from_bcs.rs

// Copyright (c) The Starcoin Core Contributors
// SPDX-License-Identifier: Apache-2.0

use crate::util::make_native_from_func;
use move_binary_format::errors::{PartialVMError, PartialVMResult};
use move_core_types::gas_algebra::{InternalGas, InternalGasPerByte, NumBytes};
use move_core_types::vm_status::StatusCode;
use move_vm_runtime::native_functions::{NativeContext, NativeFunction};
use move_vm_types::loaded_data::runtime_types::Type;
use move_vm_types::natives::function::NativeResult;
use move_vm_types::pop_arg;
use move_vm_types::values::Value;
use smallvec::smallvec;
use std::collections::VecDeque;

// !!!! NOTE !!!!
// This file is intended for natives from the util module in the framework.
// DO NOT PUT HELPER FUNCTIONS HERE!

/// Abort code when from_bytes fails (0x01 == INVALID_ARGUMENT)
const EFROM_BYTES: u64 = 0x01_0001;

/***************************************************************************************************
 * native fun from_bytes
 *
 *   gas cost: base_cost + unit_cost * bytes_len
 *
 **************************************************************************************************/

fn native_from_bytes(
    gas_params: &GasParameters,
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    debug_assert_eq!(ty_args.len(), 1);
    debug_assert_eq!(args.len(), 1);

    let mut cost = gas_params.base;

    // TODO(Gas): charge for getting the layout
    let layout = context.type_to_type_layout(&ty_args[0])?.ok_or_else(|| {
        PartialVMError::new(StatusCode::UNKNOWN_INVARIANT_VIOLATION_ERROR).with_message(format!(
            "Failed to get layout of type {:?} -- this should not happen",
            ty_args[0]
        ))
    })?;

    let bytes = pop_arg!(args, Vec<u8>);
    //context.charge(gas_params.base + gas_params.per_byte * NumBytes::new(bytes.len() as u64))?;
    cost += gas_params.per_byte * NumBytes::new(bytes.len() as u64);
    let val = match Value::simple_deserialize(&bytes, &layout) {
        Some(val) => val,
        None => {
            return Ok(NativeResult::err(cost, EFROM_BYTES));
        }
    };
    Ok(NativeResult::ok(cost, smallvec![val]))
}

/***************************************************************************************************
 * module
 *
 **************************************************************************************************/
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct GasParameters {
    pub base: InternalGas,
    pub per_byte: InternalGasPerByte,
}

pub fn make_all(gas_params: GasParameters) -> impl Iterator<Item = (String, NativeFunction)> {
    let natives = [(
        "from_bytes",
        make_native_from_func(gas_params, native_from_bytes),
    )];
    crate::helpers::make_module_natives(natives)
}