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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
use crate::metadata::{checksum_metadata, codes};
use crate::*;
use anyhow::{bail, ensure, Context, Result};
pub fn read_metadata(data: &[u8]) -> Result<Metadata> {
MetadataReader::new(data).read_metadata()
}
// Read a metadata type, this is pub so that we can test it in the metadata fixture
pub fn read_metadata_type(data: &[u8]) -> Result<Type> {
MetadataReader::new(data).read_type()
}
/// Helper struct for read_metadata()
struct MetadataReader<'a> {
// This points to the initial data we were passed in
initial_data: &'a [u8],
// This points to the remaining data to be read
buf: &'a [u8],
}
impl<'a> MetadataReader<'a> {
fn new(data: &'a [u8]) -> Self {
Self {
initial_data: data,
buf: data,
}
}
// Read a top-level metadata item
//
// This consumes self because MetadataReader is only intended to read a single item.
fn read_metadata(mut self) -> Result<Metadata> {
let value = self.read_u8()?;
Ok(match value {
codes::NAMESPACE => NamespaceMetadata {
crate_name: self.read_string()?,
name: self.read_string()?,
}
.into(),
codes::UDL_FILE => UdlFile {
module_path: self.read_string()?,
namespace: self.read_string()?,
file_stub: self.read_string()?,
}
.into(),
codes::FUNC => self.read_func()?.into(),
codes::CONSTRUCTOR => self.read_constructor()?.into(),
codes::METHOD => self.read_method()?.into(),
codes::RECORD => self.read_record()?.into(),
codes::ENUM => self.read_enum()?.into(),
codes::INTERFACE => self.read_object(ObjectImpl::Struct)?.into(),
codes::TRAIT_INTERFACE => self.read_object(ObjectImpl::Trait)?.into(),
codes::CALLBACK_TRAIT_INTERFACE => self.read_object(ObjectImpl::CallbackTrait)?.into(),
codes::CALLBACK_INTERFACE => self.read_callback_interface()?.into(),
codes::TRAIT_METHOD => self.read_trait_method()?.into(),
codes::UNIFFI_TRAIT => self.read_uniffi_trait()?.into(),
_ => bail!("Unexpected metadata code: {value:?}"),
})
}
fn read_u8(&mut self) -> Result<u8> {
if !self.buf.is_empty() {
let value = self.buf[0];
self.buf = &self.buf[1..];
Ok(value)
} else {
bail!("Buffer is empty")
}
}
fn peek_u8(&mut self) -> Result<u8> {
if !self.buf.is_empty() {
Ok(self.buf[0])
} else {
bail!("Buffer is empty")
}
}
fn read_u16(&mut self) -> Result<u16> {
if self.buf.len() >= 2 {
// read the value as little-endian
let value = u16::from_le_bytes([self.buf[0], self.buf[1]]);
self.buf = &self.buf[2..];
Ok(value)
} else {
bail!("Not enough data left in buffer to read a u16 value");
}
}
fn read_u32(&mut self) -> Result<u32> {
if self.buf.len() >= 4 {
// read the value as little-endian
let value = self.buf[0] as u32
+ ((self.buf[1] as u32) << 8)
+ ((self.buf[2] as u32) << 16)
+ ((self.buf[3] as u32) << 24);
self.buf = &self.buf[4..];
Ok(value)
} else {
bail!("Not enough data left in buffer to read a u32 value");
}
}
fn read_bool(&mut self) -> Result<bool> {
Ok(self.read_u8()? == 1)
}
fn read_string(&mut self) -> Result<String> {
let size = self.read_u8()? as usize;
let slice;
(slice, self.buf) = self.buf.split_at(size);
String::from_utf8(slice.into()).context("Invalid string data")
}
fn read_long_string(&mut self) -> Result<String> {
let size = self.read_u16()? as usize;
let slice;
(slice, self.buf) = self.buf.split_at(size);
String::from_utf8(slice.into()).context("Invalid string data")
}
fn read_optional_long_string(&mut self) -> Result<Option<String>> {
Ok(Some(self.read_long_string()?).filter(|str| !str.is_empty()))
}
fn read_type(&mut self) -> Result<Type> {
let value = self.read_u8()?;
Ok(match value {
codes::TYPE_U8 => Type::UInt8,
codes::TYPE_I8 => Type::Int8,
codes::TYPE_U16 => Type::UInt16,
codes::TYPE_I16 => Type::Int16,
codes::TYPE_U32 => Type::UInt32,
codes::TYPE_I32 => Type::Int32,
codes::TYPE_U64 => Type::UInt64,
codes::TYPE_I64 => Type::Int64,
codes::TYPE_F32 => Type::Float32,
codes::TYPE_F64 => Type::Float64,
codes::TYPE_BOOL => Type::Boolean,
codes::TYPE_STRING => Type::String,
codes::TYPE_DURATION => Type::Duration,
codes::TYPE_SYSTEM_TIME => Type::Timestamp,
codes::TYPE_RECORD => Type::Record {
module_path: self.read_string()?,
name: self.read_string()?,
},
codes::TYPE_ENUM => Type::Enum {
module_path: self.read_string()?,
name: self.read_string()?,
},
codes::TYPE_INTERFACE => Type::Object {
module_path: self.read_string()?,
name: self.read_string()?,
imp: ObjectImpl::Struct,
},
codes::TYPE_TRAIT_INTERFACE => Type::Object {
module_path: self.read_string()?,
name: self.read_string()?,
imp: ObjectImpl::Trait,
},
codes::TYPE_CALLBACK_TRAIT_INTERFACE => Type::Object {
module_path: self.read_string()?,
name: self.read_string()?,
imp: ObjectImpl::CallbackTrait,
},
codes::TYPE_CALLBACK_INTERFACE => Type::CallbackInterface {
module_path: self.read_string()?,
name: self.read_string()?,
},
codes::TYPE_CUSTOM => Type::Custom {
module_path: self.read_string()?,
name: self.read_string()?,
builtin: Box::new(self.read_type()?),
},
codes::TYPE_OPTION => Type::Optional {
inner_type: Box::new(self.read_type()?),
},
codes::TYPE_VEC => {
let inner_type = self.read_type()?;
if inner_type == Type::UInt8 {
Type::Bytes
} else {
Type::Sequence {
inner_type: Box::new(inner_type),
}
}
}
codes::TYPE_HASH_MAP => Type::Map {
key_type: Box::new(self.read_type()?),
value_type: Box::new(self.read_type()?),
},
codes::TYPE_UNIT => bail!("Unexpected TYPE_UNIT"),
codes::TYPE_RESULT => bail!("Unexpected TYPE_RESULT"),
_ => bail!("Unexpected metadata type code: {value:?}"),
})
}
fn read_optional_type(&mut self) -> Result<Option<Type>> {
Ok(match self.peek_u8()? {
codes::TYPE_UNIT => {
_ = self.read_u8();
None
}
_ => Some(self.read_type()?),
})
}
fn read_return_type(&mut self) -> Result<(Option<Type>, Option<Type>)> {
Ok(match self.peek_u8()? {
codes::TYPE_UNIT => {
_ = self.read_u8();
(None, None)
}
codes::TYPE_RESULT => {
_ = self.read_u8();
(self.read_optional_type()?, self.read_optional_type()?)
}
_ => (Some(self.read_type()?), None),
})
}
fn read_func(&mut self) -> Result<FnMetadata> {
let module_path = self.read_string()?;
let name = self.read_string()?;
let is_async = self.read_bool()?;
let inputs = self.read_inputs()?;
let (return_type, throws) = self.read_return_type()?;
let docstring = self.read_optional_long_string()?;
Ok(FnMetadata {
module_path,
name,
is_async,
inputs,
return_type,
throws,
docstring,
checksum: self.calc_checksum(),
})
}
fn read_constructor(&mut self) -> Result<ConstructorMetadata> {
let module_path = self.read_string()?;
let self_name = self.read_string()?;
let name = self.read_string()?;
let is_async = self.read_bool()?;
let inputs = self.read_inputs()?;
let (return_type, throws) = self.read_return_type()?;
let docstring = self.read_optional_long_string()?;
return_type
.filter(|t| {
matches!(
t,
Type::Object { name, imp: ObjectImpl::Struct, .. } if name == &self_name
)
})
.context("Constructor return type must be Arc<Self>")?;
Ok(ConstructorMetadata {
module_path,
self_name,
is_async,
name,
inputs,
throws,
checksum: self.calc_checksum(),
docstring,
})
}
fn read_method(&mut self) -> Result<MethodMetadata> {
let module_path = self.read_string()?;
let self_name = self.read_string()?;
let name = self.read_string()?;
let is_async = self.read_bool()?;
let inputs = self.read_inputs()?;
let (return_type, throws) = self.read_return_type()?;
let docstring = self.read_optional_long_string()?;
Ok(MethodMetadata {
module_path,
self_name,
name,
is_async,
inputs,
return_type,
throws,
takes_self_by_arc: false, // not emitted by macros
checksum: self.calc_checksum(),
docstring,
})
}
fn read_record(&mut self) -> Result<RecordMetadata> {
Ok(RecordMetadata {
module_path: self.read_string()?,
name: self.read_string()?,
fields: self.read_fields()?,
docstring: self.read_optional_long_string()?,
})
}
fn read_enum(&mut self) -> Result<EnumMetadata> {
let module_path = self.read_string()?;
let name = self.read_string()?;
let forced_flatness = match self.read_u8()? {
0 => None,
1 => Some(false),
2 => Some(true),
_ => unreachable!("invalid flatness"),
};
let discr_type = if self.read_bool()? {
Some(self.read_type()?)
} else {
None
};
let variants = if forced_flatness == Some(true) {
self.read_flat_variants()?
} else {
self.read_variants()?
};
Ok(EnumMetadata {
module_path,
name,
forced_flatness,
discr_type,
variants,
non_exhaustive: self.read_bool()?,
docstring: self.read_optional_long_string()?,
})
}
fn read_object(&mut self, imp: ObjectImpl) -> Result<ObjectMetadata> {
Ok(ObjectMetadata {
module_path: self.read_string()?,
name: self.read_string()?,
imp,
docstring: self.read_optional_long_string()?,
})
}
fn read_uniffi_trait(&mut self) -> Result<UniffiTraitMetadata> {
let code = self.read_u8()?;
let mut read_metadata_method = || -> Result<MethodMetadata> {
let code = self.read_u8()?;
ensure!(code == codes::METHOD, "expected METHOD but read {code}");
self.read_method()
};
Ok(match UniffiTraitDiscriminants::from(code)? {
UniffiTraitDiscriminants::Debug => UniffiTraitMetadata::Debug {
fmt: read_metadata_method()?,
},
UniffiTraitDiscriminants::Display => UniffiTraitMetadata::Display {
fmt: read_metadata_method()?,
},
UniffiTraitDiscriminants::Eq => UniffiTraitMetadata::Eq {
eq: read_metadata_method()?,
ne: read_metadata_method()?,
},
UniffiTraitDiscriminants::Hash => UniffiTraitMetadata::Hash {
hash: read_metadata_method()?,
},
})
}
fn read_callback_interface(&mut self) -> Result<CallbackInterfaceMetadata> {
Ok(CallbackInterfaceMetadata {
module_path: self.read_string()?,
name: self.read_string()?,
docstring: self.read_optional_long_string()?,
})
}
fn read_trait_method(&mut self) -> Result<TraitMethodMetadata> {
let module_path = self.read_string()?;
let trait_name = self.read_string()?;
let index = self.read_u32()?;
let name = self.read_string()?;
let is_async = self.read_bool()?;
let inputs = self.read_inputs()?;
let (return_type, throws) = self.read_return_type()?;
let docstring = self.read_optional_long_string()?;
Ok(TraitMethodMetadata {
module_path,
trait_name,
index,
name,
is_async,
inputs,
return_type,
throws,
takes_self_by_arc: false, // not emitted by macros
checksum: self.calc_checksum(),
docstring,
})
}
fn read_fields(&mut self) -> Result<Vec<FieldMetadata>> {
let len = self.read_u8()?;
(0..len)
.map(|_| {
let name = self.read_string()?;
let ty = self.read_type()?;
let default = self.read_optional_default(&name, &ty)?;
Ok(FieldMetadata {
name,
ty,
default,
docstring: self.read_optional_long_string()?,
})
})
.collect()
}
fn read_variants(&mut self) -> Result<Vec<VariantMetadata>> {
let len = self.read_u8()?;
(0..len)
.map(|_| {
Ok(VariantMetadata {
name: self.read_string()?,
discr: self.read_optional_default("<variant-value>", &Type::UInt64)?,
fields: self.read_fields()?,
docstring: self.read_optional_long_string()?,
})
})
.collect()
}
fn read_flat_variants(&mut self) -> Result<Vec<VariantMetadata>> {
let len = self.read_u8()?;
(0..len)
.map(|_| {
Ok(VariantMetadata {
name: self.read_string()?,
discr: None,
fields: vec![],
docstring: self.read_optional_long_string()?,
})
})
.collect()
}
fn read_inputs(&mut self) -> Result<Vec<FnParamMetadata>> {
let len = self.read_u8()?;
(0..len)
.map(|_| {
let name = self.read_string()?;
let ty = self.read_type()?;
let default = self.read_optional_default(&name, &ty)?;
Ok(FnParamMetadata {
name,
ty,
default,
// not emitted by macros
by_ref: false,
optional: false,
})
})
.collect()
}
fn calc_checksum(&self) -> Option<u16> {
let bytes_read = self.initial_data.len() - self.buf.len();
let metadata_buf = &self.initial_data[..bytes_read];
Some(checksum_metadata(metadata_buf))
}
fn read_optional_default(&mut self, name: &str, ty: &Type) -> Result<Option<LiteralMetadata>> {
if self.read_bool()? {
Ok(Some(self.read_default(name, ty)?))
} else {
Ok(None)
}
}
fn read_default(&mut self, name: &str, ty: &Type) -> Result<LiteralMetadata> {
let literal_kind = self.read_u8()?;
Ok(match literal_kind {
codes::LIT_STR => {
ensure!(
matches!(ty, Type::String),
"field {name} of type {ty:?} can't have a default value of type string"
);
LiteralMetadata::String(self.read_string()?)
}
codes::LIT_INT => {
let base10_digits = self.read_string()?;
// procmacros emit the type for discriminant values based purely on whether the constant
// is positive or negative.
let ty = if !base10_digits.is_empty()
&& base10_digits.as_bytes()[0] == b'-'
&& ty == &Type::UInt64
{
&Type::Int64
} else {
ty
};
macro_rules! parse_int {
($ty:ident, $variant:ident) => {
LiteralMetadata::$variant(
base10_digits
.parse::<$ty>()
.with_context(|| {
format!("parsing default for field {name}: {base10_digits}")
})?
.into(),
Radix::Decimal,
ty.to_owned(),
)
};
}
match ty {
Type::UInt8 => parse_int!(u8, UInt),
Type::Int8 => parse_int!(i8, Int),
Type::UInt16 => parse_int!(u16, UInt),
Type::Int16 => parse_int!(i16, Int),
Type::UInt32 => parse_int!(u32, UInt),
Type::Int32 => parse_int!(i32, Int),
Type::UInt64 => parse_int!(u64, UInt),
Type::Int64 => parse_int!(i64, Int),
_ => {
bail!("field {name} of type {ty:?} can't have a default value of type integer");
}
}
}
codes::LIT_FLOAT => match ty {
Type::Float32 | Type::Float64 => {
LiteralMetadata::Float(self.read_string()?, ty.to_owned())
}
_ => {
bail!("field {name} of type {ty:?} can't have a default value of type float");
}
},
codes::LIT_BOOL => LiteralMetadata::Boolean(self.read_bool()?),
codes::LIT_NONE => match ty {
Type::Optional { .. } => LiteralMetadata::None,
_ => bail!("field {name} of type {ty:?} can't have a default value of None"),
},
codes::LIT_SOME => match ty {
Type::Optional { inner_type, .. } => LiteralMetadata::Some {
inner: Box::new(self.read_default(name, inner_type)?),
},
_ => bail!("field {name} of type {ty:?} can't have a default value of None"),
},
codes::LIT_EMPTY_SEQ => LiteralMetadata::EmptySequence,
_ => bail!("Unexpected literal kind code: {literal_kind:?}"),
})
}
}