- long __strncpy_from_user(char * dst, const char __user * src, long count);
- Destination address, in kernel space. This buffer must be at least count bytes long.
- Source address, in user space.
- Maximum number of bytes to copy, including the trailing NUL.
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.