how will you know if a cd-rw has a data inside?

jaepi · 05-16-2007, 11:47 PM

hello there, i'm currently making a program that will burn an iso file...before burning the file, how would you know if the medium (preferably a cd-rw) has a file written inside? what functions/commands could i or should i use? thanks...

Matir · 05-17-2007, 12:55 AM

You could try to mount it and see if it can.

jaepi · 05-17-2007, 01:40 AM

Quote:

Originally Posted by Matir

You could try to mount it and see if it can.

uhmmm...im using c++ sir...how do use mount in my flow control statements?

if(cd-rw is empty){
burn files
}else{
empty the cd
burn files
}

i hope you know what i mean...

Dox Systems - Brian · 05-17-2007, 08:51 AM

You *can* exec mount and see what it returns from within c++.

Not an ideal solution of course, but it's *a* way to do it.

krizzz · 05-17-2007, 08:57 AM

You don't need to call the external mount program to mount a drive. Mount is a system call ( sys_mount (21) ) and it's available through sys/mount.h for the user space.
Try

Code:

man 2 mount

and you'll see :

Code:

       #include <sys/mount.h>

       int mount(const char *source, const char *target,
                 const char *filesystemtype, unsigned long mountflags,
                 const void *data);

       int umount(const char *target);

And actually, if you are considering also the situation when CD has a proper ISO filesystem on it but there're no files, then you need to check for the files. My choice would be the opendir and readdir commands. See man 2 readdir and man 3 opendir.