Add IsHeld method to Holder interface and implement in apt/dnf backends

Co-authored-by: taigrr <8261498+taigrr@users.noreply.github.com>

apt/apt.go

@@ -124,6 +124,11 @@ func (a *Apt) ListHeld(ctx context.Context) ([]snack.Package, error) {
 	return listHeld(ctx)
 }
 
+// IsHeld reports whether a specific package is currently held.
+func (a *Apt) IsHeld(ctx context.Context, pkg string) (bool, error) {
+	return isHeld(ctx, pkg)
+}
+
 // Autoremove removes packages no longer required as dependencies.
 func (a *Apt) Autoremove(ctx context.Context, opts ...snack.Option) error {
 	a.Lock()

apt/apt_integration_test.go

@@ -230,6 +230,16 @@ func TestIntegration_Apt(t *testing.T) {
 			require.NoError(t, err)
 		})
 
+		t.Run("IsHeld", func(t *testing.T) {
+			held, err := h.IsHeld(ctx, "tree")
+			require.NoError(t, err)
+			assert.True(t, held, "tree should be held")
+
+			notHeld, err := h.IsHeld(ctx, "curl")
+			require.NoError(t, err)
+			assert.False(t, notHeld, "curl should not be held")
+		})
+
 		t.Run("ListHeld", func(t *testing.T) {
 			held, err := h.ListHeld(ctx)
 			require.NoError(t, err)

apt/capabilities_linux.go

@@ -159,6 +159,15 @@ func listHeld(ctx context.Context) ([]snack.Package, error) {
 	return pkgs, nil
 }
 
+func isHeld(ctx context.Context, pkg string) (bool, error) {
+	cmd := exec.CommandContext(ctx, "apt-mark", "showhold", pkg)
+	out, err := cmd.Output()
+	if err != nil {
+		return false, fmt.Errorf("apt-mark showhold %s: %w", pkg, err)
+	}
+	return strings.TrimSpace(string(out)) == pkg, nil
+}
+
 // --- Cleaner ---
 
 func autoremove(ctx context.Context, opts ...snack.Option) error {

apt/capabilities_other.go

@@ -36,6 +36,10 @@ func listHeld(_ context.Context) ([]snack.Package, error) {
 	return nil, snack.ErrUnsupportedPlatform
 }
 
+func isHeld(_ context.Context, _ string) (bool, error) {
+	return false, snack.ErrUnsupportedPlatform
+}
+
 func autoremove(_ context.Context, _ ...snack.Option) error {
 	return snack.ErrUnsupportedPlatform
 }

dnf/capabilities.go

@@ -57,6 +57,11 @@ func (d *DNF) ListHeld(ctx context.Context) ([]snack.Package, error) {
 	return listHeld(ctx, d.v5)
 }
 
+// IsHeld reports whether a specific package is currently held.
+func (d *DNF) IsHeld(ctx context.Context, pkg string) (bool, error) {
+	return isHeld(ctx, pkg, d.v5)
+}
+
 // Autoremove removes orphaned packages.
 func (d *DNF) Autoremove(ctx context.Context, opts ...snack.Option) error {
 	d.Lock()

dnf/capabilities_linux.go

@@ -113,6 +113,26 @@ func listHeld(ctx context.Context, v5 bool) ([]snack.Package, error) {
 	return parseVersionLock(out), nil
 }
 
+func isHeld(ctx context.Context, pkg string, v5 bool) (bool, error) {
+	out, err := run(ctx, []string{"versionlock", "list", pkg}, snack.Options{})
+	if err != nil {
+		// versionlock list exits non-zero when no match is found on some versions
+		return false, nil
+	}
+	var pkgs []snack.Package
+	if v5 {
+		pkgs = parseVersionLockDNF5(out)
+	} else {
+		pkgs = parseVersionLock(out)
+	}
+	for _, p := range pkgs {
+		if p.Name == pkg {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
 func autoremove(ctx context.Context, opts ...snack.Option) error {
 	o := snack.ApplyOptions(opts...)
 	_, err := run(ctx, []string{"autoremove", "-y"}, o)

dnf/capabilities_other.go

@@ -36,6 +36,10 @@ func listHeld(_ context.Context, _ bool) ([]snack.Package, error) {
 	return nil, snack.ErrUnsupportedPlatform
 }
 
+func isHeld(_ context.Context, _ string, _ bool) (bool, error) {
+	return false, snack.ErrUnsupportedPlatform
+}
+
 func autoremove(_ context.Context, _ ...snack.Option) error {
 	return snack.ErrUnsupportedPlatform
 }

dnf/dnf_integration_test.go

@@ -225,6 +225,16 @@ func TestIntegration_DNF(t *testing.T) {
 				t.Skipf("versionlock plugin not available: %v", err)
 			}
 
+			t.Run("IsHeld", func(t *testing.T) {
+				held, err := h.IsHeld(ctx, "tree")
+				require.NoError(t, err)
+				assert.True(t, held, "tree should be held")
+
+				notHeld, err := h.IsHeld(ctx, "curl")
+				require.NoError(t, err)
+				assert.False(t, notHeld, "curl should not be held")
+			})
+
 			t.Run("ListHeld", func(t *testing.T) {
 				held, err := h.ListHeld(ctx)
 				require.NoError(t, err)

snack.go

@@ -125,6 +125,9 @@ type Holder interface {
 
 	// ListHeld returns all currently held/pinned packages.
 	ListHeld(ctx context.Context) ([]Package, error)
+
+	// IsHeld reports whether a specific package is currently held/pinned.
+	IsHeld(ctx context.Context, pkg string) (bool, error)
 }
 
 // Cleaner provides orphan/cache cleanup operations.