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         size_t bytes = 0;
  78         if(__builtin_mul_overflow(size, count, &bytes)) {
  79             // Multiplication overflowed.
  80             throw std::bad_alloc();
  81         }
  82                 void *addr = malloc(bytes);
  83                 memset(addr, 0, bytes);
  84                 return addr;
  85         }
  86
  87         // compare Allocators for identity
  88         virtual bool operator == (const Allocator &alloc) const throw();
  89
  90 public:
  91         // allocator chooser options
  92         enum {
  93                 normal = 0x0000,
  94                 sensitive = 0x0001
  95         };
  96
  97         static Allocator &standard(UInt32 request = normal);
  98 };
  99
 100
 101 //
 102 // You'd think that this is operator delete(const T *, Allocator &), but you'd
 103 // be wrong. Specialized operator delete is only called during constructor cleanup.
 104 // Use this to cleanly destroy things.
 105 //
 106 template <class T>
 107 inline void destroy(T *obj, Allocator &alloc) throw()
 108 {
 109         obj->~T();
 110         alloc.free(obj);
 111 }
 112
 113 // untyped (release memory only, no destructor call)
 114 inline void destroy(void *obj, Allocator &alloc) throw()
 115 {
 116         alloc.free(obj);
 117 }
 118
 119
 120 //
 121 // A mixin class to automagically manage your allocator.
 122 // To allow allocation (of your object) from any instance of Allocator,
 123 // inherit from CssmHeap. Your users can then create heap instances of your thing by
 124 //              new (an-allocator) YourClass(...)
 125 // or (still)
 126 //              new YourClass(...)
 127 // for the default allocation source. The beauty is that when someone does a
 128 //              delete pointer-to-your-instance
 129 // then the magic fairies will find the allocator that created the object and ask it
 130 // to free the memory (by calling its free() method).
 131 // The price of all that glory is memory overhead - typically one pointer per object.
 132 //
 133 class CssmHeap {
 134 public:
 135         void *operator new (size_t size, Allocator *alloc = NULL) throw(std::bad_alloc);
 136         void operator delete (void *addr, size_t size) throw();
 137         void operator delete (void *addr, size_t size, Allocator *alloc) throw();
 138 };
 139
 140
 141 //
 142 // Here is a version of auto_ptr that works with Allocators. It is designed
 143 // to be pretty much a drop-in replacement. It requires an allocator as a constructor
 144 // argument, of course.
 145 // Note that CssmAutoPtr<void> is perfectly valid, unlike its auto_ptr look-alike.
 146 // You can't dereference it, naturally.
 147 //
 148 template <class T>
 149 class CssmAutoPtr {
 150 public:
 151         Allocator &allocator;
 152
 153         CssmAutoPtr(Allocator &alloc = Allocator::standard())
 154         : allocator(alloc), mine(NULL) { }
 155         CssmAutoPtr(Allocator &alloc, T *p)
 156         : allocator(alloc), mine(p) { }
 157         CssmAutoPtr(T *p)
 158         : allocator(Allocator::standard()), mine(p) { }
 159         template <class T1> CssmAutoPtr(CssmAutoPtr<T1> &src)
 160         : allocator(src.allocator), mine(src.release()) { }
 161         template <class T1> CssmAutoPtr(Allocator &alloc, CssmAutoPtr<T1> &src)
 162         : allocator(alloc), mine(src.release()) { assert(allocator == src.allocator); }
 163
 164         ~CssmAutoPtr()                          { allocator.free(mine); }
 165
 166         T *get() const throw()          { return mine; }
 167         T *release()                            { T *result = mine; mine = NULL; return result; }
 168         void reset()                            { allocator.free(mine); mine = NULL; }
 169
 170         operator T * () const           { return mine; }
 171         T *operator -> () const         { return mine; }
 172         T &operator * () const          { assert(mine); return *mine; }
 173
 174 private:
 175         T *mine;
 176 };
 177
 178 // specialization for void (i.e. void *), omitting the troublesome dereferencing ops.
 179 template <>
 180 class CssmAutoPtr<void> {
 181 public:
 182         Allocator &allocator;
 183
 184         CssmAutoPtr(Allocator &alloc) : allocator(alloc), mine(NULL) { }
 185         CssmAutoPtr(Allocator &alloc, void *p) : allocator(alloc), mine(p) { }
 186         template <class T1> CssmAutoPtr(CssmAutoPtr<T1> &src)
 187         : allocator(src.allocator), mine(src.release()) { }
 188         template <class T1> CssmAutoPtr(Allocator &alloc, CssmAutoPtr<T1> &src)
 189         : allocator(alloc), mine(src.release()) { assert(allocator == src.allocator); }
 190
 191         ~CssmAutoPtr()                          { destroy(mine, allocator); }
 192
 193         void *get() throw()             { return mine; }
 194         void *release()                         { void *result = mine; mine = NULL; return result; }
 195         void reset()                            { allocator.free(mine); mine = NULL; }
 196
 197 private:
 198         void *mine;
 199 };
 200
 201
 202 //
 203 // Convenience forms of CssmAutoPtr that automatically make their (initial) object.
 204 //
 205 template <class T>
 206 class CssmNewAutoPtr : public CssmAutoPtr<T> {
 207 public:
 208         CssmNewAutoPtr(Allocator &alloc = Allocator::standard())
 209         : CssmAutoPtr<T>(alloc, new(alloc) T) { }
 210
 211         template <class A1>
 212         CssmNewAutoPtr(Allocator &alloc, A1 &arg1) : CssmAutoPtr<T>(alloc, new(alloc) T(arg1)) { }
 213         template <class A1>
 214         CssmNewAutoPtr(Allocator &alloc, const A1 &arg1)
 215         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1)) { }
 216
 217         template <class A1, class A2>
 218         CssmNewAutoPtr(Allocator &alloc, A1 &arg1, A2 &arg2)
 219         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1, arg2)) { }
 220         template <class A1, class A2>
 221         CssmNewAutoPtr(Allocator &alloc, const A1 &arg1, A2 &arg2)
 222         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1, arg2)) { }
 223         template <class A1, class A2>
 224         CssmNewAutoPtr(Allocator &alloc, A1 &arg1, const A2 &arg2)
 225         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1, arg2)) { }
 226         template <class A1, class A2>
 227         CssmNewAutoPtr(Allocator &alloc, const A1 &arg1, const A2 &arg2)
 228         : CssmAutoPtr<T>(alloc, new(alloc) T(arg1, arg2)) { }
 229 };
 230
 231
 232 } // end namespace Security
 233
 234
 235 //
 236 // Global C++ allocation hooks to use Allocators (global namespace)
 237 //
 238 inline void *operator new (size_t size, Allocator &allocator) throw (std::bad_alloc)
 239 { return allocator.malloc(size); }
 240
 241 inline void *operator new[] (size_t size, Allocator &allocator) throw (std::bad_alloc)
 242 { return allocator.malloc(size); }
 243
 244
 245 #endif //_H_ALLOC