Class: Win32::API

Inherits:

Object

• Object
• Win32::API

Defined in:

ext/win32/api.c

Direct Known Subclasses

Function

Defined Under Namespace

Classes: Callback, Error, Function, LoadLibraryError, PrototypeError

Constant Summary

VERSION =

The version of the win32-api library

1.4.8

Instance Attribute Summary

• #dll_name ⇒ Object readonly

  The name of the DLL that exports the API function.

• #effective_function_name ⇒ Object readonly

  The name of the actual function that is returned by the constructor.

• #function_name ⇒ Object readonly

  The name of the function passed to the constructor.

• #prototype ⇒ Object readonly

  The prototype, returned as an array of characters.

• #return_type ⇒ Object readonly

  The return type, returned as a single character, S, 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), ‘K’ (callback) or ‘S’ (string).

The default is void (‘V’).

Constant (const char*) strings should use ‘S’. Pass by reference string buffers should use ‘P’. The former is faster, but cannot be modified.

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).

Example:

require 'win32/api'
include Win32

buf = 0.chr * 260
len = [buf.length].pack('L')

GetUserName = API.new('GetUserName', 'PP', 'I', 'advapi32')
GetUserName.call(buf, len)

puts buf.strip

# File 'ext/win32/api.c', line 234

static VALUE api_init(int argc, VALUE* argv, VALUE self)
{
   HMODULE hLibrary;
   FARPROC fProc;
   Win32API* ptr;
   int i;
   const char* first  = "A";
   const char* second = "W";
   VALUE v_proc, v_proto, v_return, v_dll;

   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, "");

   // Convert a nil or empty prototype to 'V' (void) automatically
   if(NIL_P(v_proto) || RARRAY_LEN(v_proto) == 0){
      v_proto = rb_ary_new();
      rb_ary_push(v_proto, rb_str_new2("V"));
   }

   // Set an arbitrary limit of 20 parameters
   if(20 < RARRAY_LEN(v_proto))
      rb_raise(rb_eArgError, "too many parameters: %d", RARRAY_LEN(v_proto));

   // 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_PTR(v_dll)));

   // The most likely cause of failure is a bad DLL load path
   if(!hLibrary){
      rb_raise(cAPILoadError, "LoadLibrary() function failed for '%s': %s",
         RSTRING_PTR(v_dll),
         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::LoadLibraryError.
    */

   fProc = GetProcAddress(hLibrary, TEXT(RSTRING_PTR(v_proc)));

   // Skip the ANSI and Wide function checks for MSVCRT functions.
   if(!fProc){
      if(strstr(RSTRING_PTR(v_dll), "msvcr")){
         rb_raise(
            cAPILoadError,
            "Unable to load function '%s'",
            RSTRING_PTR(v_proc)
         );
      }
      else{
         VALUE v_ascii = rb_str_new3(v_proc);
         v_ascii = rb_str_cat(v_ascii, first, 1);
         fProc = GetProcAddress(hLibrary, TEXT(RSTRING_PTR(v_ascii)));

         if(!fProc){
            VALUE v_unicode = rb_str_new3(v_proc);
            v_unicode = rb_str_cat(v_unicode, second, 1);
            fProc = GetProcAddress(hLibrary, TEXT(RSTRING_PTR(v_unicode)));

            if(!fProc){
               rb_raise(
                  cAPILoadError,
                  "Unable to load function '%s', '%s', or '%s'",
                  RSTRING_PTR(v_proc),
                  RSTRING_PTR(v_ascii),
                  RSTRING_PTR(v_unicode)
               );
            }
            else{
               rb_iv_set(self, "@effective_function_name", v_unicode);
            }
         }
         else{
            rb_iv_set(self, "@effective_function_name", v_ascii);
         }
      }
   }
   else{
      rb_iv_set(self, "@effective_function_name", v_proc);
   }

   ptr->function = fProc;

   // Push the numeric prototypes onto our int array for later use.

   for(i = 0; i < RARRAY_LEN(v_proto); i++){
      SafeStringValue(RARRAY_PTR(v_proto)[i]);
      switch(*(char*)StringValuePtr(RARRAY_PTR(v_proto)[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;
         case 'S':
            ptr->prototype[i] = _T_STRING;
            break;
         default:
            rb_raise(cAPIProtoError, "Illegal prototype '%s'",
               StringValuePtr(RARRAY_PTR(v_proto)[i])
            );
      }
   }

   // Store the return type for later use.

   // Automatically convert empty strings or nil to type void.
   if(NIL_P(v_return) || RSTRING_LEN(v_return) == 0){
      v_return = rb_str_new2("V");
      ptr->return_type = _T_VOID;
   }
   else{
      SafeStringValue(v_return);
      switch(*RSTRING_PTR(v_return)){
         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;
         case 'S':
            ptr->return_type = _T_STRING;
            break;
         default:
            rb_raise(cAPIProtoError, "Illegal return type '%s'",
               RSTRING_PTR(v_return)
            );
      }
   }

   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

#effective_function_name ⇒ Object (readonly)

The name of the actual function that is returned by the constructor. For example, if you passed ‘GetUserName’ to the constructor, then the effective function name would be either ‘GetUserNameA’ or ‘GetUserNameW’.

#function_name ⇒ Object (readonly)

The name of the function passed to the constructor

#prototype ⇒ Object (readonly)

The prototype, returned as an array of characters

#return_type ⇒ Object (readonly)

The return type, returned as a single character, S, 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 741

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;
   int len;

   struct{
      unsigned long params[20];
   } 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_LEN(v_proto) != RARRAY_LEN(v_args)){
      char* c = StringValuePtr(RARRAY_PTR(v_proto)[0]);
      if(!strcmp(c, "V")){
         rb_ary_push(v_args, Qnil);
      }
      else{
         rb_raise(rb_eArgError,
            "wrong number of parameters: expected %li, got %li",
            RARRAY_LEN(v_proto), RARRAY_LEN(v_args)
         );
      }
   }

   len = RARRAY_LEN(v_proto);

   for(i = 0; i < len; i++){
      v_arg = RARRAY_PTR(v_args)[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;
               v_proto = rb_iv_get(ActiveCallback, "@prototype");
               param.params[i] = (LPARAM)NUM2ULONG(rb_iv_get(ActiveCallback, "@address"));;
               break;
            case _T_STRING:
               param.params[i] = (unsigned long)RSTRING_PTR(v_arg);
               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 = ULONG2NUM(return_value);
         break;
      case _T_VOID:
         v_return = Qnil;
         break;
      case _T_POINTER:
         if(!return_value){
            v_return = Qnil;
         }
         else{
            VALUE v_efunc = rb_iv_get(self, "@effective_function_name");
            char* efunc = RSTRING_PTR(v_efunc);
            if(efunc[strlen(efunc)-1] == 'W'){
               v_return = rb_str_new(
                  (TCHAR*)return_value,
                  wcslen((wchar_t*)return_value)*2
               );
            }
            else{
               v_return = rb_str_new2((TCHAR*)return_value);
            }
         }
         break;
      case _T_STRING:
         {
            VALUE v_efunc = rb_iv_get(self, "@effective_function_name");
            char* efunc = RSTRING_PTR(v_efunc);

            if(efunc[strlen(efunc)-1] == 'W'){
               v_return = rb_str_new(
                  (TCHAR*)return_value,
                  wcslen((wchar_t*)return_value)*2
               );
            }
            else{
               v_return = rb_str_new2((TCHAR*)return_value);
            }
         }
         break;
      default:
         v_return = INT2NUM(0);
   }

   return v_return;
}