strange bug with dbFileExist() - GameCreators Forum

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Barnski

18

Years of Service

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Joined: 26th Jan 2006

Location: Switzerland, Zurich

Posted: 28th Feb 2006 12:00 Edited at: 28th Feb 2006 13:54

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Hi,

I really can't explain why dbFileExist crashed my program, I tried following steps to find out why:

I copied the code (edit; only the one in question) into a new project and tried it: worked.

In my original project, at the place where I used dbFileExist I use fopen to find out whether the file exists: worked.

the code now looks like this, and crashes on the line of dbFileExist:

+ Code Snippet

	FILE* fd = fopen (s_full_path, "r");
	int file_exists = 0;
	if (fd != NULL) {
		file_exists = 1;
		fclose (fd);
	}
	file_exists = dbFileExist(s_full_path);

This is weird, isnt iT?????

The string at runtime in s_full_path is:

+ Code Snippet

s_full_path	0x0c7bde78 "C:\WINDOWS\fonts\lblack.TTF"  char *

edit; the forum cuts out the backslashes hmm but the string is correct, and my function returns true!!

Anyone? Understands? this?
I. Don't.

edit: any idea what I can do to determine the source of the problem?

-- I just started with DarkSDK, by translating DBP Projects. --

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Barnski

18

Years of Service

User Offline

Joined: 26th Jan 2006

Location: Switzerland, Zurich

Posted: 28th Feb 2006 13:01

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I use now following function I made:

+ Code Snippet

#include <stdio.h>
#include <cassert>
// check if a file exists.
bool file_exists (const char* a_file) {	
	// preconditions
	assert(a_file != NULL);			// a_file may not be NULL.
	assert(a_file[0] != 0);			// a_file may not be empty.

	FILE* fd = fopen (a_file, "r");
	if (fd != NULL) {
		fclose (fd);
		return true;
	}
	return false;
}

What do you think, is it ok for a replacement for dbFileExist?

-- I just started with DarkSDK, by translating DBP Projects. --

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Barnski

18

Years of Service

User Offline

Joined: 26th Jan 2006

Location: Switzerland, Zurich

Posted: 28th Feb 2006 15:11

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I found out what the problem was...

took me very long though.

in short: it was a buffer overrun that did not cause a segmentation fault.

any db Functions called afterwards that would need to look at paths/file strings were to fail and crash the program! really weird

now dbFileExist() works superb again

greets,
Barnski.

-- I just started with DarkSDK, by translating DBP Projects. --

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Dark GDK / strange bug with dbFileExist()