DockerCLI/command/container/cp.go

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package container
import (
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"github.com/docker/docker/api/types"
"github.com/docker/docker/cli"
"github.com/docker/docker/cli/command"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/system"
"github.com/spf13/cobra"
"golang.org/x/net/context"
)
type copyOptions struct {
source string
destination string
followLink bool
}
type copyDirection int
const (
fromContainer copyDirection = (1 << iota)
toContainer
acrossContainers = fromContainer | toContainer
)
type cpConfig struct {
followLink bool
}
// NewCopyCommand creates a new `docker cp` command
func NewCopyCommand(dockerCli *command.DockerCli) *cobra.Command {
var opts copyOptions
cmd := &cobra.Command{
Use: `cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH|-
docker cp [OPTIONS] SRC_PATH|- CONTAINER:DEST_PATH`,
Short: "Copy files/folders between a container and the local filesystem",
Long: strings.Join([]string{
"Copy files/folders between a container and the local filesystem\n",
"\nUse '-' as the source to read a tar archive from stdin\n",
"and extract it to a directory destination in a container.\n",
"Use '-' as the destination to stream a tar archive of a\n",
"container source to stdout.",
}, ""),
Args: cli.ExactArgs(2),
RunE: func(cmd *cobra.Command, args []string) error {
if args[0] == "" {
return errors.New("source can not be empty")
}
if args[1] == "" {
return errors.New("destination can not be empty")
}
opts.source = args[0]
opts.destination = args[1]
return runCopy(dockerCli, opts)
},
}
flags := cmd.Flags()
flags.BoolVarP(&opts.followLink, "follow-link", "L", false, "Always follow symbol link in SRC_PATH")
return cmd
}
func runCopy(dockerCli *command.DockerCli, opts copyOptions) error {
srcContainer, srcPath := splitCpArg(opts.source)
dstContainer, dstPath := splitCpArg(opts.destination)
var direction copyDirection
if srcContainer != "" {
direction |= fromContainer
}
if dstContainer != "" {
direction |= toContainer
}
cpParam := &cpConfig{
followLink: opts.followLink,
}
ctx := context.Background()
switch direction {
case fromContainer:
return copyFromContainer(ctx, dockerCli, srcContainer, srcPath, dstPath, cpParam)
case toContainer:
return copyToContainer(ctx, dockerCli, srcPath, dstContainer, dstPath, cpParam)
case acrossContainers:
// Copying between containers isn't supported.
return errors.New("copying between containers is not supported")
default:
// User didn't specify any container.
return errors.New("must specify at least one container source")
}
}
func statContainerPath(ctx context.Context, dockerCli *command.DockerCli, containerName, path string) (types.ContainerPathStat, error) {
return dockerCli.Client().ContainerStatPath(ctx, containerName, path)
}
func resolveLocalPath(localPath string) (absPath string, err error) {
if absPath, err = filepath.Abs(localPath); err != nil {
return
}
return archive.PreserveTrailingDotOrSeparator(absPath, localPath), nil
}
func copyFromContainer(ctx context.Context, dockerCli *command.DockerCli, srcContainer, srcPath, dstPath string, cpParam *cpConfig) (err error) {
if dstPath != "-" {
// Get an absolute destination path.
dstPath, err = resolveLocalPath(dstPath)
if err != nil {
return err
}
}
// if client requests to follow symbol link, then must decide target file to be copied
var rebaseName string
if cpParam.followLink {
srcStat, err := statContainerPath(ctx, dockerCli, srcContainer, srcPath)
// If the destination is a symbolic link, we should follow it.
if err == nil && srcStat.Mode&os.ModeSymlink != 0 {
linkTarget := srcStat.LinkTarget
if !system.IsAbs(linkTarget) {
// Join with the parent directory.
srcParent, _ := archive.SplitPathDirEntry(srcPath)
linkTarget = filepath.Join(srcParent, linkTarget)
}
linkTarget, rebaseName = archive.GetRebaseName(srcPath, linkTarget)
srcPath = linkTarget
}
}
content, stat, err := dockerCli.Client().CopyFromContainer(ctx, srcContainer, srcPath)
if err != nil {
return err
}
defer content.Close()
if dstPath == "-" {
// Send the response to STDOUT.
_, err = io.Copy(os.Stdout, content)
return err
}
// Prepare source copy info.
srcInfo := archive.CopyInfo{
Path: srcPath,
Exists: true,
IsDir: stat.Mode.IsDir(),
RebaseName: rebaseName,
}
preArchive := content
if len(srcInfo.RebaseName) != 0 {
_, srcBase := archive.SplitPathDirEntry(srcInfo.Path)
preArchive = archive.RebaseArchiveEntries(content, srcBase, srcInfo.RebaseName)
}
// See comments in the implementation of `archive.CopyTo` for exactly what
// goes into deciding how and whether the source archive needs to be
// altered for the correct copy behavior.
return archive.CopyTo(preArchive, srcInfo, dstPath)
}
func copyToContainer(ctx context.Context, dockerCli *command.DockerCli, srcPath, dstContainer, dstPath string, cpParam *cpConfig) (err error) {
if srcPath != "-" {
// Get an absolute source path.
srcPath, err = resolveLocalPath(srcPath)
if err != nil {
return err
}
}
// In order to get the copy behavior right, we need to know information
// about both the source and destination. The API is a simple tar
// archive/extract API but we can use the stat info header about the
// destination to be more informed about exactly what the destination is.
// Prepare destination copy info by stat-ing the container path.
dstInfo := archive.CopyInfo{Path: dstPath}
dstStat, err := statContainerPath(ctx, dockerCli, dstContainer, dstPath)
// If the destination is a symbolic link, we should evaluate it.
if err == nil && dstStat.Mode&os.ModeSymlink != 0 {
linkTarget := dstStat.LinkTarget
if !system.IsAbs(linkTarget) {
// Join with the parent directory.
dstParent, _ := archive.SplitPathDirEntry(dstPath)
linkTarget = filepath.Join(dstParent, linkTarget)
}
dstInfo.Path = linkTarget
dstStat, err = statContainerPath(ctx, dockerCli, dstContainer, linkTarget)
}
// Ignore any error and assume that the parent directory of the destination
// path exists, in which case the copy may still succeed. If there is any
// type of conflict (e.g., non-directory overwriting an existing directory
// or vice versa) the extraction will fail. If the destination simply did
// not exist, but the parent directory does, the extraction will still
// succeed.
if err == nil {
dstInfo.Exists, dstInfo.IsDir = true, dstStat.Mode.IsDir()
}
var (
content io.Reader
resolvedDstPath string
)
if srcPath == "-" {
// Use STDIN.
content = os.Stdin
resolvedDstPath = dstInfo.Path
if !dstInfo.IsDir {
return fmt.Errorf("destination \"%s:%s\" must be a directory", dstContainer, dstPath)
}
} else {
// Prepare source copy info.
srcInfo, err := archive.CopyInfoSourcePath(srcPath, cpParam.followLink)
if err != nil {
return err
}
srcArchive, err := archive.TarResource(srcInfo)
if err != nil {
return err
}
defer srcArchive.Close()
// With the stat info about the local source as well as the
// destination, we have enough information to know whether we need to
// alter the archive that we upload so that when the server extracts
// it to the specified directory in the container we get the desired
// copy behavior.
// See comments in the implementation of `archive.PrepareArchiveCopy`
// for exactly what goes into deciding how and whether the source
// archive needs to be altered for the correct copy behavior when it is
// extracted. This function also infers from the source and destination
// info which directory to extract to, which may be the parent of the
// destination that the user specified.
dstDir, preparedArchive, err := archive.PrepareArchiveCopy(srcArchive, srcInfo, dstInfo)
if err != nil {
return err
}
defer preparedArchive.Close()
resolvedDstPath = dstDir
content = preparedArchive
}
options := types.CopyToContainerOptions{
AllowOverwriteDirWithFile: false,
}
return dockerCli.Client().CopyToContainer(ctx, dstContainer, resolvedDstPath, content, options)
}
// We use `:` as a delimiter between CONTAINER and PATH, but `:` could also be
// in a valid LOCALPATH, like `file:name.txt`. We can resolve this ambiguity by
// requiring a LOCALPATH with a `:` to be made explicit with a relative or
// absolute path:
// `/path/to/file:name.txt` or `./file:name.txt`
//
// This is apparently how `scp` handles this as well:
// http://www.cyberciti.biz/faq/rsync-scp-file-name-with-colon-punctuation-in-it/
//
// We can't simply check for a filepath separator because container names may
// have a separator, e.g., "host0/cname1" if container is in a Docker cluster,
// so we have to check for a `/` or `.` prefix. Also, in the case of a Windows
// client, a `:` could be part of an absolute Windows path, in which case it
// is immediately proceeded by a backslash.
func splitCpArg(arg string) (container, path string) {
if system.IsAbs(arg) {
// Explicit local absolute path, e.g., `C:\foo` or `/foo`.
return "", arg
}
parts := strings.SplitN(arg, ":", 2)
if len(parts) == 1 || strings.HasPrefix(parts[0], ".") {
// Either there's no `:` in the arg
// OR it's an explicit local relative path like `./file:name.txt`.
return "", arg
}
return parts[0], parts[1]
}