OSX/libsecurity_utilities/lib/alloc.cpp

   1 /*
   2  * Copyright (c) 2000-2004,2011,2014 Apple Inc. All Rights Reserved.
   3  *
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   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,
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  18  * Please see the License for the specific language governing rights and
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  23
  24
  25 //
  26 // cssmalloc - memory allocation in the CDSA world.
  27 //
  28 // Don't eat heavily before inspecting this code.
  29 //
  30 #define __STDC_WANT_LIB_EXT1__ 1
  31 #include <string.h>
  32
  33 #include <security_utilities/alloc.h>
  34 #include <security_utilities/memutils.h>
  35 #include <security_utilities/globalizer.h>
  36 #include <stdlib.h>
  37 #include <errno.h>
  38
  39 using LowLevelMemoryUtilities::alignof_template;
  40 using LowLevelMemoryUtilities::increment;
  41 using LowLevelMemoryUtilities::alignUp;
  42
  43 extern "C" size_t malloc_size(void *);
  44
  45
  46 //
  47 // Features of the Allocator root class
  48 //
  49 bool Allocator::operator == (const Allocator &alloc) const throw()
  50 {
  51         return this == &alloc;
  52 }
  53
  54 Allocator::~Allocator()
  55 {
  56 }
  57
  58
  59 //
  60 // Standard Allocator variants.
  61 // Note that all calls to Allocator::standard(xxx) with the same xxx argument
  62 // must produce compatible allocators (i.e. they must be work on a common memory
  63 // pool). This is trivially achieved here by using singletons.
  64 //
  65 struct DefaultAllocator : public Allocator {
  66         void *malloc(size_t size) throw(std::bad_alloc);
  67         void free(void *addr) throw();
  68         void *realloc(void *addr, size_t size) throw(std::bad_alloc);
  69 };
  70
  71 struct SensitiveAllocator : public DefaultAllocator {
  72     void free(void *addr) throw();
  73     void *realloc(void *addr, size_t size) throw(std::bad_alloc);
  74 };
  75
  76 struct DefaultAllocators {
  77     DefaultAllocator standard;
  78     SensitiveAllocator sensitive;
  79 };
  80
  81 static ModuleNexus<DefaultAllocators> defaultAllocators;
  82
  83
  84 Allocator &Allocator::standard(UInt32 request)
  85 {
  86     switch (request) {
  87     case normal:
  88         return defaultAllocators().standard;
  89     case sensitive:
  90         return defaultAllocators().sensitive;
  91     default:
  92         UnixError::throwMe(ENOMEM);
  93     }
  94 }
  95
  96 void *DefaultAllocator::malloc(size_t size) throw(std::bad_alloc)
  97 {
  98         if (void *result = ::malloc(size))
  99                 return result;
 100         throw std::bad_alloc();
 101 }
 102
 103 void DefaultAllocator::free(void *addr) throw()
 104 {
 105         ::free(addr);
 106 }
 107
 108 void *DefaultAllocator::realloc(void *addr, size_t newSize) throw(std::bad_alloc)
 109 {
 110         if (void *result = ::realloc(addr, newSize))
 111                 return result;
 112         throw std::bad_alloc();
 113 }
 114
 115 void SensitiveAllocator::free(void *addr) throw()
 116 {
 117     size_t size = malloc_size(addr);
 118     ::memset_s(addr, size, 0, size);
 119     DefaultAllocator::free(addr);
 120 }
 121
 122 void *SensitiveAllocator::realloc(void *addr, size_t newSize) throw(std::bad_alloc)
 123 {
 124     size_t oldSize = malloc_size(addr);
 125     if (newSize < oldSize)
 126         ::memset_s(increment(addr, newSize), oldSize - newSize, 0, oldSize - newSize);
 127     return DefaultAllocator::realloc(addr, newSize);
 128 }
 129
 130
 131 //
 132 // Memory allocators for CssmHeap objects.
 133 // This implementation stores a pointer to the allocator used into memory
 134 // *after* the object's proper storage block. This allows the usual free()
 135 // functions to safely free our (hidden) pointer without knowing about it.
 136 // An allocator argument of NULL is interpreted as the standard allocator.
 137 //
 138 void *CssmHeap::operator new (size_t size, Allocator *alloc) throw(std::bad_alloc)
 139 {
 140         if (alloc == NULL)
 141                 alloc = &Allocator::standard();
 142         size = alignUp(size, alignof_template<Allocator *>());
 143         size_t totalSize = size + sizeof(Allocator *);
 144         void *addr = alloc->malloc(totalSize);
 145         *(Allocator **)increment(addr, size) = alloc;
 146         return addr;
 147 }
 148
 149 void CssmHeap::operator delete (void *addr, size_t size, Allocator *alloc) throw()
 150 {
 151         alloc->free(addr);      // as per C++ std, called (only) if construction fails
 152 }
 153
 154 void CssmHeap::operator delete (void *addr, size_t size) throw()
 155 {
 156         void *end = increment(addr, alignUp(size, alignof_template<Allocator *>()));
 157         (*(Allocator **)end)->free(addr);
 158 }
 159
 160
 161 //
 162 // CssmVector
 163 //