dap: properly map source paths to client side paths

dap/adapter.go

@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"io"
 	"path"
-	"path/filepath"
 	"slices"
 	"sync"
 	"sync/atomic"
@@ -598,22 +597,22 @@ func (b *breakpointMap) Set(fname string, sbps []dap.SourceBreakpoint) (breakpoi
 	return breakpoints
 }
 
-func (b *breakpointMap) Intersect(ctx Context, src *pb.Source, ws string) map[digest.Digest]int {
+func (b *breakpointMap) Intersect(ctx Context, src *pb.Source) map[digest.Digest]int {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
 	digests := make(map[digest.Digest]int)
 
 	for dgst, locs := range src.Locations {
-		if id := b.intersect(ctx, src, locs, ws); id > 0 {
+		if id := b.intersect(ctx, src, locs); id > 0 {
 			digests[digest.Digest(dgst)] = id
 		}
 	}
 
 	// Mark unverified breakpoints as failed at this point since we couldn't find an area
 	// in the source where they applied.
 	for _, info := range src.Infos {
-		fname := filepath.Join(ws, info.Filename)
+		fname := info.Filename
 
 		bps := b.byPath[fname]
 		for _, bp := range bps {
@@ -633,7 +632,7 @@ func (b *breakpointMap) Intersect(ctx Context, src *pb.Source, ws string) map[di
 	return digests
 }
 
-func (b *breakpointMap) intersect(ctx Context, src *pb.Source, locs *pb.Locations, ws string) int {
+func (b *breakpointMap) intersect(ctx Context, src *pb.Source, locs *pb.Locations) int {
 	overlaps := func(r *pb.Range, bp *dap.Breakpoint) bool {
 		if bp.Line < int(r.Start.Line) || bp.Line > int(r.End.Line) {
 			return false
@@ -654,7 +653,7 @@ func (b *breakpointMap) intersect(ctx Context, src *pb.Source, locs *pb.Location
 		r := loc.Ranges[0]
 
 		info := src.Infos[loc.SourceIndex]
-		fname := filepath.Join(ws, info.Filename)
+		fname := info.Filename
 
 		bps := b.byPath[fname]
 		if len(bps) == 0 {

dap/adapter_test.go

@@ -187,12 +187,12 @@ func TestBreakpointMapIntersectVerified(t *testing.T) {
 	src := &pb.Source{
 		Locations: srcLocs,
 		Infos: []*pb.SourceInfo{
-			{Filename: filename},
+			{Filename: fpath},
 		},
 	}
 
 	ctx := newBreakpointTestContext(t)
-	digests := bm.Intersect(ctx, src, ws)
+	digests := bm.Intersect(ctx, src)
 	wantMatches := 0
 	for _, bc := range breakpointCases {
 		if bc.expectVerified {

dap/thread.go

@@ -2,9 +2,9 @@ package dap
 
 import (
 	"context"
-	"path"
 	"path/filepath"
 	"slices"
+	"strings"
 	"sync"
 
 	"github.com/docker/buildx/build"
@@ -31,10 +31,10 @@ type thread struct {
 	variables *variableReferences
 
 	// Inputs to the evaluate call.
-	c          gateway.Client
-	ref        gateway.Reference
-	meta       map[string][]byte
-	sourcePath string
+	c             gateway.Client
+	ref           gateway.Reference
+	meta          map[string][]byte
+	sourceInfoMap func(*pb.Source) *pb.Source
 
 	// LLB state for the evaluate call.
 	def    *llb.Definition
@@ -107,14 +107,21 @@ func (t *thread) init(ctx Context, c gateway.Client, ref gateway.Reference, meta
 	t.c = c
 	t.ref = ref
 	t.meta = meta
-
-	// Combine the dockerfile directory with the context path to find the
-	// real base path. The frontend will report the base path as the filename.
-	dir := path.Dir(inputs.DockerfilePath)
-	if !path.IsAbs(dir) {
-		dir = path.Join(inputs.ContextPath, dir)
+	t.sourceInfoMap = func(s *pb.Source) *pb.Source {
+		s = s.CloneVT()
+		for _, sinfo := range s.Infos {
+			// Map the filename from the source info from the frontend location to the
+			// client location.
+			fname := strings.Replace(sinfo.Filename, inputs.DockerfileMappingDst, inputs.DockerfileMappingSrc, 1)
+
+			// Convert to an absolute path.
+			if abspath, err := filepath.Abs(fname); err == nil {
+				fname = abspath
+			}
+			sinfo.Filename = fname
+		}
+		return s
 	}
-	t.sourcePath = dir
 
 	if err := t.getLLBState(ctx); err != nil {
 		return err
@@ -252,7 +259,7 @@ func (t *thread) getStackFrame(dgst digest.Digest, next *step) *frame {
 		f.setNameFromMeta(meta)
 	}
 	if loc, ok := t.def.Source.Locations[string(dgst)]; ok {
-		f.fillLocation(t.def, loc, t.sourcePath, next)
+		f.fillLocation(t.def, loc, next)
 	}
 	t.frames[int32(f.Id)] = f
 	return f
@@ -296,7 +303,6 @@ func (t *thread) reset() {
 	t.c = nil
 	t.ref = nil
 	t.meta = nil
-	t.sourcePath = ""
 	t.ops = nil
 }
 
@@ -462,9 +468,12 @@ func (t *thread) getLLBState(ctx Context) error {
 		return err
 	}
 
+	if t.sourceInfoMap != nil {
+		t.def.Source = t.sourceInfoMap(t.def.Source)
+	}
+
 	for _, src := range t.def.Source.Infos {
-		fname := filepath.Join(t.sourcePath, src.Filename)
-		t.sourceMap.Put(ctx, fname, src.Data)
+		t.sourceMap.Put(ctx, src.Filename, src.Data)
 	}
 
 	t.ops = make(map[digest.Digest]*pb.Op, len(t.def.Def))
@@ -483,7 +492,7 @@ func (t *thread) getLLBState(ctx Context) error {
 }
 
 func (t *thread) setBreakpoints(ctx Context) {
-	t.bps = t.breakpointMap.Intersect(ctx, t.def.Source, t.sourcePath)
+	t.bps = t.breakpointMap.Intersect(ctx, t.def.Source)
 }
 
 func (t *thread) seekNext(ctx Context, from *step, action stepType) (string, *step, map[string]gateway.Reference, error) {

dap/variables.go

@@ -38,7 +38,7 @@ func (f *frame) setNameFromMeta(meta llb.OpMetadata) {
 	// TODO: should we infer the name from somewhere else?
 }
 
-func (f *frame) fillLocation(def *llb.Definition, loc *pb.Locations, ws string, next *step) {
+func (f *frame) fillLocation(def *llb.Definition, loc *pb.Locations, next *step) {
 	for _, l := range loc.Locations {
 		for _, r := range l.Ranges {
 			if next != nil && f.Line != 0 {
@@ -57,7 +57,7 @@ func (f *frame) fillLocation(def *llb.Definition, loc *pb.Locations, ws string,
 			info := def.Source.Infos[l.SourceIndex]
 			f.Source = &dap.Source{
 				Name: path.Base(info.Filename),
-				Path: filepath.Join(ws, info.Filename),
+				Path: info.Filename,
 			}
 
 			// If we do not have a next operation, then we don't have