lib: config list iterators

Since xapian provides the ability to restrict the iterator to a given
prefix, we expose this ability to the user. Otherwise we mimic the other
iterator interfances in notmuch (e.g. tags.c).

lib/config.cc

@@ -24,6 +24,21 @@
 
 static const std::string CONFIG_PREFIX = "C";
 
+struct _notmuch_config_list {
+    notmuch_database_t *notmuch;
+    Xapian::TermIterator iterator;
+    char *current_key;
+    char *current_val;
+};
+
+static int
+_notmuch_config_list_destroy (notmuch_config_list_t *list)
+{
+    /* invoke destructor w/o deallocating memory */
+    list->iterator.~TermIterator();
+    return 0;
+}
+
 notmuch_status_t
 notmuch_database_set_config (notmuch_database_t *notmuch,
 			     const char *key,
@@ -85,3 +100,94 @@ notmuch_database_get_config (notmuch_database_t *notmuch,
 
     return NOTMUCH_STATUS_SUCCESS;
 }
+
+notmuch_status_t
+notmuch_database_get_config_list (notmuch_database_t *notmuch,
+				  const char *prefix,
+				  notmuch_config_list_t **out)
+{
+    notmuch_config_list_t *list = NULL;
+    notmuch_status_t status = NOTMUCH_STATUS_SUCCESS;
+
+    list = talloc (notmuch, notmuch_config_list_t);
+    if (! list) {
+	status = NOTMUCH_STATUS_OUT_OF_MEMORY;
+	goto DONE;
+    }
+
+    talloc_set_destructor (list, _notmuch_config_list_destroy);
+    list->notmuch = notmuch;
+    list->current_key = NULL;
+    list->current_val = NULL;
+
+    try {
+
+	new(&(list->iterator)) Xapian::TermIterator (notmuch->xapian_db->metadata_keys_begin
+						     (CONFIG_PREFIX + (prefix ? prefix : "")));
+
+    } catch (const Xapian::Error &error) {
+	_notmuch_database_log (notmuch, "A Xapian exception occurred getting metadata iterator: %s.\n",
+			       error.get_msg().c_str());
+	notmuch->exception_reported = TRUE;
+	status = NOTMUCH_STATUS_XAPIAN_EXCEPTION;
+    }
+
+    *out = list;
+
+  DONE:
+    if (status && list)
+	talloc_free (list);
+
+    return status;
+}
+
+notmuch_bool_t
+notmuch_config_list_valid (notmuch_config_list_t *metadata)
+{
+    if (metadata->iterator == metadata->notmuch->xapian_db->metadata_keys_end ())
+	return FALSE;
+
+    return TRUE;
+}
+
+const char *
+notmuch_config_list_key (notmuch_config_list_t *list)
+{
+    if (list->current_key)
+	talloc_free (list->current_key);
+
+    list->current_key = talloc_strdup (list, (*list->iterator).c_str () + CONFIG_PREFIX.length ());
+
+    return list->current_key;
+}
+
+const char *
+notmuch_config_list_value (notmuch_config_list_t *list)
+{
+    std::string strval;
+    notmuch_status_t status;
+    const char *key = notmuch_config_list_key (list);
+
+    /* TODO: better error reporting?? */
+    status = _metadata_value (list->notmuch, key, strval);
+    if (status)
+	return NULL;
+
+    if (list->current_val)
+	talloc_free (list->current_val);
+
+    list->current_val = talloc_strdup (list, strval.c_str ());
+    return list->current_val;
+}
+
+void
+notmuch_config_list_move_to_next (notmuch_config_list_t *list)
+{
+    list->iterator++;
+}
+
+void
+notmuch_config_list_destroy (notmuch_config_list_t *list)
+{
+    talloc_free (list);
+}

lib/notmuch.h

@@ -206,6 +206,7 @@ typedef struct _notmuch_message notmuch_message_t;
 typedef struct _notmuch_tags notmuch_tags_t;
 typedef struct _notmuch_directory notmuch_directory_t;
 typedef struct _notmuch_filenames notmuch_filenames_t;
+typedef struct _notmuch_config_list notmuch_config_list_t;
 #endif /* __DOXYGEN__ */
 
 /**
@@ -1858,6 +1859,49 @@ notmuch_database_set_config (notmuch_database_t *db, const char *key, const char
 notmuch_status_t
 notmuch_database_get_config (notmuch_database_t *db, const char *key, char **value);
 
+/**
+ * Create an iterator for all config items with keys matching a given prefix
+ */
+notmuch_status_t
+notmuch_database_get_config_list (notmuch_database_t *db, const char *prefix, notmuch_config_list_t **out);
+
+/**
+ * Is 'config_list' iterator valid (i.e. _key, _value, _move_to_next can be called).
+ */
+notmuch_bool_t
+notmuch_config_list_valid (notmuch_config_list_t *config_list);
+
+/**
+ * return key for current config pair
+ *
+ * return value is owned by the iterator, and will be destroyed by the
+ * next call to notmuch_config_list_key or notmuch_config_list_destroy.
+ */
+const char *
+notmuch_config_list_key (notmuch_config_list_t *config_list);
+
+/**
+ * return 'value' for current config pair
+ *
+ * return value is owned by the iterator, and will be destroyed by the
+ * next call to notmuch_config_list_value or notmuch config_list_destroy
+ */
+const char *
+notmuch_config_list_value (notmuch_config_list_t *config_list);
+
+
+/**
+ * move 'config_list' iterator to the next pair
+ */
+void
+notmuch_config_list_move_to_next (notmuch_config_list_t *config_list);
+
+/**
+ * free any resources held by 'config_list'
+ */
+void
+notmuch_config_list_destroy (notmuch_config_list_t *config_list);
+
 /**
  * interrogate the library for compile time features
  */

test/T590-libconfig.sh

@@ -55,4 +55,64 @@ testkey2 = testvalue2
 EOF
 test_expect_equal_file EXPECTED OUTPUT
 
+
+test_begin_subtest "notmuch_database_get_config_list: empty list"
+cat c_head - c_tail <<'EOF' | test_C ${MAIL_DIR}
+{
+   notmuch_config_list_t *list;
+   RUN(notmuch_database_get_config_list (db, "nonexistent", &list));
+   printf("valid = %d\n", notmuch_config_list_valid (list));
+   notmuch_config_list_destroy (list);
+}
+EOF
+cat <<'EOF' >EXPECTED
+== stdout ==
+valid = 0
+== stderr ==
+EOF
+test_expect_equal_file EXPECTED OUTPUT
+
+
+test_begin_subtest "notmuch_database_get_config_list: all pairs"
+cat c_head - c_tail <<'EOF' | test_C ${MAIL_DIR}
+{
+   notmuch_config_list_t *list;
+   RUN(notmuch_database_set_config (db, "zzzafter", "afterval"));
+   RUN(notmuch_database_set_config (db, "aaabefore", "beforeval"));
+   RUN(notmuch_database_get_config_list (db, "", &list));
+   for (; notmuch_config_list_valid (list); notmuch_config_list_move_to_next (list)) {
+      printf("%s %s\n", notmuch_config_list_key (list), notmuch_config_list_value(list));
+   }
+   notmuch_config_list_destroy (list);
+}
+EOF
+cat <<'EOF' >EXPECTED
+== stdout ==
+aaabefore beforeval
+testkey1 testvalue1
+testkey2 testvalue2
+zzzafter afterval
+== stderr ==
+EOF
+test_expect_equal_file EXPECTED OUTPUT
+
+test_begin_subtest "notmuch_database_get_config_list: one prefix"
+cat c_head - c_tail <<'EOF' | test_C ${MAIL_DIR}
+{
+   notmuch_config_list_t *list;
+   RUN(notmuch_database_get_config_list (db, "testkey", &list));
+   for (; notmuch_config_list_valid (list); notmuch_config_list_move_to_next (list)) {
+      printf("%s %s\n", notmuch_config_list_key (list), notmuch_config_list_value(list));
+   }
+   notmuch_config_list_destroy (list);
+}
+EOF
+cat <<'EOF' >EXPECTED
+== stdout ==
+testkey1 testvalue1
+testkey2 testvalue2
+== stderr ==
+EOF
+test_expect_equal_file EXPECTED OUTPUT
+
 test_done