I need to use this function but there is no information about it in man. Where is there a good source on the web where I can find about this function and to what it belongs? I didnt find much in google. Thanks in advance.

Wow, way to give the background info on that one.. Nothing about what it would do, nothing about why you need it, nothing even about what language it was in!? With the information you have given, all we can do is either guess, which would be stupid, or search, which would yeild exactly the same results as you got. Learn to ask intelligent questions, and you'll get better answers then this one [smile]

copy_from_user is AFAIK a linux kernel function that copies data from userspace to kernelspace.

Use the Source Luke.

I have found its definition under uaccess.h.
However, I need more information about the error case.
Another question, that may be related, if I have a process that invokes int 0x80, and one of the parameters is a pointer to an array, then I can use copy_from_user to copy this array into an array in the kernel segment. Right?
However, it is possible that the pointer given in the paramter, points to somewhere which doesnt belong to the calling process address space.
How can I discover this sort of problem? Will copy_from_user give me an appropriate error if this occures? or do I need to use other means?

Thanks in advance.