OstreeMutableTree: add _remove method

There is no API method to remove a file or subdirectory from a MutableTree
besides directly manipulating the GHashTable returned by _get_files or
_get_subdirs. This isn't possible from an introspection binding that transforms
the returned GHashTable, and may also leave the tree checksum in an invalid
state. Introduce a new method so that removing files or subdirectories is
safe, and possible from bindings.

Closes: #1724
Approved by: jlebon

apidoc/ostree-sections.txt

@@ -257,6 +257,7 @@ ostree_mutable_tree_get_metadata_checksum
 ostree_mutable_tree_set_contents_checksum
 ostree_mutable_tree_get_contents_checksum
 ostree_mutable_tree_replace_file
+ostree_mutable_tree_remove
 ostree_mutable_tree_ensure_dir
 ostree_mutable_tree_lookup
 ostree_mutable_tree_ensure_parent_dirs

src/libostree/libostree-devel.sym

@@ -19,6 +19,7 @@
 
 /* Add new symbols here.  Release commits should copy this section into -released.sym. */
 LIBOSTREE_2018.9 {
+  ostree_mutable_tree_remove;
   ostree_repo_get_min_free_space_bytes;
 } LIBOSTREE_2018.7;
 

src/libostree/ostree-mutable-tree.c

@@ -332,6 +332,51 @@ ostree_mutable_tree_replace_file (OstreeMutableTree *self,
   return ret;
 }
 
+/**
+ * ostree_mutable_tree_remove:
+ * @self: Tree
+ * @name: Name of file or subdirectory to remove
+ * @allow_noent: If @FALSE, an error will be thrown if @name does not exist in the tree
+ * @error: a #GError
+ *
+ * Remove the file or subdirectory named @name from the mutable tree @self.
+ */
+gboolean
+ostree_mutable_tree_remove (OstreeMutableTree *self,
+                            const char        *name,
+                            gboolean           allow_noent,
+                            GError           **error)
+{
+  gboolean ret = FALSE;
+
+  g_return_val_if_fail (name != NULL, FALSE);
+
+  if (!ot_util_filename_validate (name, error))
+    goto out;
+
+  if (!_ostree_mutable_tree_make_whole (self, NULL, error))
+    goto out;
+
+  if (!g_hash_table_remove (self->files, name) &&
+      !g_hash_table_remove (self->subdirs, name))
+    {
+      if (allow_noent)
+        {
+          ret = TRUE;
+          goto out;
+        }
+
+      set_error_noent (error, name);
+      goto out;
+    }
+
+  invalidate_contents_checksum (self);
+
+  ret = TRUE;
+ out:
+  return ret;
+}
+
 /**
  * ostree_mutable_tree_ensure_dir:
  * @self: Tree

src/libostree/ostree-mutable-tree.h

@@ -77,6 +77,12 @@ gboolean ostree_mutable_tree_replace_file (OstreeMutableTree *self,
                                            const char        *checksum,
                                            GError           **error);
 
+_OSTREE_PUBLIC
+gboolean ostree_mutable_tree_remove (OstreeMutableTree *self,
+                                     const char        *name,
+                                     gboolean           allow_noent,
+                                     GError           **error);
+
 _OSTREE_PUBLIC
 gboolean ostree_mutable_tree_ensure_dir (OstreeMutableTree *self,
                                          const char        *name,