| |
| Kernel Functions for Drivers | copyout(9F) |
| | copyout - copy data from a driver to a user program |
SYNOPSIS
| |
#include <sys/types.h>
#include <sys/ddi.h>
int copyout(const void *driverbuf, void *userbuf, size_t cn); |
| |
Architecture independent level 1 (DDI/DKI).
|
| |
-
driverbuf
- Source address in the driver from which the data is transferred.
-
userbuf
- Destination address in the user program to which the data is transferred.
-
cn
- Number of bytes moved.
|
| |
copyout() copies data from driver buffers to user data space.
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 algorithm according to address alignment.
|
| |
Under normal conditions, a 0 is returned to indicate a successful copy. Otherwise, a -1 is returned if one of the following occurs:
- Paging fault; the driver tried to access a page of memory for which it did not have read or write access.
- Invalid user address, such as a user area or stack area.
- Invalid address that would have resulted in data being copied into the user block.
- Hardware fault; a hardware error prevented access to the specified user memory. For example, an uncorrectable parity or ECC error occurred.
If a -1 is returned to the caller, driver entry point routines should return EFAULT.
|
| |
copyout() 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 };
7
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) {
16
17 case XX_GETREGS: /* copy device regs. to user program */
18 if (copyout(rp, arg, sizeof(struct device)))
19 return(EFAULT);
20 break;
21 ...
22 }
23 ...
24 }
|
|
|
| |
Driver writers who intend to support layered ioctls in their ioctl(9E) routines should use ddi_copyout(9F) instead.
Driver defined locks should not be held across calls to this function.
copyout() should not be used from a streams driver. See M_COPYIN and M_COPYOUT in STREAMS Programming Guide.
|
| |
