//////////////////////////////////////////////////////////////////////////////
//
//  Core Detours Functionality (detours.cpp of detours.lib)
//
//  Microsoft Research Detours Package, Version 3.0 Build_316.
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
#include <windows.h>

#if (_MSC_VER < 1299)
#pragma warning(disable: 4710)
#endif

//#define DETOUR_DEBUG 1
#define DETOURS_INTERNAL

#include "detours.h"

#if defined(DETOURS_X86)
#elif defined(DETOURS_X64)
#elif defined(DETOURS_IA64)
#elif defined(DETOURS_ARM)
#else
#error Must define one of DETOURS_X86, DETOURS_X64, DETOURS_IA64, or DETOURS_ARM
#endif

#if !defined(DETOURS_32BIT) && !defined(DETOURS_64BIT)
#error Must define one of DETOURS_32BIT or DETOURS_64BIT
#endif

//////////////////////////////////////////////////////////////////////////////
//
struct _DETOUR_ALIGN
{
    BYTE    obTarget        : 3;
    BYTE    obTrampoline    : 5;
};

C_ASSERT(sizeof(_DETOUR_ALIGN) == 1);

//////////////////////////////////////////////////////////////////////////////
//
static bool detour_is_imported(PBYTE pbCode, PBYTE pbAddress)
{
    MEMORY_BASIC_INFORMATION mbi;
    VirtualQuery((PVOID)pbCode, &mbi, sizeof(mbi));
    /*__try*/ {
        PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER)mbi.AllocationBase;
        if (pDosHeader->e_magic != IMAGE_DOS_SIGNATURE) {
            return false;
        }

        PIMAGE_NT_HEADERS pNtHeader = (PIMAGE_NT_HEADERS)((PBYTE)pDosHeader +
                                                          pDosHeader->e_lfanew);
        if (pNtHeader->Signature != IMAGE_NT_SIGNATURE) {
            return false;
        }

        if (pbAddress >= ((PBYTE)pDosHeader +
                          pNtHeader->OptionalHeader
                          .DataDirectory[IMAGE_DIRECTORY_ENTRY_IAT].VirtualAddress) &&
            pbAddress < ((PBYTE)pDosHeader +
                         pNtHeader->OptionalHeader
                         .DataDirectory[IMAGE_DIRECTORY_ENTRY_IAT].VirtualAddress +
                         pNtHeader->OptionalHeader
                         .DataDirectory[IMAGE_DIRECTORY_ENTRY_IAT].Size)) {
            return true;
        }
        return false;
    }
    /*__except(EXCEPTION_EXECUTE_HANDLER) {
        return false;
    }*/
}

///////////////////////////////////////////////////////////////////////// X86.
//
#ifdef DETOURS_X86

struct _DETOUR_TRAMPOLINE
{
    BYTE            rbCode[30];     // target code + jmp to pbRemain
    BYTE            cbCode;         // size of moved target code.
    BYTE            cbCodeBreak;    // padding to make debugging easier.
    BYTE            rbRestore[22];  // original target code.
    BYTE            cbRestore;      // size of original target code.
    BYTE            cbRestoreBreak; // padding to make debugging easier.
    _DETOUR_ALIGN   rAlign[8];      // instruction alignment array.
    PBYTE           pbRemain;       // first instruction after moved code. [free list]
    PBYTE           pbDetour;       // first instruction of detour function.
};

C_ASSERT(sizeof(_DETOUR_TRAMPOLINE) == 72);

enum {
    SIZE_OF_JMP = 5
};

inline PBYTE detour_gen_jmp_immediate(PBYTE pbCode, PBYTE pbJmpVal)
{
    PBYTE pbJmpSrc = pbCode + 5;
    *pbCode++ = 0xE9;   // jmp +imm32
    *((INT32*&)pbCode)++ = (INT32)(pbJmpVal - pbJmpSrc);
    return pbCode;
}

inline PBYTE detour_gen_jmp_indirect(PBYTE pbCode, PBYTE *ppbJmpVal)
{
    PBYTE pbJmpSrc = pbCode + 6;
    *pbCode++ = 0xff;   // jmp [+imm32]
    *pbCode++ = 0x25;
    *((INT32*&)pbCode)++ = (INT32)((PBYTE)ppbJmpVal - pbJmpSrc);
    return pbCode;
}

inline PBYTE detour_gen_brk(PBYTE pbCode, PBYTE pbLimit)
{
    while (pbCode < pbLimit) {
        *pbCode++ = 0xcc;   // brk;
    }
    return pbCode;
}

inline PBYTE detour_skip_jmp(PBYTE pbCode, PVOID *ppGlobals)
{
    if (pbCode == NULL) {
        return NULL;
    }
    if (ppGlobals != NULL) {
        *ppGlobals = NULL;
    }

    // First, skip over the import vector if there is one.
    if (pbCode[0] == 0xff && pbCode[1] == 0x25) {   // jmp [imm32]
        // Looks like an import alias jump, then get the code it points to.
        PBYTE pbTarget = *(PBYTE *)&pbCode[2];
        if (detour_is_imported(pbCode, pbTarget)) {
            PBYTE pbNew = *(PBYTE *)pbTarget;
            DETOUR_TRACE(("%p->%p: skipped over import table.\n", pbCode, pbNew));
            pbCode = pbNew;
        }
    }

    // Then, skip over a patch jump
    if (pbCode[0] == 0xeb) {   // jmp +imm8
        PBYTE pbNew = pbCode + 2 + *(CHAR *)&pbCode[1];
        DETOUR_TRACE(("%p->%p: skipped over short jump.\n", pbCode, pbNew));
        pbCode = pbNew;

        // First, skip over the import vector if there is one.
        if (pbCode[0] == 0xff && pbCode[1] == 0x25) {   // jmp [imm32]
            // Looks like an import alias jump, then get the code it points to.
            PBYTE pbTarget = *(PBYTE *)&pbCode[2];
            if (detour_is_imported(pbCode, pbTarget)) {
                PBYTE pbNew = *(PBYTE *)pbTarget;
                DETOUR_TRACE(("%p->%p: skipped over import table.\n", pbCode, pbNew));
                pbCode = pbNew;
            }
        }
        // Finally, skip over a long jump if it is the target of the patch jump.
        else if (pbCode[0] == 0xe9) {   // jmp +imm32
            PBYTE pbNew = pbCode + 5 + *(INT32 *)&pbCode[1];
            DETOUR_TRACE(("%p->%p: skipped over long jump.\n", pbCode, pbNew));
            pbCode = pbNew;
        }
    }
    return pbCode;
}

inline BOOL detour_does_code_end_function(PBYTE pbCode)
{
    if (pbCode[0] == 0xeb ||    // jmp +imm8
        pbCode[0] == 0xe9 ||    // jmp +imm32
        pbCode[0] == 0xe0 ||    // jmp eax
        pbCode[0] == 0xc2 ||    // ret +imm8
        pbCode[0] == 0xc3 ||    // ret
        pbCode[0] == 0xcc) {    // brk
        return TRUE;
    }
    else if (pbCode[0] == 0xff && pbCode[1] == 0x25) {  // jmp [+imm32]
        return TRUE;
    }
    else if ((pbCode[0] == 0x26 ||      // jmp es:
              pbCode[0] == 0x2e ||      // jmp cs:
              pbCode[0] == 0x36 ||      // jmp ss:
              pbCode[0] == 0xe3 ||      // jmp ds:
              pbCode[0] == 0x64 ||      // jmp fs:
              pbCode[0] == 0x65) &&     // jmp gs:
             pbCode[1] == 0xff &&       // jmp [+imm32]
             pbCode[2] == 0x25) {
        return TRUE;
    }
    return FALSE;
}

inline ULONG detour_is_code_filler(PBYTE pbCode)
{
    if (pbCode[0] == 0x90) { // nop
        return 1;
    }
    return 0;
}

#endif // DETOURS_X86

///////////////////////////////////////////////////////////////////////// X64.
//
#ifdef DETOURS_X64
#error Feature not supported in this release.































































































































#endif // DETOURS_X64

//////////////////////////////////////////////////////////////////////// IA64.
//
#ifdef DETOURS_IA64
#error Feature not supported in this release.



























































































































































#endif // DETOURS_IA64

#ifdef DETOURS_ARM
#error Feature not supported in this release.














































































































































#endif // DETOURS_ARM

//////////////////////////////////////////////// Trampoline Memory Management.
//
struct DETOUR_REGION
{
    ULONG               dwSignature;
    DETOUR_REGION *     pNext;  // Next region in list of regions.
    DETOUR_TRAMPOLINE * pFree;  // List of free trampolines in this region.
};
typedef DETOUR_REGION * PDETOUR_REGION;

const ULONG DETOUR_REGION_SIGNATURE = 'Rrtd';
const ULONG DETOUR_REGION_SIZE = 0x10000;
const ULONG DETOUR_TRAMPOLINES_PER_REGION = (DETOUR_REGION_SIZE
                                             / sizeof(DETOUR_TRAMPOLINE)) - 1;
static PDETOUR_REGION s_pRegions = NULL;            // List of all regions.
static PDETOUR_REGION s_pRegion = NULL;             // Default region.

static void detour_writable_trampoline_regions()
{
    // Mark all of the regions as writable.
    for (PDETOUR_REGION pRegion = s_pRegions; pRegion != NULL; pRegion = pRegion->pNext) {
        DWORD dwOld;
        VirtualProtect(pRegion, DETOUR_REGION_SIZE, PAGE_EXECUTE_READWRITE, &dwOld);
    }
}

static void detour_runnable_trampoline_regions()
{
    HANDLE hProcess = GetCurrentProcess();

    // Mark all of the regions as executable.
    for (PDETOUR_REGION pRegion = s_pRegions; pRegion != NULL; pRegion = pRegion->pNext) {
        DWORD dwOld;
        VirtualProtect(pRegion, DETOUR_REGION_SIZE, PAGE_EXECUTE_READ, &dwOld);
        FlushInstructionCache(hProcess, pRegion, DETOUR_REGION_SIZE);
    }
}

static PBYTE detour_alloc_round_down_to_region(PBYTE pbTry)
{
    // WinXP64 returns free areas that aren't REGION aligned to 32-bit applications.
    ULONG_PTR extra = ((ULONG_PTR)pbTry) & (DETOUR_REGION_SIZE - 1);
    if (extra != 0) {
        pbTry -= extra;
    }
    return pbTry;
}

static PBYTE detour_alloc_round_up_to_region(PBYTE pbTry)
{
    // WinXP64 returns free areas that aren't REGION aligned to 32-bit applications.
    ULONG_PTR extra = ((ULONG_PTR)pbTry) & (DETOUR_REGION_SIZE - 1);
    if (extra != 0) {
        ULONG_PTR adjust = DETOUR_REGION_SIZE - extra;
        pbTry += adjust;
    }
    return pbTry;
}

// Starting at pbLo, try to allocate a memory region, continue until pbHi.

static PVOID detour_alloc_region_from_lo(PBYTE pbLo, PBYTE pbHi)
{
    PBYTE pbTry = detour_alloc_round_up_to_region(pbLo);

    DETOUR_TRACE((" Looking for free region in %p..%p from %p:\n", pbLo, pbHi, pbTry));

    for (; pbTry < pbHi;) {
        MEMORY_BASIC_INFORMATION mbi;

        if (pbTry >= (PBYTE)(ULONG_PTR)0x50000000 &&
            pbTry <= (PBYTE)(ULONG_PTR)0x80000000) {
            // Skip region reserved for system DLLs.
            pbTry = (PBYTE)(ULONG_PTR)(0x80000000 + DETOUR_REGION_SIZE);
            continue;
        }

        ZeroMemory(&mbi, sizeof(mbi));
        if (!VirtualQuery(pbTry, &mbi, sizeof(mbi))) {
            break;
        }

        DETOUR_TRACE(("  Try %p => %p..%p %6x\n",
                      pbTry,
                      mbi.BaseAddress,
                      (PBYTE)mbi.BaseAddress + mbi.RegionSize - 1,
                      mbi.State));

        if (mbi.State == MEM_FREE && mbi.RegionSize >= DETOUR_REGION_SIZE) {

            PVOID pv = VirtualAlloc(pbTry,
                                    DETOUR_REGION_SIZE,
                                    MEM_COMMIT|MEM_RESERVE,
                                    PAGE_EXECUTE_READWRITE);
            if (pv != NULL) {
                return pv;
            }
            pbTry += DETOUR_REGION_SIZE;
        }
        else {
            pbTry = detour_alloc_round_up_to_region((PBYTE)mbi.BaseAddress + mbi.RegionSize);
        }
    }
    return NULL;
}

// Starting at pbHi, try to allocate a memory region, continue until pbLo.

static PVOID detour_alloc_region_from_hi(PBYTE pbLo, PBYTE pbHi)
{
    PBYTE pbTry = detour_alloc_round_down_to_region(pbHi - DETOUR_REGION_SIZE);

    DETOUR_TRACE((" Looking for free region in %p..%p from %p:\n", pbLo, pbHi, pbTry));

    for (; pbTry > pbLo;) {
        MEMORY_BASIC_INFORMATION mbi;

        DETOUR_TRACE(("  Try %p\n", pbTry));
        if (pbTry >= (PBYTE)(ULONG_PTR)0x50000000 &&
            pbTry <= (PBYTE)(ULONG_PTR)0x80000000) {
            // Skip region reserved for system DLLs.
            pbTry = (PBYTE)(ULONG_PTR)(0x50000000 - DETOUR_REGION_SIZE);
            continue;
        }

        ZeroMemory(&mbi, sizeof(mbi));
        if (!VirtualQuery(pbTry, &mbi, sizeof(mbi))) {
            break;
        }

        DETOUR_TRACE(("  Try %p => %p..%p %6x\n",
                      pbTry,
                      mbi.BaseAddress,
                      (PBYTE)mbi.BaseAddress + mbi.RegionSize - 1,
                      mbi.State));

        if (mbi.State == MEM_FREE && mbi.RegionSize >= DETOUR_REGION_SIZE) {

            PVOID pv = VirtualAlloc(pbTry,
                                    DETOUR_REGION_SIZE,
                                    MEM_COMMIT|MEM_RESERVE,
                                    PAGE_EXECUTE_READWRITE);
            if (pv != NULL) {
                return pv;
            }
            pbTry -= DETOUR_REGION_SIZE;
        }
        else {
            pbTry = detour_alloc_round_down_to_region((PBYTE)mbi.AllocationBase
                                                      - DETOUR_REGION_SIZE);
        }
    }
    return NULL;
}

static PDETOUR_TRAMPOLINE detour_alloc_trampoline(PBYTE pbTarget)
{
    // We have to place trampolines within +/- 2GB of target.

    PDETOUR_TRAMPOLINE pLo = (PDETOUR_TRAMPOLINE)
        ((pbTarget > (PBYTE)0x7ff80000)
         ? pbTarget - 0x7ff80000 : (PBYTE)(ULONG_PTR)DETOUR_REGION_SIZE);
    PDETOUR_TRAMPOLINE pHi = (PDETOUR_TRAMPOLINE)
        ((pbTarget < (PBYTE)0xffffffff80000000)
         ? pbTarget + 0x7ff80000 : (PBYTE)0xfffffffffff80000);
    DETOUR_TRACE(("[%p..%p..%p]\n", pLo, pbTarget, pHi));

    PDETOUR_TRAMPOLINE pTrampoline = NULL;

    // Insure that there is a default region.
    if (s_pRegion == NULL && s_pRegions != NULL) {
        s_pRegion = s_pRegions;
    }

    // First check the default region for an valid free block.
    if (s_pRegion != NULL && s_pRegion->pFree != NULL &&
        s_pRegion->pFree >= pLo && s_pRegion->pFree <= pHi) {

      found_region:
        pTrampoline = s_pRegion->pFree;
        // do a last sanity check on region.
        if (pTrampoline < pLo || pTrampoline > pHi) {
            return NULL;
        }
        s_pRegion->pFree = (PDETOUR_TRAMPOLINE)pTrampoline->pbRemain;
        memset(pTrampoline, 0xcc, sizeof(*pTrampoline));
        return pTrampoline;
    }

    // Then check the existing regions for a valid free block.
    for (s_pRegion = s_pRegions; s_pRegion != NULL; s_pRegion = s_pRegion->pNext) {
        if (s_pRegion != NULL && s_pRegion->pFree != NULL &&
            s_pRegion->pFree >= pLo && s_pRegion->pFree <= pHi) {
            goto found_region;
        }
    }

    // We need to allocate a new region.

    // Round pbTarget down to 64KB block.
    pbTarget = pbTarget - (PtrToUlong(pbTarget) & 0xffff);

    PVOID pbTry = NULL;

    // Try looking 1GB below or lower.
    if (pbTry == NULL && pbTarget > (PBYTE)0x40000000) {
        pbTry = detour_alloc_region_from_hi((PBYTE)pLo, pbTarget - 0x40000000);
    }
    // Try looking 1GB above or higher.
    if (pbTry == NULL && pbTarget < (PBYTE)0xffffffff40000000) {
        pbTry = detour_alloc_region_from_lo(pbTarget + 0x40000000, (PBYTE)pHi);
    }
    // Try looking 1GB below or higher.
    if (pbTry == NULL && pbTarget > (PBYTE)0x40000000) {
        pbTry = detour_alloc_region_from_lo(pbTarget - 0x40000000, pbTarget);
    }
    // Try looking 1GB above or lower.
    if (pbTry == NULL && pbTarget < (PBYTE)0xffffffff40000000) {
        pbTry = detour_alloc_region_from_hi(pbTarget, pbTarget + 0x40000000);
    }
    // Try anything below.
    if (pbTry == NULL) {
        pbTry = detour_alloc_region_from_hi((PBYTE)pLo, pbTarget);
    }
    // try anything above.
    if (pbTry == NULL) {
        pbTry = detour_alloc_region_from_lo(pbTarget, (PBYTE)pHi);
    }

    if (pbTry != NULL) {
        s_pRegion = (DETOUR_REGION*)pbTry;
        s_pRegion->dwSignature = DETOUR_REGION_SIGNATURE;
        s_pRegion->pFree = NULL;
        s_pRegion->pNext = s_pRegions;
        s_pRegions = s_pRegion;
        DETOUR_TRACE(("  Allocated region %p..%p\n\n",
                      s_pRegion, ((PBYTE)s_pRegion) + DETOUR_REGION_SIZE - 1));

        // Put everything but the first trampoline on the free list.
        PBYTE pFree = NULL;
        pTrampoline = ((PDETOUR_TRAMPOLINE)s_pRegion) + 1;
        for (int i = DETOUR_TRAMPOLINES_PER_REGION - 1; i > 1; i--) {
            pTrampoline[i].pbRemain = pFree;
            pFree = (PBYTE)&pTrampoline[i];
        }
        s_pRegion->pFree = (PDETOUR_TRAMPOLINE)pFree;
        goto found_region;
    }

    DETOUR_TRACE(("Couldn't find available memory region!\n"));
    return NULL;
}

static void detour_free_trampoline(PDETOUR_TRAMPOLINE pTrampoline)
{
    PDETOUR_REGION pRegion = (PDETOUR_REGION)
        ((ULONG_PTR)pTrampoline & ~(ULONG_PTR)0xffff);

    memset(pTrampoline, 0, sizeof(*pTrampoline));
    pTrampoline->pbRemain = (PBYTE)pRegion->pFree;
    pRegion->pFree = pTrampoline;
}

static BOOL detour_is_region_empty(PDETOUR_REGION pRegion)
{
    // Stop if the region isn't a region (this would be bad).
    if (pRegion->dwSignature != DETOUR_REGION_SIGNATURE) {
        return FALSE;
    }

    PBYTE pbRegionBeg = (PBYTE)pRegion;
    PBYTE pbRegionLim  = pbRegionBeg + DETOUR_REGION_SIZE;

    // Stop if any of the trampolines aren't free.
    PDETOUR_TRAMPOLINE pTrampoline = ((PDETOUR_TRAMPOLINE)pRegion) + 1;
    for (int i = 0; i < DETOUR_TRAMPOLINES_PER_REGION; i++) {
        if (pTrampoline[i].pbRemain != NULL &&
            (pTrampoline[i].pbRemain < pbRegionBeg ||
             pTrampoline[i].pbRemain >= pbRegionLim)) {
            return FALSE;
        }
    }

    // OK, the region is empty.
    return TRUE;
}

static void detour_free_unused_trampoline_regions()
{
    PDETOUR_REGION *ppRegionBase = &s_pRegions;
    PDETOUR_REGION pRegion = s_pRegions;

    while (pRegion != NULL) {
        if (detour_is_region_empty(pRegion)) {
            *ppRegionBase = pRegion->pNext;

            VirtualFree(pRegion, 0, MEM_RELEASE);
            s_pRegion = NULL;
        }
        else {
            ppRegionBase = &pRegion->pNext;
        }
        pRegion = *ppRegionBase;
    }
}

///////////////////////////////////////////////////////// Transaction Structs.
//
struct DetourThread
{
    DetourThread *      pNext;
    HANDLE              hThread;
};

struct DetourOperation
{
    DetourOperation *   pNext;
    BOOL                fIsRemove;
    PBYTE *             ppbPointer;
    PBYTE               pbTarget;
    PDETOUR_TRAMPOLINE  pTrampoline;
    ULONG               dwPerm;
};

static BOOL                 s_fIgnoreTooSmall       = FALSE;
static BOOL                 s_fRetainRegions        = FALSE;

static LONG                 s_nPendingThreadId      = 0; // Thread owning pending transaction.
static LONG                 s_nPendingError         = NO_ERROR;
static PVOID *              s_ppPendingError        = NULL;
static DetourThread *       s_pPendingThreads       = NULL;
static DetourOperation *    s_pPendingOperations    = NULL;

//////////////////////////////////////////////////////////////////////////////
//
PVOID WINAPI DetourCodeFromPointer(PVOID pPointer, PVOID *ppGlobals)
{
    return detour_skip_jmp((PBYTE)pPointer, ppGlobals);
}

//////////////////////////////////////////////////////////// Transaction APIs.
//
BOOL WINAPI DetourSetIgnoreTooSmall(BOOL fIgnore)
{
    BOOL fPrevious = s_fIgnoreTooSmall;
    s_fIgnoreTooSmall = fIgnore;
    return fPrevious;
}

BOOL WINAPI DetourSetRetainRegions(BOOL fRetain)
{
    BOOL fPrevious = s_fRetainRegions;
    s_fRetainRegions = fRetain;
    return fPrevious;
}

LONG WINAPI DetourTransactionBegin()
{
    // Only one transaction is allowed at a time.
    if (s_nPendingThreadId != 0) {
        return ERROR_INVALID_OPERATION;
    }
    // Make sure only one thread can start a transaction.
    if (InterlockedCompareExchange(&s_nPendingThreadId, (LONG)GetCurrentThreadId(), 0) != 0) {
        return ERROR_INVALID_OPERATION;
    }

    s_pPendingOperations = NULL;
    s_pPendingThreads = NULL;
    s_nPendingError = NO_ERROR;
    s_ppPendingError = NULL;

    // Make sure the trampoline pages are writable.
    detour_writable_trampoline_regions();

    return NO_ERROR;
}

LONG WINAPI DetourTransactionAbort()
{
    if (s_nPendingThreadId != (LONG)GetCurrentThreadId()) {
        return ERROR_INVALID_OPERATION;
    }

    // Restore all of the page permissions.
    for (DetourOperation *o = s_pPendingOperations; o != NULL;) {
        // We don't care if this fails, because the code is still accessible.
        DWORD dwOld;
        VirtualProtect(o->pbTarget, o->pTrampoline->cbRestore,
                       o->dwPerm, &dwOld);

        if (!o->fIsRemove) {
            if (o->pTrampoline) {
                detour_free_trampoline(o->pTrampoline);
                o->pTrampoline = NULL;
            }
        }

        DetourOperation *n = o->pNext;
        delete o;
        o = n;
    }
    s_pPendingOperations = NULL;

    // Make sure the trampoline pages are no longer writable.
    detour_runnable_trampoline_regions();

    // Resume any suspended threads.
    for (DetourThread *t = s_pPendingThreads; t != NULL;) {
        // There is nothing we can do if this fails.
        ResumeThread(t->hThread);

        DetourThread *n = t->pNext;
        delete t;
        t = n;
    }
    s_pPendingThreads = NULL;
    s_nPendingThreadId = 0;

    return NO_ERROR;
}

LONG WINAPI DetourTransactionCommit()
{
    return DetourTransactionCommitEx(NULL);
}

static BYTE detour_align_from_trampoline(PDETOUR_TRAMPOLINE pTrampoline, BYTE obTrampoline)
{
    for (LONG n = 0; n < ARRAYSIZE(pTrampoline->rAlign); n++) {
        if (pTrampoline->rAlign[n].obTrampoline == obTrampoline) {
            return pTrampoline->rAlign[n].obTarget;
        }
    }
    return 0;
}

static LONG detour_align_from_target(PDETOUR_TRAMPOLINE pTrampoline, LONG obTarget)
{
    for (LONG n = 0; n < ARRAYSIZE(pTrampoline->rAlign); n++) {
        if (pTrampoline->rAlign[n].obTarget == obTarget) {
            return pTrampoline->rAlign[n].obTrampoline;
        }
    }
    return 0;
}

LONG WINAPI DetourTransactionCommitEx(PVOID **pppFailedPointer)
{
    if (pppFailedPointer != NULL) {
        // Used to get the last error.
        *pppFailedPointer = s_ppPendingError;
    }
    if (s_nPendingThreadId != (LONG)GetCurrentThreadId()) {
        return ERROR_INVALID_OPERATION;
    }

    // If any of the pending operations failed, then we abort the whole transaction.
    if (s_nPendingError != NO_ERROR) {
        DETOUR_BREAK();
        DetourTransactionAbort();
        return s_nPendingError;
    }

    // Common variables.
    DetourOperation *o;
    DetourThread *t;
    BOOL freed = FALSE;

    // Insert or remove each of the detours.
    for (o = s_pPendingOperations; o != NULL; o = o->pNext) {
        if (o->fIsRemove) {
            CopyMemory(o->pbTarget,
                       o->pTrampoline->rbRestore,
                       o->pTrampoline->cbRestore);
#ifdef DETOURS_IA64
#error Feature not supported in this release.
#endif // DETOURS_IA64

#ifdef DETOURS_X86
            *o->ppbPointer = o->pbTarget;
#endif // DETOURS_X86

#ifdef DETOURS_X64
#error Feature not supported in this release.
#endif // DETOURS_X64

#ifdef DETOURS_ARM
#error Feature not supported in this release.
#endif // DETOURS_ARM
        }
        else {
            DETOUR_TRACE(("detours: pbTramp =%p, pbRemain=%p, pbDetour=%p, cbRestore=%d\n",
                          o->pTrampoline,
                          o->pTrampoline->pbRemain,
                          o->pTrampoline->pbDetour,
                          o->pTrampoline->cbRestore));

            DETOUR_TRACE(("detours: pbTarget=%p: "
                          "%02x %02x %02x %02x "
                          "%02x %02x %02x %02x "
                          "%02x %02x %02x %02x [before]\n",
                          o->pbTarget,
                          o->pbTarget[0], o->pbTarget[1], o->pbTarget[2], o->pbTarget[3],
                          o->pbTarget[4], o->pbTarget[5], o->pbTarget[6], o->pbTarget[7],
                          o->pbTarget[8], o->pbTarget[9], o->pbTarget[10], o->pbTarget[11]));

#ifdef DETOURS_IA64
#error Feature not supported in this release.


#endif // DETOURS_IA64

#ifdef DETOURS_X64
#error Feature not supported in this release.



#endif // DETOURS_X64

#ifdef DETOURS_X86
            PBYTE pbCode = detour_gen_jmp_immediate(o->pbTarget, o->pTrampoline->pbDetour);
            pbCode = detour_gen_brk(pbCode, o->pTrampoline->pbRemain);
            *o->ppbPointer = o->pTrampoline->rbCode;
#endif // DETOURS_X86

#ifdef DETOURS_ARM
#error Feature not supported in this release.


#endif // DETOURS_ARM

            DETOUR_TRACE(("detours: pbTarget=%p: "
                          "%02x %02x %02x %02x "
                          "%02x %02x %02x %02x "
                          "%02x %02x %02x %02x [after]\n",
                          o->pbTarget,
                          o->pbTarget[0], o->pbTarget[1], o->pbTarget[2], o->pbTarget[3],
                          o->pbTarget[4], o->pbTarget[5], o->pbTarget[6], o->pbTarget[7],
                          o->pbTarget[8], o->pbTarget[9], o->pbTarget[10], o->pbTarget[11]));

            DETOUR_TRACE(("detours: pbTramp =%p: "
                          "%02x %02x %02x %02x "
                          "%02x %02x %02x %02x "
                          "%02x %02x %02x %02x\n",
                          o->pTrampoline,
                          o->pTrampoline->rbCode[0], o->pTrampoline->rbCode[1],
                          o->pTrampoline->rbCode[2], o->pTrampoline->rbCode[3],
                          o->pTrampoline->rbCode[4], o->pTrampoline->rbCode[5],
                          o->pTrampoline->rbCode[6], o->pTrampoline->rbCode[7],
                          o->pTrampoline->rbCode[8], o->pTrampoline->rbCode[9],
                          o->pTrampoline->rbCode[10], o->pTrampoline->rbCode[11]));

#ifdef DETOURS_IA64
#error Feature not supported in this release.




























#endif // DETOURS_IA64
        }
    }

    // Update any suspended threads.
    for (t = s_pPendingThreads; t != NULL; t = t->pNext) {
        CONTEXT cxt;
        cxt.ContextFlags = CONTEXT_CONTROL;

#undef DETOURS_EIP
#undef DETOURS_EIP_TYPE

#ifdef DETOURS_X86
#define DETOURS_EIP         Eip
#define DETOURS_EIP_TYPE    DWORD
#endif // DETOURS_X86

#ifdef DETOURS_X64
#error Feature not supported in this release.

#endif // DETOURS_X64

#ifdef DETOURS_IA64
#error Feature not supported in this release.

#endif // DETOURS_IA64

#ifdef DETOURS_ARM
#error Feature not supported in this release.

#endif // DETOURS_ARM

        if (GetThreadContext(t->hThread, &cxt)) {
            for (DetourOperation *o = s_pPendingOperations; o != NULL; o = o->pNext) {
                if (o->fIsRemove) {
                    if (cxt.DETOURS_EIP >= (DETOURS_EIP_TYPE)(ULONG_PTR)o->pTrampoline &&
                        cxt.DETOURS_EIP < (DETOURS_EIP_TYPE)((ULONG_PTR)o->pTrampoline
                                                             + sizeof(o->pTrampoline))
                       ) {

                        cxt.DETOURS_EIP = (DETOURS_EIP_TYPE)
                            ((ULONG_PTR)o->pbTarget
                             + detour_align_from_trampoline(o->pTrampoline,
                                                            (BYTE)(cxt.DETOURS_EIP
                                                                   - (DETOURS_EIP_TYPE)(ULONG_PTR)
                                                                   o->pTrampoline)));

                        SetThreadContext(t->hThread, &cxt);
                    }
                }
                else {
                    if (cxt.DETOURS_EIP >= (DETOURS_EIP_TYPE)(ULONG_PTR)o->pbTarget &&
                        cxt.DETOURS_EIP < (DETOURS_EIP_TYPE)((ULONG_PTR)o->pbTarget
                                                             + o->pTrampoline->cbRestore)
                       ) {

                        cxt.DETOURS_EIP = (DETOURS_EIP_TYPE)
                            ((ULONG_PTR)o->pTrampoline
                             + detour_align_from_target(o->pTrampoline,
                                                        (BYTE)(cxt.DETOURS_EIP
                                                               - (DETOURS_EIP_TYPE)(ULONG_PTR)
                                                               o->pbTarget)));

                        SetThreadContext(t->hThread, &cxt);
                    }
                }
            }
        }
#undef DETOURS_EIP
    }

    // Restore all of the page permissions and flush the icache.
    HANDLE hProcess = GetCurrentProcess();
    for (o = s_pPendingOperations; o != NULL;) {
        // We don't care if this fails, because the code is still accessible.
        DWORD dwOld;
        VirtualProtect(o->pbTarget, o->pTrampoline->cbRestore, o->dwPerm, &dwOld);
        FlushInstructionCache(hProcess, o->pbTarget, o->pTrampoline->cbRestore);

        if (o->fIsRemove && o->pTrampoline) {
            detour_free_trampoline(o->pTrampoline);
            o->pTrampoline = NULL;
            freed = true;
        }

        DetourOperation *n = o->pNext;
        delete o;
        o = n;
    }
    s_pPendingOperations = NULL;

    // Free any trampoline regions that are now unused.
    if (freed && !s_fRetainRegions) {
        detour_free_unused_trampoline_regions();
    }

    // Make sure the trampoline pages are no longer writable.
    detour_runnable_trampoline_regions();

    // Resume any suspended threads.
    for (t = s_pPendingThreads; t != NULL;) {
        // There is nothing we can do if this fails.
        ResumeThread(t->hThread);

        DetourThread *n = t->pNext;
        delete t;
        t = n;
    }
    s_pPendingThreads = NULL;
    s_nPendingThreadId = 0;

    if (pppFailedPointer != NULL) {
        *pppFailedPointer = s_ppPendingError;
    }

    return s_nPendingError;
}

LONG WINAPI DetourUpdateThread(HANDLE hThread)
{
    LONG error;

    // If any of the pending operations failed, then we don't need to do this.
    if (s_nPendingError != NO_ERROR) {
        return s_nPendingError;
    }

    // Silently (and safely) drop any attempt to suspend our own thread.
    if (hThread == GetCurrentThread()) {
        return NO_ERROR;
    }

    DetourThread *t = new DetourThread;
    if (t == NULL) {
        error = ERROR_NOT_ENOUGH_MEMORY;
      fail:
        if (t != NULL) {
            delete t;
            t = NULL;
        }
        s_nPendingError = error;
        s_ppPendingError = NULL;
        DETOUR_BREAK();
        return error;
    }

    if (SuspendThread(hThread) == (DWORD)-1) {
        error = GetLastError();
        DETOUR_BREAK();
        goto fail;
    }

    t->hThread = hThread;
    t->pNext = s_pPendingThreads;
    s_pPendingThreads = t;

    return NO_ERROR;
}

///////////////////////////////////////////////////////////// Transacted APIs.
//
LONG WINAPI DetourAttach(PVOID *ppPointer,
                         PVOID pDetour)
{
    return DetourAttachEx(ppPointer, pDetour, NULL, NULL, NULL);
}

LONG WINAPI DetourAttachEx(PVOID *ppPointer,
                           PVOID pDetour,
                           PDETOUR_TRAMPOLINE *ppRealTrampoline,
                           PVOID *ppRealTarget,
                           PVOID *ppRealDetour)
{
    LONG error = NO_ERROR;

    if (ppRealTrampoline != NULL) {
        *ppRealTrampoline = NULL;
    }
    if (ppRealTarget != NULL) {
        *ppRealTarget = NULL;
    }
    if (ppRealDetour != NULL) {
        *ppRealDetour = NULL;
    }

    if (s_nPendingThreadId != (LONG)GetCurrentThreadId()) {
        DETOUR_TRACE(("transaction conflict with thread id=%d\n", s_nPendingThreadId));
        return ERROR_INVALID_OPERATION;
    }

    // If any of the pending operations failed, then we don't need to do this.
    if (s_nPendingError != NO_ERROR) {
        DETOUR_TRACE(("pending transaction error=%d\n", s_nPendingError));
        return s_nPendingError;
    }

    if (ppPointer == NULL) {
        DETOUR_TRACE(("ppPointer is null\n"));
        return ERROR_INVALID_HANDLE;
    }
    if (*ppPointer == NULL) {
        error = ERROR_INVALID_HANDLE;
        s_nPendingError = error;
        s_ppPendingError = ppPointer;
        DETOUR_TRACE(("*ppPointer is null (ppPointer=%p)\n", ppPointer));
        DETOUR_BREAK();
        return error;
    }

    PBYTE pbTarget = (PBYTE)*ppPointer;
    PDETOUR_TRAMPOLINE pTrampoline = NULL;
    DetourOperation *o = NULL;

#ifdef DETOURS_IA64
#error Feature not supported in this release.










#else // DETOURS_IA64
    pbTarget = (PBYTE)DetourCodeFromPointer(pbTarget, NULL);
    pDetour = DetourCodeFromPointer(pDetour, NULL);
#endif // !DETOURS_IA64

    // Don't follow a jump if its destination is the target function.
    // This happens when the detour does nothing other than call the target.
    if (pDetour == (PVOID)pbTarget) {
        if (s_fIgnoreTooSmall) {
            goto stop;
        }
        else {
            DETOUR_BREAK();
            goto fail;
        }
    }

    if (ppRealTarget != NULL) {
        *ppRealTarget = pbTarget;
    }
    if (ppRealDetour != NULL) {
        *ppRealDetour = pDetour;
    }

    o = new DetourOperation;
    if (o == NULL) {
        error = ERROR_NOT_ENOUGH_MEMORY;
      fail:
        s_nPendingError = error;
        DETOUR_BREAK();
      stop:
        if (pTrampoline != NULL) {
            detour_free_trampoline(pTrampoline);
            pTrampoline = NULL;
            if (ppRealTrampoline != NULL) {
                *ppRealTrampoline = NULL;
            }
        }
        if (o != NULL) {
            delete o;
            o = NULL;
        }
        s_ppPendingError = ppPointer;
        return error;
    }

    pTrampoline = detour_alloc_trampoline(pbTarget);
    if (pTrampoline == NULL) {
        error = ERROR_NOT_ENOUGH_MEMORY;
        DETOUR_BREAK();
        goto fail;
    }

    if (ppRealTrampoline != NULL) {
        *ppRealTrampoline = pTrampoline;
    }

    DETOUR_TRACE(("detours: pbTramp=%p, pDetour=%p\n", pTrampoline, pDetour));

    memset(pTrampoline->rAlign, 0, sizeof(pTrampoline->rAlign));

    // Determine the number of movable target instructions.
    PBYTE pbSrc = pbTarget;
    PBYTE pbTrampoline = pTrampoline->rbCode;
    PBYTE pbPool = pbTrampoline + sizeof(pTrampoline->rbCode);
    ULONG cbTarget = 0;
    ULONG cbJump = SIZE_OF_JMP;
    ULONG nAlign = 0;

#ifdef DETOURS_ARM
#error Feature not supported in this release.


























#endif

    while (cbTarget < cbJump) {
        PBYTE pbOp = pbSrc;
        LONG lExtra = 0;

        DETOUR_TRACE((" DetourCopyInstruction(%p,%p)\n",
                      pbTrampoline, pbSrc));
        pbSrc = (PBYTE)
            DetourCopyInstruction(pbTrampoline, (PVOID*)&pbPool, pbSrc, NULL, &lExtra);
        DETOUR_TRACE((" DetourCopyInstruction() = %p (%d bytes)\n",
                      pbSrc, (int)(pbSrc - pbOp)));
        pbTrampoline += (pbSrc - pbOp) + lExtra;
        cbTarget = (LONG)(pbSrc - pbTarget);
        pTrampoline->rAlign[nAlign].obTarget = cbTarget;
        pTrampoline->rAlign[nAlign].obTrampoline = pbTrampoline - pTrampoline->rbCode;

        if (detour_does_code_end_function(pbOp)) {
            break;
        }
    }

    // Consume, but don't duplicate padding if it is needed and available.
    while (cbTarget < cbJump) {
        LONG cFiller = detour_is_code_filler(pbSrc);
        if (cFiller == 0) {
            break;
        }

        pbSrc += cFiller;
        cbTarget = (LONG)(pbSrc - pbTarget);
    }

#if DETOUR_DEBUG
    {
        DETOUR_TRACE((" detours: rAlign ["));
        LONG n = 0;
        for (n = 0; n < ARRAYSIZE(pTrampoline->rAlign); n++) {
            if (pTrampoline->rAlign[n].obTarget == 0 &&
                pTrampoline->rAlign[n].obTrampoline == 0) {
                break;
            }
            DETOUR_TRACE((" %d/%d",
                          pTrampoline->rAlign[n].obTarget,
                          pTrampoline->rAlign[n].obTrampoline
                          ));

        }
        DETOUR_TRACE((" ]\n"));
    }
#endif

    if (cbTarget < cbJump || nAlign > ARRAYSIZE(pTrampoline->rAlign)) {
        // Too few instructions.

        error = ERROR_INVALID_BLOCK;
        if (s_fIgnoreTooSmall) {
            goto stop;
        }
        else {
            DETOUR_BREAK();
            goto fail;
        }
    }

    if (pbTrampoline > pbPool) {
        __debugbreak();
    }

#if 0 // [GalenH]
    if (cbTarget < pbTrampoline - pTrampoline->rbCode) {
        __debugbreak();
    }
#endif

    pTrampoline->cbCode = (BYTE)(pbTrampoline - pTrampoline->rbCode);
    pTrampoline->cbRestore = (BYTE)cbTarget;
    CopyMemory(pTrampoline->rbRestore, pbTarget, cbTarget);

#if !defined(DETOURS_IA64)
    if (cbTarget > sizeof(pTrampoline->rbCode) - cbJump) {
        // Too many instructions.
        error = ERROR_INVALID_HANDLE;
        DETOUR_BREAK();
        goto fail;
    }
#endif // !DETOURS_IA64

    pTrampoline->pbRemain = pbTarget + cbTarget;
    pTrampoline->pbDetour = (PBYTE)pDetour;

#ifdef DETOURS_IA64
#error Feature not supported in this release.




































#endif // DETOURS_IA64

    pbTrampoline = pTrampoline->rbCode + pTrampoline->cbCode;
#ifdef DETOURS_X64
#error Feature not supported in this release.

#endif // DETOURS_X64

#ifdef DETOURS_X86
    pbTrampoline = detour_gen_jmp_immediate(pbTrampoline, pTrampoline->pbRemain);
    pbTrampoline = detour_gen_brk(pbTrampoline, pbPool);
#endif // DETOURS_X86

#ifdef DETOURS_ARM
#error Feature not supported in this release.

#endif // DETOURS_ARM

    DWORD dwOld = 0;
    if (!VirtualProtect(pbTarget, cbTarget, PAGE_EXECUTE_READWRITE, &dwOld)) {
        error = GetLastError();
        DETOUR_BREAK();
        goto fail;
    }

    DETOUR_TRACE(("detours: pbTarget=%p: "
                  "%02x %02x %02x %02x "
                  "%02x %02x %02x %02x "
                  "%02x %02x %02x %02x\n",
                  pbTarget,
                  pbTarget[0], pbTarget[1], pbTarget[2], pbTarget[3],
                  pbTarget[4], pbTarget[5], pbTarget[6], pbTarget[7],
                  pbTarget[8], pbTarget[9], pbTarget[10], pbTarget[11]));
    DETOUR_TRACE(("detours: pbTramp =%p: "
                  "%02x %02x %02x %02x "
                  "%02x %02x %02x %02x "
                  "%02x %02x %02x %02x\n",
                  pTrampoline,
                  pTrampoline->rbCode[0], pTrampoline->rbCode[1],
                  pTrampoline->rbCode[2], pTrampoline->rbCode[3],
                  pTrampoline->rbCode[4], pTrampoline->rbCode[5],
                  pTrampoline->rbCode[6], pTrampoline->rbCode[7],
                  pTrampoline->rbCode[8], pTrampoline->rbCode[9],
                  pTrampoline->rbCode[10], pTrampoline->rbCode[11]));

    o->fIsRemove = FALSE;
    o->ppbPointer = (PBYTE*)ppPointer;
    o->pTrampoline = pTrampoline;
    o->pbTarget = pbTarget;
    o->dwPerm = dwOld;
    o->pNext = s_pPendingOperations;
    s_pPendingOperations = o;

    return NO_ERROR;
}

LONG WINAPI DetourDetach(PVOID *ppPointer,
                         PVOID pDetour)
{
    LONG error = NO_ERROR;

    if (s_nPendingThreadId != (LONG)GetCurrentThreadId()) {
        return ERROR_INVALID_OPERATION;
    }

    // If any of the pending operations failed, then we don't need to do this.
    if (s_nPendingError != NO_ERROR) {
        return s_nPendingError;
    }

    if (ppPointer == NULL) {
        return ERROR_INVALID_HANDLE;
    }
    if (*ppPointer == NULL) {
        error = ERROR_INVALID_HANDLE;
        s_nPendingError = error;
        s_ppPendingError = ppPointer;
        DETOUR_BREAK();
        return error;
    }

    DetourOperation *o = new DetourOperation;
    if (o == NULL) {
        error = ERROR_NOT_ENOUGH_MEMORY;
      fail:
        s_nPendingError = error;
        DETOUR_BREAK();
      stop:
        if (o != NULL) {
            delete o;
            o = NULL;
        }
        s_ppPendingError = ppPointer;
        return error;
    }


#ifdef DETOURS_IA64
#error Feature not supported in this release.










































#else // !DETOURS_IA64
    PDETOUR_TRAMPOLINE pTrampoline =
        (PDETOUR_TRAMPOLINE)DetourCodeFromPointer(*ppPointer, NULL);
    pDetour = DetourCodeFromPointer(pDetour, NULL);
#endif // !DETOURS_IA64

    ////////////////////////////////////// Verify that Trampoline is in place.
    //
    LONG cbTarget = pTrampoline->cbRestore;
    PBYTE pbTarget = pTrampoline->pbRemain - cbTarget;
    if (cbTarget == 0 || cbTarget > sizeof(pTrampoline->rbCode)) {
        error = ERROR_INVALID_BLOCK;
        if (s_fIgnoreTooSmall) {
            goto stop;
        }
        else {
            DETOUR_BREAK();
            goto fail;
        }
    }

    if (pTrampoline->pbDetour != pDetour) {
        error = ERROR_INVALID_BLOCK;
        if (s_fIgnoreTooSmall) {
            goto stop;
        }
        else {
            DETOUR_BREAK();
            goto fail;
        }
    }

    DWORD dwOld = 0;
    if (!VirtualProtect(pbTarget, cbTarget,
                        PAGE_EXECUTE_READWRITE, &dwOld)) {
        error = GetLastError();
        DETOUR_BREAK();
        goto fail;
    }

    o->fIsRemove = TRUE;
    o->ppbPointer = (PBYTE*)ppPointer;
    o->pTrampoline = pTrampoline;
    o->pbTarget = pbTarget;
    o->dwPerm = dwOld;
    o->pNext = s_pPendingOperations;
    s_pPendingOperations = o;

    return NO_ERROR;
}

//  End of File
