anchor/lang/syn/src/codegen/program/entry.rs

76 lines
3.6 KiB
Rust

use crate::Program;
use quote::quote;
pub fn generate(_program: &Program) -> proc_macro2::TokenStream {
quote! {
#[cfg(not(feature = "no-entrypoint"))]
anchor_lang::solana_program::entrypoint!(entry);
/// The Anchor codegen exposes a programming model where a user defines
/// a set of methods inside of a `#[program]` module in a way similar
/// to writing RPC request handlers. The macro then generates a bunch of
/// code wrapping these user defined methods into something that can be
/// executed on Solana.
///
/// These methods fall into one of three categories, each of which
/// can be considered a different "namespace" of the program.
///
/// 1) Global methods - regular methods inside of the `#[program]`.
/// 2) State methods - associated methods inside a `#[state]` struct.
/// 3) Interface methods - methods inside a strait struct's
/// implementation of an `#[interface]` trait.
///
/// Care must be taken by the codegen to prevent collisions between
/// methods in these different namespaces. For this reason, Anchor uses
/// a variant of sighash to perform method dispatch, rather than
/// something like a simple enum variant discriminator.
///
/// The execution flow of the generated code can be roughly outlined:
///
/// * Start program via the entrypoint.
/// * Strip method identifier off the first 8 bytes of the instruction
/// data and invoke the identified method. The method identifier
/// is a variant of sighash. See docs.rs for `anchor_lang` for details.
/// * If the method identifier is an IDL identifier, execute the IDL
/// instructions, which are a special set of hardcoded instructions
/// baked into every Anchor program. Then exit.
/// * Otherwise, the method identifier is for a user defined
/// instruction, i.e., one of the methods in the user defined
/// `#[program]` module. Perform method dispatch, i.e., execute the
/// big match statement mapping method identifier to method handler
/// wrapper.
/// * Run the method handler wrapper. This wraps the code the user
/// actually wrote, deserializing the accounts, constructing the
/// context, invoking the user's code, and finally running the exit
/// routine, which typically persists account changes.
///
/// The `entry` function here, defines the standard entry to a Solana
/// program, where execution begins.
#[cfg(not(feature = "no-entrypoint"))]
fn entry(program_id: &Pubkey, accounts: &[AccountInfo], ix_data: &[u8]) -> ProgramResult {
#[cfg(feature = "anchor-debug")]
{
msg!("anchor-debug is active");
}
if ix_data.len() < 8 {
return Err(anchor_lang::__private::ErrorCode::InstructionMissing.into());
}
// Split the instruction data into the first 8 byte method
// identifier (sighash) and the serialized instruction data.
let mut ix_data: &[u8] = ix_data;
let sighash: [u8; 8] = {
let mut sighash: [u8; 8] = [0; 8];
sighash.copy_from_slice(&ix_data[..8]);
ix_data = &ix_data[8..];
sighash
};
dispatch(program_id, accounts, sighash, ix_data)
.map_err(|e| {
anchor_lang::solana_program::msg!(&e.to_string());
e
})
}
}
}