libsecurity_cdsa_utilities/lib/callback.cpp

   1 /*
   2  * Copyright (c) 2000-2001,2003-2004,2006 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24
  25 //
  26 // Encapsulate the callback mechanism of CSSM.
  27 //
  28 #include <security_cdsa_utilities/callback.h>
  29
  30
  31 //
  32 // Invoke a callback
  33 //
  34 void ModuleCallback::operator () (CSSM_MODULE_EVENT event,
  35                                   const Guid &guid, uint32 subId,
  36                                   CSSM_SERVICE_TYPE serviceType) const
  37 {
  38     try
  39     {
  40         if (mCallback)
  41             if (CSSM_RETURN err = mCallback(&guid, mContext, subId, serviceType, event))
  42                 CssmError::throwMe(err);
  43     }
  44     catch (...)
  45     {
  46     }
  47 }
  48
  49
  50 //
  51 // Manage Callback sets.
  52 // THREADS: Caller is ensuring single-thread access on these calls.
  53 //
  54 void ModuleCallbackSet::insert(const ModuleCallback &newCallback)
  55 {
  56     callbacks.insert(CallbackMap::value_type(newCallback, new CountingMutex));
  57 }
  58
  59 void ModuleCallbackSet::erase(const ModuleCallback &oldCallback)
  60 {
  61     CallbackMap::iterator it = callbacks.find(oldCallback);
  62     if (it == callbacks.end())  // not registered; fail
  63         CssmError::throwMe(CSSMERR_CSSM_INVALID_ADDIN_HANDLE);
  64     CountingMutex *counter = it->second;
  65     {
  66         StLock<Mutex> _(*counter);
  67         if (!counter->isIdle()) // callbacks are scheduled against this
  68             CssmError::throwMe(CSSM_ERRCODE_FUNCTION_FAILED);   // @#module is busy
  69     }
  70     // counter is zero (idle), and we hold the entry lock (via our caller)
  71     delete counter;
  72     callbacks.erase(it);
  73 }
  74
  75
  76 //
  77 // Invoke an entire callback set.
  78 // THREADS: Caller is ensuring  single-thread access on these calls.
  79 //
  80 void ModuleCallbackSet::operator () (CSSM_MODULE_EVENT event,
  81                                      const Guid &guid, uint32 subId,
  82                                      CSSM_SERVICE_TYPE serviceType) const
  83 {
  84     if (callbacks.empty())      // nothing to do; quick exit
  85         return;
  86
  87 #if _USE_THREADS == _USE_NO_THREADS || defined(SYNCHRONOUS_CALLBACKS)
  88     // no threading model supported - we HAVE to do this right here
  89     // note that the user better not re-enter CSSM too much,
  90     // or we might deadlock...
  91     for (CallbackMap::const_iterator it = callbacks.begin();
  92          it != callbacks.end(); it++) {
  93         it->first(event, guid, subId, serviceType);
  94     }
  95 #else // real threads available
  96     // lock down all callback elements - still protected by global lock (via caller)
  97     for (CallbackMap::iterator it = callbacks.begin();
  98          it != callbacks.end(); it++)
  99         it->second->enter();
 100
 101     // get out of this thread - now!
 102     (new Runner(callbacks, event, guid, subId, serviceType))->run();
 103 #endif
 104 }
 105
 106 void ModuleCallbackSet::Runner::action()
 107 {
 108     //
 109     // NOTE WELL: Our callbacks map shares (pointed-to) values with the ModuleCallbackSet
 110     // we were created from. Some of these values may be dangling pointers since they have
 111     // been destroyed by other threads, but only *after* we are done with them, since
 112     // we must call exit() on them before they become eligible for destruction.
 113     // In all cases, it is the responsibility of other threads to destroy those mutexi.
 114     //
 115     // @@@ Could also fan out to multiple callback threads in parallel.
 116     for (CallbackMap::iterator it = callbacks.begin();
 117          it != callbacks.end(); it++) {
 118         //@@@ safety vs. convenience - recheck
 119         it->first(event, guid, subserviceId, serviceType);
 120         it->second->exit();
 121     }
 122 }