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Add a 'SafeBuffer' struct which provides safe methods for reflection
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It verifies buffer against schema during construction and provides all the unsafe getters in lib.rs in a safe way
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@candysonya
candysonya committed Jan 15, 2025
1 parent d1d04f4 commit a60d076
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Showing 5 changed files with 1,108 additions and 152 deletions.
7 changes: 6 additions & 1 deletion rust/flatbuffers/src/vector.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,12 @@ impl<'a, T: Follow<'a> + 'a> Vector<'a, T> {
match f(&value, &key) {
Ordering::Equal => return Some(value),
Ordering::Less => left = mid + 1,
Ordering::Greater => right = mid - 1,
Ordering::Greater => {
if mid == 0 {
return None;
}
right = mid - 1;
},
}
}

Expand Down
110 changes: 58 additions & 52 deletions rust/reflection/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,10 +15,12 @@
*/

mod reflection_generated;
pub mod reflection_verifier;
mod reflection_verifier;
mod safe_buffer;
mod r#struct;
pub use crate::r#struct::Struct;
pub use crate::reflection_generated::reflection;
pub use crate::safe_buffer::SafeBuffer;

use flatbuffers::{
emplace_scalar, read_scalar, EndianScalar, Follow, ForwardsUOffset, InvalidFlatbuffer,
Expand All @@ -34,26 +36,30 @@ use num::traits::FromPrimitive;
use stdint::uintmax_t;
use thiserror::Error;

#[derive(Error, Debug)]
#[derive(Error, Debug, PartialEq)]
pub enum FlatbufferError {
#[error(transparent)]
VerificationError(#[from] flatbuffers::InvalidFlatbuffer),
#[error("Failed to convert between data type {0} and field type {1}")]
FieldTypeMismatch(String, String),
#[error("Set field value not supported for non-populated or non-scalar fields")]
SetValueNotSupported(),
SetValueNotSupported,
#[error(transparent)]
ParseFloatError(#[from] std::num::ParseFloatError),
#[error(transparent)]
TryFromIntError(#[from] std::num::TryFromIntError),
#[error("Couldn't set string because cache vector is polluted")]
SetStringPolluted(),
SetStringPolluted,
#[error("Invalid schema: Polluted buffer or the schema doesn't match the buffer.")]
InvalidSchema(),
InvalidSchema,
#[error("Type not supported: {0}")]
TypeNotSupported(String),
#[error("No type or invalid type found in union enum")]
InvalidUnionEnum(),
InvalidUnionEnum,
#[error("Table or Struct doesn't belong to the buffer")]
InvalidTableOrStruct,
#[error("Field not found in the table schema")]
FieldNotFound,
}

pub type FlatbufferResult<T, E = FlatbufferError> = core::result::Result<T, E>;
Expand All @@ -73,8 +79,8 @@ pub unsafe fn get_any_root(data: &[u8]) -> Table {
/// # Safety
///
/// The value of the corresponding slot must have type T
pub unsafe fn get_field_integer<'a, T: Follow<'a, Inner = T> + PrimInt + FromPrimitive + 'a>(
table: &'a Table,
pub unsafe fn get_field_integer<T: for<'a> Follow<'a, Inner = T> + PrimInt + FromPrimitive>(
table: &Table,
field: &Field,
) -> FlatbufferResult<Option<T>> {
if size_of::<T>() != get_type_size(field.type_().base_type()) {
Expand All @@ -98,8 +104,8 @@ pub unsafe fn get_field_integer<'a, T: Follow<'a, Inner = T> + PrimInt + FromPri
/// # Safety
///
/// The value of the corresponding slot must have type T
pub unsafe fn get_field_float<'a, T: Follow<'a, Inner = T> + Float + 'a>(
table: &'a Table,
pub unsafe fn get_field_float<T: for<'a> Follow<'a, Inner = T> + Float>(
table: &Table,
field: &Field,
) -> FlatbufferResult<Option<T>> {
if size_of::<T>() != get_type_size(field.type_().base_type()) {
Expand All @@ -124,7 +130,7 @@ pub unsafe fn get_field_float<'a, T: Follow<'a, Inner = T> + Float + 'a>(
///
/// The value of the corresponding slot must have type String
pub unsafe fn get_field_string<'a>(
table: &'a Table,
table: &Table<'a>,
field: &Field,
) -> FlatbufferResult<Option<&'a str>> {
if field.type_().base_type() != BaseType::String {
Expand All @@ -148,7 +154,7 @@ pub unsafe fn get_field_string<'a>(
///
/// The value of the corresponding slot must have type Struct
pub unsafe fn get_field_struct<'a>(
table: &'a Table,
table: &Table<'a>,
field: &Field,
) -> FlatbufferResult<Option<Struct<'a>>> {
// TODO inherited from C++: This does NOT check if the field is a table or struct, but we'd need
Expand All @@ -174,7 +180,7 @@ pub unsafe fn get_field_struct<'a>(
///
/// The value of the corresponding slot must have type Vector
pub unsafe fn get_field_vector<'a, T: Follow<'a, Inner = T>>(
table: &'a Table,
table: &Table<'a>,
field: &Field,
) -> FlatbufferResult<Option<Vector<'a, T>>> {
if field.type_().base_type() != BaseType::Vector
Expand All @@ -200,7 +206,7 @@ pub unsafe fn get_field_vector<'a, T: Follow<'a, Inner = T>>(
///
/// The value of the corresponding slot must have type Table
pub unsafe fn get_field_table<'a>(
table: &'a Table,
table: &Table<'a>,
field: &Field,
) -> FlatbufferResult<Option<Table<'a>>> {
if field.type_().base_type() != BaseType::Obj {
Expand All @@ -218,32 +224,6 @@ pub unsafe fn get_field_table<'a>(
Ok(table.get::<ForwardsUOffset<Table<'a>>>(field.offset(), None))
}

/// Gets a [Struct] struct field given its exact type. Returns error if the type doesn't match.
///
/// # Safety
///
/// The value of the corresponding slot must have type Struct.
pub unsafe fn get_field_struct_in_struct<'a>(
st: &'a Struct,
field: &Field,
) -> FlatbufferResult<Struct<'a>> {
// TODO inherited from C++: This does NOT check if the field is a table or struct, but we'd need
// access to the schema to check the is_struct flag.
if field.type_().base_type() != BaseType::Obj {
return Err(FlatbufferError::FieldTypeMismatch(
String::from("Obj"),
field
.type_()
.base_type()
.variant_name()
.unwrap_or_default()
.to_string(),
));
}

Ok(st.get::<Struct>(field.offset() as usize))
}

/// Returns the value of any table field as a 64-bit int, regardless of what type it is. Returns default integer if the field is not set or error if the value cannot be parsed as integer.
/// [num_traits](https://docs.rs/num-traits/latest/num_traits/cast/trait.NumCast.html) is used for number casting.
///
Expand Down Expand Up @@ -290,6 +270,32 @@ pub unsafe fn get_any_field_string(table: &Table, field: &Field, schema: &Schema
}
}

/// Gets a [Struct] struct field given its exact type. Returns error if the type doesn't match.
///
/// # Safety
///
/// The value of the corresponding slot must have type Struct.
pub unsafe fn get_field_struct_in_struct<'a>(
st: &Struct<'a>,
field: &Field,
) -> FlatbufferResult<Struct<'a>> {
// TODO inherited from C++: This does NOT check if the field is a table or struct, but we'd need
// access to the schema to check the is_struct flag.
if field.type_().base_type() != BaseType::Obj {
return Err(FlatbufferError::FieldTypeMismatch(
String::from("Obj"),
field
.type_()
.base_type()
.variant_name()
.unwrap_or_default()
.to_string(),
));
}

Ok(st.get::<Struct>(field.offset() as usize))
}

/// Returns the value of any struct field as a 64-bit int, regardless of what type it is. Returns error if the value cannot be parsed as integer.
///
/// # Safety
Expand Down Expand Up @@ -348,11 +354,11 @@ pub unsafe fn set_any_field_integer(
let table = Table::follow(buf, table_loc);

let Some(field_loc) = get_field_loc(&table, field) else {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
};

if !is_scalar(field_type) {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
}

set_any_value_integer(field_type, buf, field_loc, v)
Expand All @@ -373,11 +379,11 @@ pub unsafe fn set_any_field_float(
let table = Table::follow(buf, table_loc);

let Some(field_loc) = get_field_loc(&table, field) else {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
};

if !is_scalar(field_type) {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
}

set_any_value_float(field_type, buf, field_loc, v)
Expand All @@ -398,11 +404,11 @@ pub unsafe fn set_any_field_string(
let table = Table::follow(buf, table_loc);

let Some(field_loc) = get_field_loc(&table, field) else {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
};

if !is_scalar(field_type) {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
}

set_any_value_float(field_type, buf, field_loc, v.parse::<f64>()?)
Expand All @@ -423,7 +429,7 @@ pub unsafe fn set_field<T: EndianScalar>(
let table = Table::follow(buf, table_loc);

if !is_scalar(field_type) {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
}

if core::mem::size_of::<T>() != get_type_size(field_type) {
Expand All @@ -434,7 +440,7 @@ pub unsafe fn set_field<T: EndianScalar>(
}

let Some(field_loc) = get_field_loc(&table, field) else {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
};

if buf.len() < field_loc.saturating_add(get_type_size(field_type)) {
Expand Down Expand Up @@ -480,7 +486,7 @@ pub unsafe fn set_string(
let table = Table::follow(buf, table_loc);

let Some(field_loc) = get_field_loc(&table, field) else {
return Err(FlatbufferError::SetValueNotSupported());
return Err(FlatbufferError::SetValueNotSupported);
};

if buf.len() < field_loc + get_type_size(field_type) {
Expand Down Expand Up @@ -814,7 +820,7 @@ fn set_any_value_integer(
))
}
}
_ => Err(FlatbufferError::SetValueNotSupported()),
_ => Err(FlatbufferError::SetValueNotSupported),
}
}

Expand Down Expand Up @@ -927,7 +933,7 @@ fn set_any_value_float(
return Ok(emplace_scalar::<f64>(buf, v));
}
}
_ => return Err(FlatbufferError::SetValueNotSupported()),
_ => return Err(FlatbufferError::SetValueNotSupported),
}
return Err(FlatbufferError::FieldTypeMismatch(
String::from("f64"),
Expand All @@ -954,7 +960,7 @@ unsafe fn update_offset(
offset: isize,
) -> FlatbufferResult<()> {
if updated.len() != buf.len() {
return Err(FlatbufferError::SetStringPolluted());
return Err(FlatbufferError::SetStringPolluted);
}

if updated[table_loc] {
Expand Down
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