cdsa/cssm/cssmcontext.h

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 //
  20 // context - manage CSSM (cryptographic) contexts every which way
  21 //
  22 #ifndef _H_CSSMCONTEXT
  23 #define _H_CSSMCONTEXT
  24
  25 #include "cssmint.h"
  26 #include "cspattachment.h"
  27 #include <Security/context.h>
  28
  29 #ifdef _CPP_CSSMCONTEXT
  30 # pragma export on
  31 #endif
  32
  33
  34 //
  35 // A HandleContext adds handle semantics to the Context object.
  36 // Note that not every Context is a HandleContext - the Contexts we hand
  37 // to our API customers for fondling are not. Also note that a HandleContext
  38 // not a PODWrapper.
  39 // HandleContext has an allocation method taking a CssmAllocator. To destroy
  40 // a HandleObject, call HandleObject::destroy(the-context, the-allocator).
  41 // You are responsible for picking the same allocator used on construction.
  42 //
  43 // THREADS: HandleContexts are assumed to have single-thread use. That means that
  44 // operations on HandleContexts are NOT interlocked automatically; two users of
  45 // the same context must do any arbitration themselves. A HandleContext is howerver
  46 // safely interlocked against other objects, in particular its CSPAttachment.
  47 // The upshot is that you're safe using a HandleContext unless someone else is trying
  48 // to use the same context in parallel.
  49 //
  50 class HandleContext : public HandleObject, public Context {
  51 public:
  52     HandleContext(CSPAttachment &attach,
  53                   CSSM_CONTEXT_TYPE type,
  54                   CSSM_ALGORITHMS algorithmId)
  55     : Context(type, algorithmId), attachment(attach), extent(0) { }
  56     virtual ~HandleContext();
  57
  58     CSPAttachment &attachment;
  59
  60         using Context::find;    // guard against HandleObjec::find
  61
  62     void mergeAttributes(const CSSM_CONTEXT_ATTRIBUTE *attributes, uint32 count);
  63     CSSM_RETURN validateChange(CSSM_CONTEXT_EVENT event);
  64
  65     void *operator new (size_t size, CssmAllocator &alloc) throw(std::bad_alloc)
  66     { return alloc.malloc(size); }
  67     void operator delete (void *addr, size_t, CssmAllocator &alloc) throw()
  68     { return alloc.free(addr); }
  69     static void destroy(HandleContext *context, CssmAllocator &alloc) throw()
  70     { context->~HandleContext(); alloc.free(context); }
  71
  72     class Maker;        // deluxe builder
  73
  74 #if __GNUC__ > 2
  75 private:
  76     void operator delete (void *addr) throw() { assert(0); }
  77 #endif
  78
  79 protected:
  80     // Locking protocol, courtesy of HandleObject.
  81     // This locks the underlying attachment.
  82     void lock();
  83     bool tryLock();
  84
  85 private:
  86     void *extent;                       // extra storage extent in use
  87 };
  88
  89 inline HandleContext &enterContext(CSSM_CC_HANDLE h)
  90 {
  91     return findHandleAndLock<HandleContext>(h, CSSM_ERRCODE_INVALID_CONTEXT_HANDLE);
  92 }
  93
  94
  95 //
  96 // A Maker is a deluxe wrapper around Builder. It creates whole HandleContext
  97 // objects in one swell foop, handling object locking, construction, error
  98 // recovery, and all that jazz. A Maker cannot create plain Context objects.
  99 //
 100 class HandleContext::Maker : public Context::Builder {
 101 public:
 102     Maker(CSSM_CSP_HANDLE handle)
 103                 : Context::Builder(findHandleAndLock<CSPAttachment>(handle, CSSM_ERRCODE_INVALID_CSP_HANDLE)),
 104                 attachment(static_cast<CSPAttachment &>(allocator)), // order dependency(!)
 105                 locker(attachment, true)
 106         { attachment.finishEnter(); }
 107
 108     CSPAttachment &attachment;
 109
 110     CSSM_CC_HANDLE operator () (CSSM_CONTEXT_TYPE type,
 111                                 CSSM_ALGORITHMS algorithm);
 112
 113 private:
 114         StLock<CountingMutex, &CountingMutex::enter, &CountingMutex::exit> locker;
 115 };
 116
 117 #endif //_H_CSSMCONTEXT