if [[ ${TARGET_OS} ]]; then
    # Target explicitly set
    :
elif [[ $LOCAL_OS == Linux ]]; then
    TARGET_OS=linux
    readlink_flags="-f"
elif [[ $LOCAL_OS == Darwin ]]; then
    TARGET_OS=darwin
    readlink_flags=""
else
    echo "This system's OS, $LOCAL_OS, isn't supported"
    exit 1
fi

# Build image to use
TOOLS_REGISTRY_PROVIDER=${TOOLS_REGISTRY_PROVIDER:-gcr.io}

		exit 1
		;;
	esac
}

assert_is_supported_os() {
	case "${KNAME}" in
	Linux | FreeBSD | OpenBSD | NetBSD | DragonFly | SunOS)
		return
		;;
	Darwin)
		osx_host_version=$(env sw_vers -productVersion)
		if ! check_minimum_version "${OSX_VERSION}" "${osx_host_version}"; then
			echo "OSX version '${osx_host_version}' is not supported. Minimum supported version: ${OSX_VERSION}"

	## All binaries are static make sure to disable CGO.
	export CGO_ENABLED=0

	## List of architectures and OS to test coss compilation.
	SUPPORTED_OSARCH="linux/ppc64le linux/mips64 linux/amd64 linux/arm64 linux/s390x darwin/arm64 darwin/amd64 freebsd/amd64 windows/amd64 linux/arm linux/386 netbsd/amd64 linux/mips openbsd/amd64"
}

function _build() {
	local osarch=$1
	IFS=/ read -r -a arr <<<"$osarch"
	os="${arr[0]}"
	arch="${arr[1]}"

    echo 'behavior, create a new shell.'
    cat "$FROM_ENV"
    source "$FROM_ENV"
    rm "$FROM_ENV"
  fi
fi

# Mac builds have some specific setup needs. See setup_macos.sh for details
if [[ "${OSTYPE}" =~ darwin* ]]; then
  source ./ci/official/utilities/setup_macos.sh
fi

# Create and expand to the full path of TFCI_OUTPUT_DIR
export TFCI_OUTPUT_DIR=$(realpath "$TFCI_OUTPUT_DIR")
mkdir -p "$TFCI_OUTPUT_DIR"

    echo
    echo "$*"
    echo
    exit 1
} >&2

# OS specific support (must be 'true' or 'false').
cygwin=false
msys=false
darwin=false
nonstop=false
case "$( uname )" in                #(
  CYGWIN* )         cygwin=true  ;; #(
  Darwin* )         darwin=true  ;; #(
  MSYS* | MINGW* )  msys=true    ;; #(
  NONSTOP* )        nonstop=true ;;
esac

CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar

  if [ -f "$HOME/.mavenrc" ] ; then
    . "$HOME/.mavenrc"
  fi

fi

# OS specific support.  $var _must_ be set to either true or false.
cygwin=false;
darwin=false;
mingw=false
case "`uname`" in
  CYGWIN*) cygwin=true ;;
  MINGW*) mingw=true;;
  Darwin*) darwin=true
    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html

  local failureRegex="$1"
  shift
  local n=1
  local max=5
  while true; do
    unset SHELL # Don't let environment control which shell to use
    if isatty; then
      if [ "$(uname)" == "Darwin" ]; then
        script -q -r "${tmpFile}" "${*}"
      else
        script --flush --quiet --return "${tmpFile}" --command "${*}"
      fi
    else

  mkdir -p "${TARGET_OUT_LINUX}"
  cp "${ZTUNNEL_BIN_PATH}" "${TARGET_OUT_LINUX}/ztunnel"
  popd
}

# ztunnel binary vars (TODO handle debug builds, arm, darwin etc.)
ISTIO_ZTUNNEL_BASE_URL="${ISTIO_ZTUNNEL_BASE_URL:-https://storage.googleapis.com/istio-build/ztunnel}"

# If we are not using the default, assume its private and we need to authenticate