Merge branch '715-setenv-warnings' into 'master'

genviron: Message if g_setenv()/g_unsetenv() are used after threads spawned

See merge request GNOME/glib!1337

glib/genviron.c

@@ -42,6 +42,7 @@
 #include "gunicode.h"
 #include "gconvert.h"
 #include "gquark.h"
+#include "gthreadprivate.h"
 
 /* Environ array functions {{{1 */
 static gboolean
@@ -299,6 +300,13 @@ g_setenv (const gchar *variable,
   g_return_val_if_fail (strchr (variable, '=') == NULL, FALSE);
   g_return_val_if_fail (value != NULL, FALSE);
 
+#ifndef G_DISABLE_CHECKS
+  /* FIXME: This will be upgraded to a g_warning() in a future release of GLib.
+   * See https://gitlab.gnome.org/GNOME/glib/issues/715 */
+  if (g_thread_n_created () > 0)
+    g_debug ("setenv()/putenv() are not thread-safe and should not be used after threads are created");
+#endif
+
 #ifdef HAVE_SETENV
   result = setenv (variable, value, overwrite);
 #else
@@ -355,6 +363,13 @@ g_unsetenv (const gchar *variable)
   g_return_if_fail (variable != NULL);
   g_return_if_fail (strchr (variable, '=') == NULL);
 
+#ifndef G_DISABLE_CHECKS
+  /* FIXME: This will be upgraded to a g_warning() in a future release of GLib.
+   * See https://gitlab.gnome.org/GNOME/glib/issues/715 */
+  if (g_thread_n_created () > 0)
+    g_debug ("unsetenv() is not thread-safe and should not be used after threads are created");
+#endif
+
 #ifdef HAVE_UNSETENV
   unsetenv (variable);
 #else /* !HAVE_UNSETENV */

glib/gthread.c

@@ -512,6 +512,8 @@ static GMutex    g_once_mutex;
 static GCond     g_once_cond;
 static GSList   *g_once_init_list = NULL;
 
+static volatile guint g_thread_n_created_counter = 0;
+
 static void g_thread_cleanup (gpointer data);
 static GPrivate     g_thread_specific_private = G_PRIVATE_INIT (g_thread_cleanup);
 
@@ -807,6 +809,12 @@ g_thread_proxy (gpointer data)
   return NULL;
 }
 
+guint
+g_thread_n_created (void)
+{
+  return g_atomic_int_get (&g_thread_n_created_counter);
+}
+
 /**
  * g_thread_new:
  * @name: (nullable): an (optional) name for the new thread
@@ -898,6 +906,8 @@ g_thread_new_internal (const gchar *name,
 {
   g_return_val_if_fail (func != NULL, NULL);
 
+  g_atomic_int_inc (&g_thread_n_created_counter);
+
   return (GThread *) g_system_thread_new (proxy, stack_size, scheduler_settings,
                                           name, func, data, error);
 }

glib/gthreadprivate.h

@@ -81,6 +81,8 @@ gboolean g_thread_get_scheduler_settings (GThreadSchedulerSettings *scheduler_se
 
 gpointer        g_thread_proxy                  (gpointer      thread);
 
+guint           g_thread_n_created              (void);
+
 gpointer        g_private_set_alloc0            (GPrivate       *key,
                                                  gsize           size);