dockerfile: set error location for ONBUILD errors

Set error location for ONBUILD errors to the command
that pulled in the image with ONBUILD definitions.

Currently location was incorrectly set to the first
line as ONBUILD was parsed as a separate source code.

Location is handled both at parse time (for invalid
ONBUILD definition) and run time (when command set
via ONBUILD errors).

Signed-off-by: Tonis Tiigi <[email protected]>

Author: tonistiigi

frontend/dockerfile/dockerfile2llb/convert.go

@@ -602,7 +602,7 @@ func toDispatchState(ctx context.Context, dt []byte, opt ConvertOpt) (*dispatchS
 
 			if len(d.image.Config.OnBuild) > 0 {
 				if b, err := initOnBuildTriggers(d, d.image.Config.OnBuild, allDispatchStates); err != nil {
-					return nil, err
+					return nil, parser.SetLocation(err, d.stage.Location)
 				} else if b {
 					newDeps = true
 				}
@@ -788,7 +788,7 @@ func toCommand(ic instructions.Command, allDispatchStates *dispatchStates) (comm
 				stn, ok = allDispatchStates.findStateByName(c.From)
 				if !ok {
 					stn = &dispatchState{
-						stage:        instructions.Stage{BaseName: c.From, Location: ic.Location()},
+						stage:        instructions.Stage{BaseName: c.From, Location: c.Location()},
 						deps:         make(map[*dispatchState]instructions.Command),
 						paths:        make(map[string]struct{}),
 						unregistered: true,
@@ -1113,6 +1113,9 @@ func initOnBuildTriggers(d *dispatchState, triggers []string, allDispatchStates
 		if len(ast.AST.Children) != 1 {
 			return false, errors.New("onbuild trigger should be a single expression")
 		}
+		node := ast.AST.Children[0]
+		// reset the location to the onbuild trigger
+		node.StartLine, node.EndLine = rangeStartEnd(d.stage.Location)
 		ic, err := instructions.ParseCommand(ast.AST.Children[0])
 		if err != nil {
 			return false, err
@@ -2517,6 +2520,23 @@ func buildMetaArgs(args *llb.EnvList, shlex *shell.Lex, argCommands []instructio
 	return args, allArgs, nil
 }
 
+func rangeStartEnd(r []parser.Range) (int, int) {
+	if len(r) == 0 {
+		return 0, 0
+	}
+	start := math.MaxInt32
+	end := 0
+	for _, rng := range r {
+		if rng.Start.Line < start {
+			start = rng.Start.Line
+		}
+		if rng.End.Line > end {
+			end = rng.End.Line
+		}
+	}
+	return start, end
+}
+
 type emptyEnvs struct{}
 
 func (emptyEnvs) Get(string) (string, bool) {

frontend/dockerfile/parser/errors.go

@@ -34,12 +34,24 @@ func withLocation(err error, start, end int) error {
 
 // WithLocation extends an error with a source code location
 func WithLocation(err error, location []Range) error {
+	return setLocation(err, location, true)
+}
+
+func SetLocation(err error, location []Range) error {
+	return setLocation(err, location, false)
+}
+
+func setLocation(err error, location []Range, add bool) error {
 	if err == nil {
 		return nil
 	}
 	var el *ErrorLocation
 	if errors.As(err, &el) {
-		el.Locations = append(el.Locations, location)
+		if add {
+			el.Locations = append(el.Locations, location)
+		} else {
+			el.Locations = [][]Range{location}
+		}
 		return err
 	}
 	return stack.Enable(&ErrorLocation{