ofstream open bit

[sam]

Hi,

The following C++ line can't pass the c++ compiler:

ofstream omfile;
omfile.open(f, ios:ut | ios::trunc, 0700);

In C++, is there anyway I can create a file with the permission bit set
to executable by root?

Sam

 

[Siemel Naran]

ofstream omfile;
omfile.open(f, ios:ut | ios::trunc, 0700);

In C++, is there anyway I can create a file with the permission bit set
to executable by root?

There's no way in standard C++ because executable by root is a UNIX concept.

 

[sam]

There's no way in standard C++ because executable by root is a UNIX concept.

Then, I will to use C API to do so.

Sam.

 

[Stephen Howe]

In C++, is there anyway I can create a file with the permission bit set to

executable by root?

No, not at all. But I would suggest searching your compilers documentation.
They might have a non-standard constructor for ofstream such that you can do
it.

But it is not part of standard C++. It would a be an extension.

Stephen Howe

 

[Lionel B]

Then, I will to use C API to do so.

Since "executable by root" is OS specific, perhaps it would be cleaner to separate out the permission setting part; i.e.
open/create your file as per standard C++ and then use the appropriate system() call (chmod or whatever) to set
permissions. That way it is clear to someone reading your code that there is something OS specific going on. Is this
what you meant by "use C API"?

[As an aside, I'm not sure how you'd ascertain the success or otherwise of your system() call... I think the standard
library system() simply returns the status of the *shell* - if such exists - invoked to execute your command].

 

[sam]

Since "executable by root" is OS specific, perhaps it would be cleaner to separate out the permission setting part; i.e.
open/create your file as per standard C++ and then use the appropriate system() call (chmod or whatever) to set
permissions. That way it is clear to someone reading your code that there is something OS specific going on. Is this
what you meant by "use C API"?

Yeah, this is what I intended to do now. I used popen C API execute the
change of the file permission bit. But I don;t like the idea of use
popen() or exec(). Because I think this should be able do when creating
the file.

However, I must live with it for the time being. Perhas C++ extension
such as ACE_OS might be have a way to do that.

Thanks
Sam

[As an aside, I'm not sure how you'd ascertain the success or otherwise of your system() call... I think the standard
library system() simply returns the status of the *shell* - if such exists - invoked to execute your command].