copyin(9F)

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

     This interface is obsolete.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

PARAMETERS

     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 ade-
     quate 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 effi-
     cient move according to address alignment.

RETURN VALUES

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

        o  Paging fault; the driver tried to  access  a  page  of
           memory for which it did not have read or write access.

        o  Invalid user address, such as a  user  area  or  stack
           area.

        o  Invalid address that would have resulted in data being
           copied into the user block.

        o  Hardware fault; a hardware error prevented  access  to
           the  specified user memory. For example, an uncorrect-
           able parity or ECC error occurred.

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

CONTEXT

     copyin() can be called from user context only.

EXAMPLES

     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 condi-
     tion (line 17), the driver copies the current device  regis-
     ter  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 (copyin(arg, rp, sizeof(struct device)))
     19                return(EFAULT);
     20            break;
     21               ...
     22      }
     23               ...
     24  }

ATTRIBUTES

     See attributes(5) for a description of the following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Stability Level             | Obsolete                    |
    |_____________________________|_____________________________|

SEE ALSO

     attributes(5),    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.

     copyin() should not be  used  from  a  streams  driver.  See
     M_COPYIN and M_COPYOUT in STREAMS Programming Guide.