_copy_from_user(9) [centos man page]

_COPY_FROM_USER(9)					    Memory Management in Linux						_COPY_FROM_USER(9)

NAME

       _copy_from_user - Copy a block of data from user space.

SYNOPSIS

       unsigned long _copy_from_user(void * to, const void __user * from, unsigned long n);

ARGUMENTS

       to
	   Destination address, in kernel space.

       from
	   Source address, in user space.

       n
	   Number of bytes to copy.

CONTEXT

       User context only. This function may sleep.

DESCRIPTION

       Copy data from user space to kernel space.

       Returns number of bytes that could not be copied. On success, this will be zero.

       If some data could not be copied, this function will pad the copied data to the requested size using zero bytes.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014							_COPY_FROM_USER(9)

COPY(9) 						   BSD Kernel Developer's Manual						   COPY(9)

NAME

     copy, copyin, copyout, copystr, copyinstr -- kernel copy functions

SYNOPSIS

     #include <sys/types.h>
     #include <sys/systm.h>

     int
     copyin(const void *uaddr, void *kaddr, size_t len);

     int
     copyout(const void *kaddr, void *uaddr, size_t len);

     int
     copystr(const void *kfaddr, void *kdaddr, size_t len, size_t *done);

     int
     copyinstr(const void *uaddr, void *kaddr, size_t len, size_t *done);

DESCRIPTION

     The copy functions are designed to copy contiguous data from one address to another.  All but copystr() copy data from user-space to kernel-
     space or vice-versa.

     The copy routines provide the following functionality:

     copyin()	   Copies len bytes of data from the user-space address uaddr to the kernel-space address kaddr.

     copyout()	   Copies len bytes of data from the kernel-space address kaddr to the user-space address uaddr.

     copystr()	   Copies a NUL-terminated string, at most len bytes long, from kernel-space address kfaddr to kernel-space address kdaddr.  The
		   number of bytes actually copied, including the terminating NUL, is returned in *done (if done is non-NULL).

     copyinstr()   Copies a NUL-terminated string, at most len bytes long, from user-space address uaddr to kernel-space address kaddr.  The num-
		   ber of bytes actually copied, including the terminating NUL, is returned in *done (if done is non-NULL).

RETURN VALUES

     The copy functions return 0 on success or EFAULT if a bad address is encountered.	In addition, the copystr(), and copyinstr() functions
     return ENAMETOOLONG if the string is longer than len bytes.

SEE ALSO

     fetch(9), store(9)

BSD
								  January 7, 1996							       BSD