//从内存中加载DLL DELPHI版   unit MemLibrary;  
interface  
uses  
Windows;  
  
function memLoadLibrary(pLib: Pointer): DWord;  
function memGetProcAddress(dwLibHandle: DWord; pFunctionName: PChar): Pointer; stdcall;  
function memFreeLibrary(dwHandle: DWord): Boolean;  
  
implementation  
procedure ChangeReloc(baseorgp, basedllp, relocp: pointer; size: cardinal);  
type  
    TRelocblock = record  
        vaddress: integer;  
        size: integer;  
    end;  
    PRelocblock = ^TRelocblock;  
var  
    myreloc: PRelocblock;  
    reloccount: integer;  
    startp: ^word;  
    i: cardinal;  
    p: ^cardinal;  
    dif: cardinal;  
begin  
    myreloc := relocp;  
    dif := cardinal(basedllp)-cardinal(baseorgp);  
    startp := pointer(cardinal(relocp)+8);  
    while myreloc^.vaddress <> 0 do  
    begin  
      reloccount := (myreloc^.size-8) div sizeof(word);  
      for i := 0 to reloccount-1 do  
      begin  
        if (startp^ xor $3000 < $1000) then  
        begin  
          p := pointer(myreloc^.vaddress+startp^ mod $3000+integer(basedllp));  
          p^ := p^+dif;  
        end;  
        startp := pointer(cardinal(startp)+sizeof(word));  
      end;  
      myreloc := pointer(startp);  
      startp := pointer(cardinal(startp)+8);  
    end;  
end;  
procedure CreateImportTable(dllbasep, importp: pointer); stdcall;  
type  
    timportblock = record  
          Characteristics: cardinal;  
          TimeDateStamp: cardinal;  
          ForwarderChain: cardinal;  
          Name: pchar;  
          FirstThunk: pointer;  
    end;  
    pimportblock = ^timportblock;  
var  
    myimport: pimportblock;  
    thunksread, thunkswrite: ^pointer;  
    dllname: pchar;  
    dllh: thandle;  
    old: cardinal;  
begin  
    myimport := importp;  
    while (myimport^.FirstThunk <> nil) and (myimport^.Name <> nil) do  
    begin  
      dllname := pointer(integer(dllbasep)+integer(myimport^.name));  
      dllh := LoadLibrary(dllname);  
      thunksread := pointer(integer(myimport^.FirstThunk)+integer(dllbasep));  
      thunkswrite := thunksread;  
      if integer(myimport^.TimeDateStamp) = -1 then  
        thunksread := pointer(integer(myimport^.Characteristics)+integer(dllbasep));  
      while (thunksread^ <> nil) do  
      begin  
        if VirtualProtect(thunkswrite,4,PAGE_EXECUTE_READWRITE,old) then  
        begin  
          if (cardinal(thunksread^) and $80000000 <> 0) then  
          thunkswrite^ := GetProcAddress(dllh,pchar(cardinal(thunksread^) and $FFFF)) else  
          thunkswrite^ := GetProcAddress(dllh,pchar(integer(dllbasep)+integer(thunksread^)+2));  
          VirtualProtect(thunkswrite,4,old,old);  
        end;  
        inc(thunksread,1);  
        inc(thunkswrite,1);  
      end;  
      myimport := pointer(integer(myimport)+sizeof(timportblock));  
    end;  
end;  
  
function memLoadLibrary(pLib: Pointer): DWord;  
var  
DllMain    : function (dwHandle, dwReason, dwReserved: DWord): DWord; stdcall;  
IDH        : PImageDosHeader;  
INH        : PImageNtHeaders;  
SEC        : PImageSectionHeader;  
dwSecCount : DWord;  
dwLen      : DWord;  
dwmemsize : DWord;  
i          : Integer;  
pAll       : Pointer;  
begin  
Result := 0;  
IDH := pLib;  
if isBadReadPtr(IDH, SizeOf(TImageDosHeader)) or (IDH^.e_magic <> IMAGE_DOS_SIGNATURE) then  
    Exit;  
INH := pointer(cardinal(pLib)+cardinal(IDH^._lfanew));  
if isBadReadPtr(INH, SizeOf(TImageNtHeaders)) or (INH^.Signature <> IMAGE_NT_SIGNATURE) then  
    Exit;  
// if (pReserved <> nil) then  
//    dwLen := Length(pReserved)+1  
// else  
    dwLen := 0;  
SEC := Pointer(Integer(INH)+SizeOf(TImageNtHeaders));  
dwMemSize := INH^.OptionalHeader.SizeOfImage;  
if (dwMemSize = 0) then Exit;  
pAll := VirtualAlloc(nil,dwMemSize+dwLen,MEM_COMMIT or MEM_RESERVE,PAGE_EXECUTE_READWRITE);  
if (pAll = nil) then Exit;  
dwSecCount := INH^.FileHeader.NumberOfSections;  
CopyMemory(pAll,IDH,DWord(SEC)-DWord(IDH)+dwSecCount*SizeOf(TImageSectionHeader));  
// CopyMemory(Pointer(DWord(pAll) + dwMemSize),pReserved,dwLen-1);  
CopyMemory(Pointer(DWord(pAll) + dwMemSize),nil,dwLen-1);  
for i := 0 to dwSecCount-1 do  
begin  
    CopyMemory(Pointer(DWord(pAll)+SEC^.VirtualAddress),  
          Pointer(DWord(pLib)+DWord(SEC^.PointerToRawData)),  
          SEC^.SizeOfRawData);  
    SEC := Pointer(Integer(SEC)+SizeOf(TImageSectionHeader));  
end;  
if (INH^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].VirtualAddress <> 0) then  
    ChangeReloc(Pointer(INH^.OptionalHeader.ImageBase),  
          pAll,  
          Pointer(DWord(pAll)+INH^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].VirtualAddress),  
          INH^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].Size);  
CreateImportTable(pAll, Pointer(DWord(pAll)+INH^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress));  
@DllMain := Pointer(INH^.OptionalHeader.AddressOfEntryPoint+DWord(pAll));  
// if (INH^.OptionalHeader.AddressOfEntryPoint <> 0) and (bDllMain) then  
if INH^.OptionalHeader.AddressOfEntryPoint <> 0 then  
begin  
    try  
//      if (pReserved <> nil) then  
//        DllMain(DWord(pAll),DLL_PROCESS_ATTACH,DWord(pAll)+dwMemSize)  
//      else  
        DllMain(DWord(pAll),DLL_PROCESS_ATTACH,0);  
    except  
    end;  
end;  
Result := DWord(pAll);  
end;  
  
function memFreeLibrary(dwHandle: DWord): Boolean;  
var  
IDH: PImageDosHeader;  
INH: PImageNTHeaders;  
begin  
Result := false;  
if (dwHandle = 0) then  
    Exit;  
IDH := Pointer(dwHandle);  
if (IDH^.e_magic <> IMAGE_DOS_SIGNATURE) then  
    Exit;  
INH := Pointer(DWord(IDH^._lfanew)+DWord(IDH));  
if (INH^.Signature <> IMAGE_NT_SIGNATURE) then  
    Exit;  
if VirtualFree(Pointer(dwHandle),INH^.OptionalHeader.SizeOfImage,MEM_DECOMMIT) then  
    Result := True;  
end;  
  
function memGetProcAddress(dwLibHandle: DWord; pFunctionName: PChar): Pointer; stdcall;  
var  
NtHeader          : PImageNtHeaders;  
DosHeader          : PImageDosHeader;  
DataDirectory      : PImageDataDirectory;  
ExportDirectory    : PImageExportDirectory;  
i          : Integer;  
iExportOrdinal     : Integer;  
ExportName         : String;  
dwPosDot          : DWord;  
dwNewmodule        : DWord;  
pFirstExportName   : Pointer;  
pFirstExportAddress: Pointer;  
pFirstExportOrdinal: Pointer;  
pExportAddr        : PDWord;  
pExportNameNow     : PDWord;  
pExportOrdinalNow : PWord;  
begin  
Result := nil;  
if pFunctionName = nil then Exit;  
DosHeader := Pointer(dwLibHandle);  
if isBadReadPtr(DosHeader,sizeof(TImageDosHeader)) or (DosHeader^.e_magic <> IMAGE_DOS_SIGNATURE) then  
    Exit; {Wrong PE (DOS) Header}  
NtHeader := Pointer(DWord(DosHeader^._lfanew)+DWord(DosHeader));  
if isBadReadPtr(NtHeader, sizeof(TImageNTHeaders)) or (NtHeader^.Signature <> IMAGE_NT_SIGNATURE) then  
    Exit; {Wrong PW (NT) Header}  
DataDirectory := @NtHeader^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];  
if (DataDirectory = nil) or (DataDirectory^.VirtualAddress = 0) then  
    Exit; {Library has no exporttable}  
ExportDirectory := Pointer(DWord(DosHeader) + DWord(DataDirectory^.VirtualAddress));  
if isBadReadPtr(ExportDirectory,SizeOf(TImageExportDirectory)) then  
    Exit;  
pFirstExportName := Pointer(DWord(ExportDirectory^.AddressOfNames)+DWord(DosHeader));  
pFirstExportOrdinal := Pointer(DWord(ExportDirectory^.AddressOfNameOrdinals)+DWord(DosHeader));  
pFirstExportAddress := Pointer(DWord(ExportDirectory^.AddressOfFunctions)+DWord(DosHeader));  
if (integer(pFunctionName) > $FFFF) then {is FunctionName a PChar?}  
begin  
    iExportOrdinal := -1;          {if we dont find the correct ExportOrdinal}  
    for i := 0 to ExportDirectory^.NumberOfNames-1 do {for each export do}  
    begin  
      pExportNameNow := Pointer(Integer(pFirstExportName)+SizeOf(Pointer)*i);  
      if (not isBadReadPtr(pExportNameNow,SizeOf(DWord))) then  
      begin  
        ExportName := PChar(pExportNameNow^+ DWord(DosHeader));  
        if (ExportName = pFunctionName) then {is it the export we search? Calculate the ordinal.}  
        begin  
          pExportOrdinalNow := Pointer(Integer(pFirstExportOrdinal)+SizeOf(Word)*i);  
          if (not isBadReadPtr(pExportOrdinalNow,SizeOf(Word))) then  
          iExportOrdinal := pExportOrdinalNow^;  
        end;  
      end;  
    end;  
end else{no PChar, calculate the ordinal directly}  
    iExportOrdinal := DWord(pFunctionName)-DWord(ExportDirectory^.Base);  
if (iExportOrdinal < 0) or (iExportOrdinal > Integer(ExportDirectory^.NumberOfFunctions)) then  
    Exit; {havent found the ordinal}  
pExportAddr := Pointer(iExportOrdinal*4+Integer(pFirstExportAddress));  
if (isBadReadPtr(pExportAddr,SizeOf(DWord))) then  
    Exit;  
{Is the Export outside the ExportSection? If not its NT spezific forwared function}  
if (pExportAddr^ < DWord(DataDirectory^.VirtualAddress)) or  
     (pExportAddr^ > DWord(DataDirectory^.VirtualAddress+DataDirectory^.Size)) then  
begin  
    if (pExportAddr^ <> 0) then {calculate export address}  
      Result := Pointer(pExportAddr^+DWord(DosHeader));  
end  
else  
begin {forwarded function (like kernel32.EnterCriticalSection -> NTDLL.RtlEnterCriticalSection)}  
    ExportName := PChar(dwLibHandle+pExportAddr^);  
    dwPosDot := Pos('.',ExportName);  
    if (dwPosDot > 0) then  
    begin  
      dwNewModule := GetModuleHandle(PChar(Copy(ExportName,1,dwPosDot-1)));  
      if (dwNewModule = 0) then  
        dwNewModule := LoadLibrary(PChar(Copy(ExportName,1,dwPosDot-1)));  
      if (dwNewModule <> 0) then  
        result := GetProcAddressX(dwNewModule,PChar(Copy(ExportName,dwPosDot+1,Length(ExportName))));  
    end;  
end;  
end;  
end.  

转自：http://blog.csdn.net/aroc_lo/archive/2010/09/25/5904241.aspx