OSX/libsecurity_utilities/lib/alloc.h

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  23
  24
  25 //
  26 // alloc - abstract malloc-like allocator abstraction
  27 //
  28 #ifndef _H_ALLOC
  29 #define _H_ALLOC
  30
  31 #include <security_utilities/utilities.h>
  32 #include <cstring>
  33
  34 namespace Security
  35 {
  36
  37
  38 //
  39 // An abstract allocator superclass, based on the simple malloc/realloc/free paradigm
  40 // that CDSA loves so much. If you have an allocation strategy and want objects
  41 // to be allocated through it, inherit from this.
  42 //
  43 class Allocator {
  44 public:
  45         virtual ~Allocator();
  46         virtual void *malloc(size_t) throw(std::bad_alloc) = 0;
  47         virtual void free(void *) throw() = 0;
  48         virtual void *realloc(void *, size_t) throw(std::bad_alloc) = 0;
  49
  50         //
  51         // Template versions for added expressiveness.
  52         // Note that the integers are element counts, not byte sizes.
  53         //
  54         template <class T> T *alloc() throw(std::bad_alloc)
  55         { return reinterpret_cast<T *>(malloc(sizeof(T))); }
  56
  57         template <class T> T *alloc(UInt32 count) throw(std::bad_alloc)
  58         { return reinterpret_cast<T *>(malloc(sizeof(T) * count)); }
  59
  60         template <class T> T *alloc(T *old, UInt32 count) throw(std::bad_alloc)
  61         { return reinterpret_cast<T *>(realloc(old, sizeof(T) * count)); }
  62
  63
  64         //
  65         // Happier malloc/realloc for any type. Note that these still have
  66         // the original (byte-sized) argument profile.
  67         //
  68         template <class T> T *malloc(size_t size) throw(std::bad_alloc)
  69         { return reinterpret_cast<T *>(malloc(size)); }
  70
  71         template <class T> T *realloc(void *addr, size_t size) throw(std::bad_alloc)
  72         { return reinterpret_cast<T *>(realloc(addr, size)); }
  73
  74         // All right, if you *really* have to have calloc...
  75         void *calloc(size_t size, size_t count) throw(std::bad_alloc)
  76         {
  77                 void *addr = malloc(size * count);
  78                 memset(addr, 0, size * count);
  79                 return addr;
  80         }
  81
  82         // compare Allocators for identity
  83         virtual bool operator == (const Allocator &alloc) const throw();
  84
  85 public:
  86         // allocator chooser options
  87         enum {
  88                 normal = 0x0000,
  89                 sensitive = 0x0001
  90         };
  91
  92         static Allocator &standard(UInt32 request = normal);
  93 };
  94
  95
  96 //
  97 // You'd think that this is operator delete(const T *, Allocator &), but you'd
  98 // be wrong. Specialized operator delete is only called during constructor cleanup.
  99 // Use this to cleanly destroy things.
 100 //
 101 template <class T>
 102 inline void destroy(T *obj, Allocator &alloc) throw()
 103 {
 104         obj->~T();
 105         alloc.free(obj);
 106 }
 107
 108 // untyped (release memory only, no destructor call)
 109 inline void destroy(void *obj, Allocator &alloc) throw()
 110 {
 111         alloc.free(obj);
 112 }
 113
 114
 115 //
 116 // A mixin class to automagically manage your allocator.
 117 // To allow allocation (of your object) from any instance of Allocator,
 118 // inherit from CssmHeap. Your users can then create heap instances of your thing by
 119 //              new (an-allocator) YourClass(...)
 120 // or (still)
 121 //              new YourClass(...)
 122 // for the default allocation source. The beauty is that when someone does a
 123 //              delete pointer-to-your-instance
 124 // then the magic fairies will find the allocator that created the object and ask it
 125 // to free the memory (by calling its free() method).
 126 // The price of all that glory is memory overhead - typically one pointer per object.
 127 //
 128 class CssmHeap {
 129 public:
 130         void *operator new (size_t size, Allocator *alloc = NULL) throw(std::bad_alloc);
 131         void operator delete (void *addr, size_t size) throw();
 132         void operator delete (void *addr, size_t size, Allocator *alloc) throw();
 133 };
 134
 135
 136 //
 137 // Here is a version of auto_ptr that works with Allocators. It is designed
 138 // to be pretty much a drop-in replacement. It requires an allocator as a constructor
 139 // argument, of course.
 140 // Note that CssmAutoPtr<void> is perfectly valid, unlike its auto_ptr look-alike.
 141 // You can't dereference it, naturally.
 142 //
 143 template <class T>
 144 class CssmAutoPtr {
 145 public:
 146         Allocator &allocator;
 147
 148         CssmAutoPtr(Allocator &alloc = Allocator::standard())
 149         : allocator(alloc), mine(NULL) { }
 150         CssmAutoPtr(Allocator &alloc, T *p)
 151         : allocator(alloc), mine(p) { }
 152         CssmAutoPtr(T *p)
 153         : allocator(Allocator::standard()), mine(p) { }
 154         template <class T1> CssmAutoPtr(CssmAutoPtr<T1> &src)
 155         : allocator(src.allocator), mine(src.release()) { }
 156         template <class T1> CssmAutoPtr(Allocator &alloc, CssmAutoPtr<T1> &src)
 157         : allocator(alloc), mine(src.release()) { assert(allocator == src.allocator); }
 158
 159         ~CssmAutoPtr()                          { allocator.free(mine); }
 160
 161         T *get() const throw()          { return mine; }
 162         T *release()                            { T *result = mine; mine = NULL; return result; }
 163         void reset()                            { allocator.free(mine); mine = NULL; }
 164
 165         operator T * () const           { return mine; }
 166         T *operator -> () const         { return mine; }
 167         T &operator * () const          { assert(mine); return *mine; }
 168
 169 private:
 170         T *mine;
 171 };
 172
 173 // specialization for void (i.e. void *), omitting the troublesome dereferencing ops.
 174 template <>
 175 class CssmAutoPtr<void> {
 176 public:
 177         Allocator &allocator;
 178
 179         CssmAutoPtr(Allocator &alloc) : allocator(alloc), mine(NULL) { }
 180         CssmAutoPtr(Allocator &alloc, void *p) : allocator(alloc), mine(p) { }
 181         template <class T1> CssmAutoPtr(CssmAutoPtr<T1> &src)
 182         : allocator(src.allocator), mine(src.release()) { }
 183         template <class T1> CssmAutoPtr(Allocator &alloc, CssmAutoPtr<T1> &src)
 184         : allocator(alloc), mine(src.release()) { assert(allocator == src.allocator); }
 185
 186         ~CssmAutoPtr()                          { destroy(mine, allocator); }
 187
 188         void *get() throw()             { return mine; }
 189         void *release()                         { void *result = mine; mine = NULL; return result; }
 190         void reset()                            { allocator.free(mine); mine = NULL; }
 191
 192 private:
 193         void *mine;
 194 };
 195
 196
 197 //
 198 // Convenience forms of CssmAutoPtr that automatically make their (initial) object.
 199 //
 200 template <class T>
 201 class CssmNewAutoPtr : public CssmAutoPtr<T> {
 202 public:
 203         CssmNewAutoPtr(Allocator &alloc = Allocator::standard())
 204         : CssmAutoPtr<T>(alloc, new(alloc) T) { }
 205
 206         template <class A1>
 207         CssmNewAutoPtr(Allocator &alloc, A1 &arg1) : CssmAutoPtr<T>(alloc, new(alloc) T(arg1)) { }
 208         template <class A1>
 209         CssmNewAutoPtr(Allocator &alloc, const A1 &arg1)
 210         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1)) { }
 211
 212         template <class A1, class A2>
 213         CssmNewAutoPtr(Allocator &alloc, A1 &arg1, A2 &arg2)
 214         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1, arg2)) { }
 215         template <class A1, class A2>
 216         CssmNewAutoPtr(Allocator &alloc, const A1 &arg1, A2 &arg2)
 217         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1, arg2)) { }
 218         template <class A1, class A2>
 219         CssmNewAutoPtr(Allocator &alloc, A1 &arg1, const A2 &arg2)
 220         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1, arg2)) { }
 221         template <class A1, class A2>
 222         CssmNewAutoPtr(Allocator &alloc, const A1 &arg1, const A2 &arg2)
 223         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1, arg2)) { }
 224 };
 225
 226
 227 } // end namespace Security
 228
 229
 230 //
 231 // Global C++ allocation hooks to use Allocators (global namespace)
 232 //
 233 inline void *operator new (size_t size, Allocator &allocator) throw (std::bad_alloc)
 234 { return allocator.malloc(size); }
 235
 236 inline void *operator new[] (size_t size, Allocator &allocator) throw (std::bad_alloc)
 237 { return allocator.malloc(size); }
 238
 239
 240 #endif //_H_ALLOC