uninstall: Note pinned runtimes in --unused output

When "flatpak uninstall --unused" is run, we don't remove unused
runtimes that are pinned. List them in the output so the user knows they
are being left installed.

This commit also adds new library API,
flatpak_installation_list_pinned_refs().

app/flatpak-builtins-uninstall.c

@@ -220,14 +220,31 @@ flatpak_builtin_uninstall (int argc, char **argv, GCancellable *cancellable, GEr
           g_autoptr(FlatpakInstallation) installation = NULL;
           UninstallDir *udir;
           g_autoptr(GPtrArray) unused = NULL;
+          g_autoptr(GPtrArray) pinned = NULL;
 
           flatpak_dir_maybe_ensure_repo (dir, NULL, NULL);
           if (flatpak_dir_get_repo (dir) == NULL)
             continue;
 
+          installation = flatpak_installation_new_for_dir (dir, NULL, NULL);
+          pinned = flatpak_installation_list_pinned_refs (installation, opt_arch, cancellable, error);
+          if (pinned == NULL)
+            return FALSE;
+
+          if (pinned->len > 0)
+            {
+              g_print (_("\nThese runtimes in installation '%s' are pinned and won't be removed; see flatpak-pin(1):\n"),
+                       flatpak_dir_get_name_cached (dir));
+              for (i = 0; i < pinned->len; i++)
+                {
+                  FlatpakInstalledRef *rref = g_ptr_array_index (pinned, i);
+                  g_autofree char *ref = flatpak_ref_format_ref (FLATPAK_REF (rref));
+                  g_print ("  %s\n", ref);
+                }
+            }
+
           udir = uninstall_dir_ensure (uninstall_dirs, dir);
 
-          installation = flatpak_installation_new_for_dir (dir, NULL, NULL);
           unused = flatpak_installation_list_unused_refs (installation, opt_arch, cancellable, error);
           if (unused == NULL)
             return FALSE;

common/flatpak-installation.c

@@ -2926,7 +2926,8 @@ find_used_refs (FlatpakDir *dir,
  *
  * A reference is used if it is either an application, or an sdk,
  * or the runtime of a used ref, or an extension of a used ref.
- * Pinned runtimes are also considered used; see flatpak-pin(1).
+ * Pinned runtimes are also considered used; see flatpak-pin(1) and
+ * flatpak_installation_list_pinned_refs().
  *
  * Returns: (transfer container) (element-type FlatpakInstalledRef): a GPtrArray of
  *   #FlatpakInstalledRef instances
@@ -3046,3 +3047,57 @@ flatpak_installation_list_unused_refs (FlatpakInstallation *self,
 
   return g_steal_pointer (&refs);
 }
+
+/**
+ * flatpak_installation_list_pinned_refs:
+ * @self: a #FlatpakInstallation
+ * @arch: (nullable): if non-%NULL, the architecture of refs to collect
+ * @cancellable: (nullable): a #GCancellable
+ * @error: return location for a #GError
+ *
+ * Lists the installed references that are pinned, meaning they will not be
+ * returned by flatpak_installation_list_unused_refs() and won't be removed
+ * unless explicitly specified for removal.
+ *
+ * Refs appear here either because they have been pinned automatically by
+ * Flatpak or because the user pinned them; see flatpak-pin(1).
+ *
+ * Returns: (transfer container) (element-type FlatpakInstalledRef): a GPtrArray of
+ *   #FlatpakInstalledRef instances
+ *
+ * Since: 1.9.0
+ */
+GPtrArray *
+flatpak_installation_list_pinned_refs (FlatpakInstallation *self,
+                                       const char          *arch,
+                                       GCancellable        *cancellable,
+                                       GError             **error)
+{
+  g_autoptr(FlatpakDir) dir = NULL;
+  g_autoptr(GPtrArray) refs =  NULL;
+  g_auto(GStrv) runtime_refs = NULL;
+  int i;
+
+  dir = flatpak_installation_get_dir (self, error);
+  if (dir == NULL)
+    return NULL;
+
+  if (!flatpak_dir_list_refs (dir, "runtime", &runtime_refs, cancellable, error))
+    return NULL;
+
+  refs = g_ptr_array_new_with_free_func (g_object_unref);
+
+  for (i = 0; runtime_refs[i] != NULL; i++)
+    {
+      const char *ref = runtime_refs[i];
+      g_auto(GStrv) parts = g_strsplit (ref, "/", -1);
+
+      if (arch != NULL && strcmp (parts[2], arch) != 0)
+        continue;
+
+      if (flatpak_dir_ref_is_pinned (dir, ref))
+        g_ptr_array_add (refs, get_ref (dir, ref, NULL, NULL));
+    }
+
+  return g_steal_pointer (&refs);
+}

common/flatpak-installation.h

@@ -245,6 +245,10 @@ FLATPAK_EXTERN GPtrArray           *flatpak_installation_list_unused_refs (Flatp
                                                                            const char          *arch,
                                                                            GCancellable        *cancellable,
                                                                            GError             **error);
+FLATPAK_EXTERN GPtrArray           *flatpak_installation_list_pinned_refs (FlatpakInstallation *self,
+                                                                           const char          *arch,
+                                                                           GCancellable        *cancellable,
+                                                                           GError             **error);
 FLATPAK_EXTERN FlatpakInstalledRef * flatpak_installation_get_installed_ref (FlatpakInstallation *self,
                                                                              FlatpakRefKind       kind,
                                                                              const char          *name,