support container to container copy

Implement container to container copy.  Previously data could only be
copied from/to the host.

Fixes: containers#7370
Co-authored-by: Mehul Arora <[email protected]>
Signed-off-by: Valentin Rothberg <[email protected]>

cmd/podman/containers/cp.go

@@ -82,7 +82,9 @@ func cp(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	if len(sourceContainerStr) > 0 {
+	if len(sourceContainerStr) > 0 && len(destContainerStr) > 0 {
+		return copyContainerToContainer(sourceContainerStr, sourcePath, destContainerStr, destPath)
+	} else if len(sourceContainerStr) > 0 {
 		return copyFromContainer(sourceContainerStr, sourcePath, destPath)
 	}
 
@@ -115,6 +117,110 @@ func doCopy(funcA func() error, funcB func() error) error {
 	return errorhandling.JoinErrors(copyErrors)
 }
 
+func copyContainerToContainer(sourceContainer string, sourcePath string, destContainer string, destPath string) error {
+	if err := containerMustExist(sourceContainer); err != nil {
+		return err
+	}
+
+	if err := containerMustExist(destContainer); err != nil {
+		return err
+	}
+
+	sourceContainerInfo, err := registry.ContainerEngine().ContainerStat(registry.GetContext(), sourceContainer, sourcePath)
+	if err != nil {
+		return errors.Wrapf(err, "%q could not be found on container %s", sourcePath, sourceContainer)
+	}
+
+	var destContainerBaseName string
+	destContainerInfo, destContainerInfoErr := registry.ContainerEngine().ContainerStat(registry.GetContext(), destContainer, destPath)
+	if destContainerInfoErr != nil {
+		if strings.HasSuffix(destPath, "/") {
+			return errors.Wrapf(destContainerInfoErr, "%q could not be found on container %s", destPath, destContainer)
+		}
+		// NOTE: containerInfo may actually be set.  That happens when
+		// the container path is a symlink into nirvana.  In that case,
+		// we must use the symlinked path instead.
+		path := destPath
+		if destContainerInfo != nil {
+			destContainerBaseName = filepath.Base(destContainerInfo.LinkTarget)
+			path = destContainerInfo.LinkTarget
+		} else {
+			destContainerBaseName = filepath.Base(destPath)
+		}
+
+		parentDir, err := containerParentDir(destContainer, path)
+		if err != nil {
+			return errors.Wrapf(err, "could not determine parent dir of %q on container %s", path, destContainer)
+		}
+		destContainerInfo, err = registry.ContainerEngine().ContainerStat(registry.GetContext(), destContainer, parentDir)
+		if err != nil {
+			return errors.Wrapf(err, "%q could not be found on container %s", destPath, destContainer)
+		}
+	} else {
+		// If the specified path exists on the container, we must use
+		// its base path as it may have changed due to symlink
+		// evaluations.
+		destContainerBaseName = filepath.Base(destContainerInfo.LinkTarget)
+	}
+
+	if sourceContainerInfo.IsDir && !destContainerInfo.IsDir {
+		return errors.New("destination must be a directory when copying a directory")
+	}
+
+	sourceContainerTarget, destContainerTarget := sourceContainerInfo.LinkTarget, destContainerInfo.LinkTarget
+	if !destContainerInfo.IsDir {
+		destContainerTarget = filepath.Dir(destPath)
+	}
+
+	// If we copy a directory via the "." notation and the container path
+	// does not exist, we need to make sure that the destination on the
+	// container gets created; otherwise the contents of the source
+	// directory will be written to the destination's parent directory.
+	//
+	// Hence, whenever "." is the source and the destination does not
+	// exist, we copy the source's parent and let the copier package create
+	// the destination via the Rename option.
+	if destContainerInfoErr != nil && sourceContainerInfo.IsDir && strings.HasSuffix(sourcePath, ".") {
+		sourceContainerTarget = filepath.Dir(sourceContainerTarget)
+	}
+
+	reader, writer := io.Pipe()
+
+	sourceContainerCopy := func() error {
+		defer writer.Close()
+		copyFunc, err := registry.ContainerEngine().ContainerCopyToArchive(registry.GetContext(), sourceContainer, sourceContainerTarget, writer)
+		if err != nil {
+			return err
+		}
+		if err := copyFunc(); err != nil {
+			return errors.Wrap(err, "error copying from container")
+		}
+		return nil
+	}
+
+	destContainerCopy := func() error {
+		defer reader.Close()
+
+		copyOptions := entities.CopyOptions{Chown: chown}
+		if (!sourceContainerInfo.IsDir && !destContainerInfo.IsDir) || destContainerInfoErr != nil {
+			// If we're having a file-to-file copy, make sure to
+			// rename accordingly.
+			copyOptions.Rename = map[string]string{filepath.Base(sourceContainerTarget): destContainerBaseName}
+		}
+
+		copyFunc, err := registry.ContainerEngine().ContainerCopyFromArchive(registry.GetContext(), destContainer, destContainerTarget, reader, copyOptions)
+		if err != nil {
+			return err
+		}
+		if err := copyFunc(); err != nil {
+			return errors.Wrap(err, "error copying to container")
+		}
+		return nil
+	}
+
+	return doCopy(sourceContainerCopy, destContainerCopy)
+}
+
 // copyFromContainer copies from the containerPath on the container to hostPath.
 func copyFromContainer(container string, containerPath string, hostPath string) error {
 	if err := containerMustExist(container); err != nil {

docs/source/markdown/podman-cp.1.md

@@ -9,10 +9,10 @@ podman\-cp - Copy files/folders between a container and the local filesystem
 **podman container cp** [*options*] [*container*:]*src_path* [*container*:]*dest_path*
 
 ## DESCRIPTION
-Copy the contents of **src_path** to the **dest_path**. You can copy from the container's filesystem to the local machine or the reverse, from the local filesystem to the container.
+Copy the contents of **src_path** to the **dest_path**. You can copy from the container's filesystem to the local machine or the reverse, from the local filesystem to the container or between two containers.
 If `-` is specified for either the SRC_PATH or DEST_PATH, you can also stream a tar archive from STDIN or to STDOUT.
 
-The CONTAINER can be a running or stopped container. The **src_path** or **dest_path** can be a file or directory.
+The containers can be a running or stopped. The **src_path** or **dest_path** can be a file or directory.
 
 The **podman cp** command assumes container paths are relative to the container's root directory (i.e., `/`).
 
@@ -70,10 +70,9 @@ The default is *true*.
 
 ## ALTERNATIVES
 
-Podman has much stronger capabilities than just `podman cp` to achieve copy files between host and container.
+Podman has much stronger capabilities than just `podman cp` to achieve copying files between the host and containers.
 
-Using standard podman-mount and podman-umount takes advantage of the entire linux tool chain, rather
-then just cp.
+Using standard podman-mount and podman-umount takes advantage of the entire linux tool chain, rather than just cp.
 
 If a user wants to copy contents out of a container or into a container, they can execute a few simple commands.
 
@@ -113,6 +112,8 @@ podman cp containerID:/myapp/ /myapp/
 
 podman cp containerID:/home/myuser/. /home/myuser/
 
+podman cp containerA:/myapp containerB:/yourapp
+
 podman cp - containerID:/myfiles.tar.gz < myfiles.tar.gz
 
 ## SEE ALSO

libpod/container_api.go

@@ -840,7 +840,7 @@ func (c *Container) ShouldRestart(ctx context.Context) bool {
 
 // CopyFromArchive copies the contents from the specified tarStream to path
 // *inside* the container.
-func (c *Container) CopyFromArchive(ctx context.Context, containerPath string, chown bool, tarStream io.Reader) (func() error, error) {
+func (c *Container) CopyFromArchive(ctx context.Context, containerPath string, chown bool, rename map[string]string, tarStream io.Reader) (func() error, error) {
 	if !c.batched {
 		c.lock.Lock()
 		defer c.lock.Unlock()
@@ -850,7 +850,7 @@ func (c *Container) CopyFromArchive(ctx context.Context, containerPath string, c
 		}
 	}
 
-	return c.copyFromArchive(ctx, containerPath, chown, tarStream)
+	return c.copyFromArchive(ctx, containerPath, chown, rename, tarStream)
 }
 
 // CopyToArchive copies the contents from the specified path *inside* the

libpod/container_copy_linux.go

@@ -23,7 +23,7 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-func (c *Container) copyFromArchive(ctx context.Context, path string, chown bool, reader io.Reader) (func() error, error) {
+func (c *Container) copyFromArchive(ctx context.Context, path string, chown bool, rename map[string]string, reader io.Reader) (func() error, error) {
 	var (
 		mountPoint   string
 		resolvedRoot string
@@ -89,6 +89,7 @@ func (c *Container) copyFromArchive(ctx context.Context, path string, chown bool
 			GIDMap:     c.config.IDMappings.GIDMap,
 			ChownDirs:  idPair,
 			ChownFiles: idPair,
+			Rename:     rename,
 		}
 
 		return c.joinMountAndExec(ctx,

pkg/api/handlers/compat/containers_archive.go

@@ -1,6 +1,7 @@
 package compat
 
 import (
+	"encoding/json"
 	"fmt"
 	"net/http"
 	"os"
@@ -93,8 +94,9 @@ func handleHeadAndGet(w http.ResponseWriter, r *http.Request, decoder *schema.De
 
 func handlePut(w http.ResponseWriter, r *http.Request, decoder *schema.Decoder, runtime *libpod.Runtime) {
 	query := struct {
-		Path  string `schema:"path"`
-		Chown bool   `schema:"copyUIDGID"`
+		Path   string `schema:"path"`
+		Chown  bool   `schema:"copyUIDGID"`
+		Rename string `schema:"rename"`
 		// TODO handle params below
 		NoOverwriteDirNonDir bool `schema:"noOverwriteDirNonDir"`
 	}{
@@ -107,10 +109,19 @@ func handlePut(w http.ResponseWriter, r *http.Request, decoder *schema.Decoder,
 		return
 	}
 
+	var rename map[string]string
+	if query.Rename != "" {
+		if err := json.Unmarshal([]byte(query.Rename), &rename); err != nil {
+			utils.Error(w, "Bad Request.", http.StatusBadRequest, errors.Wrap(err, "couldn't decode the query"))
+			return
+		}
+	}
+
 	containerName := utils.GetName(r)
 	containerEngine := abi.ContainerEngine{Libpod: runtime}
 
-	copyFunc, err := containerEngine.ContainerCopyFromArchive(r.Context(), containerName, query.Path, r.Body, entities.CopyOptions{Chown: query.Chown})
+	copyOptions := entities.CopyOptions{Chown: query.Chown, Rename: rename}
+	copyFunc, err := containerEngine.ContainerCopyFromArchive(r.Context(), containerName, query.Path, r.Body, copyOptions)
 	if errors.Cause(err) == define.ErrNoSuchCtr || os.IsNotExist(err) {
 		// 404 is returned for an absent container and path.  The
 		// clients must deal with it accordingly.

pkg/api/server/register_archive.go

@@ -151,6 +151,10 @@ func (s *APIServer) registerArchiveHandlers(r *mux.Router) error {
 	//     type: string
 	//     description: Path to a directory in the container to extract
 	//     required: true
+	//   - in: query
+	//     name: rename
+	//     type: string
+	//     description: JSON encoded map[string]string to translate paths
 	//  responses:
 	//    200:
 	//      description: no error

pkg/bindings/containers/types.go

@@ -263,4 +263,6 @@ type CopyOptions struct {
 	// If used with CopyFromArchive and set to true it will change ownership of files from the source tar archive
 	// to the primary uid/gid of the target container.
 	Chown *bool `schema:"copyUIDGID"`
+	// Map to translate path names.
+	Rename map[string]string
 }

pkg/bindings/containers/types_copy_options.go

@@ -35,3 +35,19 @@ func (o *CopyOptions) GetChown() bool {
 	}
 	return *o.Chown
 }
+
+// WithRename
+func (o *CopyOptions) WithRename(value map[string]string) *CopyOptions {
+	v := value
+	o.Rename = v
+	return o
+}
+
+// GetRename
+func (o *CopyOptions) GetRename() map[string]string {
+	var rename map[string]string
+	if o.Rename == nil {
+		return rename
+	}
+	return o.Rename
+}

pkg/copy/parse.go

@@ -18,18 +18,6 @@ func ParseSourceAndDestination(source, destination string) (string, string, stri
 	sourceContainer, sourcePath := parseUserInput(source)
 	destContainer, destPath := parseUserInput(destination)
 
-	numContainers := 0
-	if len(sourceContainer) > 0 {
-		numContainers++
-	}
-	if len(destContainer) > 0 {
-		numContainers++
-	}
-
-	if numContainers != 1 {
-		return "", "", "", "", errors.Errorf("invalid arguments %q, %q: exactly 1 container expected but %d specified", source, destination, numContainers)
-	}
-
 	if len(sourcePath) == 0 || len(destPath) == 0 {
 		return "", "", "", "", errors.Errorf("invalid arguments %q, %q: you must specify paths", source, destination)
 	}

pkg/domain/entities/containers.go

@@ -165,6 +165,8 @@ type CopyOptions struct {
 	// it will change ownership of files from the source tar archive
 	// to the primary uid/gid of the destination container.
 	Chown bool
+	// Map to translate path names.
+	Rename map[string]string
 }
 
 type CommitReport struct {

pkg/domain/infra/abi/archive.go

@@ -12,7 +12,7 @@ func (ic *ContainerEngine) ContainerCopyFromArchive(ctx context.Context, nameOrI
 	if err != nil {
 		return nil, err
 	}
-	return container.CopyFromArchive(ctx, containerPath, options.Chown, reader)
+	return container.CopyFromArchive(ctx, containerPath, options.Chown, options.Rename, reader)
 }
 
 func (ic *ContainerEngine) ContainerCopyToArchive(ctx context.Context, nameOrID string, containerPath string, writer io.Writer) (entities.ContainerCopyFunc, error) {

pkg/domain/infra/tunnel/containers.go

@@ -853,7 +853,8 @@ func (ic *ContainerEngine) ContainerPort(ctx context.Context, nameOrID string, o
 }
 
 func (ic *ContainerEngine) ContainerCopyFromArchive(ctx context.Context, nameOrID, path string, reader io.Reader, options entities.CopyOptions) (entities.ContainerCopyFunc, error) {
-	return containers.CopyFromArchiveWithOptions(ic.ClientCtx, nameOrID, path, reader, new(containers.CopyOptions).WithChown(options.Chown))
+	copyOptions := new(containers.CopyOptions).WithChown(options.Chown).WithRename(options.Rename)
+	return containers.CopyFromArchiveWithOptions(ic.ClientCtx, nameOrID, path, reader, copyOptions)
 }
 
 func (ic *ContainerEngine) ContainerCopyToArchive(ctx context.Context, nameOrID string, path string, writer io.Writer) (entities.ContainerCopyFunc, error) {