include/vlc_gcrypt.h

   1 /*****************************************************************************
   2  * vlc_gcrypt.h: VLC thread support for gcrypt
   3  *****************************************************************************
   4  * Copyright (C) 2004-2008 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 /**
  22  * \file
  23  * This file implements gcrypt support functions in vlc
  24  */
  25
  26 #ifdef LIBVLC_USE_PTHREAD
  27 /**
  28  * If possible, use gcrypt-provided thread implementation. This is so that
  29  * other non-VLC components (inside the process) can also use gcrypt safely.
  30  */
  31 GCRY_THREAD_OPTION_PTHREAD_IMPL;
  32 # define gcry_threads_vlc gcry_threads_pthread
  33 #else
  34
  35 /**
  36  * gcrypt thread option VLC implementation
  37  */
  38
  39 static int gcry_vlc_mutex_init( void **p_sys )
  40 {
  41     int i_val;
  42     vlc_mutex_t *p_lock = (vlc_mutex_t *)malloc( sizeof( vlc_mutex_t ) );
  43
  44     if( p_lock == NULL)
  45         return ENOMEM;
  46
  47     i_val = vlc_mutex_init( p_lock );
  48     if( i_val )
  49         free( p_lock );
  50     else
  51         *p_sys = p_lock;
  52     return i_val;
  53 }
  54
  55 static int gcry_vlc_mutex_destroy( void **p_sys )
  56 {
  57     vlc_mutex_t *p_lock = (vlc_mutex_t *)*p_sys;
  58     vlc_mutex_destroy( p_lock );
  59     free( p_lock );
  60     return VLC_SUCCESS;
  61 }
  62
  63 static int gcry_vlc_mutex_lock( void **p_sys )
  64 {
  65     vlc_mutex_lock( (vlc_mutex_t *)*p_sys );
  66     return VLC_SUCCESS;
  67 }
  68
  69 static int gcry_vlc_mutex_unlock( void **lock )
  70 {
  71     vlc_mutex_unlock( (vlc_mutex_t *)*lock );
  72     return VLC_SUCCESS;
  73 }
  74
  75 static const struct gcry_thread_cbs gcry_threads_vlc =
  76 {
  77     GCRY_THREAD_OPTION_USER,
  78     NULL,
  79     gcry_vlc_mutex_init,
  80     gcry_vlc_mutex_destroy,
  81     gcry_vlc_mutex_lock,
  82     gcry_vlc_mutex_unlock
  83 };
  84 #endif
  85
  86 /**
  87  * Initializes gcrypt with proper locking.
  88  */
  89 static inline void vlc_gcrypt_init (void)
  90 {
  91     /* This would need a process-wide static mutex with all libraries linking
  92      * to a given instance of libgcrypt. We cannot do this as we have different
  93      * plugins linking with gcrypt, and some underlying libraries may use it
  94      * behind our back. Only way is to always link gcrypt statically (ouch!) or
  95      * have upstream gcrypt provide one shared object per threading system. */
  96     static vlc_mutex_t lock = VLC_STATIC_MUTEX;
  97     static bool done = false;
  98
  99     vlc_mutex_lock (&lock);
 100     if (!done)
 101     {
 102         gcry_control (GCRYCTL_SET_THREAD_CBS, &gcry_threads_vlc);
 103         done = true;
 104     }
 105     vlc_mutex_unlock (&lock);
 106 }