Where did the crash happen? - C / C++ / MFC Discussion Boards

::CreateFileMapping

Abin10-Oct-02 5:35

10-Oct-02 5:35

HANDLE CreateFileMapping(
  HANDLE hFile,                       // handle to file
  LPSECURITY_ATTRIBUTES lpAttributes, // security
  DWORD flProtect,                    // protection
  DWORD dwMaximumSizeHigh,            // high-order DWORD of size
  DWORD dwMaximumSizeLow,             // low-order DWORD of size
  LPCTSTR lpName                      // object name
);

That's the function prototype shown on MSDN, I have a question about the first parameter here: it can be a handle to a disk file if the handle value is not INVALID_HANDLE_VALUE, or else it will be using system page file. I wonder which should I choose, specify a disk file or just use the system page file, which one is better and why? Thanks.

Re: ::CreateFileMapping

Daniel Turini10-Oct-02 5:34

Daniel Turini

10-Oct-02 5:34

What are you trying to accomplish? IPC or only reading some pages of large file?

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Re: ::CreateFileMapping

Abin10-Oct-02 5:47

Abin

10-Oct-02 5:47

IPC. I'm trying to develop a project that requires a number of processes cooperate together, each of which needs to know exactly what other processes are doing in order to interact properly.

I'm thinking of using file mapping as my IPC approach, I'm not sure if this is a good way, though. Your help is very much appreciated.

Re: ::CreateFileMapping

Daniel Turini10-Oct-02 5:55

Daniel Turini

10-Oct-02 5:55

I would use the pagefile, because often users put it on a separate disk. I'm not a memory mapping guru, but I can see no other advantage/difference in your case.

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Re: ::CreateFileMapping

Paul M Watt10-Oct-02 6:21

Paul M Watt

10-Oct-02 6:21

File Mapping is a very good technique for IPC, in fact that is how COM implements its underlying IPC for local processes.

Using the system page sounds like a good way to go, then there is no file clean up afterwards. Other than that I do not think that it matters which way you do that.

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Light a man on fire, and he will be warm for the rest of his life!

Re: ::CreateFileMapping

Abin10-Oct-02 7:29

Abin

10-Oct-02 7:29

Thanks for you and anyone who replied. OK I still have a question here, it may sound stupid but anyway:

Is there any possibility that the mapped file will be trespassed by other process? I mean, if I have process A and B are using the mapped file(I will generate a GUID as mapping file name), is it possible, even very very slightly possible, that any contents within the mapping can be modified by processes other than A and B?

Because I need the contents to be absolutely private and secure to process A and B, this is crucial for me, otherwise I might get fired Poke tongue | ;-P

. So before I begin it I'd like to make sure. Thanks again.

Re: ::CreateFileMapping

Joe Woodbury10-Oct-02 7:42

Joe Woodbury

10-Oct-02 7:42

Bin wrote:
Is there any possibility that the mapped file will be trespassed by other process?

Yes. If you use a named object, a process with the proper security can access that object. Will it? Very unlikely, but still possible.

(Think about it, if process B can see an object owned by process A, so can process C. More importantly, your bosses need to understand that if a process has administrative rights in windows, you simply cannot make the system secure. This is akin to the adage that a physically accessable computer is not fully secure.)

Where did the crash happen?

User 665810-Oct-02 5:27

User 6658

10-Oct-02 5:27

Hi
there are some programs like MS MediaPlayer and InterVideo WinDVD which, in case of a crash, show a MessageBox with the line, the sourcefile, and a piece of the code that caused the crash. It looks like this e.g:

Unhandled exception in
"C:\Program Files\foo\main.cpp" in line: 289
ASSERT(pFoo != NULL);

How can I implement this feature into my applications?

regards
Greg

modified 12-Sep-18 21:01pm.

Re: Where did the crash happen?

Daniel Turini10-Oct-02 5:30

Daniel Turini

10-Oct-02 5:30

use this in your code:

ASSERT(pFoo != NULL);

And deliver a debug build version.

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Re: Where did the crash happen?

User 665810-Oct-02 5:59

User 6658

10-Oct-02 5:59

Well, I don't think Microsoft and Intervideo deliver debug versions of their programs tp the customers Confused | :confused:

There must be another way.
Furthermore the assertion dialog (or MessageBox) doesn't look the same like in the MediaPlayer or WinDVD.

modified 12-Sep-18 21:01pm.

Re: Where did the crash happen?

Daniel Turini10-Oct-02 6:03

Daniel Turini

10-Oct-02 6:03

Gregor S. wrote:
Well, I don't think Microsoft and Intervideo deliver debug versions of their programs tp the customers

Well, an ASSERT is suposed to only be present on debug Builds, right?

You can achieve the same by #define _DEBUG on your release build, or creating a proprietary fancy ASSERT macro.

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Re: Where did the crash happen?

Paul M Watt10-Oct-02 6:42

Paul M Watt

10-Oct-02 6:42

While in Debug mode you could use _CrtDbgReport, however that function only exists in the debug version of the C-Runtime libraries. Look at how ATLs ATLASSERT macro works.

#define _ASSERTE(expr) \
do { if (!(expr) && \
(1 == _CrtDbgReport(_CRT_ASSERT, __FILE__, __LINE__, NULL, #expr))) \
_CrtDbgBreak(); } while (0)

For release mode you could simply create your own function that reports the data in a message box, and you would use these preprocessor defines to get the line number and file: __FILE__, __LINE__

Good Luck

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Re: Where did the crash happen?

User 665810-Oct-02 6:50

User 6658

10-Oct-02 6:50

I finally managed to create my own macro, could you please take a look whether it is correct? Is seems to work however Wink | ;)

void _assert_(void *exp)
{
        char err[1024];
        sprintf(err, "Assertion Failed!\n\n\"%s\" in line %i.\nASSERT(%s)", \
                     __FILE__,										\
                      __LINE__,										\
                      exp);											\

        if(exp)
        {
                MessageBox(NULL, err,"Fatal Error", MB_OK|MB_ICONSTOP);
                PostQuitMessage(0);
        }
}

#define _ASSERT_(exp) { _assert_(#exp); }

For testing purposes:

void *pFoo = NULL;
_ASSERT_(pFoo != NULL);

thanks

btw why don't the pre-tags recognise tabs (\t) when I copy and paste my code?

modified 12-Sep-18 21:01pm.

Re: Where did the crash happen?

Paul M Watt10-Oct-02 7:46

Paul M Watt

10-Oct-02 7:46

Your macro looks good to me Smile | :)

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

It has been a privilege...

Georg Haan10-Oct-02 5:19

Georg Haan

10-Oct-02 5:19

...that's bugging me...
I wrote a message about a CreateProcessAsUser problem a few hours ago titled "Is it a bird? ... No It's Superuser!".

I've managed to narrow the problem, so it should be more easy to anwser...

Given that I know the name of my administrator account and it's password, how can I get SeAssignPrimaryTokenPrivilege, operating from a regular account, in order to succesfully place a call to CreateProcessAsUser?

The idea is to copy the functionality of Linux' su...

Regards,
Georg Haan(.NL)

Re: It has been a privilege...

Daniel Turini10-Oct-02 5:20

Daniel Turini

10-Oct-02 5:20

I think people at Cygwin had the same problem:

http://sources.redhat.com/ml/cygwin/2000-08/msg00445.html[^]

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write vertical text using GDI+

Anonymous10-Oct-02 4:33

Anonymous

10-Oct-02 4:33

I use the following two line of codes to write vertical text, it works, but the text is facing the left, reads from the top to the bottom. What shall I do if I like to have the vertical text to face the right, and read from bottom up?

stringFormat.SetFormatFlags(StringFormatFlagsDirectionVertical);
graphics->DrawString(string, -1, &myFont, origin, &stringFormat, &blackBrush);

Thanks.

Re: write vertical text using GDI+

l a u r e n10-Oct-02 4:41

l a u r e n

10-Oct-02 4:41

if there isnt a flag to set what u want (and i havent done so much text output stuff for a while) u could draw to a memdc and invert / flip it before displaying it

"... and so i said to him ... if it don't dance (or code) and you can't eat it either f**k it or throw it away"
biz stuff about me

Re: write vertical text using GDI+

Daniel Turini10-Oct-02 4:40

Daniel Turini

10-Oct-02 4:40

Turn your monitor upside down ? Smile | :)

You can try using a world transformation matrix with Graphics.Transform Property.

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Re: write vertical text using GDI+

Roger Allen10-Oct-02 6:20

Roger Allen

10-Oct-02 6:20

OK, I've never used GDI+, but in standard GDI, the font is created with the rotation factor. Check that to see whether the value of 900 for Orientation needs to be changed to 2700 where it is constructued, or visa versa.

Roger Allen
Sonork 100.10016

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Re: write vertical text using GDI+

Anonymous10-Oct-02 5:36

Anonymous

10-Oct-02 5:36

Thanks for the reply. The computer is too heavy for me to turn it upside down. Wink | ;)

I tried the following, but for some reason, I only see the ellipse, but no text 'HAPPY DAY!', am I missing something here? Confused | :confused:

Pen pen(Color(255, 0, 0, 255));
PointF origin(x, y);
WCHAR string[256];

x = 200;
y = 200;

graphics->RotateTransform(90.0f);
graphics->TranslateTransform(x, y, MatrixOrderAppend);

wcscpy(string, L"HAPPY DAY!");
graphics->DrawString(string, -1, &myFont, origin,
&stringFormat, &blackBrush);

graphics->DrawEllipse(&pen, 0, 0, 200, 80);

Thanks!

Re: write vertical text using GDI+

Daniel Turini10-Oct-02 5:56

Daniel Turini

10-Oct-02 5:56

I'm not a GDI+ guru, but it should work. For me, the only difference is the color your are drawing things. Are you drawing this on what background?

My latest articles:
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Re: write vertical text using GDI+

Anonymous10-Oct-02 6:06

Anonymous

10-Oct-02 6:06

I am drawing both the text and ellipse on an image that I uploaded using graphics.DrawImage().

I agree that this method shall work because I can see the ellipse, but not the text... weird...

Anyways, thank you again for pointing me to the right direction.

Re: write vertical text using GDI+

Alois Kraus10-Oct-02 6:27

Alois Kraus

10-Oct-02 6:27

Perhaps You are drawing the ellipse over the text ?

try it in this order

graphics->DrawEllipse(&pen, 0, 0, 200, 80);
graphics->DrawString(string, -1, &myFont, origin, &stringFormat, &blackBrush);

Re: write vertical text using GDI+

Anonymous10-Oct-02 7:28

Anonymous

10-Oct-02 7:28

Thanks. It doesn't work either.

Anybody ever tried to rotate a line of text before using GDI+?

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.