Thread: Unknown crash. LOGFONT, static, MSDN.

I'm a little confused. I found this: http://msdn.microsoft.com/library/default..../usingmenus.asp

And in the link it does this.

Code:

HFONT GetAFont(int fnFont) 
{ 
	static LOGFONT lf;  // structure for font information  
 
	// Get a handle to the ANSI fixed-pitch font, and copy 
	// information about the font to a LOGFONT structure. 
 
	GetObject(GetStockObject(ANSI_FIXED_FONT), sizeof(LOGFONT), 
		&lf); 
 
	// Set the font attributes, as appropriate.  
 
	if (fnFont == BOLD) 
		lf.lfWeight = FW_BOLD; 
	else 
		lf.lfWeight = FW_NORMAL; 
 
	lf.lfItalic = (fnFont == ITALIC); 
	lf.lfItalic = (fnFont == ULINE); 
 
	// Create the font, and then return its handle.  
 
	return CreateFont(lf.lfHeight, lf.lfWidth, 
		lf.lfEscapement, lf.lfOrientation, lf.lfWeight, 
		lf.lfItalic, lf.lfUnderline, lf.lfStrikeOut, lf.lfCharSet, 
		lf.lfOutPrecision, lf.lfClipPrecision, lf.lfQuality, 
		lf.lfPitchAndFamily, lf.lfFaceName); 
}

I was trying to do a similar thing in my own code.

Code:

		case WM_CREATE:
		{
			LOGFONT lFont;
			HFONT   hFont;

			::GetObject
				(::GetStockObject(ANSI_FIXED_FONT), 
				sizeof LOGFONT, 
				&lFont);

			_tcsncpy
				(lFont.lfFaceName,
				_T("Courier New"),
				sizeof lFont.lfFaceName);

			hFont = ::CreateFontIndirect(&lFont);
			break;
		}

Doesn't do anything. But that's because, hey, it crashes! Before it hits the break, it calls some procedure that um, does some wierd stuff, and then crashes I think with an unhandled exception (that may have been raised in this procedure). Disassembly ends up like this yo.

Code:

0040118E   . 6A 40		PUSH 40
00401190   . 8D4C24 38	        LEA ECX,DWORD PTR SS:[ESP+38]
00401194   . 68 94814000	PUSH Dialog_T.00408194
00401199   . 51			PUSH ECX
0040119A   . E8 3C020000	CALL Dialog_T.004013DB
0040119F   . 83C4 0C		ADD ESP,0C
004011A2   . 8D5424 18	        LEA EDX,DWORD PTR SS:[ESP+18]
004011A6   . 52			PUSH EDX
004011A7   . FF15 04804000      CALL DWORD PTR DS:[<&GDI32.CreateFontInd>
004011AD   . 5F			POP EDI
004011AE   . 33C0		XOR EAX,EAX
004011B0   . 5E		        POP ESI
004011B1   . 8B4C24 6C	        MOV ECX,DWORD PTR SS:[ESP+6C]
004011B5   . 33CC		XOR ECX,ESP
004011B7   . E8 10020000	CALL Dialog_T.004013CC
004011BC   . 83C4 70		ADD ESP,70
004011BF   . C2 1000		RETN 10

That CALL Dialog_T.004013CC there at the end does it. Um. Yeah, that CALL is made unconditionally, and I can't understand it. But the wierd part is, after being all mystified by the fact that it was crashing, I made my LOGFONT structure static, like in MSDN's code, and it did not crash. In fact, the disassembly does not contain that last call.

Code:

00401166   . 6A 40		PUSH 40
00401168   . 68 94814000	PUSH Dialog_T.00408194
0040116D   . 68 DCAC4000	PUSH Dialog_T.0040ACDC
00401172   . E8 04020000	CALL Dialog_T.0040137B
00401177   . 83C4 0C		ADD ESP,0C
0040117A   . 68 C0AC4000	PUSH Dialog_T.0040ACC0
0040117F   . FF15 04804000      CALL DWORD PTR DS:[<&GDI32.CreateFontInd>
00401185   . 33C0		XOR EAX,EAX
00401187   . 83C4 10		ADD ESP,10
0040118A   . C2 1000		RETN 10

See, not there. So, my question is:

Why does my LOGFONT structure have to be static, and if possible, why did it crash in the first place? Nothing in the CreateFontIndirect/LOGFONT documentation about such craziness. All replies appreciated.

http://msdn.microsoft.com/library/default....ontext_4rw4.asp
http://msdn.microsoft.com/library/default....ontext_1wmq.asp

I don't know, but that call to _tcsncpy seems quite weird to me even though I don't know what this function does. It's probably some kind of strcpy() alter-ego and well, you can juste make the pointer point to the string:

Code:

lFont.lfFaceName = "Courier New";

Also, sizeof doesn't return the number of character, you need strlen() for that and its return value doesn't count the null terminator.