Merge branch 'zero_terminate_null' into 'main'

garray: Support unallocated zero terminated arrays

See merge request GNOME/glib!4684

glib/garray.c

@@ -198,7 +198,9 @@ g_array_new_take (gpointer  data,
 
 /**
  * g_array_new_take_zero_terminated: (skip)
- * @data: (array zero-terminated=1): an array of elements of @element_size
+ * @data: (array zero-terminated=1) (transfer full) (nullable): an array
+ *     of elements of @element_size, %NULL terminated,
+ *     or %NULL for an empty array
  * @clear: %TRUE if #GArray elements should be automatically cleared
  *     to 0 when they are allocated
  * @element_size: the size of each element in bytes
@@ -271,8 +273,9 @@ g_array_new_take_zero_terminated (gpointer  data,
  * the underlying array is preserved for use elsewhere and returned
  * to the caller.
  *
- * If the array was created with the @zero_terminate property
- * set to %TRUE, the returned data is zero terminated too.
+ * Note that if the array was created with the @zero_terminate
+ * property set to %TRUE, this may still return %NULL if the length
+ * of the array was zero and data was not yet allocated.
  *
  * If array elements contain dynamically-allocated memory,
  * the array elements should also be freed by the caller.
@@ -770,11 +773,12 @@ g_array_set_size (GArray *farray,
     }
   else if (length < array->len)
     g_array_remove_range (farray, length, array->len - length);
-  
+
   array->len = length;
-  
-  g_array_zero_terminate (array);
-  
+
+  if (G_LIKELY (array->data != NULL))
+    g_array_zero_terminate (array);
+
   return farray;
 }
 
@@ -881,6 +885,9 @@ g_array_remove_range (GArray *farray,
   g_return_val_if_fail (index_ <= G_MAXUINT - length, NULL);
   g_return_val_if_fail (index_ + length <= array->len, NULL);
 
+  if (length == 0)
+    return farray;
+
   if (array->clear_func != NULL)
     {
       guint i;

glib/tests/array-test.c

@@ -100,6 +100,20 @@ array_set_size (gconstpointer test_data)
   g_array_unref (garray);
 }
 
+/* Check that unallocated zero terminated arrays can be set to size 0. */
+static void
+array_set_size_zero_terminated_null (void)
+{
+  GArray *garray;
+
+  garray = g_array_new_take_zero_terminated(NULL, FALSE, sizeof (gchar));
+
+  g_array_set_size (garray, 0);
+  g_assert_cmpuint (garray->len, ==, 0);
+
+  g_array_free (garray, TRUE);
+}
+
 /* As with array_set_size(), but with a sized array. */
 static void
 array_set_size_sized (gconstpointer test_data)
@@ -307,6 +321,24 @@ array_new_take_zero_terminated (void)
   g_clear_pointer (&old_data_copy, g_free);
 }
 
+/* Check that a non-existing array becomes a zero-terminated one when requested. */
+static void
+array_new_take_zero_terminated_null (void)
+{
+  GArray *garray;
+  gchar *out_str = NULL;
+  gsize len;
+
+  garray = g_array_new_take_zero_terminated (NULL, FALSE, sizeof (gchar));
+  g_assert_cmpuint (garray->len, ==, 0);
+
+  out_str = g_array_steal (garray, &len);
+  g_assert_cmpstr (out_str, ==, NULL);
+  g_assert_cmpuint (len, ==, 0);
+
+  g_free (out_str);
+}
+
 static void
 array_new_take_overflow (void)
 {
@@ -673,6 +705,21 @@ array_remove_range (gconstpointer test_data)
   g_array_free (garray, TRUE);
 }
 
+/* Check that g_array_remove_range() works with a zero terminated array
+ * without any data. */
+static void
+array_remove_range_zero_terminated_null (void)
+{
+  GArray *garray;
+
+  garray = g_array_new_take_zero_terminated(NULL, FALSE, sizeof (gchar));
+
+  g_array_remove_range (garray, 0, 0);
+  g_assert_cmpuint (garray->len, ==, 0);
+
+  g_array_free (garray, TRUE);
+}
+
 static void
 array_ref_count (void)
 {
@@ -3194,6 +3241,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/array/new/take/empty", array_new_take_empty);
   g_test_add_func ("/array/new/take/overflow", array_new_take_overflow);
   g_test_add_func ("/array/new/take-zero-terminated", array_new_take_zero_terminated);
+  g_test_add_func ("/array/new/take-zero-terminated/null", array_new_take_zero_terminated_null);
   g_test_add_func ("/array/ref-count", array_ref_count);
   g_test_add_func ("/array/steal", array_steal);
   g_test_add_func ("/array/clear-func", array_clear_func);
@@ -3201,6 +3249,8 @@ main (int argc, char *argv[])
   g_test_add_func ("/array/copy-sized", test_array_copy_sized);
   g_test_add_func ("/array/overflow-append-vals", array_overflow_append_vals);
   g_test_add_func ("/array/overflow-set-size", array_overflow_set_size);
+  g_test_add_func ("/array/remove-range/zero-terminated-null", array_remove_range_zero_terminated_null);
+  g_test_add_func ("/array/set-size/zero-terminated-null", array_set_size_zero_terminated_null);
 
   for (i = 0; i < G_N_ELEMENTS (array_configurations); i++)
     {