WIP/HACK: Add lots of filepath.ToFromSlash and system.FixWindowsPath

I have no idea at which layers these things are supposed to be taken
care of, but I am super-suspicious of all the 'filepath.Join("/", path)'
calls.

Signed-off-by: Paul "TBBle" Hampson <Paul.Hampson@Pobox.com>

frontend/dockerfile/instructions/parse.go

@@ -2,6 +2,7 @@ package instructions
 
 import (
 	"fmt"
+	"path/filepath"
 	"regexp"
 	"sort"
 	"strconv"
@@ -12,6 +13,7 @@ import (
 	"github.com/docker/docker/api/types/strslice"
 	"github.com/moby/buildkit/frontend/dockerfile/command"
 	"github.com/moby/buildkit/frontend/dockerfile/parser"
+	"github.com/moby/buildkit/util/system"
 	"github.com/pkg/errors"
 )
 
@@ -243,8 +245,13 @@ func parseAdd(req parseRequest) (*AddCommand, error) {
 	if err := req.flags.Parse(); err != nil {
 		return nil, err
 	}
+	destPath, err := system.CheckSystemDriveAndRemoveDriveLetter(req.args[1])
+	if err != nil {
+		return nil, err
+	}
+	paths := append(req.args[:len(req.args)-1], filepath.ToSlash(destPath))
 	return &AddCommand{
-		SourcesAndDest:  SourcesAndDest(req.args),
+		SourcesAndDest:  paths,
 		withNameAndCode: newWithNameAndCode(req),
 		Chown:           flChown.Value,
 		Chmod:           flChmod.Value,
@@ -341,8 +348,14 @@ func parseWorkdir(req parseRequest) (*WorkdirCommand, error) {
 	if err != nil {
 		return nil, err
 	}
+
+	path, err := system.CheckSystemDriveAndRemoveDriveLetter(req.args[0])
+	if err != nil {
+		return nil, err
+	}
+
 	return &WorkdirCommand{
-		Path:            req.args[0],
+		Path:            filepath.ToSlash(path),
 		withNameAndCode: newWithNameAndCode(req),
 	}, nil
 

solver/llbsolver/file/backend.go

@@ -67,7 +67,7 @@ func mapUserToChowner(user *copy.User, idmap *idtools.IdentityMapping) (copy.Cho
 }
 
 func mkdir(ctx context.Context, d string, action pb.FileActionMkDir, user *copy.User, idmap *idtools.IdentityMapping) error {
-	p, err := fs.RootPath(d, filepath.Join(filepath.Join("/", action.Path)))
+	p, err := fs.RootPath(filepath.ToSlash(d), filepath.ToSlash(filepath.Join(filepath.Join("/", action.Path))))
 	if err != nil {
 		return err
 	}
@@ -96,14 +96,16 @@ func mkdir(ctx context.Context, d string, action pb.FileActionMkDir, user *copy.
 		}
 	}
 
+	log.Printf("--- mkdir okay")
 	return nil
 }
 
 func mkfile(ctx context.Context, d string, action pb.FileActionMkFile, user *copy.User, idmap *idtools.IdentityMapping) error {
-	p, err := fs.RootPath(d, filepath.Join(filepath.Join("/", action.Path)))
+	p, err := fs.RootPath(filepath.ToSlash(d), filepath.ToSlash(filepath.Join(filepath.Join("/", action.Path))))
 	if err != nil {
 		return err
 	}
+	p = filepath.FromSlash(p)
 
 	ch, err := mapUserToChowner(user, idmap)
 	if err != nil {
@@ -146,10 +148,11 @@ func rm(ctx context.Context, d string, action pb.FileActionRm) error {
 }
 
 func rmPath(root, src string, allowNotFound bool) error {
-	p, err := fs.RootPath(root, filepath.Join(filepath.Join("/", src)))
+	p, err := fs.RootPath(filepath.ToSlash(root), filepath.ToSlash(filepath.Join(filepath.Join("/", src))))
 	if err != nil {
 		return err
 	}
+	p = filepath.FromSlash(p)
 
 	if err := os.RemoveAll(p); err != nil {
 		if errors.Is(err, os.ErrNotExist) && allowNotFound {
@@ -166,10 +169,11 @@ func docopy(ctx context.Context, src, dest string, action pb.FileActionCopy, u *
 	destPath := cleanPath(action.Dest)
 
 	if !action.CreateDestPath {
-		p, err := fs.RootPath(dest, filepath.Join(filepath.Join("/", action.Dest)))
+		p, err := fs.RootPath(filepath.ToSlash(dest), filepath.ToSlash(filepath.Join(filepath.Join("/", action.Dest))))
 		if err != nil {
 			return err
 		}
+		p = filepath.FromSlash(p)
 		if _, err := os.Lstat(filepath.Dir(p)); err != nil {
 			return errors.Wrapf(err, "failed to stat %s", action.Dest)
 		}