Teach toTar to omit extraneous leading directory paths

Imagine a directory structure like so:

  /tmp
  └── reports
      ├── result-1.xml
      └── subdir
          └── result-2.xml

Prior to this change, when toTar was given a path like "/tmp/reports",
the resulting tar would have the following structure:

  /tmp
  └── reports
      ├── result-1.xml
      └── subdir
          └── result-2.xml

With the changes in this commit, the resulting tar has the following
structure:

  .
  ├── result-1.xml
  └── subdir
      └── result-2.xml

In other words, the resulting tar file omits the extraneous /tmp and
/tmp/reports directories.

This also resolves an issue that would lead to invalid tar files when
using certain relative path structures (e.g., "../../reports").

cmd/submit.go

@@ -166,7 +166,7 @@ func toTar(dir string) (dest string, err error) {
 	}
 
 	return tarfile.Name(), filepath.Walk(dir,
-		func(path string, info os.FileInfo, err error) error {
+		func(srcpath string, info os.FileInfo, err error) error {
 			if err != nil {
 				return err
 			}
@@ -175,12 +175,17 @@ func toTar(dir string) (dest string, err error) {
 				return nil
 			}
 
-			header, err := tar.FileInfoHeader(info, path)
+			destpath, err := filepath.Rel(dir, srcpath)
 			if err != nil {
 				return err
 			}
 
-			header.Name = path
+			header, err := tar.FileInfoHeader(info, destpath)
+			if err != nil {
+				return err
+			}
+
+			header.Name = destpath
 			if err := writer.WriteHeader(header); err != nil {
 				return err
 			}
@@ -189,7 +194,7 @@ func toTar(dir string) (dest string, err error) {
 				return nil
 			}
 
-			file, err := os.Open(path)
+			file, err := os.Open(srcpath)
 			if err != nil {
 				return err
 			}

cmd/submit_test.go

@@ -315,25 +315,24 @@ func Test_toTarGz(t *testing.T) {
 	// === Verify original directory content matches resulting directory content
 	assertEqualContent(t,
 		"testdata/example-test-results/buildpulse.yml",
-		filepath.Join(dir, "testdata/example-test-results/buildpulse.yml"),
+		filepath.Join(dir, "buildpulse.yml"),
 	)
 	assertEqualContent(t,
 		"testdata/example-test-results/junit/browserstack/example-1.xml",
-		filepath.Join(dir, "testdata/example-test-results/junit/browserstack/example-1.xml"),
+		filepath.Join(dir, "junit/browserstack/example-1.xml"),
 	)
 	assertEqualContent(t,
 		"testdata/example-test-results/junit/browserstack/example-2.XML",
-		filepath.Join(dir, "testdata/example-test-results/junit/browserstack/example-2.XML"),
+		filepath.Join(dir, "junit/browserstack/example-2.XML"),
 	)
 	assertEqualContent(t,
 		"testdata/example-test-results/junit/browsertest/example-3.xml",
-		filepath.Join(dir, "testdata/example-test-results/junit/browsertest/example-3.xml"),
+		filepath.Join(dir, "junit/browsertest/example-3.xml"),
 	)
 
 	// === Verify tarball excludes files other than buildpulse.yml and XML reports
-	nonXMLPath := "testdata/example-test-results/junit/browsertest/example-3.txt"
-	assert.FileExists(t, nonXMLPath)
-	assert.NoFileExists(t, filepath.Join(dir, nonXMLPath))
+	assert.FileExists(t, "testdata/example-test-results/junit/browsertest/example-3.txt")
+	assert.NoFileExists(t, filepath.Join(dir, "junit/browsertest/example-3.txt"))
 }
 
 func unzip(src io.Reader, dest io.Writer) error {