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/* Validation function generation for Rust ABI code */
use super::helpers::{format_type_to_rust, generate_nested_field_access};
use crate::abi::resolved::{ResolvedType, ResolvedTypeKind, Size};
use std::fmt::Write;
pub fn emit_validate_fn(resolved_type: &ResolvedType) -> String {
match &resolved_type.kind {
ResolvedTypeKind::Struct { .. } => emit_validate_fn_struct(resolved_type),
ResolvedTypeKind::Enum { .. } => emit_validate_fn_enum(resolved_type),
_ => String::new(),
}
}
fn emit_validate_fn_struct(resolved_type: &ResolvedType) -> String {
let mut output = String::new();
let type_name = &resolved_type.name;
write!(
output,
"pub fn {}_validate(buffer: &[u8]) -> Result<(), &'static str> {{\n",
type_name
)
.unwrap();
/* Check minimum size */
write!(output, " /* Check minimum buffer size */\n").unwrap();
write!(
output,
" if buffer.len() < std::mem::size_of::<{}_t>() {{\n",
type_name
)
.unwrap();
write!(
output,
" return Err(\"buffer too small for struct header\");\n"
)
.unwrap();
write!(output, " }}\n\n").unwrap();
if let ResolvedTypeKind::Struct { fields, .. } = &resolved_type.kind {
let has_fams = fields
.iter()
.any(|f| matches!(f.field_type.size, Size::Variable(_)));
if has_fams {
write!(output, " /* Validate FAM sizes */\n").unwrap();
write!(
output,
" let ptr = buffer.as_ptr() as *const {}_t;\n",
type_name
)
.unwrap();
write!(
output,
" let mut offset: u64 = std::mem::size_of::<{}_t>() as u64;\n",
type_name
)
.unwrap();
for field in fields {
if let Size::Variable(var_refs) = &field.field_type.size {
/* Read field references */
for (field_ref_path, prim_type) in var_refs.values().flat_map(|m| m.iter()) {
output.push_str(&generate_nested_field_access(
field_ref_path,
type_name,
prim_type,
));
}
/* Calculate expected size for this FAM */
match &field.field_type.kind {
ResolvedTypeKind::Array { element_type, .. } => {
if let Some(var_map) = var_refs.values().next() {
if let Some((first_ref, _)) = var_map.iter().next() {
let size_var = first_ref.replace('.', "_");
/* Check for overflow */
write!(output, " if {} < 0 {{\n", size_var).unwrap();
write!(
output,
" return Err(\"FAM size cannot be negative\");\n"
)
.unwrap();
write!(output, " }}\n").unwrap();
match &element_type.size {
Size::Const(elem_size) => {
write!(
output,
" let fam_size = ({} as u64).checked_mul({})\n",
size_var, elem_size
)
.unwrap();
write!(
output,
" .ok_or(\"FAM size overflow\")?;\n"
)
.unwrap();
write!(
output,
" offset = offset.checked_add(fam_size)\n"
)
.unwrap();
write!(
output,
" .ok_or(\"offset overflow\")?;\n"
)
.unwrap();
}
Size::Variable(_) => {
/* Multi-dimensional FAM */
write!(
output,
" let elem_size = {}_footprint({});\n",
format_type_to_rust(element_type),
size_var
)
.unwrap();
write!(output, " let fam_size = ({} as u64).checked_mul(elem_size)\n", size_var).unwrap();
write!(
output,
" .ok_or(\"FAM size overflow\")?;\n"
)
.unwrap();
write!(
output,
" offset = offset.checked_add(fam_size)\n"
)
.unwrap();
write!(
output,
" .ok_or(\"offset overflow\")?;\n"
)
.unwrap();
}
}
}
}
}
_ => {
/* Non-array FAM (variable-sized nested type) */
let field_refs: Vec<String> = var_refs
.values()
.flat_map(|refs| refs.keys().map(|r| r.replace('.', "_")))
.collect();
if field_refs.is_empty() {
write!(
output,
" let field_size = {}_footprint();\n",
format_type_to_rust(&field.field_type)
)
.unwrap();
} else {
write!(
output,
" let field_size = {}_footprint({});\n",
format_type_to_rust(&field.field_type),
field_refs.join(", ")
)
.unwrap();
}
write!(output, " offset = offset.checked_add(field_size)\n")
.unwrap();
write!(output, " .ok_or(\"offset overflow\")?;\n").unwrap();
}
}
}
}
/* Final buffer size check */
write!(
output,
"\n /* Verify buffer is large enough for all FAMs */\n"
)
.unwrap();
write!(output, " if (buffer.len() as u64) < offset {{\n").unwrap();
write!(
output,
" return Err(\"buffer too small for FAM data\");\n"
)
.unwrap();
write!(output, " }}\n\n").unwrap();
}
/* Validate nested fields */
write!(output, " /* Validate nested fields */\n").unwrap();
for field in fields {
match &field.field_type.kind {
ResolvedTypeKind::Struct { .. } | ResolvedTypeKind::TypeRef { .. } => {
if matches!(field.field_type.size, Size::Const(_)) {
/* Constant-sized nested type - validate it */
write!(output, " {{\n").unwrap();
write!(
output,
" let field_offset = std::mem::offset_of!({}_t, {});\n",
type_name, field.name
)
.unwrap();
write!(
output,
" let field_slice = &buffer[field_offset..];\n"
)
.unwrap();
write!(
output,
" {}_validate(field_slice)?;\n",
format_type_to_rust(&field.field_type)
)
.unwrap();
write!(output, " }}\n").unwrap();
}
}
_ => {}
}
}
}
write!(output, "\n Ok(())\n").unwrap();
write!(output, "}}\n\n").unwrap();
output
}
fn emit_validate_fn_enum(resolved_type: &ResolvedType) -> String {
let mut output = String::new();
let type_name = &resolved_type.name;
if let ResolvedTypeKind::Enum {
variants,
tag_expression,
..
} = &resolved_type.kind
{
write!(
output,
"pub fn {}_validate(buffer: &[u8]) -> Result<(), &'static str> {{\n",
type_name
)
.unwrap();
/* Check minimum size */
write!(output, " /* Check minimum buffer size */\n").unwrap();
write!(
output,
" if buffer.len() < std::mem::size_of::<{}_t>() {{\n",
type_name
)
.unwrap();
write!(
output,
" return Err(\"buffer too small for enum\");\n"
)
.unwrap();
write!(output, " }}\n\n").unwrap();
/* Read and validate tag */
write!(output, " /* Validate tag value */\n").unwrap();
/* Extract tag field path */
if let crate::abi::expr::ExprKind::FieldRef(field_ref) = tag_expression {
let tag_path = field_ref.path.join(".");
write!(output, " let ptr = buffer.as_ptr();\n").unwrap();
write!(output, " let tag = unsafe {{\n").unwrap();
write!(output, " /* Read tag from parent structure */\n").unwrap();
write!(
output,
" /* TODO: Proper tag reading based on path: {} */\n",
tag_path
)
.unwrap();
write!(output, " 0u64 /* Placeholder */\n").unwrap();
write!(output, " }};\n\n").unwrap();
}
write!(output, " /* Check tag is valid */\n").unwrap();
write!(output, " match tag {{\n").unwrap();
for variant in variants {
write!(output, " {} => Ok(()),\n", variant.tag_value).unwrap();
}
write!(output, " _ => Err(\"invalid enum tag value\"),\n").unwrap();
write!(output, " }}\n").unwrap();
write!(output, "}}\n\n").unwrap();
}
output
}