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

copy, copyin, copyinstr, copyout, copystrkernel copy functions

#include <sys/types.h>
#include <sys/systm.h>

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

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

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

int
copystr(const void *kfaddr, void *kdaddr, size_t len, size_t *done);

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

The copy routines provide the following functionality:

()
Copies len bytes of data from the user-space address uaddr to the kernel-space address kaddr.
()
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.
()
Copies len bytes of data from the kernel-space address kaddr to the user-space address uaddr.
copystr()
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.

The copy functions return 0 on success or the following error on failure:

[EFAULT]
If a bad address is encountered. When this error is returned, the contents of the destination buffer ( *kaddr for copyin(), copyinstr(), and copystr(); *uaddr for copyout()) are undefined. For copyinstr() and copystr(), the contents of the *done parameter are also undefined on a return of EFAULT.

In addition to EFAULT, copystr() and copyinstr() on failure will return:

[ENAMETOLONG]
When the string is longer than len bytes. On this error return, the destination buffer is not null-terminated, but the *done parameter is maintained.

fetch(9), store(9)

October 2, 2008 macOS 14.4