Class: Win32::API

Inherits:

Object

• Object
• Win32::API

Defined in:

ext/win32/api.c

Defined Under Namespace

Classes: Callback, Error

Constant Summary

VERSION =

The version of this library, returned as a String

1.0.0

Instance Attribute Summary

• #dll_name ⇒ Object readonly

  The name of the DLL that exports the API function.

• #function_name ⇒ Object readonly

  The name of the function.

• #prototype ⇒ Object readonly

  The prototype, returned as an array of characters.

• #return_type ⇒ Object readonly

  The return type, returned as a single character, P, L, I, V or B.

Instance Method Summary

• #Win32::API ⇒ Object

  Calls the function pointer with the given arguments (if any).

• #Win32::API.new(function, prototype = 'V') ⇒ Object constructor

  Creates and returns a new Win32::API object.

Constructor Details

#Win32::API.new(function, prototype = 'V') ⇒ Object

Creates and returns a new Win32::API object. The function is the name of the Windows function.

The prototype is the function prototype for function. This can be a string or an array of characters. The possible valid characters are ‘I’ (integer), ‘L’ (long), ‘V’ (void), ‘P’ (pointer), or ‘K’ (callback). The default is void (‘V’).

The return argument is the return type for the function. The valid characters are the same as for the prototype. The default is ‘L’ (long).

The dll is the name of the DLL file that the function is exported from. The default is ‘kernel32’.

If the function cannot be found then an API::Error is raised (a subclass of RuntimeError).

# File 'ext/win32/api.c', line 143

static VALUE api_init(int argc, VALUE* argv, VALUE self)
{
   HMODULE hLibrary;
   FARPROC fProc;
   Win32API* ptr;
   int i;
   VALUE v_proc, v_proto, v_return, v_dll, v_bool, v_name;
   
   rb_scan_args(argc, argv, "13", &v_proc, &v_proto, &v_return, &v_dll);
   
   Data_Get_Struct(self, Win32API, ptr);

   /* Convert a string prototype to an array of characters */
   if(rb_respond_to(v_proto, rb_intern("split")))
      v_proto = rb_str_split(v_proto, "");

   /* Set an arbitrary limit of 16 parameters */
   if(16 < RARRAY(v_proto)->len)
      rb_raise(rb_eArgError, "too many parameters: %d\n", RARRAY(v_proto)->len);

   /* Convert a nil or empty prototype to 'V' (void) automatically */
   if(NIL_P(v_proto) || RARRAY(v_proto)->len == 0){
      v_proto = rb_ary_new();
      rb_ary_push(v_proto, rb_str_new2("V"));
   }
   
   /* Set the default dll to 'kernel32' */
   if(NIL_P(v_dll))
   	v_dll = rb_str_new2("kernel32");
   	
   /* Set the default return type to 'L' (DWORD) */
   if(NIL_P(v_return))
   	v_return = rb_str_new2("L");

   SafeStringValue(v_dll);
   SafeStringValue(v_proc);

   hLibrary = LoadLibrary(TEXT(RSTRING(v_dll)->ptr));

   /* The most likely cause of failure is a bad DLL load path */
   if(!hLibrary){
      rb_raise(cAPIError, "LoadLibrary() function failed for '%s': %s",
         RSTRING(v_dll)->ptr,
         StringError(GetLastError())
      );
   }

   ptr->library = hLibrary;

   /* Attempt to get the function.  If it fails, try again with an 'A'
    * appended.  If that fails, try again with a 'W' appended.  If that
    * still fails, raise an API::Error.
    */
   fProc = GetProcAddress(hLibrary, TEXT(RSTRING(v_proc)->ptr));

   if(!fProc){
      VALUE v_ascii = rb_str_new3(v_proc);
      v_ascii = rb_str_cat(v_ascii, "A", 1);
      fProc = GetProcAddress(hLibrary, TEXT(RSTRING(v_ascii)->ptr));

      if(!fProc){
         VALUE v_unicode = rb_str_new3(v_proc);
         v_unicode = rb_str_cat(v_unicode, "W", 1);
         fProc = GetProcAddress(hLibrary, TEXT(RSTRING(v_unicode)->ptr));

         if(!fProc){
            rb_raise(
               cAPIError,
               "GetProcAddress() failed for '%s', '%s' and '%s': %s",
               RSTRING(v_proc)->ptr,
               RSTRING(v_ascii)->ptr,
               RSTRING(v_unicode)->ptr,
               StringError(GetLastError())
            );
         }
      }
   }

   ptr->function = fProc;

   /* Push the numeric prototypes onto our int array for later use. */
   for(i = 0; i < RARRAY(v_proto)->len; i++){
      SafeStringValue(RARRAY(v_proto)->ptr[i]);
      switch(*(char*)StringValuePtr(RARRAY(v_proto)->ptr[i])){
         case 'L':
            ptr->prototype[i] = _T_LONG;
            break;
         case 'P':
            ptr->prototype[i] = _T_POINTER;
            break;
         case 'I': case 'B':
            ptr->prototype[i] = _T_INTEGER;
            break;
         case 'V':
            ptr->prototype[i] = _T_VOID;
            break;
         case 'K':
            ptr->prototype[i] = _T_CALLBACK;
            break;
         default:
            rb_raise(cAPIError, "Illegal prototype '%s'", RARRAY(v_proto)->ptr[i]);
      }
   }

   /* Store the return type for later use.  Automatically convert empty
    * strings or nil to type void.
    */
   if(NIL_P(v_return) || RSTRING(v_return)->len == 0){
      v_return = rb_str_new2("V");
      ptr->return_type = _T_VOID;
   }
   else{
      SafeStringValue(v_return);
      switch(*RSTRING(v_return)->ptr){
         case 'L':
            ptr->return_type = _T_LONG;
            break;
         case 'P':
            ptr->return_type = _T_POINTER;
            break;
         case 'I': case 'B':
            ptr->return_type = _T_INTEGER;
            break;
         case 'V':
            ptr->return_type = _T_VOID;
            break;
         default:
            rb_raise(cAPIError, "Illegal prototype '%s'", RARRAY(v_proto)->ptr[i]);
      }
   }

   rb_iv_set(self, "@dll_name", v_dll);
   rb_iv_set(self, "@function_name", v_proc);
   rb_iv_set(self, "@prototype", v_proto);
   rb_iv_set(self, "@return_type", v_return);

   return self;
}

Instance Attribute Details

#dll_name ⇒ Object (readonly)

The name of the DLL that exports the API function

#function_name ⇒ Object (readonly)

The name of the function

#prototype ⇒ Object (readonly)

The prototype, returned as an array of characters

#return_type ⇒ Object (readonly)

The return type, returned as a single character, P, L, I, V or B

Instance Method Details

#Win32::API ⇒ Object

Calls the function pointer with the given arguments (if any). Note that, while this method will catch some prototype mismatches (raising a TypeError in the process), it is not fulproof. It is ultimately your job to make sure the arguments match the prototype specified in the constructor.

For convenience, nil is converted to NULL, true is converted to TRUE (1) and false is converted to FALSE (0).

# File 'ext/win32/api.c', line 372

static VALUE api_call(int argc, VALUE* argv, VALUE self){
   VALUE v_proto, v_args, v_arg, v_return;
   Win32API* ptr;
   unsigned long return_value;
   int i = 0;

   struct{
      unsigned long params[16];
   } param;

   Data_Get_Struct(self, Win32API, ptr);

   rb_scan_args(argc, argv, "0*", &v_args);

   v_proto = rb_iv_get(self, "@prototype");

   /* For void prototypes, allow either no args or an explicit nil */
   if(RARRAY(v_proto)->len != RARRAY(v_args)->len){
      char* c = StringValuePtr(RARRAY(v_proto)->ptr[0]);
      if(!strcmp(c, "V")){
         rb_ary_push(v_args, Qnil);
      }
      else{
         rb_raise(rb_eArgError,
            "wrong number of parameters: expected %d, got %d",
            RARRAY(v_proto)->len, RARRAY(v_args)->len
         );
      }
   }

   for(i = 0; i < RARRAY(v_proto)->len; i++){
      v_arg = RARRAY(v_args)->ptr[i];

      /* Convert nil to NULL.  Otherwise convert as appropriate. */
      if(NIL_P(v_arg))
         param.params[i] = (unsigned long)NULL;
      else if(v_arg == Qtrue)
         param.params[i] = TRUE;
      else if(v_arg == Qfalse)
         param.params[i] = FALSE;
      else
         switch(ptr->prototype[i]){
            case _T_LONG:
               param.params[i] = NUM2ULONG(v_arg);
               break;
            case _T_INTEGER:
               param.params[i] = NUM2INT(v_arg);
               break;
            case _T_POINTER:
               if(FIXNUM_P(v_arg)){
                  param.params[i] = NUM2ULONG(v_arg);
               }
               else{
                  StringValue(v_arg);
                  rb_str_modify(v_arg);
                  param.params[i] = (unsigned long)StringValuePtr(v_arg);
               }
               break;
            case _T_CALLBACK:
               ActiveCallback = v_arg;
               param.params[i] = (LPARAM)CallbackFunction;	
               break;
            default:
               param.params[i] = NUM2ULONG(v_arg);
         }
   }

   /* Call the function, get the return value */
   return_value = ptr->function(param);

   /* Return the appropriate type based on the return type specified
    * in the constructor.
    */
   switch(ptr->return_type){
      case _T_INTEGER:
         v_return = INT2NUM(return_value);
         break;
      case _T_LONG:
         v_return = LONG2NUM(return_value);
         break;
      case _T_VOID:
         v_return = Qnil;
         break;
      case _T_POINTER:
         v_return = rb_str_new2((TCHAR*)return_value);
         break;
      default:
         v_return = INT2NUM(0);
   }

   return v_return;
}