OSX/libsecurity_cssm/lib/cssmcontext.h

   1 /*
   2  * Copyright (c) 2000-2004,2011-2012,2014 Apple Inc. All Rights Reserved.
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   6  * This file contains Original Code and/or Modifications of Original Code
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   8  * Version 2.0 (the 'License'). You may not use this file except in
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  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
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  23
  24
  25 //
  26 // context - manage CSSM (cryptographic) contexts every which way
  27 //
  28 #ifndef _H_CSSMCONTEXT
  29 #define _H_CSSMCONTEXT
  30
  31 #include "cssmint.h"
  32 #include "cspattachment.h"
  33 #include <security_cdsa_utilities/context.h>
  34
  35 #ifdef _CPP_CSSMCONTEXT
  36 # pragma export on
  37 #endif
  38
  39
  40 //
  41 // A HandleContext adds handle semantics to the Context object.
  42 // Note that not every Context is a HandleContext - the Contexts we hand
  43 // to our API customers for fondling are not. Also note that a HandleContext
  44 // not a PODWrapper.
  45 // HandleContext has an allocation method taking a Allocator. To destroy
  46 // a HandleObject, call HandleObject::destroy(the-context, the-allocator).
  47 // You are responsible for picking the same allocator used on construction.
  48 //
  49 // THREADS: HandleContexts are assumed to have single-thread use. That means that
  50 // operations on HandleContexts are NOT interlocked automatically; two users of
  51 // the same context must do any arbitration themselves. A HandleContext is howerver
  52 // safely interlocked against other objects, in particular its CSPAttachment.
  53 // The upshot is that you're safe using a HandleContext unless someone else is trying
  54 // to use the same context in parallel.
  55 //
  56 class HandleContext : public HandleObject, public Context {
  57 public:
  58     HandleContext(CSPAttachment &attach,
  59                   CSSM_CONTEXT_TYPE type,
  60                   CSSM_ALGORITHMS algorithmId)
  61     : Context(type, algorithmId), attachment(attach), extent(0) { }
  62     virtual ~HandleContext();
  63
  64     CSPAttachment &attachment;
  65
  66         using Context::find;    // guard against HandleObjec::find
  67
  68     void mergeAttributes(const CSSM_CONTEXT_ATTRIBUTE *attributes, uint32 count);
  69     CSSM_RETURN validateChange(CSSM_CONTEXT_EVENT event);
  70
  71     void *operator new (size_t size, Allocator &alloc)
  72     { return alloc.malloc(size); }
  73     void operator delete (void *addr, size_t, Allocator &alloc) _NOEXCEPT
  74     { return alloc.free(addr); }
  75     static void destroy(HandleContext *context, Allocator &alloc) _NOEXCEPT
  76     { context->~HandleContext(); alloc.free(context); }
  77
  78     class Maker;        // deluxe builder
  79
  80 #if __GNUC__ > 2
  81 private:
  82     void operator delete (void *addr) _NOEXCEPT { assert(0); }
  83 #endif
  84
  85 protected:
  86     // Locking protocol, courtesy of HandleObject.
  87     // This locks the underlying attachment.
  88     void lock();
  89     bool tryLock();
  90
  91 private:
  92     void *extent;                       // extra storage extent in use
  93 };
  94
  95 inline HandleContext &enterContext(CSSM_CC_HANDLE h)
  96 {
  97     return HandleObject::findAndLock<HandleContext>((CSSM_HANDLE)h, CSSM_ERRCODE_INVALID_CONTEXT_HANDLE);
  98 }
  99
 100
 101 //
 102 // A Maker is a deluxe wrapper around Builder. It creates whole HandleContext
 103 // objects in one swell foop, handling object locking, construction, error
 104 // recovery, and all that jazz. A Maker cannot create plain Context objects.
 105 //
 106 class HandleContext::Maker : public Context::Builder {
 107 public:
 108     Maker(CSSM_CSP_HANDLE handle)
 109                 : Context::Builder(HandleObject::findAndLock<CSPAttachment>(handle, CSSM_ERRCODE_INVALID_CSP_HANDLE)),
 110                 attachment(static_cast<CSPAttachment &>(allocator)), // order dependency(!)
 111                 locker(attachment, true)
 112         { attachment.finishEnter(); }
 113
 114     CSPAttachment &attachment;
 115
 116     CSSM_CC_HANDLE operator () (CSSM_CONTEXT_TYPE type,
 117                                 CSSM_ALGORITHMS algorithm);
 118
 119 private:
 120         StLock<CountingMutex, &CountingMutex::enter, &CountingMutex::exit> locker;
 121 };
 122
 123 #endif //_H_CSSMCONTEXT