Ensure we use proper path separators

In dockerfile2llb we ensure we use proper path separators before we send
them to LLB.

In LLB we default to linux/amd64 if no constraints are set by the
caller.

Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>

Author: gabriel-samfira

client/llb/fileop.go

@@ -460,7 +460,6 @@ func Copy(input CopyInput, src, dest string, opts ...CopyOption) *FileAction {
 	for _, o := range opts {
 		o.SetCopyOption(&mi)
 	}
-
 	return &FileAction{
 		action: &fileActionCopy{
 			state: state,
@@ -539,10 +538,12 @@ func (a *fileActionCopy) toProtoAction(ctx context.Context, parent string, base
 }
 
 func (a *fileActionCopy) sourcePath(ctx context.Context, platform string) (string, error) {
-	p := filepath.Clean(a.src)
+	// filepath.Clean() also does a filepath.FromSlash(). Explicitly convert back to UNIX path
+	// separators.
+	p := filepath.ToSlash(filepath.Clean(a.src))
+	dir := "/"
+	var err error
 	if !system.IsAbs(p, platform) {
-		var dir string
-		var err error
 		if a.state != nil {
 			dir, err = a.state.GetDir(ctx)
 		} else if a.fas != nil {
@@ -551,10 +552,10 @@ func (a *fileActionCopy) sourcePath(ctx context.Context, platform string) (strin
 		if err != nil {
 			return "", err
 		}
-		p, err = system.NormalizePath(dir, p, platform, false)
-		if err != nil {
-			return "", errors.Wrap(err, "normalizing source path")
-		}
+	}
+	p, err = system.NormalizePath(dir, p, platform, false)
+	if err != nil {
+		return "", errors.Wrap(err, "normalizing source path")
 	}
 	return p, nil
 }

client/llb/state.go

@@ -301,8 +301,10 @@ func (s State) File(a *FileAction, opts ...ConstraintsOpt) State {
 
 	// No platform was set by constraint options. Set the current OS and arch.
 	if c.Platform == nil {
-		platform := platforms.DefaultSpec()
-		c.Platform = &platform
+		c.Platform = &ocispecs.Platform{
+			OS:           "linux",
+			Architecture: "amd64",
+		}
 	}
 	return s.WithOutput(NewFileOp(s, a, c).Output())
 }

frontend/dockerfile/dockerfile2llb/convert.go

@@ -997,8 +997,15 @@ func dispatchWorkdir(d *dispatchState, c *instructions.WorkdirCommand, commit bo
 		return errors.Wrap(err, "normalizing workdir")
 	}
 
-	d.state = d.state.Dir(wd)
+	// NormalizeWorkdir returns paths with platform specific separators. For Windows
+	// this will be of the form: \some\path, which is needed later when we pass it to
+	// HCS.
 	d.image.Config.WorkingDir = wd
+
+	// From this point forward, we can use UNIX style paths.
+	wd = filepath.ToSlash(wd)
+	d.state = d.state.Dir(wd)
+
 	if commit {
 		withLayer := false
 		if wd != "/" {
@@ -1027,11 +1034,10 @@ func dispatchWorkdir(d *dispatchState, c *instructions.WorkdirCommand, commit bo
 }
 
 func dispatchCopy(d *dispatchState, cfg copyConfig) error {
-	pp, err := pathRelativeToWorkingDir(d.state, cfg.params.DestPath, *d.platform)
+	dest, err := pathRelativeToWorkingDir(d.state, cfg.params.DestPath, *d.platform)
 	if err != nil {
 		return err
 	}
-	dest := filepath.Join("/", pp)
 
 	if cfg.params.DestPath == "." || cfg.params.DestPath == "" || cfg.params.DestPath[len(cfg.params.DestPath)-1] == filepath.Separator {
 		dest += string(filepath.Separator)
@@ -1136,7 +1142,7 @@ func dispatchCopy(d *dispatchState, cfg copyConfig) error {
 				a = a.Copy(st, f, dest, opts...)
 			}
 		} else {
-			src, err = system.CheckSystemDriveAndRemoveDriveLetter(src, d.platform.OS)
+			src, err = system.NormalizePath("/", src, d.platform.OS, false)
 			if err != nil {
 				return errors.Wrap(err, "removing drive letter")
 			}
@@ -1152,9 +1158,9 @@ func dispatchCopy(d *dispatchState, cfg copyConfig) error {
 			}}, copyOpt...)
 
 			if a == nil {
-				a = llb.Copy(cfg.source, filepath.Join("/", src), dest, opts...)
+				a = llb.Copy(cfg.source, src, dest, opts...)
 			} else {
-				a = a.Copy(cfg.source, filepath.Join("/", src), dest, opts...)
+				a = a.Copy(cfg.source, src, dest, opts...)
 			}
 		}
 	}
@@ -1178,15 +1184,10 @@ func dispatchCopy(d *dispatchState, cfg copyConfig) error {
 			CreateDestPath: true,
 		}}, copyOpt...)
 
-		dest, err = system.CheckSystemDriveAndRemoveDriveLetter(dest, d.platform.OS)
-		if err != nil {
-			return errors.Wrap(err, "removing drive letter")
-		}
-
 		if a == nil {
-			a = llb.Copy(st, f, dest, opts...)
+			a = llb.Copy(st, filepath.ToSlash(f), dest, opts...)
 		} else {
-			a = a.Copy(st, f, dest, opts...)
+			a = a.Copy(st, filepath.ToSlash(f), dest, opts...)
 		}
 	}