches!(
parser_after_header().parse(&[10], false),
Ok(Chunk::NeedMoreData(1))
);
assert_matches!(
parser_after_header().parse(&[10, 1], false),
Ok(Chunk::NeedMoreData(1))
);
let mut p = parser_after_header();
assert_matches!(
p.parse(&[10, 1, 0], false),
Ok(Chunk::Parsed {
consumed: 3,
payload: Payload::CodeSectionStart { count: 0, .. },
}),
);
assert_matches!(
p.parse(&[], true),
Ok(Chunk::Parsed {
consumed: 0,
payload: Payload::End(11),
}),
);
let mut p = parser_after_header();
assert_matches!(
p.parse(&[10, 2, 1, 0], false),
Ok(Chunk::Parsed {
consumed: 3,
payload: Payload::CodeSectionStart { count: 1, .. },
}),
);
assert_matches!(
p.parse(&[0], false),
Ok(Chunk::Parsed {
consumed: 1,
payload: Payload::CodeSectionEntry(_),
}),
);
assert_matches!(
p.parse(&[], true),
Ok(Chunk::Parsed {
consumed: 0,
payload: Payload::End(12),
}),
);
// 1 byte section with 1 function can't read the function body because
// the section is too small
let mut p = parser_after_header();
assert_matches!(
p.parse(&[10, 1, 1], false),
Ok(Chunk::Parsed {
consumed: 3,
payload: Payload::CodeSectionStart { count: 1, .. },
}),
);
assert_eq!(
p.parse(&[0], false).unwrap_err().message(),
"unexpected end-of-file"
);
// section with 2 functions but section is cut off
let mut p = parser_after_header();
assert_matches!(
p.parse(&[10, 2, 2], false),
Ok(Chunk::Parsed {
consumed: 3,
payload: Payload::CodeSectionStart { count: 2, .. },
}),
);
assert_matches!(
p.parse(&[0], false),
Ok(Chunk::Parsed {
consumed: 1,
payload: Payload::CodeSectionEntry(_),
}),
);
assert_matches!(p.parse(&[], false), Ok(Chunk::NeedMoreData(1)));
assert_eq!(
p.parse(&[0], false).unwrap_err().message(),
"unexpected end-of-file",
);
// trailing data is bad
let mut p = parser_after_header();
assert_matches!(
p.parse(&[10, 3, 1], false),
Ok(Chunk::Parsed {
consumed: 3,
payload: Payload::CodeSectionStart { count: 1, .. },
}),
);
assert_matches!(
p.parse(&[0], false),
Ok(Chunk::Parsed {
consumed: 1,
payload: Payload::CodeSectionEntry(_),
}),
);
assert_eq!(
p.parse(&[0], false).unwrap_err().message(),
"trailing bytes at end of section",
);
}
#[test]
fn single_module() {
let mut p = parser_after_component_header();
assert_matches!(p.parse(&[4], false), Ok(Chunk::NeedMoreData(1)));
// A module that's 8 bytes in length
let mut sub = match p.parse(&[1, 8], false) {
Ok(Chunk::Parsed {
consumed: 2,
payload: Payload::ModuleSection { parser, .. },
}) => parser,
other => panic!("bad parse {:?}", other),
};
// Parse the header of the submodule with the sub-parser.
assert_matches!(sub.parse(&[], false), Ok(Chunk::NeedMoreData(4)));
assert_matches!(sub.parse(b"\0asm", false), Ok(Chunk::NeedMoreData(4)));
assert_matches!(
sub.parse(b"\0asm\x01\0\0\0", false),
Ok(Chunk::Parsed {
consumed: 8,
payload: Payload::Version {
num: 1,
encoding: Encoding::Module,
..
},
}),
);
// The sub-parser should be byte-limited so the next byte shouldn't get
// consumed, it's intended for the parent parser.
assert_matches!(
sub.parse(&[10], false),
Ok(Chunk::Parsed {
consumed: 0,
payload: Payload::End(18),
}),
);
// The parent parser should now be back to resuming, and we simulate it
// being done with bytes to ensure that it's safely at the end,
// completing the module code section.
assert_matches!(p.parse(&[], false), Ok(Chunk::NeedMoreData(1)));
assert_matches!(
p.parse(&[], true),
Ok(Chunk::Parsed {
consumed: 0,
payload: Payload::End(18),
}),
);
}
#[test]
fn nested_section_too_big() {
let mut p = parser_after_component_header();
// A module that's 10 bytes in length
let mut sub = match p.parse(&[1, 10], false) {
Ok(Chunk::Parsed {
consumed: 2,
payload: Payload::ModuleSection { parser, .. },
}) => parser,
other => panic!("bad parse {:?}", other),
};
// use 8 bytes to parse the header, leaving 2 remaining bytes in our
// module.
assert_matches!(
sub.parse(b"\0asm\x01\0\0\0", false),
Ok(Chunk::Parsed {
consumed: 8,
payload: Payload::Version { num: 1, .. },
}),
);
// We can't parse a section which declares its bigger than the outer
// module. This is a custom section, one byte big, with one content byte. The
// content byte, however, lives outside of the parent's module code
// section.
assert_eq!(
sub.parse(&[0, 1, 0], false).unwrap_err().message(),
"section too large",
);
}
}