// Loads .dll/.so and
// in case of error it checks if .dll/.so was built for the
// same architecture as Hotspot is running on

void * os::dll_load(const char *name, char *ebuf, int ebuflen)
{

  {- -------------------------------------------
  (1) LoadLibrary() が成功すればそれを返す.
      ---------------------------------------- -}

      void * result = LoadLibrary(name);
      if (result != NULL)
      {
        return result;
      }

  {- -------------------------------------------
  (1) (以下は LoadLibrary() が失敗した場合の処理.
       失敗の原因を少し調べて分かりやすいエラーメッセージを返すようにしている.)
      ---------------------------------------- -}

      long errcode = GetLastError();
      if (errcode == ERROR_MOD_NOT_FOUND) {
        strncpy(ebuf, "Can't find dependent libraries", ebuflen-1);
        ebuf[ebuflen-1]='\0';
        return NULL;
      }

      // Parsing dll below
      // If we can read dll-info and find that dll was built
      // for an architecture other than Hotspot is running in
      // - then print to buffer "DLL was built for a different architecture"
      // else call getLastErrorString to obtain system error message

      // Read system error message into ebuf
      // It may or may not be overwritten below (in the for loop and just above)
      getLastErrorString(ebuf, (size_t) ebuflen);
      ebuf[ebuflen-1]='\0';
      int file_descriptor=::open(name, O_RDONLY | O_BINARY, 0);
      if (file_descriptor<0)
      {
        return NULL;
      }

      uint32_t signature_offset;
      uint16_t lib_arch=0;
      bool failed_to_get_lib_arch=
      (
        //Go to position 3c in the dll
        (os::seek_to_file_offset(file_descriptor,IMAGE_FILE_PTR_TO_SIGNATURE)<0)
        ||
        // Read loacation of signature
        (sizeof(signature_offset)!=
          (os::read(file_descriptor, (void*)&signature_offset,sizeof(signature_offset))))
        ||
        //Go to COFF File Header in dll
        //that is located after"signature" (4 bytes long)
        (os::seek_to_file_offset(file_descriptor,
          signature_offset+IMAGE_FILE_SIGNATURE_LENGTH)<0)
        ||
        //Read field that contains code of architecture
        // that dll was build for
        (sizeof(lib_arch)!=
          (os::read(file_descriptor, (void*)&lib_arch,sizeof(lib_arch))))
      );

      ::close(file_descriptor);
      if (failed_to_get_lib_arch)
      {
        // file i/o error - report getLastErrorString(...) msg
        return NULL;
      }

      typedef struct
      {
        uint16_t arch_code;
        char* arch_name;
      } arch_t;

      static const arch_t arch_array[]={
        {IMAGE_FILE_MACHINE_I386,      (char*)"IA 32"},
        {IMAGE_FILE_MACHINE_AMD64,     (char*)"AMD 64"},
        {IMAGE_FILE_MACHINE_IA64,      (char*)"IA 64"}
      };
      #if   (defined _M_IA64)
        static const uint16_t running_arch=IMAGE_FILE_MACHINE_IA64;
      #elif (defined _M_AMD64)
        static const uint16_t running_arch=IMAGE_FILE_MACHINE_AMD64;
      #elif (defined _M_IX86)
        static const uint16_t running_arch=IMAGE_FILE_MACHINE_I386;
      #else
        #error Method os::dll_load requires that one of following \
               is defined :_M_IA64,_M_AMD64 or _M_IX86
      #endif


      // Obtain a string for printf operation
      // lib_arch_str shall contain string what platform this .dll was built for
      // running_arch_str shall string contain what platform Hotspot was built for
      char *running_arch_str=NULL,*lib_arch_str=NULL;
      for (unsigned int i=0;i<ARRAY_SIZE(arch_array);i++)
      {
        if (lib_arch==arch_array[i].arch_code)
          lib_arch_str=arch_array[i].arch_name;
        if (running_arch==arch_array[i].arch_code)
          running_arch_str=arch_array[i].arch_name;
      }

      assert(running_arch_str,
        "Didn't find runing architecture code in arch_array");

      // If the architure is right
      // but some other error took place - report getLastErrorString(...) msg
      if (lib_arch == running_arch)
      {
        return NULL;
      }

      if (lib_arch_str!=NULL)
      {
        ::_snprintf(ebuf, ebuflen-1,
          "Can't load %s-bit .dll on a %s-bit platform",
          lib_arch_str,running_arch_str);
      }
      else
      {
        // don't know what architecture this dll was build for
        ::_snprintf(ebuf, ebuflen-1,
          "Can't load this .dll (machine code=0x%x) on a %s-bit platform",
          lib_arch,running_arch_str);
      }

      return NULL;
    }