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

NAME

copy, copyin, copyin_nofault, copyout, copyout_nofault, 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
copyin_nofault(const void *uaddr, void *kaddr, size_t len);

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

int
copyout_nofault(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 copyin() and copyin_nofault() functions copy len bytes of data from the user-space address uaddr to the kernel-space address kaddr.

The copyout() and copyout_nofault() functions copy len bytes of data from the kernel-space address kaddr to the user-space address uaddr.

The copyin_nofault() and copyout_nofault() functions require that the kernel-space and user-space data be accessible without incurring a page fault. The source and destination addresses must be physically mapped for read and write access, respectively, and neither the source nor destination addresses may be pageable.

The copystr() function 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).

The copyinstr() function copies a NUL-terminated string, at most len bytes long, from user-space address uaddr to kernel-space address kaddr. The number 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. All but copystr() return EFAULT if a bad address is encountered. The copyin_nofault() and copyout_nofault() functions return EFAULT if a page fault occurs. The copystr() and copyinstr() functions return ENAMETOOLONG if the string is longer than len bytes.

SEE ALSO

fetch(9), store(9)
June 15, 2017 Linux 4.19.0-13-amd64