Programs

In the Solana ecosystem, "smart contracts" are called programs. Each program is an on-chain account that stores executable logic, organized into specific functions referred to as instructions.

Key Points #

Programs are on-chain accounts that contain executable code. This code is organized into distinct functions known as instructions.
Programs are stateless but can include instructions to create new accounts, which are used to store and manage program state.
Programs can be updated by an upgrade authority. A program becomes immutable when the upgrade authority is set to null.
Verifiable builds enable users to verify that onchain programs match the publicly available source code.

Writing Solana Programs #

Solana programs are predominantly written in the Rust programming language, with two common approaches for development:

Anchor: A framework designed for Solana program development. It provides a faster and simpler way to write programs, using Rust macros to significantly reduce boilerplate code. For beginners, it is recommended to start with the Anchor framework.
Native Rust: This approach involves writing Solana programs in Rust without leveraging any frameworks. It offers more flexibility but comes with increased complexity.

Updating Solana Programs #

On-chain programs can be directly modified by an account designated as the "upgrade authority", which is typically the account that originally deployed the program.

If the upgrade authority is revoked and set to None, the program becomes immutable and can no longer be updated.

Verifiable Programs #

Ensuring the integrity and verifiability of on-chain code is essential. A verifiable build ensures that the executable code deployed on-chain can be independently verified to match its public source code by any third party. This process enhances transparency and trust, making it possible to detect discrepancies between the source code and the deployed program.

The Solana developer community has introduced tools to support verifiable builds, enabling both developers and users to verify that onchain programs accurately reflect their publicly shared source code.

Searching for Verified Programs: To quickly check for verified programs, users can search for a program address on the SolanaFM Explorer and navigate to the "Verification" tab. View an example of a verified program here.
Verification Tools: The Solana Verifiable Build CLI by Ellipsis Labs enables users to independently verify onchain programs against published source code.
Support for Verifiable Builds in Anchor: Anchor provides built-in support for verifiable builds. Details can be found in the Anchor documentation.

Berkeley Packet Filter (BPF) #

Solana leverages the LLVM compiler infrastructure to compile programs into Executable and Linkable Format (ELF) files. These files include a modified version of Berkeley Packet Filter (eBPF) bytecode for Solana programs, known as "Solana Bytecode Format" (sBPF).

The use of LLVM enables Solana to potentially support any programming language that can compile to LLVM's BPF backend. This significantly enhances the flexibility of Solana as a development platform.