no_std & the Program Environment

Solana programs compile to SBF and run in a sandbox without std. You get solana_program syscalls, optional alloc, and a strict CU budget.

Recipe

#![no_std]
 
extern crate alloc;
 
use solana_program::{
    account_info::AccountInfo, entrypoint, program_error::ProgramError,
    pubkey::Pubkey,
};

When to reach for this:

• Starting any native (non-Anchor) program crate.
• Auditing why a dependency fails to build for cargo build-sbf.
• Choosing between alloc collections and fixed-size account layouts.

Working Example

#![no_std]
 
extern crate alloc;
 
use alloc::vec::Vec;
use solana_program::{
    account_info::AccountInfo, entrypoint, entrypoint::ProgramResult,
    program_error::ProgramError, pubkey::Pubkey,
};
 
entrypoint!(process_instruction);
 
pub fn process_instruction(
    _program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8],
) -> ProgramResult {
    if instruction_data.is_empty() {
        return Err(ProgramError::InvalidInstructionData);
    }
    let _owner = accounts.get(0).ok_or(ProgramError::NotEnoughAccountKeys)?;
    let buf: Vec<u8> = instruction_data.to_vec();
    solana_program::msg!("bytes: {}", buf.len());
    Ok(())
}

What this demonstrates:

• #![no_std] plus extern crate alloc is the default native program layout.
• Instruction data arrives as a byte slice - copy only when mutation is required.
• Account access goes through AccountInfo references supplied by the runtime.

Deep Dive

How It Works

• The Agave 4.1.1 runtime loads your .so and invokes the symbol registered by entrypoint!.
• Syscalls (logging, CPI, account borrow) are the only way to interact with chain state.
• Panics abort the instruction; there is no unwinding across the host boundary.

Available Crates

Rust Notes

// Prefer &[u8] over Vec unless you must own bytes.
// solana_program re-exports Pubkey, ProgramError, and sysvars.

Gotchas

• Importing std - Adding a crate that pulls std breaks cargo build-sbf.. Fix: Pin deps with cargo tree and prefer no_std-compatible crates.
• Heap churn - Vec::push in hot paths allocates and costs CUs.. Fix: Use fixed account sizes or stack arrays with known bounds.
• Panic on parse - unwrap on bad client data aborts the whole transaction.. Fix: Return ProgramError::InvalidAccountData instead.
• Missing alloc - Using Vec without extern crate alloc fails to link.. Fix: Add extern crate alloc at crate root.
• Debug prints - println! is unavailable on-chain.. Fix: Use msg! or custom errors sparingly.

Alternatives

FAQs

Related

• Rust for Solana Basics - Section orientation
• Borsh Serialization - Data encoding
• Program Size & CU Discipline - Performance

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.