Create read-only file using c++

Hi,
I want to create a log file that captures all the actions happening...anyway i got code for that from internet.
Now what i want to do is, make that file read only so that the data is not modified by external application or user.

Code:

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log(char* msg)
{ 
    time_t now = time(0); 
    struct tm* tm = localtime(&now);     
    ofstream out( "logfileBrandNew.log",ios::app);
 
    out << tm->tm_year << '/' << tm->tm_mon << '/' << tm->tm_mday       
        << ' ' << tm->tm_hour << ':' << tm->tm_min << ':' << tm->tm_sec
        << ": "; 
    out << msg << "\n"; 
    out.close();
}

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There's no real easy way to do that. If you really need it to be secure, your best bet is to encrypt it and use some kind of check sum to verify its integrity.

Simple put this line..

system ("attrib +r logfileBrandNew.log");

or use SetFileAttributes API..

Quote:

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Originally Posted by hypheni

Simple put this line..

system ("attrib +r logfileBrandNew.log");

or use SetFileAttributes API..

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And then all a user has to do is use explorer, turn off the read only attribute, and do whatever they want to the file. I could be wrong, but I think he needs something more secure than that.

Quote:

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Originally Posted by hypheni

Simple put this line..

system ("attrib +r logfileBrandNew.log");

or use SetFileAttributes API..

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thanks dude.....

but this is restricting the program to modify or update log details.......
how to solve this

Quote:

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Originally Posted by GCDEF

There's no real easy way to do that. If you really need it to be secure, your best bet is to encrypt it and use some kind of check sum to verify its integrity.

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thank you......

can you just mention some functions or methods to achieve this....

thank you

Quote:

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Originally Posted by neoraghav

thanks dude.....

but this is restricting the program to modify or update log details.......
how to solve this

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You could always keep the file open yourself so nobody can write to it, but as soon as your program closes, the lock is gone.

Quote:

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Originally Posted by Skizmo

You could always keep the file open yourself so nobody can write to it, but as soon as your program closes, the lock is gone.

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dude.....i want to achieve this using code man.......give me good suggestion

Quote:

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Originally Posted by neoraghav

dude.....i want to achieve this using code man.......give me good suggestion

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We don't really know what your requirements are and from your OP it seems you're just starting out. It's not a simple topic and you may be getting in over your head. Probably the simplest encryption is just to XOR a bit pattern over your data. There are various checksum algorithms you can use to help ensure the data hasn't been modified by someone other than you. You'll need to decide what your program does if the user deletes your file, or replaces it with an earlier version. Making it really secure won't be easy.

Quote:

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Originally Posted by GCDEF

We don't really know what your requirements are and from your OP it seems you're just starting out. It's not a simple topic and you may be getting in over your head. Probably the simplest encryption is just to XOR a bit pattern over your data. There are various checksum algorithms you can use to help ensure the data hasn't been modified by someone other than you. You'll need to decide what your program does if the user deletes your file, or replaces it with an earlier version. Making it really secure won't be easy.

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yes i'm a newbie ...

i'll try with checksum algorithms as you mentioned.....

thank you very much GCDEF....

Well, I'd say the real solution isn't one you're likely to want to use.

The problem is that anything your program can do, another program can also do... if it's run by the same user with the same permissions. Simply put: if the person has control over the machine, it's their machine. They get to do what they want with it.

So the solution is to limit access to your program to machines you control, and only give the user limited access to those machines. Basically you create a user account with limited privileges that cannot edit anything outside of their directory. You then let them use your program, and if they wanted to edit the log file they would then have to give an admin password, which they would not have.

If you have to make it so that they cannot edit their logfiles on *their* machines when they have full access, then things get a lot harder. As someone suggested, I guess you can try encryption or something, but this probably isn't a very good solution. I guess it comes down to why you can't let them edit the log files.

Personally, my advice would probably be to just let them.

I think people making OP much confuser to find his and.. Do one simple thing..

Make your file normal before reading it by SetFileAttributes (FileName, FILE_ATTRIBUTE_NORMAL) then just before closing your program call the same API with FILE_ATTRIBUTE_HIDDEN.

I think there is no more confusion. Also do the same approach with system() with +r and -r.

Quote:

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Originally Posted by hypheni

I think people making OP much confuser to find his and.. Do one simple thing..

Make your file normal before reading it by SetFileAttributes (FileName, FILE_ATTRIBUTE_NORMAL) then just before closing your program call the same API with FILE_ATTRIBUTE_HIDDEN.

I think there is no more confusion. Also do the same approach with system() with +r and -r.

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As has been explained already, all a user has to do is turn off those attributes and they can do what they want with the file. That isn't secure.

Quote:

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Originally Posted by Ankheg

Well, I'd say the real solution isn't one you're likely to want to use.

The problem is that anything your program can do, another program can also do... if it's run by the same user with the same permissions. Simply put: if the person has control over the machine, it's their machine. They get to do what they want with it.

So the solution is to limit access to your program to machines you control, and only give the user limited access to those machines. Basically you create a user account with limited privileges that cannot edit anything outside of their directory. You then let them use your program, and if they wanted to edit the log file they would then have to give an admin password, which they would not have.

If you have to make it so that they cannot edit their logfiles on *their* machines when they have full access, then things get a lot harder. As someone suggested, I guess you can try encryption or something, but this probably isn't a very good solution. I guess it comes down to why you can't let them edit the log files.

Personally, my advice would probably be to just let them.

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yes...you're right
i tried with some options and they didnt work well...
but this "read only " thing is part of my case study where i have to capture all the actions using a log file and make that log file read only. i know that its lot complex and since i'm a newbie i'm not getting many things mentioned by some guys in other forums......

anyway i'll go with using the checksum algorithm now.....

thank you

Quote:

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Originally Posted by hypheni

I think people making OP much confuser to find his and.. Do one simple thing..

Make your file normal before reading it by SetFileAttributes (FileName, FILE_ATTRIBUTE_NORMAL) then just before closing your program call the same API with FILE_ATTRIBUTE_HIDDEN.

I think there is no more confusion. Also do the same approach with system() with +r and -r.

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thank you very much......your suggesstion has solved my problem as of now .......

Quote:

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Originally Posted by neoraghav

thank you very much......your suggesstion has solved my problem as of now .......

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How?

Quote:

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Originally Posted by GCDEF

How?

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bcoz......other concepts are not getting into my mind.......

so ill go with just changing the attribute flag ......as needed....

Quote:

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Originally Posted by neoraghav

bcoz......other concepts are not getting into my mind.......

so ill go with just changing the attribute flag ......as needed....

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The fact that you don't understand the solution doesn't change the fact that just changing the attributes does nothing to solve your problem.

Quote:

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Originally Posted by GCDEF

The fact that you don't understand the solution doesn't change the fact that just changing the attributes does nothing to solve your problem.

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I suppose if he just needs it to prevent accidental deletion, it solves his problem. He never really explained why he needed it read only. If it's part of a homework assignment for example, it might be enough that he did it. If it's a pointy-haired boss making random demands, then again it might be enough. If he has a real need for security... not so much.

Quote:

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Originally Posted by Ankheg

I suppose if he just needs it to prevent accidental deletion, it solves his problem. He never really explained why he needed it read only. If it's part of a homework assignment for example, it might be enough that he did it. If it's a pointy-haired boss making random demands, then again it might be enough. If he has a real need for security... not so much.

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it solves my problem. i made it read only using

Code:

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system("attrib -r logfileBrandNew.log");
system("attrib +r logfileBrandNew.log");

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i know how to hide the file.
but is it possible to prevent the file from deletion.........

Quote:

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it solves my problem. i made it read only using

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This is no solution. This is just setting the read-only marker. Every dumbass can remove it.

Quote:

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but is it possible to prevent the file from deletion.........

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No.

Quote:

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Originally Posted by Skizmo

This is no solution. This is just setting the read-only marker. Every dumbass can remove it.


No.

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do you have a solution.......!!

Quote:

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Originally Posted by neoraghav

do you have a solution.......!!

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You can't have a solution until you have clearly defined requirements, which you have yet to provide. We don't know how secure this needs to be.