src/cmd/cos_kernel/actions/download.go

package actions

import (
	"context"
	"fmt"
	"path"

	"cloud.google.com/go/storage"
	"cos.googlesource.com/cos/tools.git/src/pkg/cos"
	"cos.googlesource.com/cos/tools.git/src/pkg/kernel"
	"github.com/spf13/cobra"
	"google.golang.org/api/option"
)

var downloadDir string

func defaultDownloader(ctx context.Context) (*cos.GCSDownloader, error) {
	if build == "" {
		return nil, fmt.Errorf("must specify --build")
	}
	guessedBuild, err := cos.GuessBuildNumber(build)
	if err != nil {
		return nil, fmt.Errorf("could not get build number from build %s: %v", build, err)
	}
	build = guessedBuild

	if board == "" {
		return nil, fmt.Errorf("must specify --board")
	}

	client, err := storage.NewClient(ctx, option.WithoutAuthentication())
	if err != nil {
		return nil, err
	}

	prefix := path.Join(build, board)
	downloader := cos.NewGCSDownloader(client, nil, "", prefix, "", "", useRegional)

	return downloader, nil
}

var downloadCmd = &cobra.Command{
	Use:   "download",
	Short: "Download COS kernel artifacts",
	Long:  "Download COS kernel artifacts such as toolchains and headers.",
}

var toolchainCmd = &cobra.Command{
	Use:   "toolchain",
	Short: "Download the COS C toolchain",
	Long: `Determine the correct toolchain location in the cos-tools GCS bucket
and download it to the provided output directory, or the local directory
if no output dir is provided.

When the download is fully complete, a blank toolchain-installed.txt file
will be written in the output directory. This ensures that the toolchain
download is atomic and can be skipped if the toolchain-installed.txt file
is already present.`,
	RunE: func(cmd *cobra.Command, args []string) error {
		ctx := context.Background()
		downloader, err := defaultDownloader(ctx)
		if err != nil {
			return fmt.Errorf("failed to create artifact downloader: %v", err)
		}

		return kernel.InstallCompilerToolchainAtomic(ctx, downloader, downloadDir)
	},
}

var headersCmd = &cobra.Command{
	Use:   "headers",
	Short: "Download the COS kernel headers",
	Long: `Determine the correct kernel headers location in the cos-tools GCS bucket
and download them to the provided output directory, or the local directory
if no output dir is provided.

When the download is fully complete, a blank kernel-headers-installed.txt file
will be written in the output directory. This ensures that the download
is atomic and can be skipped if the kernel-headers-installed.txt file is already
present.`,
	RunE: func(cmd *cobra.Command, args []string) error {
		ctx := context.Background()
		downloader, err := defaultDownloader(ctx)
		if err != nil {
			return fmt.Errorf("failed to create artifact downloader: %v", err)
		}

		return kernel.InstallKernelHeadersAtomic(ctx, downloader, downloadDir)
	},
}

func init() {
	cmds := []*cobra.Command{downloadCmd, toolchainCmd, headersCmd}
	for _, cmd := range cmds {
		cmdFlags := cmd.PersistentFlags()
		cmdFlags.StringVarP(&downloadDir, "out", "o", ".",
			"the output directory for the downloaded files")

		addCommonFlags(cmdFlags)
	}

	rootCmd.AddCommand(downloadCmd)
	downloadCmd.AddCommand(toolchainCmd)
	downloadCmd.AddCommand(headersCmd)
}