suse man page for __strncpy_from_user

__STRNCPY_FROM_USER(9)					    Memory Management in Linux					    __STRNCPY_FROM_USER(9)

NAME
       __strncpy_from_user - Copy a NUL terminated string from userspace, with less checking.

SYNOPSIS
       long __strncpy_from_user(char * dst, const char __user * src, long count);

ARGUMENTS
       dst
	   Destination address, in kernel space. This buffer must be at least count bytes long.

       src
	   Source address, in user space.

       count
	   Maximum number of bytes to copy, including the trailing NUL.

DESCRIPTION
       Copies a NUL-terminated string from userspace to kernel space. Caller must check the specified block with access_ok before calling this
       function.

       On success, returns the length of the string (not including the trailing NUL).

       If access to userspace fails, returns -EFAULT (some data may have been copied).

       If count is smaller than the length of the string, copies count bytes and returns count.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010						    __STRNCPY_FROM_USER(9)