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 #include <errno.h>
  27
  28 #ifdef LIBVLC_USE_PTHREAD
  29 /**
  30  * If possible, use gcrypt-provided thread implementation. This is so that
  31  * other non-VLC components (inside the process) can also use gcrypt safely.
  32  */
  33 GCRY_THREAD_OPTION_PTHREAD_IMPL;
  34 # define gcry_threads_vlc gcry_threads_pthread
  35 #else
  36
  37 /**
  38  * gcrypt thread option VLC implementation
  39  */
  40
  41 static int gcry_vlc_mutex_init( void **p_sys )
  42 {
  43     vlc_mutex_t *p_lock = (vlc_mutex_t *)malloc( sizeof( vlc_mutex_t ) );
  44     if( p_lock == NULL)
  45         return ENOMEM;
  46
  47     vlc_mutex_init( p_lock );
  48     *p_sys = p_lock;
  49     return VLC_SUCCESS;
  50 }
  51
  52 static int gcry_vlc_mutex_destroy( void **p_sys )
  53 {
  54     vlc_mutex_t *p_lock = (vlc_mutex_t *)*p_sys;
  55     vlc_mutex_destroy( p_lock );
  56     free( p_lock );
  57     return VLC_SUCCESS;
  58 }
  59
  60 static int gcry_vlc_mutex_lock( void **p_sys )
  61 {
  62     vlc_mutex_lock( (vlc_mutex_t *)*p_sys );
  63     return VLC_SUCCESS;
  64 }
  65
  66 static int gcry_vlc_mutex_unlock( void **lock )
  67 {
  68     vlc_mutex_unlock( (vlc_mutex_t *)*lock );
  69     return VLC_SUCCESS;
  70 }
  71
  72 static const struct gcry_thread_cbs gcry_threads_vlc =
  73 {
  74     GCRY_THREAD_OPTION_USER,
  75     NULL,
  76     gcry_vlc_mutex_init,
  77     gcry_vlc_mutex_destroy,
  78     gcry_vlc_mutex_lock,
  79     gcry_vlc_mutex_unlock
  80 };
  81 #endif
  82
  83 /**
  84  * Initializes gcrypt with proper locking.
  85  */
  86 static inline void vlc_gcrypt_init (void)
  87 {
  88     /* This would need a process-wide static mutex with all libraries linking
  89      * to a given instance of libgcrypt. We cannot do this as we have different
  90      * plugins linking with gcrypt, and some underlying libraries may use it
  91      * behind our back. Only way is to always link gcrypt statically (ouch!) or
  92      * have upstream gcrypt provide one shared object per threading system. */
  93     static vlc_mutex_t lock = VLC_STATIC_MUTEX;
  94     static bool done = false;
  95
  96     vlc_mutex_lock (&lock);
  97     if (!done)
  98     {
  99         gcry_control (GCRYCTL_SET_THREAD_CBS, &gcry_threads_vlc);
 100         done = true;
 101     }
 102     vlc_mutex_unlock (&lock);
 103 }