src/transwalkers.cpp

   1 /*
   2  * Copyright (c) 2003-2004 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
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   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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  20  * Please see the License for the specific language governing rights and
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  25
  26
  27 //
  28 // transwalkers - server side transition data walking support
  29 //
  30 // These are data walker operators for securely marshaling and unmarshaling
  31 // data structures across IPC. They are also in charge of fixing byte order
  32 // inconsistencies between server and clients.
  33 //
  34 #include <transwalkers.h>
  35
  36
  37 using LowLevelMemoryUtilities::increment;
  38 using LowLevelMemoryUtilities::difference;
  39
  40
  41 bool flipClient()
  42 {
  43         return Server::process().byteFlipped();
  44 }
  45
  46
  47 //
  48 // CheckingRelocateWalkers
  49 //
  50 CheckingReconstituteWalker::CheckingReconstituteWalker(void *ptr, void *base, size_t size, bool flip)
  51         : mBase(base), mFlip(flip)
  52 {
  53         if (mFlip)
  54                 Flippers::flip(mBase);  // came in reversed; fix for base use
  55         mOffset = difference(ptr, mBase);
  56         mLimit = increment(mBase, size);
  57 }
  58
  59
  60 //
  61 // Relocation support
  62 //
  63 void relocate(Context &context, void *base, Context::Attr *attrs, uint32 attrSize)
  64 {
  65         flip(context);
  66         CheckingReconstituteWalker relocator(attrs, base, attrSize, flipClient());
  67         context.ContextAttributes = attrs;      // fix context->attr vector link
  68         for (uint32 n = 0; n < context.attributesInUse(); n++)
  69                 walk(relocator, context[n]);
  70 }
  71
  72
  73 //
  74 // Outbound flipping support
  75 //
  76 FlipWalker::~FlipWalker()
  77 {
  78         for (set<Flipper>::const_iterator it = mFlips.begin(); it != mFlips.end(); it++)
  79                 delete it->impl;
  80 }
  81
  82 void FlipWalker::doFlips(bool active)
  83 {
  84         if (active) {
  85                 secdebug("flipwalkers", "starting outbound flips");
  86                 for (set<Flipper>::const_iterator it = mFlips.begin(); it != mFlips.end(); it++)
  87                         it->impl->flip();
  88                 secdebug("flipwalkers", "outbound flips done");
  89         }
  90 }