Add symlink info to file metadata (#153)

* Add symlink info to file metadata

* use pointer type

* simplify

* remove print

* IsDangling

* fix tests

* fmt

* rm unused

* fix msg

* set target even if dangling

* apply fix

* func name

* rm testFileParams

go.sum

@@ -32,6 +32,7 @@ github.com/bazelbuild/remote-apis v0.0.0-20190507145712-5556e9c6153f h1:KLZodm2m
 github.com/bazelbuild/remote-apis v0.0.0-20190507145712-5556e9c6153f/go.mod h1:9Y+1FnaNUGVV6wKE0Jdh+mguqDUsyd9uUqokalrC7DQ=
 github.com/bazelbuild/remote-apis v0.0.0-20191104140458-e77c4eb2ca48 h1:bgj+Oufa8F4rCHe/8omhml7cBlg3VmNhF66ed1vT2Bw=
 github.com/bazelbuild/remote-apis v0.0.0-20191104140458-e77c4eb2ca48/go.mod h1:9Y+1FnaNUGVV6wKE0Jdh+mguqDUsyd9uUqokalrC7DQ=
+github.com/bazelbuild/remote-apis v0.0.0-20200624085034-0afc3700d177 h1:JeDdP1ZsFOMctOzhcwYfLkGaLT8Nzxc1AXkXKUrWbAw=
 github.com/boombuler/barcode v1.0.0 h1:s1TvRnXwL2xJRaccrdcBQMZxq6X7DvsMogtmJeHDdrc=
 github.com/boombuler/barcode v1.0.0/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
 github.com/bradfitz/go-smtpd v0.0.0-20170404230938-deb6d6237625 h1:ckJgFhFWywOx+YLEMIJsTb+NV6NexWICk5+AMSuz3ss=
@@ -111,6 +112,7 @@ github.com/golang/protobuf v1.3.2 h1:6nsPYzhq5kReh6QImI3k5qWzO4PEbvbIW2cwSfR/6xs
 github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.3.3 h1:gyjaxf+svBWX08ZjK86iN9geUJF0H6gp2IRKX6Nf6/I=
 github.com/golang/protobuf v1.3.3/go.mod h1:vzj43D7+SQXF/4pzW/hwtAqwc6iTitCiVSaWz5lYuqw=
+github.com/golang/protobuf v1.4.2 h1:+Z5KGCizgyZCbGh1KZqA0fcLLkwbsjIzS4aV2v7wJX0=
 github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db h1:woRePGFeVFfLKN/pOkfl+p/TAqKOfFu+7KPlMVpok/w=
 github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/gonum/blas v0.0.0-20181208220705-f22b278b28ac h1:Q0Jsdxl5jbxouNs1TQYt0gxesYMU4VXRbsTlgDloZ50=

go/pkg/filemetadata/filemetadata.go

@@ -8,19 +8,25 @@ import (
 	"github.com/bazelbuild/remote-apis-sdks/go/pkg/digest"
 )
 
+// SymlinkMetadata contains details if the given path is a symlink.
+type SymlinkMetadata struct {
+	Target     string
+	IsDangling bool
+}
+
 // Metadata contains details for a particular file.
 type Metadata struct {
 	Digest       digest.Digest
 	IsExecutable bool
 	Err          error
+	Symlink      *SymlinkMetadata
 }
 
 // FileError is the error returned by the Compute function.
 type FileError struct {
-	IsDirectory      bool
-	IsNotFound       bool
-	IsInvalidSymlink bool
-	Err              error
+	IsDirectory bool
+	IsNotFound  bool
+	Err         error
 }
 
 // Error returns the error message.
@@ -41,11 +47,25 @@ func isSymlink(filename string) (bool, error) {
 func Compute(filename string) *Metadata {
 	md := &Metadata{Digest: digest.Empty}
 	file, err := os.Stat(filename)
+	if isSym, _ := isSymlink(filename); isSym {
+		md.Symlink = &SymlinkMetadata{}
+		if dest, rlErr := os.Readlink(filename); rlErr != nil {
+			md.Err = &FileError{Err: rlErr}
+			return md
+		} else {
+			// If Readlink was OK, we set Target, even if this could be a dangling symlink.
+			md.Symlink.Target = dest
+		}
+
+		if err != nil {
+			md.Err = &FileError{Err: err}
+			md.Symlink.IsDangling = true
+			return md
+		}
+	}
+
 	if err != nil {
 		fe := &FileError{Err: err}
-		if s, err := isSymlink(filename); err == nil && s {
-			fe.IsInvalidSymlink = true
-		}
 		if os.IsNotExist(err) {
 			fe.IsNotFound = true
 		}

go/pkg/filemetadata/filemetadata_test.go

@@ -3,13 +3,14 @@ package filemetadata
 import (
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/bazelbuild/remote-apis-sdks/go/pkg/digest"
 	"github.com/google/go-cmp/cmp"
 )
 
-func TestCompute(t *testing.T) {
+func TestComputeFiles(t *testing.T) {
 	tests := []struct {
 		name       string
 		contents   string
@@ -66,6 +67,90 @@ func TestComputeDirectory(t *testing.T) {
 	}
 }
 
+func TestComputeSymlinksToFile(t *testing.T) {
+	tests := []struct {
+		name       string
+		contents   string
+		executable bool
+	}{
+		{
+			name:     "valid",
+			contents: "bla",
+		},
+		{
+			name:       "valid-executable",
+			contents:   "executable",
+			executable: true,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			symlinkPath := filepath.Join(os.TempDir(), tc.name)
+			defer os.RemoveAll(symlinkPath)
+			targetPath, err := createSymlinkToFile(t, symlinkPath, tc.executable, tc.contents)
+			if err != nil {
+				t.Fatalf("Failed to create tmp symlink for testing digests: %v", err)
+			}
+			got := Compute(symlinkPath)
+
+			if got.Err != nil {
+				t.Errorf("Compute(%v) failed. Got error: %v", symlinkPath, got.Err)
+			}
+			want := &Metadata{
+				Symlink: &SymlinkMetadata{
+					Target:     targetPath,
+					IsDangling: false,
+				},
+				Digest:       digest.NewFromBlob([]byte(tc.contents)),
+				IsExecutable: tc.executable,
+			}
+
+			if diff := cmp.Diff(want, got); diff != "" {
+				t.Errorf("Compute(%v) returned diff. (-want +got)\n%s", symlinkPath, diff)
+			}
+		})
+	}
+}
+
+func TestComputeDanglingSymlinks(t *testing.T) {
+	// Create a temporary fake target so that os.Symlink() can work.
+	symlinkPath := filepath.Join(os.TempDir(), "dangling")
+	defer os.RemoveAll(symlinkPath)
+	targetPath, err := createSymlinkToFile(t, symlinkPath, false, "transient")
+	if err != nil {
+		t.Fatalf("Failed to create tmp symlink for testing digests: %v", err)
+	}
+	// Make the symlink dangling
+	os.RemoveAll(targetPath)
+
+	got := Compute(symlinkPath)
+	if got.Err == nil || !got.Symlink.IsDangling {
+		t.Errorf("Compute(%v) should fail because the symlink is dangling", symlinkPath)
+	}
+	if got.Symlink.Target != targetPath {
+		t.Errorf("Compute(%v) should still set Target for the dangling symlink, want=%v got=%v", symlinkPath, targetPath, got.Symlink.Target)
+	}
+}
+
+func TestComputeSymlinksToDirectory(t *testing.T) {
+	symlinkPath := filepath.Join(os.TempDir(), "dir-symlink")
+	defer os.RemoveAll(symlinkPath)
+	targetPath, err := ioutil.TempDir(os.TempDir(), "")
+	if err != nil {
+		t.Fatalf("Failed to create tmp directory: %v", err)
+	}
+	err = createSymlinkToTarget(t, symlinkPath, targetPath)
+
+	if err != nil {
+		t.Fatalf("Failed to create tmp symlink for testing digests: %v", err)
+	}
+
+	got := Compute(symlinkPath)
+	if fe, ok := got.Err.(*FileError); !ok || !fe.IsDirectory {
+		t.Errorf("Compute(%v).Err = %v, want FileError{IsDirectory:true}", symlinkPath, got.Err)
+	}
+}
+
 func createFile(t *testing.T, executable bool, contents string) (string, error) {
 	t.Helper()
 	perm := os.FileMode(0666)
@@ -88,3 +173,20 @@ func createFile(t *testing.T, executable bool, contents string) (string, error)
 	}
 	return filename, nil
 }
+
+func createSymlinkToFile(t *testing.T, symlinkPath string, executable bool, contents string) (string, error) {
+	t.Helper()
+	targetPath, err := createFile(t, executable, contents)
+	if err != nil {
+		return "", err
+	}
+	if err := createSymlinkToTarget(t, symlinkPath, targetPath); err != nil {
+		return "", err
+	}
+	return targetPath, nil
+}
+
+func createSymlinkToTarget(t *testing.T, symlinkPath string, targetPath string) error {
+	t.Helper()
+	return os.Symlink(targetPath, symlinkPath)
+}

go/pkg/tree/tree.go

@@ -65,14 +65,14 @@ func loadFiles(execRoot string, excl []*command.InputExclusion, path string, fs
 	absPath := filepath.Clean(filepath.Join(execRoot, path))
 	meta := cache.Get(absPath)
 	t := command.FileInputType
+	if smd := meta.Symlink; smd != nil && smd.IsDangling {
+		return nil
+	}
 	if meta.Err != nil {
 		e, ok := meta.Err.(*filemetadata.FileError)
 		if !ok {
 			return meta.Err
 		}
-		if e.IsInvalidSymlink {
-			return nil
-		}
 		if !e.IsDirectory {
 			return meta.Err
 		}