copyin(D3) copyin(D3)
NAME
copyin - copy data from a user buffer to a driver buffer
SYNOPSIS
#include <sys/types.h>
#include <sys/ddi.h>
int copyin(caddr_t userbuf, caddr_t driverbuf, size_t count);
Arguments
userbuf User source address from which copy is made.
driverbuf Driver destination address to which copy is made.
count Number of bytes to copy.
DESCRIPTION
copyin copies count bytes of data from the user virtual
address specified by userbuf to the kernel virtual address
specified by driverbuf.
Return Values
If the copy is successful, 0 is returned. Otherwise, -1 is
returned to indicate that the specified user address range is
not valid.
USAGE
The driver must ensure that adequate space is allocated for
the destination address.
copyin chooses the best algorithm based on address alignment
and number of bytes to copy. Although the source and
destination addresses are not required to be word aligned,
word aligned addresses may result in a more efficient copy.
Drivers usually convert a return value of -1 into an EFAULT
error.
Level
Base only.
Synchronization Constraints
Can sleep.
Driver-defined basic locks and read/write locks may not be
held across calls to this function.
Copyright 1994 Novell, Inc. Page 1
copyin(D3) copyin(D3)
Driver-defined sleep locks may be held across calls to this
function.
Warnings
The driver source buffer must be completely within the kernel
address space, or the system can panic.
When holding sleep locks across calls to this function,
multithreaded drivers must be careful to avoid creating a
deadlock. During the data transfer, page fault resolution
might result in another I/O to the same device. For example,
this could occur if the driver controls the disk drive used as
the swap device.
Examples
A driver ioctl(D2) routine (line 5) can be used to get or set
device attributes or registers. If the specified command is
XX_SETREGS (line 9), the driver copies user data to the device
registers (line 11). If the user address is invalid, an error
code is returned.
1 struct device { /* device registers layout */
...
2 int command; /* device command word */
3 };
4 extern struct device xx_dev[]; /* physical device registers */
...
5 xxioctl(dev_t dev, int cmd, void *arg, int mode, cred_t *crp, int *rvp)
6 {
7 struct device *dp;
8 switch (cmd) {
9 case XX_SETREGS: /* copy user program data to device registers */
10 dp = &xx_dev[getminor(dev)];
11 if (copyin(arg, (caddr_t)dp, sizeof(struct device)))
12 return (EFAULT);
13 break;
REFERENCES
bcopy(D3), copyout(D3), uiomove(D3), ureadc(D3), uwritec(D3)
NOTICES
Portability
All processors
Copyright 1994 Novell, Inc. Page 2
copyin(D3) copyin(D3)
Applicability
ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp
Copyright 1994 Novell, Inc. Page 3