tools/devshell/contrib/download-rust-toolchain

#!/bin/bash
# Copyright 2025 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

#### CATEGORY=Toolchain
#### PREBUILTS=${PREBUILT_BB} ${PREBUILT_CAS} ${PREBUILT_JQ}
### Download the Rust toolchain to the latest green build from toolchain.ci

## usage: fx download-rust-toolchain [x64|arm64]
##
## This script downloads the latest green build of the Rust toolchain
## for the specified architecture (x64 or arm64) and places
## it in '//local/rust'. It also provides instructions on how to
## configure your build to use this toolchain.

source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/../lib/vars.sh || exit $?
fx-config-read

function usage {
  fx-command-help download-rust-toolchain
  exit 1
}

if [ -z "$1" ]; then
  echo "Error: Architecture (x64 or arm64) argument required."
  usage
fi

ARCH=$1
BUILDER=""

if [ "${ARCH}" == "x64" ]; then
  BUILDER="fuchsia/toolchain.ci/rust-linux-x64"
elif [ "${ARCH}" == "arm64" ]; then
  BUILDER="fuchsia/toolchain.ci/rust-linux-arm64"
else
  echo "Error: Invalid architecture '${ARCH}'. Must be 'x64' or 'arm64'."
  usage
fi

set -e

DOWNLOAD_DIR="$(git rev-parse --show-toplevel)/local/rust"

# Check for jq
if ! command -v jq &> /dev/null
then
    echo "jq could not be found, please install it." >&2
    exit 1
fi

BB_TOOL="$(git rev-parse --show-toplevel)/prebuilt/tools/buildbucket/bb"

# Check for bb
if [ ! -x "${BB_TOOL}" ]; then
    echo "bb tool not found or not executable at ${BB_TOOL}" >&2
    exit 1
fi

# Check if logged in with bb
if ! "${BB_TOOL}" auth-info >/dev/null 2>&1; then
    echo "Login required, run \`${BB_TOOL} auth-login\`" >&2
    exit 1
fi

# Check for cas
CAS_TOOL="$(git rev-parse --show-toplevel)/prebuilt/tools/cas/cas"
if [ ! -x "${CAS_TOOL}" ]; then
    echo "cas tool not found or not executable at ${CAS_TOOL}" >&2
    exit 1
fi

# Check if logged in with cas
if ! "${CAS_TOOL}" whoami >/dev/null 2>&1; then
    echo "Login required, run \`${CAS_TOOL} login\`" >&2
    exit 1
fi

echo "Fetching latest green build for ${BUILDER}..."
BUILD_INFO=$("${BB_TOOL}" ls ${BUILDER} -status SUCCESS -n 1 -json)

if [ -z "${BUILD_INFO}" ] || [ "${BUILD_INFO}" == "[]" ]; then
    echo "Error: No successful builds found for ${BUILDER}." >&2
    exit 1
fi

BUILD_ID=$(echo "${BUILD_INFO}" | jq -s -r '.[0].id')

if [ -z "${BUILD_ID}" ] || [ "${BUILD_ID}" == "null" ]; then
    echo "Could not find latest green build ID." >&2
    exit 1
fi

echo "Fetching details for build ${BUILD_ID}..."
BUILD_DETAILS=$("${BB_TOOL}" get ${BUILD_ID} -json -p)

CAS_DIGEST=$(echo "${BUILD_DETAILS}" | jq -r '.output.properties.isolated')

if [ -z "${CAS_DIGEST}" ] || [ "${CAS_DIGEST}" == "null" ]; then
    echo "Could not find output.properties.isolated in build details for build ${BUILD_ID}." >&2
    echo "Build Details: ${BUILD_DETAILS}" >&2 # Debug output
    exit 1
fi

echo "Found latest green build ID: ${BUILD_ID}"
echo "Found CAS digest: ${CAS_DIGEST}"

echo "Cleaning up old artifacts in ${DOWNLOAD_DIR}..."
rm -rf "${DOWNLOAD_DIR}"
mkdir -p "${DOWNLOAD_DIR}"

echo "Downloading artifacts to ${DOWNLOAD_DIR}..."
"${CAS_TOOL}" download -cas-instance projects/chromium-swarm/instances/default_instance -digest "${CAS_DIGEST}" -dir "${DOWNLOAD_DIR}"

echo "Download complete."

echo "To use this toolchain, modify your GN arguments (using fx args) to include:"
echo "  rustc_prefix = \"//local/rust\""
echo ""
echo "And add the following to universe_package_labels:"
echo '  universe_package_labels = ['
echo '    "//vendor/google/bundles/kitchen_sink",'
echo '    "//vendor/google/bundles/buildbot/core",'
echo '  ]'
echo ""
echo "Then run: fx build"