Merge pull request #5699 from thaJeztah/27.x_backport_remove_system_i…

…sabs

[27.x backport] cli/command/container: use local copy of pkg/system.IsAbs

cli/command/container/cp.go

@@ -17,7 +17,6 @@ import (
 	"github.com/docker/cli/cli/streams"
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/pkg/archive"
-	"github.com/docker/docker/pkg/system"
 	units "github.com/docker/go-units"
 	"github.com/morikuni/aec"
 	"github.com/pkg/errors"
@@ -235,7 +234,7 @@ func copyFromContainer(ctx context.Context, dockerCli command.Cli, copyConfig cp
 		// 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) {
+			if !isAbs(linkTarget) {
 				// Join with the parent directory.
 				srcParent, _ := archive.SplitPathDirEntry(srcPath)
 				linkTarget = filepath.Join(srcParent, linkTarget)
@@ -319,7 +318,7 @@ func copyToContainer(ctx context.Context, dockerCli command.Cli, copyConfig cpCo
 	// 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) {
+		if !isAbs(linkTarget) {
 			// Join with the parent directory.
 			dstParent, _ := archive.SplitPathDirEntry(dstPath)
 			linkTarget = filepath.Join(dstParent, linkTarget)
@@ -434,7 +433,7 @@ func copyToContainer(ctx context.Context, dockerCli command.Cli, copyConfig cpCo
 // client, a `:` could be part of an absolute Windows path, in which case it
 // is immediately proceeded by a backslash.
 func splitCpArg(arg string) (ctr, path string) {
-	if system.IsAbs(arg) {
+	if isAbs(arg) {
 		// Explicit local absolute path, e.g., `C:\foo` or `/foo`.
 		return "", arg
 	}
@@ -448,3 +447,15 @@ func splitCpArg(arg string) (ctr, path string) {
 
 	return ctr, path
 }
+
+// IsAbs is a platform-agnostic wrapper for filepath.IsAbs.
+//
+// On Windows, golang filepath.IsAbs does not consider a path \windows\system32
+// as absolute as it doesn't start with a drive-letter/colon combination. However,
+// in docker we need to verify things such as WORKDIR /windows/system32 in
+// a Dockerfile (which gets translated to \windows\system32 when being processed
+// by the daemon). This SHOULD be treated as absolute from a docker processing
+// perspective.
+func isAbs(path string) bool {
+	return filepath.IsAbs(path) || strings.HasPrefix(path, string(os.PathSeparator))
+}