Add g_thread_get_name

This is meant to improve debugging of thread-related problems outside
of GLib. This commit adds an implementation for Posix. The Win32
implementation is a stub.

Test included.

Fixes: #3546

glib/gthread-posix.c

@@ -732,7 +732,8 @@ g_system_thread_new (GThreadFunc proxy,
   base_thread->thread.joinable = TRUE;
   base_thread->thread.func = func;
   base_thread->thread.data = data;
-  base_thread->name = g_strdup (name);
+  if (name)
+    g_strlcpy (base_thread->name, name, sizeof (base_thread->name));
   thread->proxy = proxy;
 
   posix_check_cmd (pthread_attr_init (&attr));
@@ -766,7 +767,6 @@ g_system_thread_new (GThreadFunc proxy,
     {
       g_set_error (error, G_THREAD_ERROR, G_THREAD_ERROR_AGAIN, 
                    "Error creating thread: %s", g_strerror (ret));
-      g_free (thread->thread.name);
       g_slice_free (GThreadPosix, thread);
       return NULL;
     }
@@ -827,6 +827,18 @@ g_system_thread_set_name (const gchar *name)
 #endif
 }
 
+void
+g_system_thread_get_name (char  *buffer,
+                          gsize  length)
+{
+#ifdef HAVE_PTHREAD_GETNAME_NP
+  pthread_getname_np (pthread_self (), buffer, length);
+#else
+  g_assert (length >= 1);
+  buffer[0] = '\0';
+#endif
+}
+
 /* {{{1 GMutex and GCond futex implementation */
 
 #if defined(USE_NATIVE_MUTEX)

glib/gthread-win32.c

@@ -464,7 +464,8 @@ g_system_thread_new (GThreadFunc proxy,
   base_thread->thread.joinable = TRUE;
   base_thread->thread.func = func;
   base_thread->thread.data = data;
-  base_thread->name = g_strdup (name);
+  if (name)
+    g_strlcpy (base_thread->name, name, 16);
 
   thread->handle = (HANDLE) _beginthreadex (NULL, stack_size, g_thread_win32_proxy, thread,
                                             CREATE_SUSPENDED, &ignore);
@@ -649,6 +650,15 @@ g_system_thread_set_name (const gchar *name)
     SetThreadName ((DWORD) -1, name);
 }
 
+void
+g_system_thread_get_name (char  *buffer,
+                          gsize  length)
+{
+  /* FIXME: Not implemented yet */
+  g_assert (length >= 1);
+  buffer[0] = '\0';
+}
+
 /* {{{1 Epilogue */
 
 void

glib/gthread.c

@@ -882,12 +882,10 @@ g_thread_proxy (gpointer data)
   TRACE (GLIB_THREAD_SPAWNED (thread->thread.func, thread->thread.data,
                               thread->name));
 
-  if (thread->name)
-    {
-      g_system_thread_set_name (thread->name);
-      g_free (thread->name);
-      thread->name = NULL;
-    }
+  if (thread->name[0] != '\0')
+    g_system_thread_set_name (thread->name);
+  else
+    g_system_thread_get_name (thread->name, sizeof (thread->name));
 
   thread->retval = thread->thread.func (thread->thread.data);
 
@@ -1106,6 +1104,26 @@ g_thread_self (void)
   return (GThread*) thread;
 }
 
+/**
+ * g_thread_get_name:
+ * @thread: a thread
+ *
+ * Gets the name of the thread.
+ *
+ * This function is intended for debugging purposes.
+ *
+ * Returns: the name of the thread
+ *
+ * Since: 2.84
+ */
+const char *
+g_thread_get_name (GThread *thread)
+{
+  GRealThread *real = (GRealThread*) thread;
+
+  return real->name;
+}
+
 /**
  * g_get_num_processors:
  *

glib/gthread.h

@@ -165,6 +165,8 @@ gpointer        g_thread_join                   (GThread        *thread);
 GLIB_AVAILABLE_IN_ALL
 void            g_thread_yield                  (void);
 
+GLIB_AVAILABLE_IN_2_84
+const char *    g_thread_get_name               (GThread        *thread);
 
 GLIB_AVAILABLE_IN_2_32
 void            g_mutex_init                    (GMutex         *mutex);

glib/gthreadprivate.h

@@ -34,7 +34,7 @@ struct  _GRealThread
 
   gint ref_count;
   gboolean ours;
-  gchar *name;
+  char name[16];
   gpointer retval;
 };
 
@@ -159,6 +159,8 @@ void            g_system_thread_free            (GRealThread  *thread);
 
 G_NORETURN void g_system_thread_exit            (void);
 void            g_system_thread_set_name        (const gchar  *name);
+void            g_system_thread_get_name        (char         *buffer,
+                                                 gsize         length);
 
 /* gthread.c */
 GThread *g_thread_new_internal (const gchar *name,

glib/tests/thread.c

@@ -194,10 +194,15 @@ thread6_func (gpointer data)
 {
 #if defined (HAVE_PTHREAD_SETNAME_NP_WITH_TID) && defined (HAVE_PTHREAD_GETNAME_NP)
   char name[16];
+  const char *name2;
 
   pthread_getname_np (pthread_self(), name, 16);
 
   g_assert_cmpstr (name, ==, data);
+
+  name2 = g_thread_get_name (g_thread_self ());
+
+  g_assert_cmpstr (name2, ==, data);
 #endif
 
   return NULL;