diff --git a/fetch-rust-toolchain.sh b/fetch-rust-toolchain.sh
new file mode 100755
index 0000000..7aed0e2
--- /dev/null
+++ b/fetch-rust-toolchain.sh
@@ -0,0 +1,178 @@
+#!/bin/bash
+#
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Fetches the rust toolchain from cloud storage
+
+PUBLIC_ARTIFACTS_PATH="gs://shodan-public-artifacts"
+PUBLIC_ARTIFACTS_URL="https://storage.googleapis.com/shodan-public-artifacts"
+
+function die {
+    echo "$@" >/dev/stderr
+    exit 1
+}
+
+function try {
+    echo "$@"
+    "$@" || die "Failed to execute '$@': exited with return code $?"
+}
+
+function in-dir {
+    local directory="$1"; shift
+    local exitcode=""
+
+    echo "Entering directory ${directory}"
+    (cd "$directory" && "$@")
+    exitcode="$?"
+    echo "Leaving directory ${directory}"
+
+    if [[ "${exitcode}" != "0" ]]; then
+        die "Failed to execute '$@': exited with return code ${exitcode}"
+    fi
+}
+
+function list-tarballs {
+    if [[ "$EUID" == 0 ]]; then
+        die "This script must NOT be run as root."
+    fi
+    if ! hash gsutil 2>/dev/null; then
+        die "Google cloud SDK is not installed."
+    fi
+
+    echo "Available tarballs:"
+    echo
+    gsutil ls "${PUBLIC_ARTIFACTS_PATH}/rust_toolchain*.tar.xz"
+}
+
+function generate-tarball-name {
+    local version="$1"; shift
+    if [[ -z "${version}" ]]; then
+        die "No version specified."
+    fi
+
+    echo "rust_toolchain_${version}.tar.xz"
+}
+
+function get-original-name {
+    local tarball="$1"; shift
+    cat "${tarball}.sha256sum" |awk '{ print $2 }'
+}
+
+function download-tarball {
+    local version="$1"; shift
+    local tarball="$(generate-tarball-name ${version})"
+    local checksum="${tarball}.sha256sum"
+
+    try mkdir -p "${OUT}"
+
+    try wget -O "${OUT}/${tarball}" "${PUBLIC_ARTIFACTS_URL}/${tarball}"
+    try wget -O "${OUT}/${checksum}" "${PUBLIC_ARTIFACTS_URL}/${checksum}"
+
+    # Workaround the fact that we use the datestamped version of the filename
+    # at sha256sum creation time. IOW, "latest" is a symbolic name to make
+    # fetching easier, so we have to rename the tarball to the original name.
+    # Conveniently, this also allows us to determine which tarball is currently
+    # set as the latest in storage.
+    if [[ "${version}" == "latest" ]]; then
+        local original_name=$(get-original-name "${OUT}/${tarball}")
+        try mv "${OUT}/${tarball}" "${OUT}/${original_name}"
+        try mv "${OUT}/${checksum}" "${OUT}/${original_name}.sha256sum"
+        tarball="${original_name}"
+        checksum="${original_name}.sha256sum"
+    fi
+
+    try in-dir "${OUT}" sha256sum -c "${checksum}"
+    try mkdir -p "${CACHE}"
+    try tar -C "${CACHE}" -xf "${OUT}/${tarball}"
+}
+
+function show-usage {
+    cat >/dev/stderr <<EOF
+Usage: fetch-rust-toolchain.sh <-d|-l> [-v <date|latest>]
+
+Fetches, verifies, and untars Rust toolchain tarballs from upstram cloud storage
+into cache/.
+
+Options:
+  -l | --list        List available rust tarballs. Note: this requires the
+                         Google Cloud SDK to be installed and logged in.
+  -d | --download    Download a tarball. If -v is not provided, assumes
+                         "latest".
+  -v <date|latest> | --version <date|latest>
+                     Download either the tarball of the specified version, or
+                         the latest one from upstream storage. If this option is
+                         not specified, defaults to "latest".
+EOF
+}
+
+function main {
+    local usage="Usage: install-rust-toolchain.sh [-d|-l|-v <datestamp>]"
+    local args=$(getopt -o hdlv: \
+                        --long help,download,list:,version: \
+                        -n fetch-rust-toolchain.sh -- "$@")
+    eval set -- "$args"
+
+    local version="latest"
+    local mode=""
+
+    while true; do
+        case "$1" in
+            -d|--download)
+                mode="download"
+                shift
+                ;;
+
+            -l|--list)
+                mode="list"
+                shift
+                ;;
+
+            -v|--version)
+                version="$2"
+                shift
+                shift
+                ;;
+
+            --)
+                shift
+                break
+                ;;
+
+            *)
+                die "${usage}"
+                ;;
+        esac
+    done
+
+    case "${mode}" in
+        list)
+            list-tarballs
+            ;;
+
+        download)
+            download-tarball "${version}"
+            ;;
+
+        *)
+            show-usage
+            ;;
+    esac
+}
+
+if [[ -z "${ROOTDIR}" || -z "${RUSTDIR}" ]]; then
+    die "Source build/setup.sh first"
+fi
+
+main "$@"
diff --git a/install-rust-toolchain.sh b/install-rust-toolchain.sh
index b524aca..5a0887c 100755
--- a/install-rust-toolchain.sh
+++ b/install-rust-toolchain.sh
@@ -1,29 +1,132 @@
-#! /bin/bash
+#!/bin/bash
+#
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 # Install the rust toolchain to specified version and variant
 
-if [[ "$#" -ne 3 || $1 == "--help" ]]; then
-  echo "Usage: install-rust-toolchain.sh <rust dir> <build version|rust-toolchain path> <target>"
-  exit 1
+RUSTUP="${RUSTDIR}/bin/rustup"
+
+function die {
+    echo "$@" >/dev/stderr
+    exit 1
+}
+
+function try {
+    echo "$@"
+    "$@" || die "Failed to execute '$@': exited with return code $?"
+}
+
+function in-dir {
+    local directory="$1"; shift
+    local exitcode=""
+
+    echo "Entering directory ${directory}"
+    (cd "$directory" && "$@")
+    exitcode="$?"
+    echo "Leaving directory ${directory}"
+
+    if [[ "${exitcode}" != "0" ]]; then
+        die "Failed to execute '$@': exited with return code ${exitcode}"
+    fi
+}
+
+function main {
+    local usage="Usage: install-rust-toolchain.sh [-v <version> | -p <project-dir>] <target-to-install>"
+    local args=$(getopt -o hv:p: \
+                        --long help,version:,project: \
+                        -n install-rust-toolchain.sh -- "$@")
+    eval set -- "$args"
+
+    local version=""
+    local project_dir=""
+
+    while true; do
+        case "$1" in
+            -v|--version)
+                version="$2"
+                shift
+                shift
+                ;;
+
+            -p|--project)
+                project_dir="$2"
+                shift
+                shift
+                ;;
+
+            -h|--help)
+                die "$usage"
+                ;;
+
+            --)
+                shift
+                break
+                ;;
+        esac
+    done
+
+    if [[ ! -z "${version}" && ! -z "${project_dir}" ]]; then
+        echo "${usage}"
+        echo
+        die "-p and -v are mutually exclusive."
+    fi
+
+    local target="$1"; shift
+    try mkdir -p "${RUSTDIR}"
+
+    if [[ ! -f "${RUSTUP}" ]]; then
+        local yesorno=""
+        echo "========================================================================"
+        echo "Rustup not found locally -- do you want to install it?"
+        echo
+        echo "Please verify that you understand this will fetch binaries"
+        echo "from potentially untrusted sources. Googlers *must* use"
+        echo "internally verified builds of the rust compiler toolchains from"
+        echo "the internal toolchain tarball repository instead. Do not use this"
+        echo "tool to install Rust locally!"
+        echo
+        read -p "Type YES (in all caps) to proceed: " yesorno
+
+        [[ "${yesorno}" != "YES" ]] && die "User did not indicate agreement."
+        try "${ROOTDIR}/scripts/thirdparty/rustup-install.sh" -y
+    fi
+
+    if [[ -f "${project_dir}" ]]; then
+        # The project specifies its own version of the rust toolchain, and the
+        # user is pointing to its specification files, so let rustup use that to
+        # install the needed toolchain.
+
+        local project_dir=$(dirname $(realpath "${project_dir}"))
+        echo "Installing the rust toolchain for project ${project_dir}..."
+        try in-dir "${project_dir}" "${RUSTUP}" target add "${target}"
+    elif [[ ! -z "${version}" ]]; then
+        # We're being asked to install a specific version of the rust toolchain.
+
+        echo "Installing rust toolchain ${version} for target ${target}..."
+        try "${RUSTUP}" "+${version}" target add "${target}"
+    else
+        die "One of -p or -v must be specified."
+    fi
+}
+
+if [[ "$EUID" == 0 ]]; then
+    die "This script must NOT be run as root."
 fi
 
-RUST_DIR=$1
-
-BUILD_TOOLCHAIN=$2
-TARGET=$3
-
-RUSTUP_BIN="${RUST_DIR}/bin/rustup"
-
-mkdir -p "${RUST_DIR}"
-
-if [[ ! -f "${RUSTUP_BIN}" ]]; then
-  bash -c 'curl https://sh.rustup.rs -sSf | sh -s -- -y --no-modify-path'
+if [[ -z "${ROOTDIR}" || -z "${RUSTDIR}" ]]; then
+    die "Source build/setup.sh first"
 fi
 
-if [[ -f "${BUILD_TOOLCHAIN}" ]]; then
-  BUILD_PROJECT=$(dirname $(realpath "${BUILD_TOOLCHAIN}"))
-  echo "Build rust toolchain specified for project ${BUILD_PROJECT}..."
-  cd "${BUILD_PROJECT}"; "${RUSTUP_BIN}" target add "${TARGET}"
-else
-  echo "Build specified toolchain ${BUILD_TOOLCHAIN}..."
-  "${RUSTUP_BIN}" "+${BUILD_TOOLCHAIN}" target add "${TARGET}"
-fi
+main "$@"
diff --git a/manage-rust-toolchain.sh b/manage-rust-toolchain.sh
new file mode 100755
index 0000000..3a700f2
--- /dev/null
+++ b/manage-rust-toolchain.sh
@@ -0,0 +1,208 @@
+#!/bin/bash
+#
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Build a rust toolchain tarball for download use later.
+
+PUBLIC_ARTIFACTS_PATH="gs://shodan-public-artifacts"
+
+function die {
+    echo "$@" >/dev/stderr
+    exit 1
+}
+
+function try {
+    echo "$@"
+    "$@" || die "Failed to execute '$@': exited with return code $?"
+}
+
+function show-usage {
+    cat >/dev/stderr <<EOF
+Usage: manage-rust-toolchain.sh [-c|-u|-p <date>]
+
+Creates, uploads, and promotes Rust toolchain tarballs from toolchain installs
+on local disk in cache/.
+
+Options:
+  -l | --list        List available rust tarballs.
+  -c | --create      Create a new toolchain tarball and sha256sum from files in
+                         cache/.
+  -u | --upload      Upload the existing toolchain tarball to Google storage.
+                         Note: requires the Google Cloud SDK to be installed and
+                         logged in to function.
+  -p <date> | --promote <date>
+                     Promote the given date stamp tarball to latest.
+EOF
+    exit 1
+}
+
+function generate-tarball-name {
+    local datestamp=$(date -I)
+    echo "rust_toolchain_${datestamp}.tar.xz"
+}
+
+function create-tarball {
+    if [[ ! -d "${RUSTDIR}" ]]; then
+        die "No rust toolchain installed at ${RUSTDIR}. Please install it first, and try again."
+    fi
+
+    local tarball="$(generate-tarball-name)"
+
+    if [[ -f "${OUT}/${tarball}" ]]; then
+        die "Tarball ${tarball} already exists -- cowardly refusing to overwrite it."
+    fi
+
+    mkdir -p "${OUT}"
+
+    echo "Creating tarball in ${OUT}/${tarball}..."
+    tar -C "${ROOTDIR}/cache" -c -f - rust_toolchain \
+        |xz -T0 -9 \
+        > "${OUT}/${tarball}"
+
+    if [[ "$?" != 0 ]]; then
+        die "Couldn't create tarball."
+    fi
+
+    echo "Generating sha256sums..."
+    (cd "${OUT}" && sha256sum "${tarball}") > "${OUT}/${tarball}.sha256sum"
+
+    if [[ "$?" != 0 ]]; then
+        die "Couldn't create sha256sum checksum file."
+    fi
+
+    echo "Verifying sha256sum is valid..."
+    (cd "${OUT}" && sha256sum -c "${tarball}.sha256sum")
+
+    if [[ "$?" != 0 ]]; then
+        die "Couldn't verify sha256sum!"
+    fi
+}
+
+function list-tarballs {
+    echo "Available tarballs:"
+    echo
+    gsutil ls "${PUBLIC_ARTIFACTS_PATH}/rust_toolchain*.tar.xz"
+}
+
+function upload-tarball {
+    local tarball="$(generate-tarball-name)"
+
+    echo "Uploading tarball..."
+    try gsutil cp "${OUT}/${tarball}" "${PUBLIC_ARTIFACTS_PATH}/${tarball}"
+    try gsutil cp "${OUT}/${tarball}.sha256sum" "${PUBLIC_ARTIFACTS_PATH}/${tarball}.sha256sum"
+}
+
+function promote-tarball {
+    local promote_date="$1"; shift
+
+    echo "Removing old latest toolchain..."
+    try gsutil rm \
+        "${PUBLIC_ARTIFACTS_PATH}/rust_toolchain_latest.tar.xz"
+    try gsutil rm \
+        "${PUBLIC_ARTIFACTS_PATH}/rust_toolchain_latest.tar.xz.sha256sum"
+
+    echo "Promoting tarball rust_toolchain_${promote_date}.tar.xz to rust_toolchain_latest.tar.xz"
+    try gsutil cp \
+        "${PUBLIC_ARTIFACTS_PATH}/rust_toolchain_${promote_date}.tar.xz" \
+        "${PUBLIC_ARTIFACTS_PATH}/rust_toolchain_latest.tar.xz"
+    try gsutil cp \
+        "${PUBLIC_ARTIFACTS_PATH}/rust_toolchain_${promote_date}.tar.xz.sha256sum" \
+        "${PUBLIC_ARTIFACTS_PATH}/rust_toolchain_latest.tar.xz.sha256sum"
+}
+
+function main {
+    local usage="Usage: manage-rust-toolchain.sh [-l|-c|-u|-p <date>]"
+    local args=$(getopt -o h,l,c,u,p: --long help,list,create,upload,promote: \
+                 -n manage-rust-toolchain.sh -- "$@")
+    eval set -- "$args"
+
+    local mode=""
+    local promote_date=""
+
+    while true; do
+        case "$1" in
+            -l|--list)
+                mode="list"
+                shift
+                ;;
+
+            -c|--create)
+                mode="create-tarball"
+                shift
+                ;;
+
+            -u|--upload)
+                mode="upload"
+                shift
+                ;;
+
+            -p|--promote)
+                mode="promote"
+                promote_date="$2"
+                shift
+                shift
+                ;;
+
+            -h|--help)
+                show-usage
+                ;;
+
+            --)
+                shift
+                break
+                ;;
+
+            *)
+                die "Unknown option '$1'; maybe try --help?"
+                ;;
+        esac
+    done
+
+    case "${mode}" in
+        list)
+            list-tarballs
+            ;;
+
+        create-tarball)
+            create-tarball
+            ;;
+
+        upload)
+            upload-tarball
+            ;;
+
+        promote)
+            promote-tarball "${promote_date}"
+            ;;
+
+        *)
+            show-usage
+            ;;
+    esac
+}
+
+if [[ "$EUID" == 0 ]]; then
+    die "This script must NOT be run as root."
+fi
+
+if [[ -z "${ROOTDIR}" || -z "${RUSTDIR}" ]]; then
+    die "Source build/setup.sh first"
+fi
+
+if ! hash gsutil 2>/dev/null; then
+    die "This script requires the Google SDK to be installed."
+fi
+
+main "$@"
diff --git a/thirdparty/rustup-install.sh b/thirdparty/rustup-install.sh
new file mode 100755
index 0000000..a4a79a2
--- /dev/null
+++ b/thirdparty/rustup-install.sh
@@ -0,0 +1,662 @@
+#!/bin/sh
+# shellcheck shell=dash
+
+# This is just a little script that can be downloaded from the internet to
+# install rustup. It just does platform detection, downloads the installer
+# and runs it.
+
+# It runs on Unix shells like {a,ba,da,k,z}sh. It uses the common `local`
+# extension. Note: Most shells limit `local` to 1 var per line, contra bash.
+
+if [ "$KSH_VERSION" = 'Version JM 93t+ 2010-03-05' ]; then
+    # The version of ksh93 that ships with many illumos systems does not
+    # support the "local" extension.  Print a message rather than fail in
+    # subtle ways later on:
+    echo 'rustup does not work with this ksh93 version; please try bash!' >&2
+    exit 1
+fi
+
+
+set -u
+
+# If RUSTUP_UPDATE_ROOT is unset or empty, default it.
+RUSTUP_UPDATE_ROOT="${RUSTUP_UPDATE_ROOT:-https://static.rust-lang.org/rustup}"
+
+#XXX: If you change anything here, please make the same changes in setup_mode.rs
+usage() {
+    cat 1>&2 <<EOF
+rustup-init 1.24.3 (c1c769109 2021-05-31)
+The installer for rustup
+
+USAGE:
+    rustup-init [FLAGS] [OPTIONS]
+
+FLAGS:
+    -v, --verbose           Enable verbose output
+    -q, --quiet             Disable progress output
+    -y                      Disable confirmation prompt.
+        --no-modify-path    Don't configure the PATH environment variable
+    -h, --help              Prints help information
+    -V, --version           Prints version information
+
+OPTIONS:
+        --default-host <default-host>              Choose a default host triple
+        --default-toolchain <default-toolchain>    Choose a default toolchain to install
+        --default-toolchain none                   Do not install any toolchains
+        --profile [minimal|default|complete]       Choose a profile
+    -c, --component <components>...                Component name to also install
+    -t, --target <targets>...                      Target name to also install
+EOF
+}
+
+main() {
+    downloader --check
+    need_cmd uname
+    need_cmd mktemp
+    need_cmd chmod
+    need_cmd mkdir
+    need_cmd rm
+    need_cmd rmdir
+
+    get_architecture || return 1
+    local _arch="$RETVAL"
+    assert_nz "$_arch" "arch"
+
+    local _ext=""
+    case "$_arch" in
+        *windows*)
+            _ext=".exe"
+            ;;
+    esac
+
+    local _url="${RUSTUP_UPDATE_ROOT}/dist/${_arch}/rustup-init${_ext}"
+
+    local _dir
+    _dir="$(ensure mktemp -d)"
+    local _file="${_dir}/rustup-init${_ext}"
+
+    local _ansi_escapes_are_valid=false
+    if [ -t 2 ]; then
+        if [ "${TERM+set}" = 'set' ]; then
+            case "$TERM" in
+                xterm*|rxvt*|urxvt*|linux*|vt*)
+                    _ansi_escapes_are_valid=true
+                ;;
+            esac
+        fi
+    fi
+
+    # check if we have to use /dev/tty to prompt the user
+    local need_tty=yes
+    for arg in "$@"; do
+        case "$arg" in
+            -h|--help)
+                usage
+                exit 0
+                ;;
+            -y)
+                # user wants to skip the prompt -- we don't need /dev/tty
+                need_tty=no
+                ;;
+            *)
+                ;;
+        esac
+    done
+
+    if $_ansi_escapes_are_valid; then
+        printf "\33[1minfo:\33[0m downloading installer\n" 1>&2
+    else
+        printf '%s\n' 'info: downloading installer' 1>&2
+    fi
+
+    ensure mkdir -p "$_dir"
+    ensure downloader "$_url" "$_file" "$_arch"
+    ensure chmod u+x "$_file"
+    if [ ! -x "$_file" ]; then
+        printf '%s\n' "Cannot execute $_file (likely because of mounting /tmp as noexec)." 1>&2
+        printf '%s\n' "Please copy the file to a location where you can execute binaries and run ./rustup-init${_ext}." 1>&2
+        exit 1
+    fi
+
+    if [ "$need_tty" = "yes" ]; then
+        # The installer is going to want to ask for confirmation by
+        # reading stdin.  This script was piped into `sh` though and
+        # doesn't have stdin to pass to its children. Instead we're going
+        # to explicitly connect /dev/tty to the installer's stdin.
+        if [ ! -t 1 ]; then
+            err "Unable to run interactively. Run with -y to accept defaults, --help for additional options"
+        fi
+
+        ignore "$_file" "$@" < /dev/tty
+    else
+        ignore "$_file" "$@"
+    fi
+
+    local _retval=$?
+
+    ignore rm "$_file"
+    ignore rmdir "$_dir"
+
+    return "$_retval"
+}
+
+check_proc() {
+    # Check for /proc by looking for the /proc/self/exe link
+    # This is only run on Linux
+    if ! test -L /proc/self/exe ; then
+        err "fatal: Unable to find /proc/self/exe.  Is /proc mounted?  Installation cannot proceed without /proc."
+    fi
+}
+
+get_bitness() {
+    need_cmd head
+    # Architecture detection without dependencies beyond coreutils.
+    # ELF files start out "\x7fELF", and the following byte is
+    #   0x01 for 32-bit and
+    #   0x02 for 64-bit.
+    # The printf builtin on some shells like dash only supports octal
+    # escape sequences, so we use those.
+    local _current_exe_head
+    _current_exe_head=$(head -c 5 /proc/self/exe )
+    if [ "$_current_exe_head" = "$(printf '\177ELF\001')" ]; then
+        echo 32
+    elif [ "$_current_exe_head" = "$(printf '\177ELF\002')" ]; then
+        echo 64
+    else
+        err "unknown platform bitness"
+    fi
+}
+
+is_host_amd64_elf() {
+    need_cmd head
+    need_cmd tail
+    # ELF e_machine detection without dependencies beyond coreutils.
+    # Two-byte field at offset 0x12 indicates the CPU,
+    # but we're interested in it being 0x3E to indicate amd64, or not that.
+    local _current_exe_machine
+    _current_exe_machine=$(head -c 19 /proc/self/exe | tail -c 1)
+    [ "$_current_exe_machine" = "$(printf '\076')" ]
+}
+
+get_endianness() {
+    local cputype=$1
+    local suffix_eb=$2
+    local suffix_el=$3
+
+    # detect endianness without od/hexdump, like get_bitness() does.
+    need_cmd head
+    need_cmd tail
+
+    local _current_exe_endianness
+    _current_exe_endianness="$(head -c 6 /proc/self/exe | tail -c 1)"
+    if [ "$_current_exe_endianness" = "$(printf '\001')" ]; then
+        echo "${cputype}${suffix_el}"
+    elif [ "$_current_exe_endianness" = "$(printf '\002')" ]; then
+        echo "${cputype}${suffix_eb}"
+    else
+        err "unknown platform endianness"
+    fi
+}
+
+get_architecture() {
+    local _ostype _cputype _bitness _arch _clibtype
+    _ostype="$(uname -s)"
+    _cputype="$(uname -m)"
+    _clibtype="gnu"
+
+    if [ "$_ostype" = Linux ]; then
+        if [ "$(uname -o)" = Android ]; then
+            _ostype=Android
+        fi
+        if ldd --version 2>&1 | grep -q 'musl'; then
+            _clibtype="musl"
+        fi
+    fi
+
+    if [ "$_ostype" = Darwin ] && [ "$_cputype" = i386 ]; then
+        # Darwin `uname -m` lies
+        if sysctl hw.optional.x86_64 | grep -q ': 1'; then
+            _cputype=x86_64
+        fi
+    fi
+
+    if [ "$_ostype" = SunOS ]; then
+        # Both Solaris and illumos presently announce as "SunOS" in "uname -s"
+        # so use "uname -o" to disambiguate.  We use the full path to the
+        # system uname in case the user has coreutils uname first in PATH,
+        # which has historically sometimes printed the wrong value here.
+        if [ "$(/usr/bin/uname -o)" = illumos ]; then
+            _ostype=illumos
+        fi
+
+        # illumos systems have multi-arch userlands, and "uname -m" reports the
+        # machine hardware name; e.g., "i86pc" on both 32- and 64-bit x86
+        # systems.  Check for the native (widest) instruction set on the
+        # running kernel:
+        if [ "$_cputype" = i86pc ]; then
+            _cputype="$(isainfo -n)"
+        fi
+    fi
+
+    case "$_ostype" in
+
+        Android)
+            _ostype=linux-android
+            ;;
+
+        Linux)
+            check_proc
+            _ostype=unknown-linux-$_clibtype
+            _bitness=$(get_bitness)
+            ;;
+
+        FreeBSD)
+            _ostype=unknown-freebsd
+            ;;
+
+        NetBSD)
+            _ostype=unknown-netbsd
+            ;;
+
+        DragonFly)
+            _ostype=unknown-dragonfly
+            ;;
+
+        Darwin)
+            _ostype=apple-darwin
+            ;;
+
+        illumos)
+            _ostype=unknown-illumos
+            ;;
+
+        MINGW* | MSYS* | CYGWIN*)
+            _ostype=pc-windows-gnu
+            ;;
+
+        *)
+            err "unrecognized OS type: $_ostype"
+            ;;
+
+    esac
+
+    case "$_cputype" in
+
+        i386 | i486 | i686 | i786 | x86)
+            _cputype=i686
+            ;;
+
+        xscale | arm)
+            _cputype=arm
+            if [ "$_ostype" = "linux-android" ]; then
+                _ostype=linux-androideabi
+            fi
+            ;;
+
+        armv6l)
+            _cputype=arm
+            if [ "$_ostype" = "linux-android" ]; then
+                _ostype=linux-androideabi
+            else
+                _ostype="${_ostype}eabihf"
+            fi
+            ;;
+
+        armv7l | armv8l)
+            _cputype=armv7
+            if [ "$_ostype" = "linux-android" ]; then
+                _ostype=linux-androideabi
+            else
+                _ostype="${_ostype}eabihf"
+            fi
+            ;;
+
+        aarch64 | arm64)
+            _cputype=aarch64
+            ;;
+
+        x86_64 | x86-64 | x64 | amd64)
+            _cputype=x86_64
+            ;;
+
+        mips)
+            _cputype=$(get_endianness mips '' el)
+            ;;
+
+        mips64)
+            if [ "$_bitness" -eq 64 ]; then
+                # only n64 ABI is supported for now
+                _ostype="${_ostype}abi64"
+                _cputype=$(get_endianness mips64 '' el)
+            fi
+            ;;
+
+        ppc)
+            _cputype=powerpc
+            ;;
+
+        ppc64)
+            _cputype=powerpc64
+            ;;
+
+        ppc64le)
+            _cputype=powerpc64le
+            ;;
+
+        s390x)
+            _cputype=s390x
+            ;;
+        riscv64)
+            _cputype=riscv64gc
+            ;;
+        *)
+            err "unknown CPU type: $_cputype"
+
+    esac
+
+    # Detect 64-bit linux with 32-bit userland
+    if [ "${_ostype}" = unknown-linux-gnu ] && [ "${_bitness}" -eq 32 ]; then
+        case $_cputype in
+            x86_64)
+                if [ -n "${RUSTUP_CPUTYPE:-}" ]; then
+                    _cputype="$RUSTUP_CPUTYPE"
+                else {
+                    # 32-bit executable for amd64 = x32
+                    if is_host_amd64_elf; then {
+                         echo "This host is running an x32 userland; as it stands, x32 support is poor," 1>&2
+                         echo "and there isn't a native toolchain -- you will have to install" 1>&2
+                         echo "multiarch compatibility with i686 and/or amd64, then select one" 1>&2
+                         echo "by re-running this script with the RUSTUP_CPUTYPE environment variable" 1>&2
+                         echo "set to i686 or x86_64, respectively." 1>&2
+                         echo 1>&2
+                         echo "You will be able to add an x32 target after installation by running" 1>&2
+                         echo "  rustup target add x86_64-unknown-linux-gnux32" 1>&2
+                         exit 1
+                    }; else
+                        _cputype=i686
+                    fi
+                }; fi
+                ;;
+            mips64)
+                _cputype=$(get_endianness mips '' el)
+                ;;
+            powerpc64)
+                _cputype=powerpc
+                ;;
+            aarch64)
+                _cputype=armv7
+                if [ "$_ostype" = "linux-android" ]; then
+                    _ostype=linux-androideabi
+                else
+                    _ostype="${_ostype}eabihf"
+                fi
+                ;;
+            riscv64gc)
+                err "riscv64 with 32-bit userland unsupported"
+                ;;
+        esac
+    fi
+
+    # Detect armv7 but without the CPU features Rust needs in that build,
+    # and fall back to arm.
+    # See https://github.com/rust-lang/rustup.rs/issues/587.
+    if [ "$_ostype" = "unknown-linux-gnueabihf" ] && [ "$_cputype" = armv7 ]; then
+        if ensure grep '^Features' /proc/cpuinfo | grep -q -v neon; then
+            # At least one processor does not have NEON.
+            _cputype=arm
+        fi
+    fi
+
+    _arch="${_cputype}-${_ostype}"
+
+    RETVAL="$_arch"
+}
+
+say() {
+    printf 'rustup: %s\n' "$1"
+}
+
+err() {
+    say "$1" >&2
+    exit 1
+}
+
+need_cmd() {
+    if ! check_cmd "$1"; then
+        err "need '$1' (command not found)"
+    fi
+}
+
+check_cmd() {
+    command -v "$1" > /dev/null 2>&1
+}
+
+assert_nz() {
+    if [ -z "$1" ]; then err "assert_nz $2"; fi
+}
+
+# Run a command that should never fail. If the command fails execution
+# will immediately terminate with an error showing the failing
+# command.
+ensure() {
+    if ! "$@"; then err "command failed: $*"; fi
+}
+
+# This is just for indicating that commands' results are being
+# intentionally ignored. Usually, because it's being executed
+# as part of error handling.
+ignore() {
+    "$@"
+}
+
+# This wraps curl or wget. Try curl first, if not installed,
+# use wget instead.
+downloader() {
+    local _dld
+    local _ciphersuites
+    local _err
+    local _status
+    if check_cmd curl; then
+        _dld=curl
+    elif check_cmd wget; then
+        _dld=wget
+    else
+        _dld='curl or wget' # to be used in error message of need_cmd
+    fi
+
+    if [ "$1" = --check ]; then
+        need_cmd "$_dld"
+    elif [ "$_dld" = curl ]; then
+        get_ciphersuites_for_curl
+        _ciphersuites="$RETVAL"
+        if [ -n "$_ciphersuites" ]; then
+            _err=$(curl --proto '=https' --tlsv1.2 --ciphers "$_ciphersuites" --silent --show-error --fail --location "$1" --output "$2" 2>&1)
+            _status=$?
+        else
+            echo "Warning: Not enforcing strong cipher suites for TLS, this is potentially less secure"
+            if ! check_help_for "$3" curl --proto --tlsv1.2; then
+                echo "Warning: Not enforcing TLS v1.2, this is potentially less secure"
+                _err=$(curl --silent --show-error --fail --location "$1" --output "$2" 2>&1)
+                _status=$?
+            else
+                _err=$(curl --proto '=https' --tlsv1.2 --silent --show-error --fail --location "$1" --output "$2" 2>&1)
+                _status=$?
+            fi
+        fi
+        if [ -n "$_err" ]; then
+            echo "$_err" >&2
+            if echo "$_err" | grep -q 404$; then
+                err "installer for platform '$3' not found, this may be unsupported"
+            fi
+        fi
+        return $_status
+    elif [ "$_dld" = wget ]; then
+        get_ciphersuites_for_wget
+        _ciphersuites="$RETVAL"
+        if [ -n "$_ciphersuites" ]; then
+            _err=$(wget --https-only --secure-protocol=TLSv1_2 --ciphers "$_ciphersuites" "$1" -O "$2" 2>&1)
+            _status=$?
+        else
+            echo "Warning: Not enforcing strong cipher suites for TLS, this is potentially less secure"
+            if ! check_help_for "$3" wget --https-only --secure-protocol; then
+                echo "Warning: Not enforcing TLS v1.2, this is potentially less secure"
+                _err=$(wget "$1" -O "$2" 2>&1)
+                _status=$?
+            else
+                _err=$(wget --https-only --secure-protocol=TLSv1_2 "$1" -O "$2" 2>&1)
+                _status=$?
+            fi
+        fi
+        if [ -n "$_err" ]; then
+            echo "$_err" >&2
+            if echo "$_err" | grep -q ' 404 Not Found$'; then
+                err "installer for platform '$3' not found, this may be unsupported"
+            fi
+        fi
+        return $_status
+    else
+        err "Unknown downloader"   # should not reach here
+    fi
+}
+
+check_help_for() {
+    local _arch
+    local _cmd
+    local _arg
+    _arch="$1"
+    shift
+    _cmd="$1"
+    shift
+
+    local _category
+    if "$_cmd" --help | grep -q 'For all options use the manual or "--help all".'; then
+      _category="all"
+    else
+      _category=""
+    fi
+
+    case "$_arch" in
+
+        *darwin*)
+        if check_cmd sw_vers; then
+            case $(sw_vers -productVersion) in
+                10.*)
+                    # If we're running on macOS, older than 10.13, then we always
+                    # fail to find these options to force fallback
+                    if [ "$(sw_vers -productVersion | cut -d. -f2)" -lt 13 ]; then
+                        # Older than 10.13
+                        echo "Warning: Detected macOS platform older than 10.13"
+                        return 1
+                    fi
+                    ;;
+                11.*)
+                    # We assume Big Sur will be OK for now
+                    ;;
+                *)
+                    # Unknown product version, warn and continue
+                    echo "Warning: Detected unknown macOS major version: $(sw_vers -productVersion)"
+                    echo "Warning TLS capabilities detection may fail"
+                    ;;
+            esac
+        fi
+        ;;
+
+    esac
+
+    for _arg in "$@"; do
+        if ! "$_cmd" --help $_category | grep -q -- "$_arg"; then
+            return 1
+        fi
+    done
+
+    true # not strictly needed
+}
+
+# Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
+# if support by local tools is detected. Detection currently supports these curl backends: 
+# GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
+get_ciphersuites_for_curl() {
+    if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
+        # user specified custom cipher suites, assume they know what they're doing
+        RETVAL="$RUSTUP_TLS_CIPHERSUITES"
+        return
+    fi
+
+    local _openssl_syntax="no"
+    local _gnutls_syntax="no"
+    local _backend_supported="yes"
+    if curl -V | grep -q ' OpenSSL/'; then
+        _openssl_syntax="yes"
+    elif curl -V | grep -iq ' LibreSSL/'; then
+        _openssl_syntax="yes"
+    elif curl -V | grep -iq ' BoringSSL/'; then
+        _openssl_syntax="yes"
+    elif curl -V | grep -iq ' GnuTLS/'; then
+        _gnutls_syntax="yes"
+    else
+        _backend_supported="no"
+    fi
+
+    local _args_supported="no"
+    if [ "$_backend_supported" = "yes" ]; then
+        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
+        if check_help_for "notspecified" "curl" "--tlsv1.2" "--ciphers" "--proto"; then
+            _args_supported="yes"
+        fi
+    fi
+
+    local _cs=""
+    if [ "$_args_supported" = "yes" ]; then
+        if [ "$_openssl_syntax" = "yes" ]; then
+            _cs=$(get_strong_ciphersuites_for "openssl")
+        elif [ "$_gnutls_syntax" = "yes" ]; then
+            _cs=$(get_strong_ciphersuites_for "gnutls")
+        fi
+    fi
+
+    RETVAL="$_cs"
+}
+
+# Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
+# if support by local tools is detected. Detection currently supports these wget backends: 
+# GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
+get_ciphersuites_for_wget() {
+    if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
+        # user specified custom cipher suites, assume they know what they're doing
+        RETVAL="$RUSTUP_TLS_CIPHERSUITES"
+        return
+    fi
+
+    local _cs=""
+    if wget -V | grep -q '\-DHAVE_LIBSSL'; then
+        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
+        if check_help_for "notspecified" "wget" "TLSv1_2" "--ciphers" "--https-only" "--secure-protocol"; then
+            _cs=$(get_strong_ciphersuites_for "openssl")
+        fi
+    elif wget -V | grep -q '\-DHAVE_LIBGNUTLS'; then
+        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
+        if check_help_for "notspecified" "wget" "TLSv1_2" "--ciphers" "--https-only" "--secure-protocol"; then
+            _cs=$(get_strong_ciphersuites_for "gnutls")
+        fi
+    fi
+
+    RETVAL="$_cs"
+}
+
+# Return strong TLS 1.2-1.3 cipher suites in OpenSSL or GnuTLS syntax. TLS 1.2 
+# excludes non-ECDHE and non-AEAD cipher suites. DHE is excluded due to bad 
+# DH params often found on servers (see RFC 7919). Sequence matches or is
+# similar to Firefox 68 ESR with weak cipher suites disabled via about:config.  
+# $1 must be openssl or gnutls.
+get_strong_ciphersuites_for() {
+    if [ "$1" = "openssl" ]; then
+        # OpenSSL is forgiving of unknown values, no problems with TLS 1.3 values on versions that don't support it yet.
+        echo "TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384"
+    elif [ "$1" = "gnutls" ]; then
+        # GnuTLS isn't forgiving of unknown values, so this may require a GnuTLS version that supports TLS 1.3 even if wget doesn't.
+        # Begin with SECURE128 (and higher) then remove/add to build cipher suites. Produces same 9 cipher suites as OpenSSL but in slightly different order.
+        echo "SECURE128:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS-ALL:-CIPHER-ALL:-MAC-ALL:-KX-ALL:+AEAD:+ECDHE-ECDSA:+ECDHE-RSA:+AES-128-GCM:+CHACHA20-POLY1305:+AES-256-GCM"
+    fi 
+}
+
+main "$@" || exit 1