tailscale/tool/go

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#!/bin/sh
#
# This script acts like the "go" command, but uses Tailscale's
# currently-desired version from https://github.com/tailscale/go,
# downloading it first if necessary.
set -eu
log() {
echo "$@" >&2
}
DEFAULT_TOOLCHAIN_DIR="${HOME}/.cache/tailscale-go"
TOOLCHAIN="${TOOLCHAIN-${DEFAULT_TOOLCHAIN_DIR}}"
TOOLCHAIN_GO="${TOOLCHAIN}/bin/go"
read -r REV < "$(dirname "$0")/../go.toolchain.rev"
# Fast, quiet path, when Tailscale is already current.
if [ -e "${TOOLCHAIN_GO}" ]; then
short_hash=$("${TOOLCHAIN_GO}" version | sed 's/.*-ts//; s/ .*//')
case $REV in
"$short_hash"*)
unset GOROOT
exec "${TOOLCHAIN_GO}" "$@"
esac
fi
# This works for linux and darwin, which is sufficient
# (we do not build tailscale-go for other targets).
GOOS=$(uname -s | tr A-Z a-z)
ARCH="$(uname -m)"
if [ "$ARCH" = "aarch64" ]; then
# Go uses the name "arm64".
ARCH="arm64"
elif [ "$ARCH" = "x86_64" ]; then
# Go uses the name "amd64".
ARCH="amd64"
fi
get_cached() {
if [ ! -d "$TOOLCHAIN" ]; then
mkdir -p "$TOOLCHAIN"
fi
archive="$TOOLCHAIN-$REV.tar.gz"
mark="$TOOLCHAIN.extracted"
extracted=
# Ignore the error from read, which may error if the mark file does not contain a line end.
read -r extracted < "$mark" || true
if [ "$extracted" = "$REV" ] && [ -e "${TOOLCHAIN_GO}" ]; then
# already ok
log "Go toolchain '$REV' already extracted."
return 0
fi
rm -f "$archive.new" "$TOOLCHAIN.extracted"
if [ ! -e "$archive" ]; then
log "Need to download go '$REV'."
if [ "$ARCH" = "amd64" ]; then
# For historic reasons, the tailscale/go amd64 release artifacts don't
# have the arch in their name.
BUILD="$GOOS"
else
BUILD="$GOOS-$ARCH"
fi
curl -f -L -o "$archive.new" "https://github.com/tailscale/go/releases/download/build-${REV}/${BUILD}.tar.gz"
rm -f "$archive"
mv "$archive.new" "$archive"
fi
log "Extracting tailscale/go rev '$REV'" >&2
log " into '$TOOLCHAIN'." >&2
rm -rf "$TOOLCHAIN"
mkdir -p "$TOOLCHAIN"
(cd "$TOOLCHAIN" && tar --strip-components=1 -xf "$archive")
echo "$REV" >$mark
}
if [ "${REV}" = "SKIP" ] ||
[ "${GOOS}" != "darwin" -a "${GOOS}" != "linux" ] ||
[ "${ARCH}" != "amd64" -a "${ARCH}" != "arm64" ]; then
# Use whichever go is available
exec go "$@"
else
get_cached
fi
unset GOROOT
exec "${TOOLCHAIN_GO}" "$@"