31 lines
1.8 KiB
C++
31 lines
1.8 KiB
C++
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#include "Relocation.h"
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// the goal of this file is to support pointers in to a relocated binary with as little runtime overhead, code bloat, and hassle as possible
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//
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// since the main executable will always be loaded before the dll, the easiest solution is to perform the relocation in the constructor of
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// a pointer class that supports conversion to T*. however, since we can't control anything about initialization order, each constructor
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// must call GetModuleHandle(NULL) locally, which sucks. each pointer will need an entry in the static init table, and nothing can be done
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// with the pointers in any other static constructors.
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//
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// one solution to this problem is init_seg(lib). any objects constructed in a file containing this pragma will be constructed before standard
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// 'user' level code. this means we can use the constructor of that object to call GetModuleHandle once and initialize a global with the load
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// address, which the pointer class constructor then references to fix up the addresses. this still creates an entry in the static init table
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// for each pointer, but only calls GetModuleHandle once. pointers are not fixed up until all static init has finished, so other static ctors
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// can't safely use pointers.
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//
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// the problem can't be solved further without moving the RelocPtr constructors in to init_seg(lib), which doesn't appear to be possible
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// without forcing all pointers to be defined in a file with init_seg(lib). that is really ugly and doesn't seem like a good idea.
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// anything in this file will initialized after the crt but before any user code
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#pragma warning(disable: 4073) // yes this is intentional
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#pragma init_seg(lib)
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static RelocationManager s_relocMgr;
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uintptr_t RelocationManager::s_baseAddr = 0;
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RelocationManager::RelocationManager()
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{
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s_baseAddr = reinterpret_cast<uintptr_t>(GetModuleHandle(NULL));
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}
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