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simple.rs
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simple.rs
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use ink_env::Environment;
use ink_lang as ink;
/// Custom chain extension to read to and write from the runtime.
#[ink::chain_extension]
pub trait RuntimeReadWrite {
type ErrorCode = ReadWriteErrorCode;
/// Reads from runtime storage.
#[ink(extension = 1, expect_ok)]
fn read(key: &[u8]) -> Vec<u8>;
/// Reads from runtime storage.
///
/// Returns the number of bytes read and up to 32 bytes of the
/// read value. Unused bytes in the output are set to 0.
///
/// # Errors
///
/// If the runtime storage cell stores a value that requires more than
/// 32 bytes.
#[ink(extension = 2)]
fn read_small(key: &[u8]) -> Result<(u32, [u8; 32]), ReadWriteError>;
/// Writes into runtime storage.
#[ink(extension = 3, expect_ok)]
fn write(key: &[u8], value: &[u8]);
/// Returns the access allowed for the key for the caller.
#[ink(extension = 4, expect_ok, expect_output)]
fn access(key: &[u8]) -> Option<Access>;
/// Unlocks previously aquired permission to access key.
///
/// # Errors
///
/// If the permission was not granted.
#[ink(extension = 5, expect_output)]
fn unlock_access(key: &[u8], access: Access) -> Result<(), UnlockAccessError>;
}
/// The shared error code for the read write chain extension.
#[derive(
Debug, Copy, Clone, PartialEq, Eq, scale::Encode, scale::Decode, scale_info::TypeInfo,
)]
pub enum ReadWriteErrorCode {
InvalidKey,
CannotWriteToKey,
CannotReadFromKey,
}
/// Returned by `read_small` in case there were too few bytes available in the buffer.
///
/// Provides the number of bytes required to read the storage cell.
#[derive(
Debug, Copy, Clone, PartialEq, Eq, scale::Encode, scale::Decode, scale_info::TypeInfo,
)]
pub enum ReadWriteError {
ErrorCode(ReadWriteErrorCode),
BufferTooSmall { required_bytes: u32 },
}
impl From<ReadWriteErrorCode> for ReadWriteError {
fn from(error_code: ReadWriteErrorCode) -> Self {
Self::ErrorCode(error_code)
}
}
impl From<scale::Error> for ReadWriteError {
fn from(_: scale::Error) -> Self {
panic!("encountered unexpected invalid SCALE encoding")
}
}
/// Returned by `unlock_access` if permission to access key was not granted with reason.
#[derive(Debug, PartialEq, Eq, scale::Encode, scale::Decode, scale_info::TypeInfo)]
pub struct UnlockAccessError {
reason: String,
}
impl From<scale::Error> for UnlockAccessError {
fn from(_: scale::Error) -> Self {
panic!("encountered unexpected invalid SCALE encoding")
}
}
/// The kind of access allows for a storage cell.
#[derive(
Debug, Copy, Clone, PartialEq, Eq, scale::Encode, scale::Decode, scale_info::TypeInfo,
)]
pub enum Access {
ReadWrite,
ReadOnly,
WriteOnly,
}
impl ink_env::chain_extension::FromStatusCode for ReadWriteErrorCode {
fn from_status_code(status_code: u32) -> Result<(), Self> {
match status_code {
0 => Ok(()),
1 => Err(Self::InvalidKey),
2 => Err(Self::CannotWriteToKey),
3 => Err(Self::CannotReadFromKey),
_ => panic!("encountered unknown status code"),
}
}
}
pub enum CustomEnvironment {}
impl Environment for CustomEnvironment {
const MAX_EVENT_TOPICS: usize =
<ink_env::DefaultEnvironment as Environment>::MAX_EVENT_TOPICS;
type AccountId = <ink_env::DefaultEnvironment as Environment>::AccountId;
type Balance = <ink_env::DefaultEnvironment as Environment>::Balance;
type Hash = <ink_env::DefaultEnvironment as Environment>::Hash;
type BlockNumber = <ink_env::DefaultEnvironment as Environment>::BlockNumber;
type Timestamp = <ink_env::DefaultEnvironment as Environment>::Timestamp;
type ChainExtension = RuntimeReadWrite;
}
#[ink::contract(env = crate::CustomEnvironment)]
mod read_writer {
use super::{Access, ReadWriteErrorCode, ReadWriteError, UnlockAccessError};
#[ink(storage)]
pub struct ReadWriter {}
impl ReadWriter {
#[ink(constructor)]
pub fn new() -> Self {
Self {}
}
#[ink(message)]
pub fn read(&self, key: Vec<u8>) -> Result<Vec<u8>, ReadWriteErrorCode> {
self.env()
.extension()
.read(&key)
}
#[ink(message)]
pub fn read_small(&self, key: Vec<u8>) -> Result<(u32, [u8; 32]), ReadWriteError> {
self.env()
.extension()
.read_small(&key)
}
#[ink(message)]
pub fn write(
&self,
key: Vec<u8>,
value: Vec<u8>,
) -> Result<(), ReadWriteErrorCode> {
self.env()
.extension()
.write(&key, &value)
}
#[ink(message)]
pub fn access(&self, key: Vec<u8>) -> Option<Access> {
self.env()
.extension()
.access(&key)
}
#[ink(message)]
pub fn unlock_access(&self, key: Vec<u8>, access: Access) -> Result<(), UnlockAccessError> {
self.env()
.extension()
.unlock_access(&key, access)
}
}
}
fn main() {}