Fix patching from dir with gomod generator

This is just a difference in how the states are stored when there is a
subpath in a directory that is the patch source (as compared to a patch
file).

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

source.go

@@ -527,8 +527,14 @@ func patchSource(worker, sourceState llb.State, sourceToState map[string]llb.Sta
  patchState := sourceToState[p.Source]
  // on each iteration, mount source state to /src to run `patch`, and
  // set the state under /src to be the source state for the next iteration
+
+ subPath := p.Source
+ if p.Path != "" {
+ subPath = p.Path
+ }
+
  sourceState = worker.Run(
- llb.AddMount("/patch", patchState, llb.Readonly, llb.SourcePath(filepath.Join(p.Source, p.Path))),
+ llb.AddMount("/patch", patchState, llb.Readonly, llb.SourcePath(subPath)),
  llb.Dir("src"),
  ShArgs(fmt.Sprintf("patch -p%d < /patch", *p.Strip)),
  WithConstraints(opts...),

test/source_test.go

@@ -260,6 +260,7 @@ index ea874f5..ba38f84 100644
 
  // Note: module here should be moduyle+version because this is checking the go module path on disk
  checkModule := func(ctx context.Context, gwc gwclient.Client, module string, spec *dalec.Spec) {
+ t.Helper()
  res, err := gwc.Solve(ctx, newSolveRequest(withBuildTarget("debug/gomods"), withSpec(ctx, t, spec)))
  if err != nil {
  t.Fatal(err)
@@ -314,24 +315,49 @@ index ea874f5..ba38f84 100644
  })
 
  t.Run("with patch", func(t *testing.T) {
- t.Parallel()
- testEnv.RunTest(baseCtx, t, func(ctx context.Context, gwc gwclient.Client) {
- spec := baseSpec()
+ t.Run("file", func(t *testing.T) {
+ t.Parallel()
+ testEnv.RunTest(baseCtx, t, func(ctx context.Context, gwc gwclient.Client) {
+ spec := baseSpec()
 
- patchName := "patch"
- spec.Sources[patchName] = dalec.Source{
- Inline: &dalec.SourceInline{
- File: &dalec.SourceInlineFile{
- Contents: downgradePatch,
+ patchName := "patch"
+ spec.Sources[patchName] = dalec.Source{
+ Inline: &dalec.SourceInline{
+ File: &dalec.SourceInlineFile{
+ Contents: downgradePatch,
+ },
  },
- },
- }
+ }
 
- spec.Patches = map[string][]dalec.PatchSpec{
- srcName: {{Source: patchName}},
- }
+  spec.Patches = map[string][]dalec.PatchSpec{
+  srcName: {{Source: patchName}},
+  }
 
- checkModule(ctx, gwc, "github.com/cpuguy83/tar2go@v0.3.0", spec)
+ checkModule(ctx, gwc, "github.com/cpuguy83/tar2go@v0.3.0", spec)
+ })
+ })
+ t.Run("dir", func(t *testing.T) {
+ t.Parallel()
+ testEnv.RunTest(baseCtx, t, func(ctx context.Context, gwc gwclient.Client) {
+ spec := baseSpec()
+
+ patchName := "patch"
+ spec.Sources[patchName] = dalec.Source{
+ Inline: &dalec.SourceInline{
+ Dir: &dalec.SourceInlineDir{
+ Files: map[string]*dalec.SourceInlineFile{
+ "patch-file": {Contents: downgradePatch},
+ },
+ },
+ },
+ }
+
+ spec.Patches = map[string][]dalec.PatchSpec{
+ srcName: {{Source: patchName, Path: "patch-file"}},
+ }
+
+ checkModule(ctx, gwc, "github.com/cpuguy83/tar2go@v0.3.0", spec)
+ })
  })
  })
 }