| __COPY_FROM_USER(9) - phpMan
__COPY_FROM_USER(9) Memory Management in Linux __COPY_FROM_USER(9)
NAME
__copy_from_user - Copy a block of data from user space, with less checking.
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 if pagefaults are enabled.
DESCRIPTION
Copy data from user space to kernel space. Caller must check the specified block with
access_ok before calling this function.
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.
An alternate version - __copy_from_user_inatomic - may be called from atomic context and
will fail rather than sleep. In this case the uncopied bytes will *NOT* be padded with
zeros. See fs/filemap.h for explanation of why this is needed.
COPYRIGHT
Kernel Hackers Manual 4.8. January 2017 __COPY_FROM_USER(9)
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