NAME

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

SYNOPSIS

#include <sys/types.h>

#include <sys/ddi.h>

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

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

ARGUMENTS

userbuf

User program source address from which data is transferred.

driverbuf

Driver destination address to which data is transferred.

cn

Number of bytes transferred.

DESCRIPTION

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.

RETURN VALUES

Under normal conditions a 0 is returned indicating 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

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

CONTEXT

copyin( ) can be called from user context only.

EXAMPLES

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_SETREGS: /* copy device regs. to user program * /
18      if (copyin(arg, rp, sizeof(struct device)))
19         return(EFAULT);
20      break;
21        ...
22   }
23        ...
24 }

SEE ALSO

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

Writing Device Drivers

NOTES

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.