server: replace blob prefix separator from ':' to '-' (#3146)

This fixes issues with blob file names that contain ':' characters to be rejected by file systems that do not support them.

server/fixblobs_test.go

@@ -0,0 +1,83 @@
+package server
+
+import (
+	"io/fs"
+	"os"
+	"path/filepath"
+	"runtime"
+	"slices"
+	"strings"
+	"testing"
+)
+
+func TestFixBlobs(t *testing.T) {
+	cases := []struct {
+		path []string
+		want []string
+	}{
+		{path: []string{"sha256-1234"}, want: []string{"sha256-1234"}},
+		{path: []string{"sha256:1234"}, want: []string{"sha256-1234"}},
+		{path: []string{"sha259:5678"}, want: []string{"sha259:5678"}},
+		{path: []string{"sha256:abcd"}, want: []string{"sha256-abcd"}},
+		{path: []string{"x/y/sha256:abcd"}, want: []string{"x/y/sha256-abcd"}},
+		{path: []string{"x:y/sha256:abcd"}, want: []string{"x:y/sha256-abcd"}},
+		{path: []string{"x:y/sha256:abcd"}, want: []string{"x:y/sha256-abcd"}},
+		{path: []string{"x:y/sha256:abcd", "sha256:1234"}, want: []string{"x:y/sha256-abcd", "sha256-1234"}},
+		{path: []string{"x:y/sha256:abcd", "sha256-1234"}, want: []string{"x:y/sha256-abcd", "sha256-1234"}},
+	}
+
+	for _, tt := range cases {
+		t.Run(strings.Join(tt.path, "|"), func(t *testing.T) {
+			hasColon := slices.ContainsFunc(tt.path, func(s string) bool { return strings.Contains(s, ":") })
+			if hasColon && runtime.GOOS == "windows" {
+				t.Skip("skipping test on windows")
+			}
+
+			rootDir := t.TempDir()
+			for _, path := range tt.path {
+				fullPath := filepath.Join(rootDir, path)
+				fullDir, _ := filepath.Split(fullPath)
+
+				t.Logf("creating dir %s", fullDir)
+				if err := os.MkdirAll(fullDir, 0o755); err != nil {
+					t.Fatal(err)
+				}
+
+				t.Logf("writing file %s", fullPath)
+				if err := os.WriteFile(fullPath, nil, 0o644); err != nil {
+					t.Fatal(err)
+				}
+			}
+
+			if err := fixBlobs(rootDir); err != nil {
+				t.Fatal(err)
+			}
+
+			got := slurpFiles(os.DirFS(rootDir))
+
+			slices.Sort(tt.want)
+			slices.Sort(got)
+			if !slices.Equal(got, tt.want) {
+				t.Fatalf("got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func slurpFiles(fsys fs.FS) []string {
+	var sfs []string
+	fn := func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+		sfs = append(sfs, path)
+		return nil
+	}
+	if err := fs.WalkDir(fsys, ".", fn); err != nil {
+		panic(err)
+	}
+	return sfs
+}