cdsa/cdsa_utilities/ReadWriteSection.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 // ReadWriteSection.h
  21 //
  22
  23 #ifndef _H_APPLEDL_READWRITESECTION
  24 #define _H_APPLEDL_READWRITESECTION
  25
  26 #include <Security/cssmalloc.h>
  27 #include <Security/AtomicFile.h>
  28
  29 namespace Security
  30 {
  31
  32 //
  33 // Atom -- An Atom is a 32-bit unsigned integer value that is always internally
  34 // represented using network byte order.
  35 //
  36 class Atom
  37 {
  38 public:
  39         typedef constVector<Atom> Vector;
  40
  41         Atom() : mValue(0) {}
  42         Atom(uint32 value) : mValue(htonl(value)) {}
  43
  44         operator uint32 () const { return ntohl(mValue); }
  45         Atom &operator = (uint32 value) { mValue = htonl(value); return *this; }
  46
  47 private:
  48         uint32 mValue;
  49 };
  50
  51 enum {
  52         AtomSize = sizeof(uint32) // XXX Why not just use sizeof(Atom)?
  53 };
  54
  55 //
  56 // Class representing a range (or subrange of a buffer).
  57 //
  58 class Range
  59 {
  60 public:
  61         Range(uint32 inOffset, uint32 inSize) : mOffset(inOffset), mSize(inSize) {}
  62         uint32 mOffset;
  63         uint32 mSize;
  64 };
  65
  66 //
  67 // Class representing a packed record.  All the accessors on this class are const since the
  68 // underlying data is read-only
  69 //
  70 // XXX Should be replaced by Atom::Vector
  71 class ReadSection
  72 {
  73 public:
  74         ReadSection() : mAddress(NULL), mLength(0) {}
  75     ReadSection(const uint8 *inAddress, size_t inLength) :
  76             mAddress(const_cast<uint8 *>(inAddress)), mLength(inLength) {}
  77
  78     uint32 size() const { return mLength; }
  79
  80     uint32 at(uint32 inOffset) const
  81     {
  82         return ntohl(*reinterpret_cast<const uint32 *>(mAddress + inOffset));
  83     }
  84
  85     uint32 operator[](uint32 inOffset) const
  86     {
  87         if (inOffset + sizeof(uint32) > mLength)
  88             CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
  89         return at(inOffset);
  90     }
  91
  92         // Return a subsection from inOffset to end of section.
  93     ReadSection subsection(uint32 inOffset) const
  94     {
  95         if (inOffset > mLength)
  96             CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
  97         return ReadSection(mAddress + inOffset, mLength - inOffset);
  98     }
  99
 100         // Return a subsection from inOffset of inLength bytes.
 101     ReadSection subsection(uint32 inOffset, uint32 inLength) const
 102     {
 103         if (inOffset + inLength > mLength)
 104             CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
 105         return ReadSection(mAddress + inOffset, inLength);
 106     }
 107
 108         ReadSection subsection(const Range &inRange) const
 109         {
 110                 return subsection(inRange.mOffset, inRange.mSize);
 111         }
 112
 113     const uint8 *range(const Range &inRange) const
 114     {
 115         if (inRange.mOffset + inRange.mSize > mLength)
 116             CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
 117         return mAddress + inRange.mOffset;
 118     }
 119
 120         uint8 *allocCopyRange(const Range &inRange, CssmAllocator &inAllocator) const
 121         {
 122             uint8 *aData;
 123             if (inRange.mSize == 0)
 124                 aData = NULL;
 125             else
 126             {
 127                 if (inRange.mOffset + inRange.mSize > mLength)
 128                     CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
 129
 130                 aData = reinterpret_cast<uint8 *>(inAllocator.malloc(inRange.mSize));
 131                 memcpy(aData, mAddress + inRange.mOffset, inRange.mSize);
 132             }
 133
 134                 return aData;
 135         }
 136
 137         static uint32 align(uint32 offset) { return (offset + AtomSize - 1) & ~(AtomSize - 1); }
 138
 139 protected:
 140     ReadSection(uint8 *inAddress, size_t inLength) : mAddress(inAddress), mLength(inLength) {}
 141     uint8 *mAddress;
 142     size_t mLength;
 143 };
 144
 145 //
 146 // Class representing a packed record (or buffer) used for writing.
 147 //
 148 class WriteSection : public ReadSection
 149 {
 150 public:
 151         static const size_t DefaultCapacity = 64;
 152
 153     WriteSection(CssmAllocator &inAllocator, size_t inCapacity) :
 154         ReadSection(reinterpret_cast<uint8 *>(inAllocator.malloc(inCapacity)), 0),
 155         mAllocator(inAllocator),
 156         mCapacity(inCapacity)
 157         {
 158                 if (mCapacity > 0)
 159                         memset(mAddress, 0, mCapacity);
 160         }
 161
 162     WriteSection(CssmAllocator &inAllocator = CssmAllocator::standard()) :
 163         ReadSection(reinterpret_cast<uint8 *>(inAllocator.malloc(DefaultCapacity)), 0),
 164         mAllocator(inAllocator),
 165         mCapacity(DefaultCapacity)
 166         {
 167         }
 168
 169         WriteSection(const WriteSection &ws, int length) :
 170                 ReadSection(reinterpret_cast<uint8 *>(ws.mAllocator.malloc(length)), length),
 171                 mAllocator(ws.mAllocator),
 172                 mCapacity(length)
 173         {
 174                 memcpy(mAddress, ws.mAddress, length);
 175         }
 176
 177     ~WriteSection() { mAllocator.free(mAddress); }
 178
 179 #if BUG_GCC
 180         uint32 size() const { return ReadSection::size(); }
 181 #else
 182         // XXX This should work but egcs-2.95.2 doesn't like it.
 183         using ReadSection::size;
 184 #endif
 185
 186     void size(uint32 inLength) { mLength = inLength; }
 187     uint32 put(uint32 inOffset, uint32 inValue)
 188     {
 189         uint32 aLength = inOffset + sizeof(inValue);
 190         if (aLength > mCapacity)
 191             grow(aLength);
 192
 193         *reinterpret_cast<uint32 *>(mAddress + inOffset) = htonl(inValue);
 194         return aLength;
 195     }
 196
 197     uint32 put(uint32 inOffset, uint32 inLength, const uint8 *inData)
 198     {
 199         uint32 aLength = inOffset + inLength;
 200         // Round up to nearest multiple of 4 bytes, to pad with zeros
 201         uint32 aNewOffset = align(aLength);
 202         if (aNewOffset > mCapacity)
 203             grow(aNewOffset);
 204
 205         memcpy(mAddress + inOffset, inData, inLength);
 206
 207         for (uint32 anOffset = aLength; anOffset < aNewOffset; anOffset++)
 208             mAddress[anOffset] = 0;
 209
 210         return aNewOffset;
 211     }
 212
 213     const uint8 *address() const { return mAddress; }
 214     uint8 *release()
 215     {
 216         uint8 *anAddress = mAddress;
 217         mAddress = NULL;
 218         mCapacity = 0;
 219         return anAddress;
 220     }
 221
 222 private:
 223     void grow(size_t inNewCapacity)
 224     {
 225         size_t aNewCapacity = max(mCapacity * 2, inNewCapacity);
 226         mAddress = reinterpret_cast<uint8 *>(mAllocator.realloc(mAddress, aNewCapacity));
 227                 memset(mAddress + mCapacity, 0, aNewCapacity - mCapacity);
 228         mCapacity = aNewCapacity;
 229     }
 230
 231     CssmAllocator &mAllocator;
 232     size_t mCapacity;
 233 };
 234
 235 } // end namespace Security
 236
 237 #endif // _H_APPLEDL_READWRITESECTION