Query: __copy_from_user
OS: centos
Section: 9
Links: centos man pages all man pages
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__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.SYNOPSISunsigned long __copy_from_user(void * to, const void __user * from, unsigned long n);ARGUMENTSto Destination address, in kernel space. from Source address, in user space. n Number of bytes to copy.CONTEXTUser context only. This function may sleep.DESCRIPTIONCopy 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.COPYRIGHTKernel Hackers Manual 3.10 June 2014 __COPY_FROM_USER(9)