/**
 * This file has no copyright assigned and is placed in the Public Domain.
 * This file is part of the w64 mingw-runtime package.
 * No warranty is given; refer to the file DISCLAIMER within this package.
 *
 * This file is derived from Microsoft implementation file delayhlp.cpp, which
 * is free for users to modify and derive.
 */
#define WIN32_LEAN_AND_MEAN
#include <windows.h>

#include <delayimp.h>

static size_t __strlen(const char *sz)
{
  const char *szEnd = sz;
  while(*szEnd++ != 0)
    ;
  return szEnd - sz - 1;
}

static int __memcmp(const void *pv1,const void *pv2,size_t cb)
{
  if(!cb)
    return 0;
  while(--cb && *(char *)pv1 == *(char *)pv2) {
    pv1 = ((char *)pv1) + 1;
    pv2 = ((char *)pv2) + 1;
  }
  return *((unsigned char *)pv1) - *((unsigned char *)pv2);
}

static void *__memcpy(void *pvDst,const void *pvSrc,size_t cb)
{
  void *pvRet = pvDst;
  while(cb--) {
    *(char *)pvDst = *(char *)pvSrc;
    pvDst = ((char *)pvDst) + 1;
    pvSrc = ((char *)pvSrc) + 1;
  }
  return pvRet;
}

static unsigned IndexFromPImgThunkData(PCImgThunkData pitdCur,PCImgThunkData pitdBase)
{
  return (unsigned) (pitdCur - pitdBase);
}

#define __ImageBase _image_base__
extern IMAGE_DOS_HEADER __ImageBase;

#define PtrFromRVA(RVA)   (((PBYTE)&__ImageBase) + (RVA))

typedef struct UnloadInfo *PUnloadInfo;
typedef struct UnloadInfo {
  PUnloadInfo puiNext;
  PCImgDelayDescr pidd;
} UnloadInfo;

static unsigned CountOfImports(PCImgThunkData pitdBase)
{
  unsigned cRet = 0;
  PCImgThunkData pitd = pitdBase;
  while(pitd->u1.Function) {
    pitd++;
    cRet++;
  }
  return cRet;
}

PUnloadInfo __puiHead = 0;

static UnloadInfo *add_ULI(PCImgDelayDescr pidd_)
{
    UnloadInfo *ret = (UnloadInfo *) LocalAlloc(LPTR,sizeof(UnloadInfo));
    ret->pidd = pidd_;
    ret->puiNext = __puiHead;
    __puiHead = ret;
}

static void del_ULI(UnloadInfo *p)
{
    if (p) {
        PUnloadInfo *ppui = &__puiHead;
        while(*ppui && *ppui!=p) {
          ppui = &((*ppui)->puiNext);
        }
        if(*ppui==p) *ppui = p->puiNext;
        LocalFree((void *)p);
    }
}

typedef struct InternalImgDelayDescr {
  DWORD grAttrs;
  LPCSTR szName;
  HMODULE *phmod;
  PImgThunkData pIAT;
  PCImgThunkData pINT;
  PCImgThunkData pBoundIAT;
  PCImgThunkData pUnloadIAT;
  DWORD dwTimeStamp;
} InternalImgDelayDescr;

typedef InternalImgDelayDescr *PIIDD;
typedef const InternalImgDelayDescr *PCIIDD;

static PIMAGE_NT_HEADERS WINAPI PinhFromImageBase(HMODULE hmod)
{
  return (PIMAGE_NT_HEADERS) (((PBYTE)(hmod)) + ((PIMAGE_DOS_HEADER)(hmod))->e_lfanew);
}

static void WINAPI OverlayIAT(PImgThunkData pitdDst,PCImgThunkData pitdSrc)
{
  __memcpy(pitdDst,pitdSrc,CountOfImports(pitdDst) * sizeof(IMAGE_THUNK_DATA));
}

static DWORD WINAPI TimeStampOfImage(PIMAGE_NT_HEADERS pinh)
{
  return pinh->FileHeader.TimeDateStamp;
}

static int WINAPI FLoadedAtPreferredAddress(PIMAGE_NT_HEADERS pinh,HMODULE hmod)
{
  return ((UINT_PTR)(hmod)) == pinh->OptionalHeader.ImageBase;
}

#if(defined(_X86_) && !defined(__x86_64))
#undef InterlockedExchangePointer
#define InterlockedExchangePointer(Target,Value) (PVOID)(LONG_PTR)InterlockedExchange((PLONG)(Target),(LONG)(LONG_PTR)(Value))
typedef unsigned long *PULONG_PTR;
#endif

FARPROC WINAPI __delayLoadHelper2(PCImgDelayDescr pidd,FARPROC *ppfnIATEntry)
{
  InternalImgDelayDescr idd = {
    pidd->grAttrs,(LPCTSTR) PtrFromRVA(pidd->rvaDLLName),(HMODULE *) PtrFromRVA(pidd->rvaHmod),
    (PImgThunkData) PtrFromRVA(pidd->rvaIAT), (PCImgThunkData) PtrFromRVA(pidd->rvaINT),
    (PCImgThunkData) PtrFromRVA(pidd->rvaBoundIAT), (PCImgThunkData) PtrFromRVA(pidd->rvaUnloadIAT),
    pidd->dwTimeStamp};
  DelayLoadInfo dli = {
    sizeof(DelayLoadInfo),pidd,ppfnIATEntry,idd.szName,{ 0},0,0,0
  };
  HMODULE hmod;
  unsigned iIAT, iINT;
  PCImgThunkData pitd;
  FARPROC pfnRet;
  
  if(!(idd.grAttrs & dlattrRva)) {
    PDelayLoadInfo rgpdli[1] = { &dli};
    RaiseException(VcppException(ERROR_SEVERITY_ERROR,ERROR_INVALID_PARAMETER),0,1,(PULONG_PTR)(rgpdli));
    return 0;
  }
  hmod = *idd.phmod;
  iIAT = IndexFromPImgThunkData((PCImgThunkData)(ppfnIATEntry),idd.pIAT);
  iINT = iIAT;
  pitd = &(idd.pINT[iINT]);

  dli.dlp.fImportByName = !IMAGE_SNAP_BY_ORDINAL(pitd->u1.Ordinal);
  if(dli.dlp.fImportByName)
    dli.dlp.szProcName =
      (LPCSTR)
      (
        ((PIMAGE_IMPORT_BY_NAME) PtrFromRVA(
        				     (RVA)((UINT_PTR)(pitd->u1.AddressOfData))
        				   )
        )->Name
      );
  else dli.dlp.dwOrdinal = (DWORD)(IMAGE_ORDINAL(pitd->u1.Ordinal));
  pfnRet = NULL;
  if(__pfnDliNotifyHook2) {
    pfnRet = ((*__pfnDliNotifyHook2)(dliStartProcessing,&dli));
    if(pfnRet!=NULL) goto HookBypass;
  }
  if(hmod==0) {
    if(__pfnDliNotifyHook2)
      hmod = (HMODULE) (((*__pfnDliNotifyHook2)(dliNotePreLoadLibrary,&dli)));
    if(hmod==0) hmod = LoadLibrary(dli.szDll);
    if(hmod==0) {
      dli.dwLastError = GetLastError();
      if(__pfnDliFailureHook2)
        hmod = (HMODULE) ((*__pfnDliFailureHook2)(dliFailLoadLib,&dli));
      if(hmod==0) {
	PDelayLoadInfo rgpdli[1] = { &dli};
	RaiseException(VcppException(ERROR_SEVERITY_ERROR,ERROR_MOD_NOT_FOUND),0,1,(PULONG_PTR)(rgpdli));
	return dli.pfnCur;
      }
    }
    HMODULE hmodT = (HMODULE)(InterlockedExchangePointer((PVOID *) idd.phmod,(PVOID)(hmod)));
    if(hmodT!=hmod) {
      if(pidd->rvaUnloadIAT) add_ULI(pidd);
    } else FreeLibrary(hmod);
  }
  dli.hmodCur = hmod;
  if(__pfnDliNotifyHook2) pfnRet = (*__pfnDliNotifyHook2)(dliNotePreGetProcAddress,&dli);
  if(pfnRet==0) {
    if(pidd->rvaBoundIAT && pidd->dwTimeStamp) {
      PIMAGE_NT_HEADERS pinh = (PIMAGE_NT_HEADERS) (PinhFromImageBase(hmod));
      if(pinh->Signature==IMAGE_NT_SIGNATURE &&
	TimeStampOfImage(pinh)==idd.dwTimeStamp &&
	FLoadedAtPreferredAddress(pinh,hmod)) {
	  pfnRet = (FARPROC) ((UINT_PTR)(idd.pBoundIAT[iIAT].u1.Function));
	  if(pfnRet!=0) goto SetEntryHookBypass;
      }
    }
    pfnRet = GetProcAddress(hmod,dli.dlp.szProcName);
  }
  if(!pfnRet) {
    dli.dwLastError = GetLastError();
    if(__pfnDliFailureHook2) pfnRet = (*__pfnDliFailureHook2)(dliFailGetProc,&dli);
    if(!pfnRet) {
      PDelayLoadInfo rgpdli[1] = { &dli};
      RaiseException(VcppException(ERROR_SEVERITY_ERROR,ERROR_PROC_NOT_FOUND),0,1,(PULONG_PTR)(rgpdli));
      pfnRet = dli.pfnCur;
    }
  }
SetEntryHookBypass:
  *ppfnIATEntry = pfnRet;
HookBypass:
  if(__pfnDliNotifyHook2) {
    dli.dwLastError = 0;
    dli.hmodCur = hmod;
    dli.pfnCur = pfnRet;
    (*__pfnDliNotifyHook2)(dliNoteEndProcessing,&dli);
  }
  return pfnRet;
}

WINBOOL WINAPI __FUnloadDelayLoadedDLL2(LPCSTR szDll)
{
  WINBOOL fRet = FALSE;
  PUnloadInfo pui = __puiHead;

  for(pui = __puiHead;pui;pui = pui->puiNext) {
    LPCSTR szName = (LPCTSTR) PtrFromRVA(pui->pidd->rvaDLLName);
    size_t cbName = __strlen(szName);
    if(cbName==__strlen(szDll) && __memcmp(szDll,szName,cbName)==0) break;
  }
  if(pui && pui->pidd->rvaUnloadIAT) {
    PCImgDelayDescr pidd = pui->pidd;
    HMODULE *phmod = (HMODULE *) PtrFromRVA(pidd->rvaHmod);
    HMODULE hmod = *phmod;
    OverlayIAT((PImgThunkData) PtrFromRVA(pidd->rvaIAT), (PCImgThunkData) PtrFromRVA(pidd->rvaUnloadIAT));
    FreeLibrary(hmod);
    *phmod = NULL;
    del_ULI((UnloadInfo *) pui);
    fRet = TRUE;
  }
  return fRet;
}

HRESULT WINAPI __HrLoadAllImportsForDll(LPCSTR szDll)
{
  HRESULT hrRet = HRESULT_FROM_WIN32(ERROR_MOD_NOT_FOUND);
  PIMAGE_NT_HEADERS pinh = PinhFromImageBase((HMODULE) (&__ImageBase));
  if(pinh->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_DELAY_IMPORT].Size) {
    PCImgDelayDescr pidd;
    pidd = (PCImgDelayDescr) PtrFromRVA(pinh->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_DELAY_IMPORT].VirtualAddress);
    while(pidd->rvaDLLName) {
      LPCSTR szDllCur = (LPCSTR) PtrFromRVA(pidd->rvaDLLName);
      size_t cchDllCur = __strlen(szDllCur);
      if(cchDllCur==__strlen(szDll) && __memcmp(szDll,szDllCur,cchDllCur)==0) break;
      pidd++;
    }
    if(pidd->rvaDLLName) {
      FARPROC *ppfnIATEntry = (FARPROC *) PtrFromRVA(pidd->rvaIAT);
      size_t cpfnIATEntries = CountOfImports((PCImgThunkData) (ppfnIATEntry));
      FARPROC *ppfnIATEntryMax = ppfnIATEntry + cpfnIATEntries;
      for(;ppfnIATEntry < ppfnIATEntryMax;ppfnIATEntry++) {
        __delayLoadHelper2(pidd,ppfnIATEntry);
      }
      hrRet = S_OK;
    }
  }
  return hrRet;
}