copy_to_user,copy_from_use…

原文地址：copy_to_user,copy_from_user,get_user,put_user函数作者：卓俊

copy_to_user,copy_from_user,get_user,put_user函数比较

copy_to_user

-- Copy a block of data into user space.

copy_from_user

-- Copy a block of data from user space.

get_user

-- Get a simple
variable from user space.

put_user

-- Write a simple value into user space.

copy_from_user

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);[/code]

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.

 

copy_to_user

Name

copy_to_user --
Copy a block of data into user space.

Synopsis

unsigned long copy_to_user

(void
__user * to, const void * from, unsigned long
n);[/code]

Arguments

to

Destination
address, in user space.

from

Source
address, in kernel space.

n

Number of
bytes to copy.

Context

User context
only. This function may sleep.

Description

Copy data
from kernel space to user space.

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

put_user

Name

put_user --
Write a simple value into user space.

Synopsis

put_user

( x,
ptr);[/code]

Arguments

x

Value to
copy to user space.

ptr

Destination
address, in user space.

Context

User context
only. This function may sleep.

Description

This macro
copies a single simple value from kernel space to user space. It
supports simple types like char and int, but not larger data types
like structures or arrays.

ptr must
have pointer-to-simple-variable type, and x must be assignable to
the result of dereferencing ptr.

Returns zero
on success, or -EFAULT on error.

get_user

Name

get_user -- Get
a simple variable from user space.

Synopsis

get_user

( x,
ptr);[/code]

Arguments

x

Variable to
store result.

ptr

Source
address, in user space.

Context

User context
only. This function may sleep.

Description

This macro
copies a single simple variable from user space to kernel space. It
supports simple types like char and int, but not larger data types
like structures or arrays.

ptr must
have pointer-to-simple-variable type, and the result of
dereferencing ptr must be assignable to x without a
cast.

Returns zero
on success, or -EFAULT on error. On error, the variable x is set to
zero.