db: Refactor internal helpers in preparation for diff API

This will make it easier to query two commits at once.  Note that
`RpmOstreeRefSack` now can hold a reference to a temporary directory.

src/lib/rpmostree-db.c

@@ -36,41 +36,17 @@
  * OSTree repository.
  */
 
-/**
- * rpm_ostree_db_query:
- * @repo: An OSTree repository
- * @ref: A branch name or commit
- * @query: (allow-none): Currently, this must be %NULL
- * @cancellable: Cancellable
- * @error: Error
- *
- * Query the RPM packages present in the @ref branch or commit in
- * @repo. At present, @query must be %NULL; all packages will be
- * returned.  A future enhancement to this API may allow querying a
- * subset of packages.
- *
- * Returns: (transfer container) (element-type RpmOstreePackage): A query result, or %NULL on error
- */
-GPtrArray *
-rpm_ostree_db_query (OstreeRepo                *repo,
-                     const char                *ref,
-                     GVariant                  *query,
-                     GCancellable              *cancellable,
-                     GError                   **error)
+static RpmOstreeRefSack *
+get_refsack_for_commit (OstreeRepo                *repo,
+                        const char                *ref,
+                        GCancellable              *cancellable,
+                        GError                   **error)
 {
-  int rc;
-  OstreeRepoCheckoutOptions checkout_options = { 0, };
   g_autofree char *commit = NULL;
-  g_autoptr(RpmOstreeRefSack) sack = NULL;
-  _cleanup_hyquery_ HyQuery hquery = NULL;
-  _cleanup_hypackagelist_ HyPackageList pkglist = NULL;
   g_autofree char *tempdir = g_strdup ("/tmp/rpmostree-dbquery-XXXXXXXX");
-  g_autofree char *rpmdb_tempdir = NULL;
-  gs_unref_object GFile* commit_rpmdb = NULL;
+  OstreeRepoCheckoutOptions checkout_options = { 0, };
   glnx_fd_close int tempdir_dfd = -1;
 
-  g_return_val_if_fail (query == NULL, FALSE);
-
   if (!ostree_repo_resolve_rev (repo, ref, FALSE, &commit, error))
     goto out;
 
@@ -103,35 +79,64 @@ rpm_ostree_db_query (OstreeRepo                *repo,
                                       &hsack, cancellable, error))
       goto out;
 
-    sack = _rpm_ostree_refsack_new (hsack);
+    return _rpm_ostree_refsack_new (hsack, AT_FDCWD, tempdir);
   }
 
-  rc = hy_sack_load_system_repo (sack->sack, NULL, 0);
-  if (!hif_error_set_from_hawkey (rc, error))
-    {
-      g_prefix_error (error, "Failed to load system repo: ");
-      goto out;
-    }
-  hquery = hy_query_create (sack->sack);
-  hy_query_filter (hquery, HY_PKG_REPONAME, HY_EQ, HY_SYSTEM_REPO_NAME);
-  pkglist = hy_query_run (hquery);
-
-  (void) glnx_shutil_rm_rf_at (AT_FDCWD, tempdir, cancellable, NULL);
-
-  /* Do output creation now, no errors can be thrown */
-  {
-    GPtrArray *result = g_ptr_array_new_with_free_func (g_object_unref);
-    int i, c;
-
-    c = hy_packagelist_count (pkglist);
-    for (i = 0; i < c; i++)
-      {
-        HyPackage pkg = hy_packagelist_get (pkglist, i);
-        g_ptr_array_add (result, _rpm_ostree_package_new (sack, pkg));
-      }
-    
-    return g_steal_pointer (&result);
-  }
  out:
   return NULL;
 }
+
+static GPtrArray *
+query_all_packages_in_sack (RpmOstreeRefSack *rsack)
+{
+  _cleanup_hyquery_ HyQuery hquery = NULL;
+  _cleanup_hypackagelist_ HyPackageList pkglist = NULL;
+  GPtrArray *result;
+  int i, c;
+
+  hquery = hy_query_create (rsack->sack);
+  hy_query_filter (hquery, HY_PKG_REPONAME, HY_EQ, HY_SYSTEM_REPO_NAME);
+  pkglist = hy_query_run (hquery);
+
+  result = g_ptr_array_new_with_free_func (g_object_unref);
+  
+  c = hy_packagelist_count (pkglist);
+  for (i = 0; i < c; i++)
+    {
+      HyPackage pkg = hy_packagelist_get (pkglist, i);
+      g_ptr_array_add (result, _rpm_ostree_package_new (rsack, pkg));
+    }
+  
+  return g_steal_pointer (&result);
+}
+
+/**
+ * rpm_ostree_db_query:
+ * @repo: An OSTree repository
+ * @ref: A branch name or commit
+ * @query: (allow-none): Currently, this must be %NULL
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Query the RPM packages present in the @ref branch or commit in
+ * @repo. At present, @query must be %NULL; all packages will be
+ * returned.  A future enhancement to this API may allow querying a
+ * subset of packages.
+ *
+ * Returns: (transfer container) (element-type RpmOstreePackage): A query result, or %NULL on error
+ */
+GPtrArray *
+rpm_ostree_db_query (OstreeRepo                *repo,
+                     const char                *ref,
+                     GVariant                  *query,
+                     GCancellable              *cancellable,
+                     GError                   **error)
+{
+  g_autoptr(RpmOstreeRefSack) rsack = NULL;
+
+  g_return_val_if_fail (query == NULL, FALSE);
+
+  rsack = get_refsack_for_commit (repo, ref, cancellable, error);
+
+  return query_all_packages_in_sack (rsack);
+}

src/lib/rpmostree-priv.h

@@ -29,13 +29,15 @@
 typedef struct {
   volatile gint refcount;
   HySack sack;
+  int temp_base_dfd;
+  char *temp_path;
 } RpmOstreeRefSack;
 
 RpmOstreePackage *
 _rpm_ostree_package_new (RpmOstreeRefSack *rsack, HyPackage hypkg);
 
 RpmOstreeRefSack *
-_rpm_ostree_refsack_new (HySack sack);
+_rpm_ostree_refsack_new (HySack sack, int temp_base_dfd, const char *temp_path);
 
 RpmOstreeRefSack *
 _rpm_ostree_refsack_ref (RpmOstreeRefSack *rsack);

src/lib/rpmostree-refsack.c

@@ -24,11 +24,13 @@
 #include "rpmostree-priv.h"
 
 RpmOstreeRefSack *
-_rpm_ostree_refsack_new (HySack sack)
+_rpm_ostree_refsack_new (HySack sack, int temp_base_dfd, const char *temp_path)
 {
   RpmOstreeRefSack *rsack = g_new0 (RpmOstreeRefSack, 1);
   rsack->sack = sack;
   rsack->refcount = 1;
+  rsack->temp_base_dfd = temp_base_dfd;
+  rsack->temp_path = g_strdup (temp_path);
   return rsack;
 }
 
@@ -45,5 +47,13 @@ _rpm_ostree_refsack_unref (RpmOstreeRefSack *rsack)
   if (!g_atomic_int_dec_and_test (&rsack->refcount))
     return;
   hy_sack_free (rsack->sack);
+  
+  /* The sack might point to a temporarily allocated rpmdb copy, if so,
+   * prune it now.
+   */
+  if (rsack->temp_path)
+    (void) glnx_shutil_rm_rf_at (rsack->temp_base_dfd, rsack->temp_path, NULL, NULL);
+
+  g_free (rsack->temp_path);
   g_free (rsack);
 }