Merge branch 'vasprintf-leak-fix' into 'main'

gprintf: Fix a memory leak with an invalid format in g_vasprintf()

See merge request GNOME/glib!2547

glib/gprintf.c

@@ -295,7 +295,8 @@ g_vsnprintf (gchar	 *string,
 
 /**
  * g_vasprintf:
- * @string: (not optional) (nullable): the return location for the newly-allocated string.
+ * @string: (not optional) (nullable): the return location for the newly-allocated string,
+ *   which will be %NULL if (and only if) this function fails
  * @format: (not nullable): a standard printf() format string, but notice
  *          [string precision pitfalls][string-precision]
  * @args: the list of arguments to insert in the output.
@@ -312,7 +313,7 @@ g_vsnprintf (gchar	 *string,
  *
  * `glib/gprintf.h` must be explicitly included in order to use this function.
  *
- * Returns: the number of bytes printed.
+ * Returns: the number of bytes printed, or `-1` on failure
  *
  * Since: 2.4
  **/
@@ -356,6 +357,12 @@ g_vasprintf (gchar      **string,
 
     len = _g_vsprintf (*string, format, args2);
     va_end (args2);
+
+    if (len < 0)
+      {
+        g_free (*string);
+        *string = NULL;
+      }
   }
 #endif
 

glib/tests/string.c

@@ -215,6 +215,44 @@ test_string_append (void)
   g_string_free (string, TRUE);
 }
 
+static void string_append_vprintf_va (GString     *string,
+                                      const gchar *format,
+                                      ...) G_GNUC_PRINTF (2, 3);
+
+/* Wrapper around g_string_append_vprintf() which takes varargs */
+static void
+string_append_vprintf_va (GString     *string,
+                          const gchar *format,
+                          ...)
+{
+  va_list args;
+
+  va_start (args, format);
+  g_string_append_vprintf (string, format, args);
+  va_end (args);
+}
+
+static void
+test_string_append_vprintf (void)
+{
+  GString *string;
+
+  /* append */
+  string = g_string_new ("firsthalf");
+
+  string_append_vprintf_va (string, "some %s placeholders", "format");
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat"
+#pragma GCC diagnostic ignored "-Wformat-extra-args"
+  string_append_vprintf_va (string, "%l", "invalid");
+#pragma GCC diagnostic pop
+
+  g_assert_cmpstr (string->str, ==, "firsthalfsome format placeholders");
+
+  g_string_free (string, TRUE);
+}
+
 static void
 test_string_prepend_c (void)
 {
@@ -571,6 +609,7 @@ main (int   argc,
   g_test_add_func ("/string/test-string-assign", test_string_assign);
   g_test_add_func ("/string/test-string-append-c", test_string_append_c);
   g_test_add_func ("/string/test-string-append", test_string_append);
+  g_test_add_func ("/string/test-string-append-vprintf", test_string_append_vprintf);
   g_test_add_func ("/string/test-string-prepend-c", test_string_prepend_c);
   g_test_add_func ("/string/test-string-prepend", test_string_prepend);
   g_test_add_func ("/string/test-string-insert", test_string_insert);

glib/tests/test-printf.c

@@ -895,6 +895,44 @@ test_upper_bound (void)
   g_assert_cmpint (res, ==, 20);
 }
 
+static gint test_vasprintf_va (gchar       **string,
+                               const gchar  *format,
+                               ...) G_GNUC_PRINTF (2, 3);
+
+/* Wrapper around g_vasprintf() which takes varargs */
+static gint
+test_vasprintf_va (gchar       **string,
+                   const gchar  *format,
+                   ...)
+{
+  va_list args;
+  gint len;
+
+  va_start (args, format);
+  len = g_vasprintf (string, format, args);
+  va_end (args);
+
+  return len;
+}
+
+static void
+test_vasprintf_invalid_format_placeholder (void)
+{
+  gint len = 0;
+  gchar *buf = "some non-null string";
+
+  g_test_summary ("Test error handling for invalid format placeholder in g_vasprintf()");
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat"
+#pragma GCC diagnostic ignored "-Wformat-extra-args"
+  len = test_vasprintf_va (&buf, "%l", "nope");
+#pragma GCC diagnostic pop
+
+  g_assert_cmpint (len, ==, -1);
+  g_assert_null (buf);
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -935,5 +973,7 @@ main (int   argc,
   g_test_add_func ("/sprintf/test-positional-params", test_positional_params3);
   g_test_add_func ("/sprintf/upper-bound", test_upper_bound);
 
+  g_test_add_func ("/vasprintf/invalid-format-placeholder", test_vasprintf_invalid_format_placeholder);
+
   return g_test_run();
 }