dockerfile: keep mapping on #syntax error

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

frontend/dockerfile/builder/build.go

@@ -317,9 +317,13 @@ func Build(ctx context.Context, c client.Client) (*client.Result, error) {
 	}
 
 	if _, ok := opts["cmdline"]; !ok {
-		ref, cmdline, ok := dockerfile2llb.DetectSyntax(bytes.NewBuffer(dtDockerfile))
+		ref, cmdline, loc, ok := dockerfile2llb.DetectSyntax(bytes.NewBuffer(dtDockerfile))
 		if ok {
-			return forwardGateway(ctx, c, ref, cmdline)
+			res, err := forwardGateway(ctx, c, ref, cmdline)
+			if err != nil && len(errdefs.Sources(err)) == 0 {
+				return nil, wrapSource(err, sourceMap, loc)
+			}
+			return res, err
 		}
 	}
 

frontend/dockerfile/dockerfile2llb/directives.go

@@ -5,34 +5,51 @@ import (
 	"io"
 	"regexp"
 	"strings"
+
+	"github.com/moby/buildkit/frontend/dockerfile/parser"
 )
 
 const keySyntax = "syntax"
 
 var reDirective = regexp.MustCompile(`^#\s*([a-zA-Z][a-zA-Z0-9]*)\s*=\s*(.+?)\s*$`)
 
-func DetectSyntax(r io.Reader) (string, string, bool) {
+type Directive struct {
+	Name     string
+	Value    string
+	Location []parser.Range
+}
+
+func DetectSyntax(r io.Reader) (string, string, []parser.Range, bool) {
 	directives := ParseDirectives(r)
 	if len(directives) == 0 {
-		return "", "", false
+		return "", "", nil, false
 	}
 	v, ok := directives[keySyntax]
 	if !ok {
-		return "", "", false
+		return "", "", nil, false
 	}
-	p := strings.SplitN(v, " ", 2)
-	return p[0], v, true
+	p := strings.SplitN(v.Value, " ", 2)
+	return p[0], v.Value, v.Location, true
 }
 
-func ParseDirectives(r io.Reader) map[string]string {
-	m := map[string]string{}
+func ParseDirectives(r io.Reader) map[string]Directive {
+	m := map[string]Directive{}
 	s := bufio.NewScanner(r)
+	var l int
 	for s.Scan() {
+		l++
 		match := reDirective.FindStringSubmatch(s.Text())
 		if len(match) == 0 {
 			return m
 		}
-		m[strings.ToLower(match[1])] = match[2]
+		m[strings.ToLower(match[1])] = Directive{
+			Name:  match[1],
+			Value: match[2],
+			Location: []parser.Range{{
+				Start: parser.Position{Line: l},
+				End:   parser.Position{Line: l},
+			}},
+		}
 	}
 	return m
 }

frontend/dockerfile/dockerfile2llb/directives_test.go

@@ -22,11 +22,11 @@ func TestDirectives(t *testing.T) {
 
 	v, ok := d["escape"]
 	require.True(t, ok)
-	require.Equal(t, v, "\\")
+	require.Equal(t, v.Value, "\\")
 
 	v, ok = d["key"]
 	require.True(t, ok)
-	require.Equal(t, v, "FOO bar")
+	require.Equal(t, v.Value, "FOO bar")
 
 	// for some reason Moby implementation in case insensitive for escape
 	dt = `# EScape=\
@@ -40,11 +40,11 @@ func TestDirectives(t *testing.T) {
 
 	v, ok = d["escape"]
 	require.True(t, ok)
-	require.Equal(t, v, "\\")
+	require.Equal(t, v.Value, "\\")
 
 	v, ok = d["key"]
 	require.True(t, ok)
-	require.Equal(t, v, "FOO bar")
+	require.Equal(t, v.Value, "FOO bar")
 }
 
 func TestSyntaxDirective(t *testing.T) {
@@ -54,15 +54,17 @@ func TestSyntaxDirective(t *testing.T) {
 FROM busybox
 `
 
-	ref, cmdline, ok := DetectSyntax(bytes.NewBuffer([]byte(dt)))
+	ref, cmdline, loc, ok := DetectSyntax(bytes.NewBuffer([]byte(dt)))
 	require.True(t, ok)
 	require.Equal(t, ref, "dockerfile:experimental")
 	require.Equal(t, cmdline, "dockerfile:experimental // opts")
+	require.Equal(t, 1, loc[0].Start.Line)
+	require.Equal(t, 1, loc[0].End.Line)
 
 	dt = `FROM busybox
 RUN ls
 `
-	ref, cmdline, ok = DetectSyntax(bytes.NewBuffer([]byte(dt)))
+	ref, cmdline, _, ok = DetectSyntax(bytes.NewBuffer([]byte(dt)))
 	require.False(t, ok)
 	require.Equal(t, ref, "")
 	require.Equal(t, cmdline, "")