Crate ewasm_api

Expand description

ewasm_api is a library used to interface with Ethereum’s EEI in Ewasm, a set of enhancements to the Ethereum smart contract platform. ewasm_api exposes both a set of unsafe “native” functions representing the actual EEI functions, and a set of safe wrappers around them. It is recommended not to use the native functions as they do not perform bounds-checking.

To use ewasm_api, simply include it as a dependency in your project. ewasm_api can be built with various feature sets:

default: Builds with wee_alloc as the global allocator and with the Rust standard library.
qimalloc: Builds with qimalloc as the global allocator.
debug: Exposes the debugging interface.
experimental: Exposes the experimental bignum system library API.

§Examples

use ewasm_api::prelude::*;

fn entry() {
    let a: Hash = block_hash(1);
    finish_data(&a.bytes);
}

ewasm_entry_point!(entry);

Using lower-level primitives:

use ewasm_api::{types::Hash, block_hash, finish_data};

#[cfg(target_arch = "wasm32")]
#[no_mangle]
pub extern "C" fn main() {
    let a: types::Hash = block_hash(1);
    finish_data(&a.bytes);
}

Modules§

prelude: Re-export of all the basic features.
types: High-level types commonly used in Ethereum contracts.

Macros§

ewasm_entry_point: Declare entry point for a contract. Expects a Rust function name to be executed. This will only compile in when using the wasm32 target.

Enums§

CallResult: Enum describing the result of a call. Used by call, callCode, callDelegate, and callStatic.
CreateResult: Enum describing the result of create. On success, the data contained is the address of the newly created contract.
Error: Enum representing an error code for EEI calls. Currently used by codeCopy, callDataCopy, externalCodeCopy, and returnDataCopy.

Functions§

abort: Halts execution, reverts all changes to the state and consumes all gas.
block_coinbase: Returns the beneficiary address for the block this transaction is in (current block)
block_difficulty: Returns the difficulty of the most recent block.
block_gas_limit: Returns the gas limit of the most recent block.
block_hash: Returns the hash of the numberth most recent block.
block_number: Returns the number of the most recent block.
block_timestamp: Returns the timestamp of the most recent block.
call_code: Executes another account’s code in the context of the caller.
call_delegate: Executes a call similar to call_code, but retaining the currently executing call’s sender and value.
call_mutable: Executes a standard call to the specified address with the given gas limit, ether value, and data.
call_static: Executes a static call which cannot mutate the state.
calldata_acquire: Returns a vector containing all data passed with the currently executing call.
calldata_copy: Returns the segment of call data beginning at from, and continuing for length bytes.
calldata_size: Returns the length of the call data supplied with the currently executing call.
caller: Returns the sender of the currently executing call.
callvalue: Returns the value sent with the currently executing call.
code_acquire: Returns the currently executing code.
code_copy: Copies the segment of running code beginning at from and continuing for length bytes.
code_size: Returns the size of the currently executing code.
consume_gas: Subtracts the given amount from the VM’s gas counter. This is usually injected by the metering contract at deployment time, and hence is unneeded in most cases.
create: Creates a contract with the the given code, sending the specified ether value to its address.
current_address: Returns the executing address.
external_balance: Returns the balance of the address given.
external_code_acquire: Returns the code at the specified address.
external_code_copy: Returns the segment of code at address beginning at from and continuing for length bytes.
external_code_size: Returns the size of the code at the specified address.
finish: Ends execution, signalling success.
finish_data: Fills the return buffer with the given data and halts execution, signalling success.
gas_left: Returns the gas left in the current call.
log0: Appends log data without a topic.
log1: Appends log data with one topic.
log2: Appends log data with two topics.
log3: Appends log data with three topics.
log4: Appends log data with four topics.
returndata_acquire: Returns the data in the VM’s return buffer.
returndata_copy: Returns the segment of return buffer data beginning at from and continuing for length bytes.
returndata_size: Returns the length of the data in the VM’s return buffer.
revert: Halts execution and reverts all changes to the state.
revert_data: Fills the return buffer with the given data and halts execution, reverting all state changes.
selfdestruct: Self-destructs the running contract, sending all its ether to a specified beneficiary address.
storage_load: Accesses the storage data at the specified key.
storage_store: Sets the storage data at the specified key.
tx_gas_price: Returns the gas price of the currently executing call.
tx_origin: Returns the address of the original transaction sender.
unsafe_calldata_copy: Executes callDataCopy, but does not check for overflow.
unsafe_code_copy: Executes codeCopy, but does not check for overflow.
unsafe_external_code_copy: Executes externalCodeCopy, but does not check for overflow.
unsafe_returndata_copy: Executes returnDataCopy, but does not check for overflow.