Manual Pages for UNIX Operating System command usage for man copyout

Kernel Functions for Drivers                          copyout(9F)



NAME
     copyout - copy data from a driver to a user program

SYNOPSIS
     #include 
     #include 



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


INTERFACE LEVEL
     This interface is obsolete. ddi_copyout(9F) should  be  used
     instead.

PARAMETERS
     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.


DESCRIPTION
     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 effi-
     cient move algorithm according to address alignment.

RETURN VALUES
     Under normal conditions, a 0 is returned to indicate 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.



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Kernel Functions for Drivers                          copyout(9F)



         o    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  rou-
     tines should return EFAULT.

CONTEXT
     copyout() 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 con-
     dition (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  }


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



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Kernel Functions for Drivers                          copyout(9F)



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


SEE ALSO
     attributes(5),     ioctl(9E),     bcopy(9F),     copyin(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_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.






























SunOS 5.11          Last change: 27 Sep 2002                    3