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use super::{ModuleError, ModulePreset, ModuleTranslator};
use parity_wasm::elements::*;
struct ExportWhitelist {
pub entries: Vec<ExportEntry>,
}
pub struct TrimExports {
whitelist: ExportWhitelist,
}
fn cmp_internal_variant(a: &Internal, b: &Internal) -> bool {
std::mem::discriminant(a) == std::mem::discriminant(b)
}
impl ModulePreset for ExportWhitelist {
fn with_preset(preset: &str) -> Result<Self, ()> {
match preset {
"ewasm" => Ok(ExportWhitelist {
entries: vec![
ExportEntry::new("main".to_string(), Internal::Function(0)),
ExportEntry::new("memory".to_string(), Internal::Memory(0)),
],
}),
"pwasm" => Ok(ExportWhitelist {
entries: vec![ExportEntry::new("_call".to_string(), Internal::Function(0))],
}),
_ => Err(()),
}
}
}
impl ExportWhitelist {
fn new() -> Self {
ExportWhitelist {
entries: Vec::new(),
}
}
fn lookup(&self, export: &ExportEntry) -> bool {
self.entries
.iter()
.find(|matched_export| {
export.field() == matched_export.field()
&& cmp_internal_variant(export.internal(), matched_export.internal())
})
.is_some()
}
}
impl TrimExports {
pub fn new() -> Self {
TrimExports {
whitelist: ExportWhitelist::new(),
}
}
pub fn with_preset(preset: &str) -> Result<Self, ()> {
match preset {
"ewasm" => Ok(TrimExports {
whitelist: ExportWhitelist::with_preset("ewasm").unwrap(),
}),
"pwasm" => Ok(TrimExports {
whitelist: ExportWhitelist::with_preset("pwasm").unwrap(),
}),
_ => Err(()),
}
}
fn trim_exports(&self, module: &mut Module) -> bool {
if let Some(section) = module.export_section_mut() {
let new_section = ExportSection::with_entries(
section
.entries()
.iter()
.cloned()
.filter(|entry| self.whitelist.lookup(entry))
.collect(),
);
if new_section.entries().len() < section.entries().len() {
*section = new_section;
return true;
}
false
} else {
false
}
}
}
impl ModuleTranslator for TrimExports {
fn translate_inplace(&self, module: &mut Module) -> Result<bool, ModuleError> {
Ok(self.trim_exports(module))
}
fn translate(&self, module: &Module) -> Result<Option<Module>, ModuleError> {
let mut ret = module.clone();
let modified = self.trim_exports(&mut ret);
if modified {
return Ok(Some(ret));
}
Ok(None)
}
}
#[cfg(test)]
mod tests {
use super::*;
use parity_wasm::builder;
#[test]
fn builder_all_exports_good_ewasm() {
let mut module = builder::module()
.function()
.signature()
.build()
.body()
.build()
.build()
.export()
.field("main")
.internal()
.func(0)
.build()
.export()
.field("memory")
.internal()
.memory(0)
.build()
.build();
let trimmer = TrimExports::with_preset("ewasm").unwrap();
let did_change = trimmer.translate_inplace(&mut module).unwrap();
assert_eq!(false, did_change);
}
#[test]
fn builder_one_wrong_mem_export_ewasm() {
let mut module = builder::module()
.function()
.signature()
.build()
.body()
.build()
.build()
.export()
.field("main")
.internal()
.func(0)
.build()
.export()
.field("memory")
.internal()
.memory(0)
.build()
.export()
.field("foo")
.internal()
.memory(0)
.build()
.build();
let trimmer = TrimExports::with_preset("ewasm").unwrap();
let did_change = trimmer.translate_inplace(&mut module).unwrap();
assert_eq!(true, did_change);
}
#[test]
fn builder_no_export_ewasm() {
let mut module = builder::module()
.function()
.signature()
.build()
.body()
.build()
.build()
.build();
let trimmer = TrimExports::with_preset("ewasm").unwrap();
let did_change = trimmer.translate_inplace(&mut module).unwrap();
assert_eq!(false, did_change);
}
#[test]
fn builder_all_exports_good_pwasm() {
let mut module = builder::module()
.function()
.signature()
.build()
.body()
.build()
.build()
.export()
.field("_call")
.internal()
.func(0)
.build()
.build();
let trimmer = TrimExports::with_preset("pwasm").unwrap();
let did_change = trimmer.translate_inplace(&mut module).unwrap();
assert_eq!(false, did_change);
}
}