Re: [AD] Fwd: [sam@xxxxxxxxxx: allegro crashes when unloading the svgalib module]

[Peter Wang <tjaden@xxxxxxxxxx>]

On 2003-04-07, Eric <ebotcazou@xxxxxxxxxx> wrote:
> 
> You are the specialist of modules so commit whatever you want on both 
> branches.

The attached patch was applied to both.

-- 
王浩禎

Index: src/linux/svgalib.c
===================================================================
RCS file: /cvsroot/alleg/allegro/src/linux/svgalib.c,v
retrieving revision 1.29.2.3
diff -u -r1.29.2.3 svgalib.c
--- src/linux/svgalib.c	7 Feb 2003 13:35:56 -0000	1.29.2.3
+++ src/linux/svgalib.c	9 Apr 2003 07:07:56 -0000
@@ -92,6 +92,15 @@
 
 
 
+#ifdef ALLEGRO_MODULE
+
+/* If this is non-zero, this module won't be unloaded.  */
+int _module_dont_unload_me_dirty_hack = 0;
+
+#endif
+
+
+
 /* _svgalib_read_line:
  *  Return linear offset for reading line.
  */
@@ -177,6 +186,13 @@
    tcgetattr(__al_linux_console_fd, &termio);
 
    ret = vga_setmode(num);
+
+#ifdef ALLEGRO_MODULE
+   /* A side-effect of vga_setmode() is that it will register an
+    * atexit handler.  See umodules.c for this problem.
+    */
+   _module_dont_unload_me_dirty_hack = 1;
+#endif
 
    tcsetattr(__al_linux_console_fd, TCSANOW, &termio);
    if (tio) 
Index: src/unix/umodules.c
===================================================================
RCS file: /cvsroot/alleg/allegro/src/unix/umodules.c,v
retrieving revision 1.5.2.3
diff -u -r1.5.2.3 umodules.c
--- src/unix/umodules.c	14 Mar 2003 13:56:36 -0000	1.5.2.3
+++ src/unix/umodules.c	9 Apr 2003 07:07:56 -0000
@@ -156,13 +156,26 @@
 {
    MODULE *m, *next;
    void (*shutdown)(void);
+   int *dont_unload;
    
    for (m = module_list; m; m = next) {
       next = m->next;
+
       shutdown = dlsym(m->handle, "_module_shutdown");
       if (shutdown)
          shutdown();
-      dlclose(m->handle);
+
+      /* Dirty hack: If the loaded module registers its own cleanup
+       * function with atexit, we mustn't unload the module, otherwise
+       * the atexit machinery will end up referring to a function that
+       * won't exist by the end of the program.  This problem only
+       * affects SVGAlib currently.
+       */
+      dont_unload = dlsym(m->handle, "_module_dont_unload_me_dirty_hack");
+
+      if ((!dont_unload) || !(*dont_unload))
+	  dlclose(m->handle);
+
       free(m);
    }