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copyin - copy data from a user program to a driver buffer


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

int copyin(const void *userbuf, void *driverbuf, size_t cn);


This interface is obsolete. ddi_copyin(9F) should be used instead.



User program source address from which data is transferred.


Driver destination address to which data is transferred.


Number of bytes transferred.


copyin() copies data from a user program source address to a driver buffer. The driver developer must ensure that adequate space is allocated for the destination address.

Addresses that are word-aligned are moved most efficiently. However, the driver developer is not obligated to ensure alignment. This function automatically finds the most efficient move according to address alignment.


Under normal conditions, a 0 is returned indicating a successful copy. Otherwise, a −1 is returned if one of the following occurs:

oPaging fault; the driver tried to access a page of memory for which it did not have read or write access.
oInvalid user address, such as a user area or stack area.
oInvalid address that would have resulted in data being copied into the user block.
oHardware fault; a hardware error prevented access to the specified user memory. For example, an uncorrectable parity or ECC error occurred.
oADI version mismatch; the hardware detected a mismatch between the version specified for the source address and the actual in-memory version. For more information, see the adi(3C) man page.

If a −1 is returned to the caller, driver entry point routines should return EFAULT.


copyin() can be called from user context only.


Example 1 An ioctl() Routine

A driver ioctl(9E) routine (line 10) can be used to get or set device attributes or registers. In the XX_GETREGS condition (line 17), the driver copies the current device register values to a user data area (line 18). If the specified argument contains an invalid address, an error code is returned.

1 struct device { /* layout of physical device registers */
2 int control; /* physical device control word */
3 int status; /* physical device status word */
4 short recv_char; /* receive character from device */
5 short xmit_char; /* transmit character to device */
6 };
8 extern struct device xx_addr[]; /* phys. device regs. location */
9 . . .
10 xx_ioctl(dev_t dev, int cmd, int arg, int mode,
11 cred_t *cred_p, int *rval_p)
12 …
13 {
14 register struct device *rp = &xx_addr[getminor(dev) » 4];
15 switch (cmd) {
17 case XX_GETREGS: /* copy device regs. to user program */
18 if (copyin(arg, rp, sizeof(struct device)))
19 return(EFAULT);
20 break;
21 …
22 }
23 …
24 }


See attributes(7) for a description of the following attributes:


uiomove(9F), attributes(7), ioctl(9E), ddi_copyin(9F), bcopy(9F), copyout(9F), ddi_copyout(9F).

Writing Device Drivers in Oracle Solaris 11.4


Driver writers who intend to support layered ioctls in their ioctl(9E) routines should use ddi_copyin(9F) instead.

Driver defined locks should not be held across calls to this function.

copyin() should not be used from a streams driver. For more information, see M_COPYIN and M_COPYOUT in STREAMS Programming Guide.

solaris/copyin.9f.txt · Last modified: 2023/07/19 08:58 by A User Not Logged in