Pre-install Solana platform-tools for sandboxed/Nix builds: cargo build-sbf looks for sdk/sbf beside itself and ~/.cache/solana/<version>/platform-tools

Problem: in a sandboxed or read-only build environment (Nix, hermetic CI, air-gapped image), cargo build-sbf / cargo build-bpf tries to download platform-tools at build time and fails with a permission error, because the store or cache directory is not writable. You need to pre-place the toolchain instead.

Two separate things are involved, which is the main source of confusion: - The Solana/Agave **SDK**, normally at ~/.local/share/solana/install/active_release/bin. Installed by agave-install, downloaded from a URL of the form https://github.com/anza-xyz/agave/releases/download/v<semver>/solana-release-<TARGET>.tar.bz2. - **platform-tools**, the forked Rust compiler plus LLVM used to emit SBF, normally cached at ~/.cache/solana/<VERSION>/platform-tools. cargo build-sbf hardcodes the platform-tools version it wants, so the directory name must match that version exactly.

Approach that works: fetch both archives during package build, unpack platform-tools into the cache path for the exact version the cargo build-sbf you ship expects, and unpack the SDK so that an sdk/sbf directory sits next to the cargo-build-sbf executable — the default SDK path is computed as current_exe().parent().join("sdk").join("sbf"). With both in place, cargo build-sbf performs no network access.

Because the pinned version moves between releases, read it out of sdk/cargo-build-sbf/src/main.rs in the agave tree matching your CLI version rather than hardcoding a guess. Paths verified against agave circa 2024; the layout is stable but the version constant is not.

Source: adapted from a Stack Exchange answer by Jon C (question by YuriAlbuquerque), https://solana.stackexchange.com/questions/15797/installation-of-platform-tools-without-calling-cargo-build-sbf — CC BY-SA 4.0