fix: clear binaries dir before relink and make sure link paths are th…

…e same (cashapp#393)

These changes fixes two bugs happen when hermit download and relink due
to manifest destination changes for a given package.

1. relink is skipped due to only checking the existance for the link.
   Instead, link destination should also be checked.

2. relink failed due to link exists previously.  => solved by remove the
   link directories prior to creation

state/state.go

@@ -343,6 +343,11 @@ func (s *State) CacheAndDigest(b *ui.Task, p *manifest.Package) (string, error)
 
 func (s *State) linkBinaries(p *manifest.Package) error {
  dir := filepath.Join(s.binaryDir, p.Reference.String())
+ // clean up the binaryDir before
+ if err := os.RemoveAll(dir); err != nil {
+ return errors.WithStack(err)
+ }
+
  if err := os.MkdirAll(dir, 0700); err != nil {
  return errors.WithStack(err)
  }
@@ -424,6 +429,15 @@ func (s *State) areBinariesLinked(p *manifest.Package) bool {
  if _, err := os.Stat(linkPath); err != nil {
  return false
  }
+ // also checks the link destination matches the binary path.
+ ld, err := os.Readlink(linkPath)
+ if err != nil {
+ return false
+ }
+
+ if bin != ld {
+ return false
+ }
  }
  return true
 }

state/state_test.go

@@ -140,3 +140,41 @@ func TestCacheAndUnpackCreatesBinarySymlinks(t *testing.T) {
  _, err = os.Stat(filepath.Join(state.BinaryDir(), pkg.Reference.String(), "linux_exe"))
  assert.NoError(t, err)
 }
+
+func TestUpdateSymlinks(t *testing.T) {
+ fixture := NewStateTestFixture(t).
+ WithHTTPHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+ fr, err := os.Open("../archive/testdata/archive.tar.gz")
+ assert.NoError(t, err)
+ defer fr.Close() // nolint
+ _, err = io.Copy(w, fr)
+ assert.NoError(t, err)
+ }))
+ defer fixture.Clean()
+ state := fixture.State()
+ log, _ := ui.NewForTesting()
+ pkgDir := state.PkgDir()
+ pkg := manifesttest.NewPkgBuilder(pkgDir).
+ WithSource(fixture.Server.URL).
+ WithName("test").
+ Result()
+ assert.NoError(t, state.CacheAndUnpack(log.Task("test"), pkg))
+ newPkg := manifesttest.NewPkgBuilder(pkgDir + "-new").
+ WithSource(fixture.Server.URL).
+ WithName("test").
+ Result()
+
+ // unpack and make new links
+ assert.NoError(t, state.CacheAndUnpack(log.Task("test"), newPkg))
+
+ darwinExec := filepath.Join(state.BinaryDir(), newPkg.Reference.String(), "darwin_exe")
+ linuxExec := filepath.Join(state.BinaryDir(), newPkg.Reference.String(), "linux_exe")
+ darwinLink, err := os.Readlink(darwinExec)
+ assert.NoError(t, err)
+ assert.Equal(t, filepath.Join(newPkg.Dest, "darwin_exe"), darwinLink)
+
+ linuxLink, err := os.Readlink(linuxExec)
+ assert.NoError(t, err)
+ assert.Equal(t, filepath.Join(newPkg.Dest, "linux_exe"), linuxLink)
+
+}