cp: consolidate and simplify

Consolidate and simplify code in `podman cp` a bit.  PR #11049
introduced some code duplicates that were worth tackling.

[NO TESTS NEEDED]

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

cmd/podman/containers/cp.go

@@ -131,43 +131,17 @@ func copyContainerToContainer(sourceContainer string, sourcePath string, destCon
 		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)
+	destContainerBaseName, destContainerInfo, destResolvedToParentDir, err := resolvePathOnDestinationContainer(destContainer, destPath, false)
 	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)
+		return err
 	}
 
 	if sourceContainerInfo.IsDir && !destContainerInfo.IsDir {
 		return errors.New("destination must be a directory when copying a directory")
 	}
 
-	sourceContainerTarget, destContainerTarget := sourceContainerInfo.LinkTarget, destContainerInfo.LinkTarget
+	sourceContainerTarget := sourceContainerInfo.LinkTarget
+	destContainerTarget := destContainerInfo.LinkTarget
 	if !destContainerInfo.IsDir {
 		destContainerTarget = filepath.Dir(destPath)
 	}
@@ -180,7 +154,7 @@ func copyContainerToContainer(sourceContainer string, sourcePath string, destCon
 	// 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, ".") {
+	if destResolvedToParentDir && sourceContainerInfo.IsDir && strings.HasSuffix(sourcePath, ".") {
 		sourceContainerTarget = filepath.Dir(sourceContainerTarget)
 	}
 
@@ -202,7 +176,7 @@ func copyContainerToContainer(sourceContainer string, sourcePath string, destCon
 		defer reader.Close()
 
 		copyOptions := entities.CopyOptions{Chown: chown}
-		if (!sourceContainerInfo.IsDir && !destContainerInfo.IsDir) || destContainerInfoErr != nil {
+		if (!sourceContainerInfo.IsDir && !destContainerInfo.IsDir) || destResolvedToParentDir {
 			// If we're having a file-to-file copy, make sure to
 			// rename accordingly.
 			copyOptions.Rename = map[string]string{filepath.Base(sourceContainerTarget): destContainerBaseName}
@@ -239,6 +213,7 @@ func copyFromContainer(container string, containerPath string, hostPath string)
 	}
 
 	var hostBaseName string
+	var resolvedToHostParentDir bool
 	hostInfo, hostInfoErr := copy.ResolveHostPath(hostPath)
 	if hostInfoErr != nil {
 		if strings.HasSuffix(hostPath, "/") {
@@ -254,6 +229,7 @@ func copyFromContainer(container string, containerPath string, hostPath string)
 		// it'll be created while copying.  Hence, we use it as the
 		// base path.
 		hostBaseName = filepath.Base(hostPath)
+		resolvedToHostParentDir = true
 	} else {
 		// If the specified path exists on the host, we must use its
 		// base path as it may have changed due to symlink evaluations.
@@ -281,7 +257,7 @@ func copyFromContainer(container string, containerPath string, hostPath string)
 	// we copy the source's parent and let the copier package create the
 	// destination via the Rename option.
 	containerTarget := containerInfo.LinkTarget
-	if hostInfoErr != nil && containerInfo.IsDir && strings.HasSuffix(containerTarget, ".") {
+	if resolvedToHostParentDir && containerInfo.IsDir && strings.HasSuffix(containerTarget, ".") {
 		containerTarget = filepath.Dir(containerTarget)
 	}
 
@@ -322,7 +298,7 @@ func copyFromContainer(container string, containerPath string, hostPath string)
 			ChownFiles:    &idPair,
 			IgnoreDevices: true,
 		}
-		if (!containerInfo.IsDir && !hostInfo.IsDir) || hostInfoErr != nil {
+		if (!containerInfo.IsDir && !hostInfo.IsDir) || resolvedToHostParentDir {
 			// If we're having a file-to-file copy, make sure to
 			// rename accordingly.
 			putOptions.Rename = map[string]string{filepath.Base(containerTarget): hostBaseName}
@@ -369,42 +345,9 @@ func copyToContainer(container string, containerPath string, hostPath string) er
 		return errors.Wrapf(err, "%q could not be found on the host", hostPath)
 	}
 
-	// If the path on the container does not exist.  We need to make sure
-	// that it's parent directory exists.  The destination may be created
-	// while copying.
-	var containerBaseName string
-	containerInfo, containerInfoErr := registry.ContainerEngine().ContainerStat(registry.GetContext(), container, containerPath)
-	if containerInfoErr != nil {
-		if strings.HasSuffix(containerPath, "/") {
-			return errors.Wrapf(containerInfoErr, "%q could not be found on container %s", containerPath, container)
-		}
-		if isStdin {
-			return errors.New("destination must be a directory when copying from stdin")
-		}
-		// 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 := containerPath
-		if containerInfo != nil {
-			containerBaseName = filepath.Base(containerInfo.LinkTarget)
-			path = containerInfo.LinkTarget
-		} else {
-			containerBaseName = filepath.Base(containerPath)
-		}
-
-		parentDir, err := containerParentDir(container, path)
+	containerBaseName, containerInfo, containerResolvedToParentDir, err := resolvePathOnDestinationContainer(container, containerPath, isStdin)
 	if err != nil {
-			return errors.Wrapf(err, "could not determine parent dir of %q on container %s", path, container)
-		}
-		containerInfo, err = registry.ContainerEngine().ContainerStat(registry.GetContext(), container, parentDir)
-		if err != nil {
-			return errors.Wrapf(err, "%q could not be found on container %s", containerPath, container)
-		}
-	} else {
-		// If the specified path exists on the container, we must use
-		// its base path as it may have changed due to symlink
-		// evaluations.
-		containerBaseName = filepath.Base(containerInfo.LinkTarget)
+		return err
 	}
 
 	// If we copy a directory via the "." notation and the container path
@@ -416,7 +359,7 @@ func copyToContainer(container string, containerPath string, hostPath string) er
 	// exist, we copy the source's parent and let the copier package create
 	// the destination via the Rename option.
 	hostTarget := hostInfo.LinkTarget
-	if containerInfoErr != nil && hostInfo.IsDir && strings.HasSuffix(hostTarget, ".") {
+	if containerResolvedToParentDir && hostInfo.IsDir && strings.HasSuffix(hostTarget, ".") {
 		hostTarget = filepath.Dir(hostTarget)
 	}
 
@@ -468,7 +411,7 @@ func copyToContainer(container string, containerPath string, hostPath string) er
 			// copy the base directory.
 			KeepDirectoryNames: hostInfo.IsDir && filepath.Base(hostTarget) != ".",
 		}
-		if (!hostInfo.IsDir && !containerInfo.IsDir) || containerInfoErr != nil {
+		if (!hostInfo.IsDir && !containerInfo.IsDir) || containerResolvedToParentDir {
 			// If we're having a file-to-file copy, make sure to
 			// rename accordingly.
 			getOptions.Rename = map[string]string{filepath.Base(hostTarget): containerBaseName}
@@ -499,6 +442,52 @@ func copyToContainer(container string, containerPath string, hostPath string) er
 	return doCopy(hostCopy, containerCopy)
 }
 
+// resolvePathOnDestinationContainer resolves the specified path on the
+// container.  If the path does not exist, it attempts to use the parent
+// directory.
+func resolvePathOnDestinationContainer(container string, containerPath string, isStdin bool) (baseName string, containerInfo *entities.ContainerStatReport, resolvedToParentDir bool, err error) {
+	containerInfo, err = registry.ContainerEngine().ContainerStat(registry.GetContext(), container, containerPath)
+	if err == nil {
+		baseName = filepath.Base(containerInfo.LinkTarget)
+		return
+	}
+
+	if strings.HasSuffix(containerPath, "/") {
+		err = errors.Wrapf(err, "%q could not be found on container %s", containerPath, container)
+		return
+	}
+	if isStdin {
+		err = errors.New("destination must be a directory when copying from stdin")
+		return
+	}
+
+	// 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 := containerPath
+	if containerInfo != nil {
+		baseName = filepath.Base(containerInfo.LinkTarget)
+		path = containerInfo.LinkTarget
+	} else {
+		baseName = filepath.Base(containerPath)
+	}
+
+	parentDir, err := containerParentDir(container, path)
+	if err != nil {
+		err = errors.Wrapf(err, "could not determine parent dir of %q on container %s", path, container)
+		return
+	}
+
+	containerInfo, err = registry.ContainerEngine().ContainerStat(registry.GetContext(), container, parentDir)
+	if err != nil {
+		err = errors.Wrapf(err, "%q could not be found on container %s", containerPath, container)
+		return
+	}
+
+	resolvedToParentDir = true
+	return baseName, containerInfo, resolvedToParentDir, nil
+}
+
 // containerParentDir returns the parent directory of the specified path on the
 // container.  If the path is relative, it will be resolved relative to the
 // container's working directory (or "/" if the work dir isn't set).