COPYIN(9) | Kernel Developer's Manual | COPYIN(9)

# NAME

`copyin`, `copyout`, `copyinstr`, `copyoutstr`, `kcopy` — 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
`copyinstr`(const void *uaddr, void *kaddr, size_t len, size_t *done);

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

int
`kcopy`(const void *kfaddr, void *kdaddr, size_t len);

# DESCRIPTION

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

The `copyin` 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.
`copyinstr`()
  Copies a null-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 null, is returned in *done, if done is not `NULL`.
`copyoutstr`()
  Copies a null-terminated string, at most len bytes long, from kernel-space address kaddr to user-space address uaddr. The number of bytes actually copied, including the terminating null, is returned in *done, if done is not `NULL`.
`kcopy`()
  Copies len bytes of data from the kernel-space address kfaddr to the kernel-space address kdaddr.

# RETURN VALUES

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

January 6, 2023 | Debian