use different file name for attestation files on windows

Signed-off-by: Meredith Lancaster <malancas@github.com>

pkg/cmd/attestation/download/download.go

@@ -47,6 +47,11 @@ func NewDownloadCmd(f *cmdutil.Factory, runF func(*Options) error) *cobra.Comman
 			Any associated bundle(s) will be written to a file in the
 			current directory named after the artifact's digest. For example, if the
 			digest is "sha256:1234", the file will be named "sha256:1234.jsonl".
+
+			Because colons are special characters in Windows and cannot be used in
+			file names, the digest will be formatted with a dash separating the algorithm
+			from the digest. For example, if the digest is "sha256:1234", the file
+			will be named "sha256-1234.jsonl".
 		`, "`"),
 		Example: heredoc.Doc(`
 			# Download attestations for a local artifact linked with an organization

pkg/cmd/attestation/download/metadata.go

@@ -5,6 +5,8 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"runtime"
+	"strings"
 
 	"github.com/cli/cli/v2/pkg/cmd/attestation/api"
 )
@@ -20,6 +22,12 @@ type LiveStore struct {
 }
 
 func (s *LiveStore) createJSONLinesFilePath(artifact string) string {
+	if runtime.GOOS == "windows" {
+		// Colons are special characters in Windows and cannot be used in file names.
+		// Replace them with dashes to avoid issues.
+		artifact = strings.ReplaceAll(artifact, ":", "-")
+	}
+
 	path := fmt.Sprintf("%s.jsonl", artifact)
 	if s.outputPath != "" {
 		return fmt.Sprintf("%s/%s", s.outputPath, path)

pkg/cmd/attestation/download/metadata_test.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path"
+	"runtime"
 	"testing"
 
 	"github.com/cli/cli/v2/pkg/cmd/attestation/api"
@@ -31,7 +32,15 @@ func TestCreateJSONLinesFilePath(t *testing.T) {
 	artifact, err := artifact.NewDigestedArtifact(oci.MockClient{}, "../test/data/sigstore-js-2.1.0.tgz", "sha512")
 	require.NoError(t, err)
 
-	outputFileName := fmt.Sprintf("%s.jsonl", artifact.DigestWithAlg())
+	expectedPosixFileName := fmt.Sprintf("%s.jsonl", artifact.DigestWithAlg())
+	expectedWindowsFileName := fmt.Sprintf("%s-%s.jsonl", artifact.Algorithm(), artifact.Digest())
+
+	var expectedFileName string
+	if runtime.GOOS == "windows" {
+		expectedFileName = expectedWindowsFileName
+	} else {
+		expectedFileName = expectedPosixFileName
+	}
 
 	testCases := []struct {
 		name       string
@@ -41,22 +50,22 @@ func TestCreateJSONLinesFilePath(t *testing.T) {
 		{
 			name:       "with output path",
 			outputPath: tempDir,
-			expected:   path.Join(tempDir, outputFileName),
+			expected:   path.Join(tempDir, expectedFileName),
 		},
 		{
 			name:       "with nested output path",
 			outputPath: path.Join(tempDir, "subdir"),
-			expected:   path.Join(tempDir, "subdir", outputFileName),
+			expected:   path.Join(tempDir, "subdir", expectedFileName),
 		},
 		{
 			name:       "with output path with beginning slash",
 			outputPath: path.Join("/", tempDir, "subdir"),
-			expected:   path.Join("/", tempDir, "subdir", outputFileName),
+			expected:   path.Join("/", tempDir, "subdir", expectedFileName),
 		},
 		{
 			name:       "without output path",
 			outputPath: "",
-			expected:   outputFileName,
+			expected:   expectedFileName,
 		},
 	}