Line data    Source code

       1             : /*
       2             :  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
       3             :  * Copyright (c) 1997 by Silicon Graphics.  All rights reserved.
       4             :  * Copyright (c) 2000 by Hewlett-Packard Company.  All rights reserved.
       5             :  *
       6             :  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
       7             :  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
       8             :  *
       9             :  * Permission is hereby granted to use or copy this program
      10             :  * for any purpose,  provided the above notices are retained on all copies.
      11             :  * Permission to modify the code and to distribute modified code is granted,
      12             :  * provided the above notices are retained, and a notice that the code was
      13             :  * modified is included with the above copyright notice.
      14             :  *
      15             :  * Original author: Bill Janssen
      16             :  * Heavily modified by Hans Boehm and others
      17             :  */
      18             : 
      19             : #include "private/gc_priv.h"
      20             : 
      21             : /* This used to be in dyn_load.c.  It was extracted into a separate     */
      22             : /* file to avoid having to link against libdl.{a,so} if the client      */
      23             : /* doesn't call dlopen.  Of course this fails if the collector is in    */
      24             : /* a dynamic library. -HB                                               */
      25             : #if defined(GC_PTHREADS) && !defined(GC_NO_DLOPEN)
      26             : 
      27             : #undef GC_MUST_RESTORE_REDEFINED_DLOPEN
      28             : #if defined(dlopen) && !defined(GC_USE_LD_WRAP)
      29             :   /* To support various threads pkgs, gc.h interposes on dlopen by      */
      30             :   /* defining "dlopen" to be "GC_dlopen", which is implemented below.   */
      31             :   /* However, both GC_FirstDLOpenedLinkMap() and GC_dlopen() use the    */
      32             :   /* real system dlopen() in their implementation. We first remove      */
      33             :   /* gc.h's dlopen definition and restore it later, after GC_dlopen().  */
      34             : # undef dlopen
      35             : # define GC_MUST_RESTORE_REDEFINED_DLOPEN
      36             : #endif
      37             : 
      38             : /* Make sure we're not in the middle of a collection, and make sure we  */
      39             : /* don't start any.  This is invoked prior to a dlopen call to avoid    */
      40             : /* synchronization issues.  We can't just acquire the allocation lock,  */
      41             : /* since startup code in dlopen may try to allocate.  This solution     */
      42             : /* risks heap growth (or, even, heap overflow) in the presence of many  */
      43             : /* dlopen calls in either a multi-threaded environment, or if the       */
      44             : /* library initialization code allocates substantial amounts of GC'ed   */
      45             : /* memory.                                                              */
      46             : #ifndef USE_PROC_FOR_LIBRARIES
      47           0 :   static void disable_gc_for_dlopen(void)
      48             :   {
      49             :     DCL_LOCK_STATE;
      50           0 :     LOCK();
      51           0 :     while (GC_incremental && GC_collection_in_progress()) {
      52           0 :       GC_collect_a_little_inner(1000);
      53             :     }
      54           0 :     ++GC_dont_gc;
      55           0 :     UNLOCK();
      56           0 :   }
      57             : #endif
      58             : 
      59             : /* Redefine dlopen to guarantee mutual exclusion with           */
      60             : /* GC_register_dynamic_libraries.  Should probably happen for   */
      61             : /* other operating systems, too.                                */
      62             : 
      63             : /* This is similar to WRAP/REAL_FUNC() in pthread_support.c.    */
      64             : #ifdef GC_USE_LD_WRAP
      65             : # define WRAP_DLFUNC(f) __wrap_##f
      66             : # define REAL_DLFUNC(f) __real_##f
      67             :   void * REAL_DLFUNC(dlopen)(const char *, int);
      68             : #else
      69             : # define WRAP_DLFUNC(f) GC_##f
      70             : # define REAL_DLFUNC(f) f
      71             : #endif
      72             : 
      73           0 : GC_API void * WRAP_DLFUNC(dlopen)(const char *path, int mode)
      74             : {
      75             :   void * result;
      76             : 
      77             : # ifndef USE_PROC_FOR_LIBRARIES
      78             :     /* Disable collections.  This solution risks heap growth (or,       */
      79             :     /* even, heap overflow) but there seems no better solutions.        */
      80           0 :     disable_gc_for_dlopen();
      81             : # endif
      82           0 :   result = REAL_DLFUNC(dlopen)(path, mode);
      83             : # ifndef USE_PROC_FOR_LIBRARIES
      84           0 :     GC_enable(); /* undoes disable_gc_for_dlopen */
      85             : # endif
      86           0 :   return(result);
      87             : }
      88             : 
      89             : #ifdef GC_USE_LD_WRAP
      90             :   /* Define GC_ function as an alias for the plain one, which will be   */
      91             :   /* intercepted.  This allows files which include gc.h, and hence      */
      92             :   /* generate references to the GC_ symbol, to see the right symbol.    */
      93             :   GC_API void *GC_dlopen(const char *path, int mode)
      94             :   {
      95             :     return dlopen(path, mode);
      96             :   }
      97             : #endif /* GC_USE_LD_WRAP */
      98             : 
      99             : #ifdef GC_MUST_RESTORE_REDEFINED_DLOPEN
     100             : # define dlopen GC_dlopen
     101             : #endif
     102             : 
     103             : #endif  /* GC_PTHREADS && !GC_NO_DLOPEN */