tool/gocross: a tool for building Tailscale binaries

Signed-off-by: David Anderson <danderson@tailscale.com>

tool/go

@@ -4,81 +4,4 @@
 # 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).
-host_os=$(uname -s | tr A-Z a-z)
-host_arch="$(uname -m)"
-if [ "$host_arch" = "aarch64" ]; then
-    # Go uses the name "arm64".
-    host_arch="arm64"
-elif [ "$host_arch" = "x86_64" ]; then
-    # Go uses the name "amd64".
-    host_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'."
-            curl -f -L -o "$archive.new" "https://github.com/tailscale/go/releases/download/build-${REV}/${host_os}-${host_arch}.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" ] ||
-   [ "${host_os}" != "darwin" -a "${host_os}" != "linux" ] ||
-   [ "${host_arch}" != "amd64" -a "${host_arch}" != "arm64" ]; then
-    # Use whichever go is available
-    exec go "$@"
-else
-    get_cached
-fi
-
-unset GOROOT
-exec "${TOOLCHAIN_GO}" "$@"
+exec "$(dirname "$0")/../tool/gocross/gocross-wrapper.sh" "$@"