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//! Configuring the shape of generated Wasm modules.
use crate::InstructionKinds;
use arbitrary::{Arbitrary, Result, Unstructured};
use std::borrow::Cow;
/// Configuration for a generated module.
///
/// Don't care to configure your generated modules? Just use
/// [`Module`][crate::Module], which internally uses
/// [`DefaultConfig`][crate::DefaultConfig].
///
/// If you want to configure generated modules, then define a `MyConfig` type,
/// implement this trait for it, and use
/// [`ConfiguredModule<MyConfig>`][crate::ConfiguredModule] instead of `Module`.
///
/// Every trait method has a provided default implementation, so that you only
/// need to override the methods for things you want to change away from the
/// default.
pub trait Config: 'static + std::fmt::Debug {
/// The minimum number of types to generate. Defaults to 0.
fn min_types(&self) -> usize {
0
}
/// The maximum number of types to generate. Defaults to 100.
fn max_types(&self) -> usize {
100
}
/// The minimum number of imports to generate. Defaults to 0.
///
/// Note that if the sum of the maximum function[^1], table, global and
/// memory counts is less than the minimum number of imports, then it will
/// not be possible to satisfy all constraints (because imports count
/// against the limits for those element kinds). In that case, we strictly
/// follow the max-constraints, and can fail to satisfy this minimum number.
///
/// [^1]: the maximum number of functions is also limited by the number of
/// function types arbitrarily chosen; strictly speaking, then, the
/// maximum number of imports that can be created due to
/// max-constraints is `sum(min(num_func_types, max_funcs), max_tables,
/// max_globals, max_memories)`.
fn min_imports(&self) -> usize {
0
}
/// The maximum number of imports to generate. Defaults to 100.
fn max_imports(&self) -> usize {
100
}
/// The minimum number of tags to generate. Defaults to 0.
fn min_tags(&self) -> usize {
0
}
/// The maximum number of tags to generate. Defaults to 100.
fn max_tags(&self) -> usize {
100
}
/// The imports that may be used when generating the module.
///
/// Defaults to `None` which means that any arbitrary import can be generated.
///
/// To only allow specific imports, override this method to return a WebAssembly module which
/// describes the imports allowed.
///
/// Note that [`Self::min_imports`] is ignored when `available_imports` are enabled.
///
/// # Panics
///
/// The returned value must be a valid binary encoding of a WebAssembly module. `wasm-smith`
/// will panic if the module cannot be parsed.
///
/// # Example
///
/// An implementation of this method could use the `wat` crate to provide a human-readable and
/// maintainable description:
///
/// ```rust
/// Some(wat::parse_str(r#"
/// (module
/// (import "env" "ping" (func (param i32)))
/// (import "env" "pong" (func (result i32)))
/// (import "env" "memory" (memory 1))
/// (import "env" "table" (table 1))
/// (import "env" "tag" (tag (param i32)))
/// )
/// "#))
/// # ;
/// ```
fn available_imports(&self) -> Option<Cow<'_, [u8]>> {
None
}
/// The minimum number of functions to generate. Defaults to 0. This
/// includes imported functions.
fn min_funcs(&self) -> usize {
0
}
/// The maximum number of functions to generate. Defaults to 100. This
/// includes imported functions.
fn max_funcs(&self) -> usize {
100
}
/// The minimum number of globals to generate. Defaults to 0. This includes
/// imported globals.
fn min_globals(&self) -> usize {
0
}
/// The maximum number of globals to generate. Defaults to 100. This
/// includes imported globals.
fn max_globals(&self) -> usize {
100
}
/// The minimum number of exports to generate. Defaults to 0.
fn min_exports(&self) -> usize {
0
}
/// The maximum number of exports to generate. Defaults to 100.
fn max_exports(&self) -> usize {
100
}
/// The minimum number of element segments to generate. Defaults to 0.
fn min_element_segments(&self) -> usize {
0
}
/// The maximum number of element segments to generate. Defaults to 100.
fn max_element_segments(&self) -> usize {
100
}
/// The minimum number of elements within a segment to generate. Defaults to
/// 0.
fn min_elements(&self) -> usize {
0
}
/// The maximum number of elements within a segment to generate. Defaults to
/// 100.
fn max_elements(&self) -> usize {
100
}
/// The minimum number of data segments to generate. Defaults to 0.
fn min_data_segments(&self) -> usize {
0
}
/// The maximum number of data segments to generate. Defaults to 100.
fn max_data_segments(&self) -> usize {
100
}
/// The maximum number of instructions to generate in a function
/// body. Defaults to 100.
///
/// Note that some additional `end`s, `else`s, and `unreachable`s may be
/// appended to the function body to finish block scopes.
fn max_instructions(&self) -> usize {
100
}
/// The minimum number of memories to use. Defaults to 0. This includes
/// imported memories.
fn min_memories(&self) -> u32 {
0
}
/// The maximum number of memories to use. Defaults to 1. This includes
/// imported memories.
///
/// Note that more than one memory is in the realm of the multi-memory wasm
/// proposal.
fn max_memories(&self) -> usize {
1
}
/// The minimum number of tables to use. Defaults to 0. This includes
/// imported tables.
fn min_tables(&self) -> u32 {
0
}
/// The maximum number of tables to use. Defaults to 1. This includes
/// imported tables.
///
/// Note that more than one table is in the realm of the reference types
/// proposal.
fn max_tables(&self) -> usize {
1
}
/// The maximum, in 64k Wasm pages, of any memory's initial or maximum size.
///
/// Defaults to 2^16 = 65536 for 32-bit Wasm and 2^48 for 64-bit wasm.
fn max_memory_pages(&self, is_64: bool) -> u64 {
if is_64 {
1 << 48
} else {
1 << 16
}
}
/// Whether every Wasm memory must have a maximum size specified. Defaults
/// to `false`.
fn memory_max_size_required(&self) -> bool {
false
}
/// The maximum number of instances to use. Defaults to 10. This includes
/// imported instances.
///
/// Note that this is irrelevant unless module linking is enabled.
fn max_instances(&self) -> usize {
10
}
/// The maximum number of modules to use. Defaults to 10. This includes
/// imported modules.
///
/// Note that this is irrelevant unless component model support is enabled.
fn max_modules(&self) -> usize {
10
}
/// The maximum number of components to use. Defaults to 10. This includes
/// imported components.
///
/// Note that this is irrelevant unless component model support is enabled.
fn max_components(&self) -> usize {
10
}
/// The maximum number of values to use. Defaults to 10. This includes
/// imported values.
///
/// Note that this is irrelevant unless value model support is enabled.
fn max_values(&self) -> usize {
10
}
/// Control the probability of generating memory offsets that are in bounds
/// vs. potentially out of bounds.
///
/// Return a tuple `(a, b, c)` where
///
/// * `a / (a+b+c)` is the probability of generating a memory offset within
/// `0..memory.min_size`, i.e. an offset that is definitely in bounds of a
/// non-empty memory. (Note that if a memory is zero-sized, however, no
/// offset will ever be in bounds.)
///
/// * `b / (a+b+c)` is the probability of generating a memory offset within
/// `memory.min_size..memory.max_size`, i.e. an offset that is possibly in
/// bounds if the memory has been grown.
///
/// * `c / (a+b+c)` is the probability of generating a memory offset within
/// the range `memory.max_size..`, i.e. an offset that is definitely out
/// of bounds.
///
/// At least one of `a`, `b`, and `c` must be non-zero.
///
/// If you want to always generate memory offsets that are definitely in
/// bounds of a non-zero-sized memory, for example, you could return `(1, 0,
/// 0)`.
///
/// By default, returns `(75, 24, 1)`.
fn memory_offset_choices(&self) -> (u32, u32, u32) {
(75, 24, 1)
}
/// The minimum size, in bytes, of all leb-encoded integers. Defaults to 1.
///
/// This is useful for ensuring that all leb-encoded integers are decoded as
/// such rather than as simply one byte. This will forcibly extend leb
/// integers with an over-long encoding in some locations if the size would
/// otherwise be smaller than number returned here.
fn min_uleb_size(&self) -> u8 {
1
}
/// Determines whether the bulk memory proposal is enabled for generating
/// instructions.
///
/// Defaults to `false`.
fn bulk_memory_enabled(&self) -> bool {
false
}
/// Determines whether the reference types proposal is enabled for
/// generating instructions.
///
/// Defaults to `false`.
fn reference_types_enabled(&self) -> bool {
false
}
/// Determines whether the SIMD proposal is enabled for
/// generating instructions.
///
/// Defaults to `false`.
fn simd_enabled(&self) -> bool {
false
}
/// Determines whether the Relaxed SIMD proposal is enabled for
/// generating instructions.
///
/// Defaults to `false`.
fn relaxed_simd_enabled(&self) -> bool {
false
}
/// Determines whether the exception-handling proposal is enabled for
/// generating instructions.
///
/// Defaults to `false`.
fn exceptions_enabled(&self) -> bool {
false
}
/// Determines whether the multi-value results are enabled.
///
/// Defaults to `true`.
fn multi_value_enabled(&self) -> bool {
true
}
/// Determines whether the nontrapping-float-to-int-conversions propsal is enabled.
///
/// Defaults to `true`.
fn saturating_float_to_int_enabled(&self) -> bool {
true
}
/// Determines whether the sign-extension-ops propsal is enabled.
///
/// Defaults to `true`.
fn sign_extension_ops_enabled(&self) -> bool {
true
}
/// Determines whether a `start` export may be included. Defaults to `true`.
fn allow_start_export(&self) -> bool {
true
}
/// Returns the maximal size of the `alias` section.
fn max_aliases(&self) -> usize {
1_000
}
/// Returns the maximal nesting depth of modules with the module linking
/// proposal.
fn max_nesting_depth(&self) -> usize {
10
}
/// Returns the maximal effective size of any type generated by wasm-smith.
///
/// Note that this number is roughly in units of "how many types would be
/// needed to represent the recursive type". A function with 8 parameters
/// and 2 results would take 11 types (one for the type, 10 for
/// params/results). A module type with 2 imports and 3 exports would
/// take 6 (module + imports + exports) plus the size of each import/export
/// type. This is a somewhat rough measurement that is not intended to be
/// very precise.
fn max_type_size(&self) -> u32 {
1_000
}
/// Returns whether 64-bit memories are allowed.
///
/// Note that this is the gate for the memory64 proposal to WebAssembly.
fn memory64_enabled(&self) -> bool {
false
}
/// Returns whether NaN values are canonicalized after all f32/f64
/// operation.
///
/// This can be useful when a generated wasm module is executed in multiple
/// runtimes which may produce different NaN values. This ensures that the
/// generated module will always use the same NaN representation for all
/// instructions which have visible side effects, for example writing floats
/// to memory or float-to-int bitcast instructions.
fn canonicalize_nans(&self) -> bool {
false
}
/// Returns the kinds of instructions allowed in the generated wasm
/// programs.
///
/// The categories of instructions match the categories used by the
/// [WebAssembly
/// specification](https://webassembly.github.io/spec/core/syntax/instructions.html);
/// e.g., numeric, vector, control, memory, etc. Note that modifying this
/// setting is separate from the proposal flags; that is, if `simd_enabled()
/// == true` but `allowed_instruction()` does not include vector
/// instructions, the generated programs will not include these instructions
/// but could contain vector types.
fn allowed_instructions(&self) -> InstructionKinds {
InstructionKinds::all()
}
/// Returns whether we should generate custom sections or not.
///
/// This is false by default.
fn generate_custom_sections(&self) -> bool {
false
}
}
/// The default configuration.
#[derive(Arbitrary, Debug, Default, Copy, Clone)]
pub struct DefaultConfig;
impl Config for DefaultConfig {}
/// A module configuration that uses [swarm testing].
///
/// Dynamically -- but still deterministically, via its `Arbitrary`
/// implementation -- chooses configuration options.
///
/// [swarm testing]: https://www.cs.utah.edu/~regehr/papers/swarm12.pdf
///
/// Note that we pick only *maximums*, not minimums, here because it is more
/// complex to describe the domain of valid configs when minima are involved
/// (`min <= max` for each variable) and minima are mostly used to ensure
/// certain elements are present, but do not widen the range of generated Wasm
/// modules.
#[derive(Clone, Debug)]
#[allow(missing_docs)]
pub struct SwarmConfig {
pub allow_start_export: bool,
pub available_imports: Option<Vec<u8>>,
pub bulk_memory_enabled: bool,
pub canonicalize_nans: bool,
pub exceptions_enabled: bool,
pub max_aliases: usize,
pub max_components: usize,
pub max_data_segments: usize,
pub max_element_segments: usize,
pub max_elements: usize,
pub max_exports: usize,
pub max_funcs: usize,
pub max_globals: usize,
pub max_imports: usize,
pub max_instances: usize,
pub max_instructions: usize,
pub max_memories: usize,
pub max_memory_pages: u64,
pub max_modules: usize,
pub max_nesting_depth: usize,
pub max_tables: usize,
pub max_tags: usize,
pub max_type_size: u32,
pub max_types: usize,
pub max_values: usize,
pub memory64_enabled: bool,
pub memory_max_size_required: bool,
pub memory_offset_choices: (u32, u32, u32),
pub min_data_segments: usize,
pub min_element_segments: usize,
pub min_elements: usize,
pub min_exports: usize,
pub min_funcs: usize,
pub min_globals: usize,
pub min_imports: usize,
pub min_memories: u32,
pub min_tables: u32,
pub min_tags: usize,
pub min_types: usize,
pub min_uleb_size: u8,
pub multi_value_enabled: bool,
pub reference_types_enabled: bool,
pub relaxed_simd_enabled: bool,
pub saturating_float_to_int_enabled: bool,
pub sign_extension_enabled: bool,
pub simd_enabled: bool,
}
impl<'a> Arbitrary<'a> for SwarmConfig {
fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
const MAX_MAXIMUM: usize = 1000;
let reference_types_enabled: bool = u.arbitrary()?;
let max_tables = if reference_types_enabled { 100 } else { 1 };
Ok(SwarmConfig {
max_types: u.int_in_range(0..=MAX_MAXIMUM)?,
max_imports: u.int_in_range(0..=MAX_MAXIMUM)?,
max_tags: u.int_in_range(0..=MAX_MAXIMUM)?,
max_funcs: u.int_in_range(0..=MAX_MAXIMUM)?,
max_globals: u.int_in_range(0..=MAX_MAXIMUM)?,
max_exports: u.int_in_range(0..=MAX_MAXIMUM)?,
max_element_segments: u.int_in_range(0..=MAX_MAXIMUM)?,
max_elements: u.int_in_range(0..=MAX_MAXIMUM)?,
max_data_segments: u.int_in_range(0..=MAX_MAXIMUM)?,
max_instructions: u.int_in_range(0..=MAX_MAXIMUM)?,
max_memories: u.int_in_range(0..=100)?,
max_tables,
max_memory_pages: u.arbitrary()?,
min_uleb_size: u.int_in_range(0..=5)?,
bulk_memory_enabled: reference_types_enabled || u.arbitrary()?,
reference_types_enabled,
simd_enabled: u.arbitrary()?,
multi_value_enabled: u.arbitrary()?,
max_aliases: u.int_in_range(0..=MAX_MAXIMUM)?,
max_nesting_depth: u.int_in_range(0..=10)?,
saturating_float_to_int_enabled: u.arbitrary()?,
sign_extension_enabled: u.arbitrary()?,
// These fields, unlike the ones above, are less useful to set.
// They either make weird inputs or are for features not widely
// implemented yet so they're turned off by default.
min_types: 0,
min_imports: 0,
min_tags: 0,
min_funcs: 0,
min_globals: 0,
min_exports: 0,
min_element_segments: 0,
min_elements: 0,
min_data_segments: 0,
min_memories: 0,
min_tables: 0,
memory_max_size_required: false,
max_instances: 0,
max_modules: 0,
max_components: 0,
max_values: 0,
memory_offset_choices: (75, 24, 1),
allow_start_export: true,
relaxed_simd_enabled: false,
exceptions_enabled: false,
memory64_enabled: false,
max_type_size: 1000,
canonicalize_nans: false,
available_imports: None,
})
}
}
impl Config for SwarmConfig {
fn min_types(&self) -> usize {
self.min_types
}
fn max_types(&self) -> usize {
self.max_types
}
fn min_imports(&self) -> usize {
self.min_imports
}
fn max_imports(&self) -> usize {
self.max_imports
}
fn available_imports(&self) -> Option<Cow<'_, [u8]>> {
self.available_imports
.as_ref()
.map(|is| Cow::Borrowed(&is[..]))
}
fn min_funcs(&self) -> usize {
self.min_funcs
}
fn max_funcs(&self) -> usize {
self.max_funcs
}
fn min_globals(&self) -> usize {
self.min_globals
}
fn max_globals(&self) -> usize {
self.max_globals
}
fn min_exports(&self) -> usize {
self.min_exports
}
fn max_exports(&self) -> usize {
self.max_exports
}
fn min_element_segments(&self) -> usize {
self.min_element_segments
}
fn max_element_segments(&self) -> usize {
self.max_element_segments
}
fn min_elements(&self) -> usize {
self.min_elements
}
fn max_elements(&self) -> usize {
self.max_elements
}
fn min_data_segments(&self) -> usize {
self.min_data_segments
}
fn max_data_segments(&self) -> usize {
self.max_data_segments
}
fn max_instructions(&self) -> usize {
self.max_instructions
}
fn min_memories(&self) -> u32 {
self.min_memories
}
fn max_memories(&self) -> usize {
self.max_memories
}
fn min_tables(&self) -> u32 {
self.min_tables
}
fn max_tables(&self) -> usize {
self.max_tables
}
fn max_memory_pages(&self, is_64: bool) -> u64 {
if is_64 {
self.max_memory_pages.min(1 << 48)
} else {
self.max_memory_pages.min(1 << 16)
}
}
fn memory_max_size_required(&self) -> bool {
self.memory_max_size_required
}
fn max_instances(&self) -> usize {
self.max_instances
}
fn max_modules(&self) -> usize {
self.max_modules
}
fn memory_offset_choices(&self) -> (u32, u32, u32) {
self.memory_offset_choices
}
fn min_uleb_size(&self) -> u8 {
self.min_uleb_size
}
fn bulk_memory_enabled(&self) -> bool {
self.bulk_memory_enabled
}
fn reference_types_enabled(&self) -> bool {
self.reference_types_enabled
}
fn simd_enabled(&self) -> bool {
self.simd_enabled
}
fn relaxed_simd_enabled(&self) -> bool {
self.relaxed_simd_enabled
}
fn exceptions_enabled(&self) -> bool {
self.exceptions_enabled
}
fn multi_value_enabled(&self) -> bool {
self.multi_value_enabled
}
fn saturating_float_to_int_enabled(&self) -> bool {
self.saturating_float_to_int_enabled
}
fn sign_extension_ops_enabled(&self) -> bool {
self.sign_extension_enabled
}
fn allow_start_export(&self) -> bool {
self.allow_start_export
}
fn max_aliases(&self) -> usize {
self.max_aliases
}
fn max_nesting_depth(&self) -> usize {
self.max_nesting_depth
}
fn max_type_size(&self) -> u32 {
self.max_type_size
}
fn memory64_enabled(&self) -> bool {
self.memory64_enabled
}
fn canonicalize_nans(&self) -> bool {
self.canonicalize_nans
}
}