Add experimental support for interposing vmethods of known classes.
The hairiest bit is the abuse of compiler-specific pointer-to-member internals in order to provide more or less transparent API.develop
Alexander Gavrilov
parent
bcc41c081a
commit
236ffd578b
@ -0,0 +1,238 @@
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/*
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https://github.com/peterix/dfhack
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Copyright (c) 2009-2011 Petr Mrázek (peterix@gmail.com)
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any
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damages arising from the use of this software.
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Permission is granted to anyone to use this software for any
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purpose, including commercial applications, and to alter it and
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redistribute it freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must
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not claim that you wrote the original software. If you use this
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software in a product, an acknowledgment in the product documentation
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would be appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and
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must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source
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distribution.
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*/
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#include "Internal.h"
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#include <string>
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#include <vector>
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#include <map>
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#include "MemAccess.h"
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#include "Core.h"
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#include "VersionInfo.h"
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#include "VTableInterpose.h"
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#include "MiscUtils.h"
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using namespace DFHack;
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/*
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* Code for accessing method pointers directly. Very compiler-specific.
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*/
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#if defined(_MSC_VER)
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struct MSVC_MPTR {
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void *method;
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intptr_t this_shift;
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};
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bool DFHack::is_vmethod_pointer_(void *pptr)
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{
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auto pobj = (MSVC_MPTR*)pptr;
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if (!pobj->method) return false;
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// MSVC implements pointers to vmethods via thunks.
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// This expects that they all follow a very specific pattern.
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auto pval = (unsigned*)pobj->method;
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switch (pval[0]) {
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case 0x60FF018BU: // mov eax, [ecx]; jmp [eax+0x??]
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case 0xA0FF018BU: // mov eax, [ecx]; jmp [eax+0x????????]
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return true;
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default:
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return false;
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}
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}
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int DFHack::vmethod_pointer_to_idx_(void *pptr)
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{
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auto pobj = (MSVC_MPTR*)pptr;
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if (!pobj->method || pobj->this_shift != 0) return -1;
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auto pval = (unsigned*)pobj->method;
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switch (pval[0]) {
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case 0x60FF018BU: // mov eax, [ecx]; jmp [eax+0x??]
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return ((int8_t)pval[1])/sizeof(void*);
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case 0xA0FF018BU: // mov eax, [ecx]; jmp [eax+0x????????]
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return ((int32_t)pval[1])/sizeof(void*);
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default:
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return -1;
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}
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}
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void* DFHack::method_pointer_to_addr_(void *pptr)
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{
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if (is_vmethod_pointer_(pptr)) return NULL;
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auto pobj = (MSVC_MPTR*)pptr;
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return pobj->method;
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}
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void DFHack::addr_to_method_pointer_(void *pptr, void *addr)
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{
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auto pobj = (MSVC_MPTR*)pptr;
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pobj->method = addr;
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pobj->this_shift = 0;
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}
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#elif defined(__GXX_ABI_VERSION)
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struct GCC_MPTR {
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intptr_t method;
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intptr_t this_shift;
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};
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bool DFHack::is_vmethod_pointer_(void *pptr)
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{
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auto pobj = (GCC_MPTR*)pptr;
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return (pobj->method & 1) != 0;
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}
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int DFHack::vmethod_pointer_to_idx_(void *pptr)
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{
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auto pobj = (GCC_MPTR*)pptr;
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if ((pobj->method & 1) == 0 || pobj->this_shift != 0)
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return -1;
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return (pobj->method-1)/sizeof(void*);
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}
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void* DFHack::method_pointer_to_addr_(void *pptr)
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{
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auto pobj = (GCC_MPTR*)pptr;
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if ((pobj->method & 1) != 0 || pobj->this_shift != 0)
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return NULL;
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return (void*)pobj->method;
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}
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void DFHack::addr_to_method_pointer_(void *pptr, void *addr)
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{
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auto pobj = (GCC_MPTR*)pptr;
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pobj->method = (intptr_t)addr;
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pobj->this_shift = 0;
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}
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#else
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#error Unknown compiler type
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#endif
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void *virtual_identity::get_vmethod_ptr(int idx)
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{
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assert(idx >= 0);
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void **vtable = (void**)vtable_ptr;
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if (!vtable) return NULL;
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return vtable[idx];
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}
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bool virtual_identity::set_vmethod_ptr(int idx, void *ptr)
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{
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assert(idx >= 0);
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void **vtable = (void**)vtable_ptr;
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if (!vtable) return NULL;
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return Core::getInstance().p->patchMemory(&vtable[idx], &ptr, sizeof(void*));
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}
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void VMethodInterposeLinkBase::set_chain(void *chain)
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{
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saved_chain = chain;
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addr_to_method_pointer_(chain_mptr, chain);
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}
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VMethodInterposeLinkBase::VMethodInterposeLinkBase(virtual_identity *host, int vmethod_idx, void *interpose_method, void *chain_mptr)
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: host(host), vmethod_idx(vmethod_idx), interpose_method(interpose_method), chain_mptr(chain_mptr),
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saved_chain(NULL), next(NULL), prev(NULL)
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{
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}
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VMethodInterposeLinkBase::~VMethodInterposeLinkBase()
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{
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if (is_applied())
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remove();
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}
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bool VMethodInterposeLinkBase::apply()
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{
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if (is_applied())
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return true;
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if (!host->vtable_ptr)
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return false;
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// Retrieve the current vtable entry
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void *old_ptr = host->get_vmethod_ptr(vmethod_idx);
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assert(old_ptr != NULL);
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// Check if there are other interpose entries for the same slot
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VMethodInterposeLinkBase *old_link = NULL;
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for (int i = host->interpose_list.size()-1; i >= 0; i--)
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{
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if (host->interpose_list[i]->vmethod_idx != vmethod_idx)
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continue;
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old_link = host->interpose_list[i];
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assert(old_link->next == NULL && old_ptr == old_link->interpose_method);
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break;
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}
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// Apply the new method ptr
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if (!host->set_vmethod_ptr(vmethod_idx, interpose_method))
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return false;
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set_chain(old_ptr);
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// Link into the chain if any
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if (old_link)
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{
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old_link->next = this;
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prev = old_link;
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}
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return true;
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}
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void VMethodInterposeLinkBase::remove()
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{
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if (!is_applied())
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return;
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// Remove from the list in the identity
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for (int i = host->interpose_list.size()-1; i >= 0; i--)
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if (host->interpose_list[i] == this)
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vector_erase_at(host->interpose_list, i);
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// Remove from the chain
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if (prev)
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prev->next = next;
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if (next)
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{
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next->set_chain(saved_chain);
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next->prev = prev;
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}
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else
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{
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host->set_vmethod_ptr(vmethod_idx, saved_chain);
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}
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prev = next = NULL;
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set_chain(NULL);
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}
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@ -0,0 +1,158 @@
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/*
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https://github.com/peterix/dfhack
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Copyright (c) 2009-2011 Petr Mrázek (peterix@gmail.com)
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any
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damages arising from the use of this software.
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Permission is granted to anyone to use this software for any
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purpose, including commercial applications, and to alter it and
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redistribute it freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must
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not claim that you wrote the original software. If you use this
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software in a product, an acknowledgment in the product documentation
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would be appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and
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must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source
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distribution.
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*/
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#pragma once
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#include "DataFuncs.h"
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namespace DFHack
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{
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template<bool> struct StaticAssert;
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template<> struct StaticAssert<true> {};
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#define STATIC_ASSERT(condition) { StaticAssert<(condition)>(); }
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/* Wrapping around compiler-specific representation of pointers to methods. */
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#if defined(_MSC_VER)
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#define METHOD_POINTER_SIZE (sizeof(void*)*2)
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#elif defined(__GXX_ABI_VERSION)
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#define METHOD_POINTER_SIZE (sizeof(void*)*2)
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#else
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#error Unknown compiler type
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#endif
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#define ASSERT_METHOD_POINTER(type) \
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STATIC_ASSERT(df::return_type<type>::is_method && sizeof(type)==METHOD_POINTER_SIZE);
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DFHACK_EXPORT bool is_vmethod_pointer_(void*);
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DFHACK_EXPORT int vmethod_pointer_to_idx_(void*);
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DFHACK_EXPORT void* method_pointer_to_addr_(void*);
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DFHACK_EXPORT void addr_to_method_pointer_(void*,void*);
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template<class T> bool is_vmethod_pointer(T ptr) {
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ASSERT_METHOD_POINTER(T);
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return is_vmethod_pointer_(&ptr);
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}
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template<class T> int vmethod_pointer_to_idx(T ptr) {
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ASSERT_METHOD_POINTER(T);
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return vmethod_pointer_to_idx_(&ptr);
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}
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template<class T> void *method_pointer_to_addr(T ptr) {
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ASSERT_METHOD_POINTER(T);
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return method_pointer_to_addr_(&ptr);
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}
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template<class T> T addr_to_method_pointer(void *addr) {
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ASSERT_METHOD_POINTER(T);
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T rv;
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addr_to_method_pointer_(&rv, addr);
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return rv;
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}
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/* Access to vmethod pointers from the vtable. */
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template<class P>
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P virtual_identity::get_vmethod_ptr(P selector)
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{
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typedef typename df::return_type<P>::class_type host_class;
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virtual_identity &identity = host_class::_identity;
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int idx = vmethod_pointer_to_idx(selector);
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return addr_to_method_pointer<P>(identity.get_vmethod_ptr(idx));
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}
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/* VMethod interpose API
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Usage:
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struct my_hack : public someclass {
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typedef someclass interpose_base;
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DEFINE_VMETHOD_INTERPOSE(void, foo, (int arg)) {
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...
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INTERPOSE_NEXT(foo)(arg) // call the original
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...
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}
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};
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IMPLEMENT_VMETHOD_INTERPOSE(my_hack, foo);
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void init() {
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my_hack::interpose_foo.apply()
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}
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*/
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#define DEFINE_VMETHOD_INTERPOSE(rtype, name, args) \
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typedef rtype (interpose_base::*interpose_ptr_##name)args; \
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static DFHack::VMethodInterposeLink<interpose_base,interpose_ptr_##name> interpose_##name; \
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rtype interpose_fn_##name args
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#define IMPLEMENT_VMETHOD_INTERPOSE(class,name) \
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DFHack::VMethodInterposeLink<class::interpose_base,class::interpose_ptr_##name> \
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class::interpose_##name(&class::interpose_base::name, &class::interpose_fn_##name);
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#define INTERPOSE_NEXT(name) (this->*interpose_##name.chain)
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class DFHACK_EXPORT VMethodInterposeLinkBase {
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/*
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These link objects try to:
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1) Allow multiple hooks into the same vmethod
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2) Auto-remove hooks when a plugin is unloaded.
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*/
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virtual_identity *host; // Class with the vtable
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int vmethod_idx;
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void *interpose_method; // Pointer to the code of the interposing method
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void *chain_mptr; // Pointer to the chain field below
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void *saved_chain; // Previous pointer to the code
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VMethodInterposeLinkBase *next, *prev; // Other hooks for the same method
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void set_chain(void *chain);
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public:
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VMethodInterposeLinkBase(virtual_identity *host, int vmethod_idx, void *interpose_method, void *chain_mptr);
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~VMethodInterposeLinkBase();
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bool is_applied() { return saved_chain != NULL; }
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bool apply();
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void remove();
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};
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template<class Base, class Ptr>
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class VMethodInterposeLink : public VMethodInterposeLinkBase {
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public:
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Ptr chain;
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operator Ptr () { return chain; }
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template<class Ptr2>
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VMethodInterposeLink(Ptr target, Ptr2 src)
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: VMethodInterposeLinkBase(
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&Base::_identity,
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vmethod_pointer_to_idx(target),
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method_pointer_to_addr(src),
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&chain
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)
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{ src = target; /* check compatibility */ }
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};
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}
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@ -0,0 +1,61 @@
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#include "Core.h"
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#include <Console.h>
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#include <Export.h>
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#include <PluginManager.h>
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#include <modules/Gui.h>
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#include <vector>
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#include <cstdio>
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#include <stack>
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#include <string>
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#include <cmath>
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#include <VTableInterpose.h>
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#include "df/graphic.h"
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#include "df/viewscreen_titlest.h"
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using std::vector;
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using std::string;
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using std::stack;
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using namespace DFHack;
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using df::global::gps;
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DFHACK_PLUGIN("vshook");
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struct title_hook : df::viewscreen_titlest {
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typedef df::viewscreen_titlest interpose_base;
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DEFINE_VMETHOD_INTERPOSE(void, render, ())
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{
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INTERPOSE_NEXT(render)();
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if (gps) {
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uint8_t *buf = gps->screen;
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int32_t *stp = gps->screentexpos;
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for (const char *p = "DFHack " DFHACK_VERSION; *p; p++) {
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*buf++ = *p; *buf++ = 7; *buf++ = 0; *buf++ = 1;
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*stp++ = 0;
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}
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}
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}
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};
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IMPLEMENT_VMETHOD_INTERPOSE(title_hook, render);
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DFhackCExport command_result plugin_init ( color_ostream &out, std::vector <PluginCommand> &commands)
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{
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if (gps)
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{
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if (!title_hook::interpose_render.apply())
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out.printerr("Could not interpose viewscreen_titlest::render\n");
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}
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return CR_OK;
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}
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DFhackCExport command_result plugin_shutdown ( color_ostream &out )
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{
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title_hook::interpose_render.remove();
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return CR_OK;
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}
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