validate: Fix multi variable in a single structure field

We were keeping using the GMatchInfo even after modifying the string
which is explicitly stated as invalid in the GRegex documentation

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-devtools/-/merge_requests/179>

validate/gst/validate/gst-validate-utils.c

@@ -1028,7 +1028,7 @@ gst_validate_replace_variables_in_string (GstStructure * local_vars,
     const gchar * in_string)
 {
   gint varname_len;
-  GMatchInfo *match_info;
+  GMatchInfo *match_info = NULL;
   const gchar *var_value = NULL;
   gchar *tmpstring, *string = g_strdup (in_string);
 
@@ -1037,51 +1037,54 @@ gst_validate_replace_variables_in_string (GstStructure * local_vars,
 
   gst_validate_set_globals (NULL);
 
-  g_regex_match (_variables_regex, string, 0, &match_info);
-  while (g_match_info_matches (match_info)) {
-    GRegex *replace_regex;
-    gchar *tmp, *varname, *pvarname = g_match_info_fetch (match_info, 0);
+  while (g_regex_match (_variables_regex, string, 0, &match_info)) {
+    if (g_match_info_matches (match_info)) {
+      GRegex *replace_regex;
+      gchar *tmp, *varname, *pvarname = g_match_info_fetch (match_info, 0);
 
-    varname_len = strlen (pvarname);
-    varname = g_malloc (sizeof (gchar) * (varname_len - 2));
-    strncpy (varname, &pvarname[2], varname_len - 3);
-    varname[varname_len - 3] = '\0';
+      varname_len = strlen (pvarname);
+      varname = g_malloc (sizeof (gchar) * (varname_len - 2));
+      strncpy (varname, &pvarname[2], varname_len - 3);
+      varname[varname_len - 3] = '\0';
 
-    if (local_vars && gst_structure_has_field_typed (local_vars, varname,
-            G_TYPE_DOUBLE)) {
-      var_value = varname;
-    } else {
-      if (local_vars)
-        var_value = gst_structure_get_string (local_vars, varname);
+      if (local_vars && gst_structure_has_field_typed (local_vars, varname,
+              G_TYPE_DOUBLE)) {
+        var_value = varname;
+      } else {
+        if (local_vars)
+          var_value = gst_structure_get_string (local_vars, varname);
 
-      if (!var_value)
-        var_value = gst_structure_get_string (global_vars, varname);
+        if (!var_value)
+          var_value = gst_structure_get_string (global_vars, varname);
 
-      if (!var_value) {
-        g_error
-            ("Trying to use undefined variable : %s (\nlocals: %s\nglobals: %s\n)",
-            varname, gst_structure_to_string (local_vars),
-            gst_structure_to_string (global_vars));
+        if (!var_value) {
+          g_error
+              ("Trying to use undefined variable : %s (\nlocals: %s\nglobals: %s\n)",
+              varname, gst_structure_to_string (local_vars),
+              gst_structure_to_string (global_vars));
 
-        return NULL;
+          return NULL;
+        }
       }
+
+      tmp = g_strdup_printf ("\\$\\(%s\\)", varname);
+      replace_regex = g_regex_new (tmp, 0, 0, NULL);
+      g_free (tmp);
+      tmpstring = string;
+      string =
+          g_regex_replace (replace_regex, string, -1, 0, var_value, 0, NULL);
+
+      GST_INFO ("Setting variable %s to %s", varname, var_value);
+      g_free (tmpstring);
+      g_regex_unref (replace_regex);
+      g_free (pvarname);
+      g_free (varname);
     }
-
-    tmp = g_strdup_printf ("\\$\\(%s\\)", varname);
-    replace_regex = g_regex_new (tmp, 0, 0, NULL);
-    g_free (tmp);
-    tmpstring = string;
-    string = g_regex_replace (replace_regex, string, -1, 0, var_value, 0, NULL);
-
-    GST_INFO ("Setting variable %s to %s", varname, var_value);
-    g_free (tmpstring);
-    g_regex_unref (replace_regex);
-    g_free (pvarname);
-    g_free (varname);
-
-    g_match_info_next (match_info, NULL);
+    g_clear_pointer (&match_info, g_match_info_free);
   }
-  g_match_info_free (match_info);
+
+  if (match_info)
+    g_match_info_free (match_info);
 
   return string;
 }

validate/gst/validate/gst-validate-utils.h

@@ -73,6 +73,7 @@ void gst_validate_spin_on_fault_signals (void);
 GST_VALIDATE_API
 gboolean gst_validate_element_matches_target (GstElement * element, GstStructure * s);
 gchar * gst_validate_replace_variables_in_string (GstStructure * local_vars, const gchar * in_string);
+GST_VALIDATE_API
 void gst_validate_structure_resolve_variables (GstStructure *structure, GstStructure *local_variables);
 void gst_validate_set_globals (GstStructure *structure);
 

validate/tests/check/meson.build

@@ -5,6 +5,7 @@ validate_tests = [
   ['validate/reporting'],
   ['validate/overrides'],
   ['validate/scenario'],
+  ['validate/utilities'],
   ['validate/expression_parser'],
 ]
 

validate/tests/check/validate/utilities.c

@@ -0,0 +1,37 @@
+#include <gst/check/gstcheck.h>
+#include <gst/validate/validate.h>
+#include <gst/validate/gst-validate-utils.h>
+
+GST_START_TEST (test_resolve_variables)
+{
+  GstStructure *s1 =
+      gst_structure_from_string ("vars, a=(string)1, b=(string)2", NULL);
+  GstStructure *s2 = gst_structure_from_string ("test, n=\"$(a)/$(b)\"", NULL);
+
+  gst_validate_structure_resolve_variables (s2, s1);
+  fail_unless_equals_string (gst_structure_get_string (s2, "n"), "1/2");
+  gst_structure_free (s1);
+  gst_structure_free (s2);
+}
+
+GST_END_TEST;
+
+static Suite *
+gst_validate_suite (void)
+{
+  Suite *s = suite_create ("utilities");
+  TCase *tc_chain = tcase_create ("utilities");
+  suite_add_tcase (s, tc_chain);
+
+  if (atexit (gst_validate_deinit) != 0) {
+    GST_ERROR ("failed to set gst_validate_deinit as exit function");
+  }
+
+  gst_validate_init ();
+  tcase_add_test (tc_chain, test_resolve_variables);
+  gst_validate_deinit ();
+
+  return s;
+}
+
+GST_CHECK_MAIN (gst_validate);