darkfi_sdk/wasm/util.rs
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/* This file is part of DarkFi (https://dark.fi)
*
* Copyright (C) 2020-2025 Dyne.org foundation
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
use darkfi_serial::{Decodable, Encodable};
use std::io::Cursor;
use crate::{
error::{ContractError, GenericResult},
tx::TransactionHash,
};
/// Calls the `set_return_data` WASM function. Returns Ok(()) on success.
/// Otherwise, convert the i64 error code into a [`ContractError`].
pub fn set_return_data(data: &[u8]) -> Result<(), ContractError> {
// Ensure that the number of bytes fits within the u32 data type.
match u32::try_from(data.len()) {
Ok(len) => unsafe {
match set_return_data_(data.as_ptr(), len) {
0 => Ok(()),
errcode => Err(ContractError::from(errcode)),
}
},
Err(_) => Err(ContractError::DataTooLarge),
}
}
/// Internal function, get raw bytes from the objects store
pub fn get_object_bytes(data: &mut [u8], object_index: u32) -> i64 {
unsafe { get_object_bytes_(data.as_mut_ptr(), object_index) }
}
/// Internal function, get bytes size for an object in the store
pub fn get_object_size(object_index: u32) -> i64 {
unsafe { get_object_size_(object_index) }
}
/// Auxiliary function to parse db_get return value.
/// If either of these functions returns a negative integer error code,
/// convert it into a [`ContractError`].
pub(crate) fn parse_ret(ret: i64) -> GenericResult<Option<Vec<u8>>> {
// Negative values represent an error code.
if ret < 0 {
// However here on the special case, we'll return Ok(None)
if ret == crate::error::DB_GET_EMPTY {
return Ok(None)
}
return Err(ContractError::from(ret))
}
// Ensure that the returned value fits into the u32 datatype.
// Note that any negative cases should be caught by the `unimplemented`
// match arm above.
let obj = match u32::try_from(ret) {
Ok(obj) => obj,
Err(_) => return Err(ContractError::SetRetvalError),
};
let obj_size = get_object_size(obj);
let mut buf = vec![0u8; obj_size as usize];
get_object_bytes(&mut buf, obj);
Ok(Some(buf))
}
fn parse_retval_u32(ret: i64) -> GenericResult<u32> {
if ret < 0 {
return Err(ContractError::from(ret))
}
assert!(ret >= 0);
// This should always be possible
let obj = ret as u32;
Ok(obj)
}
/// Everyone can call this. Will return runtime configured
/// verifying block height.
///
/// ```
/// block_height = get_verifying_block_height();
/// ```
pub fn get_verifying_block_height() -> GenericResult<u32> {
let ret = unsafe { get_verifying_block_height_() };
parse_retval_u32(ret)
}
/// Everyone can call this. Will return runtime configured
/// block target.
///
/// ```
/// block_target = get_block_target();
/// ```
pub fn get_block_target() -> GenericResult<u32> {
let ret = unsafe { get_block_target_() };
parse_retval_u32(ret)
}
/// Only deploy(), metadata() and exec() can call this. Will return runtime configured
/// transaction hash.
///
/// ```
/// tx_hash = get_tx_hash();
/// ```
pub fn get_tx_hash() -> GenericResult<TransactionHash> {
let ret = unsafe { get_tx_hash_() };
let obj = parse_retval_u32(ret)?;
let mut tx_hash_data = [0u8; 32];
assert_eq!(get_object_size(obj), 32);
get_object_bytes(&mut tx_hash_data, obj);
Ok(TransactionHash(tx_hash_data))
}
/// Only deploy(), metadata() and exec() can call this. Will return runtime configured
/// verifying block height.
///
/// ```
/// call_idx = get_call_index();
/// ```
pub fn get_call_index() -> GenericResult<u8> {
let ret = unsafe { get_call_index_() };
if ret < 0 {
return Err(ContractError::from(ret))
}
assert!(ret >= 0);
// This should always be possible
let obj = ret as u8;
Ok(obj)
}
/// Everyone can call this. Will return current blockchain timestamp.
///
/// ```
/// timestamp = get_blockchain_time();
/// ```
pub fn get_blockchain_time() -> GenericResult<Option<Vec<u8>>> {
let ret = unsafe { get_blockchain_time_() };
parse_ret(ret)
}
/// Only exec() can call this. Will return last block height.
///
/// ```
/// last_block_height = get_last_block_height();
/// ```
pub fn get_last_block_height() -> GenericResult<Option<Vec<u8>>> {
let ret = unsafe { get_last_block_height_() };
parse_ret(ret)
}
/// Only metadata() and exec() can call this. Will return transaction
/// bytes by provided hash.
///
/// ```
/// tx_bytes = get_tx(hash);
/// tx = deserialize(&tx_bytes)?;
/// ```
pub fn get_tx(hash: &TransactionHash) -> GenericResult<Option<Vec<u8>>> {
let mut buf = vec![];
hash.encode(&mut buf)?;
let ret = unsafe { get_tx_(buf.as_ptr()) };
parse_ret(ret)
}
/// Only metadata() and exec() can call this. Will return transaction
/// location by provided hash.
///
/// ```
/// (block_height, tx_index) = get_tx_location(hash)?;
/// ```
pub fn get_tx_location(hash: &TransactionHash) -> GenericResult<(u32, u16)> {
let mut buf = vec![];
hash.encode(&mut buf)?;
let ret = unsafe { get_tx_location_(buf.as_ptr()) };
let loc_data = parse_ret(ret)?.ok_or(ContractError::DbGetFailed)?;
let mut cursor = Cursor::new(loc_data);
Ok((Decodable::decode(&mut cursor)?, Decodable::decode(&mut cursor)?))
}
extern "C" {
fn set_return_data_(ptr: *const u8, len: u32) -> i64;
fn get_object_bytes_(ptr: *const u8, len: u32) -> i64;
fn get_object_size_(len: u32) -> i64;
fn get_verifying_block_height_() -> i64;
fn get_block_target_() -> i64;
fn get_tx_hash_() -> i64;
fn get_call_index_() -> i64;
fn get_blockchain_time_() -> i64;
fn get_last_block_height_() -> i64;
fn get_tx_(ptr: *const u8) -> i64;
fn get_tx_location_(ptr: *const u8) -> i64;
}