FSH_DEVIOCTL - Send IOCTL request to device driver

Purpose   

This function sends an IOCTL request to a device driver. 

Calling Sequence   

int far pascal FSH_DEVIOCTL(flag, hDev, sfn, cat, func, pParm, cbParm, pData,
                            cbData)

unsigned short flag;
unsigned long hDev;
unsigned short sfn;
unsigned short cat;
unsigned short func;
char far * pParm;
unsigned short cbParm;
char far * pData;
unsigned short cbData;

Where   

flag indicates whether the FSD initiated the call or not. 

IOflag == 0x0000 indicates that the FSD is just passing user pointers on 
to the helper. 
IOflag == 0x0001 indicates that the FSD initiated the DevIOCtl call as 
opposed to passing a DevIOCtl that it had received. 

All other bits are reserved. 

hDev is the device handle obtained from VPB 

sfn is the system file number from open instance that caused the 
FSH_DEVIOCTL call. 

This field should be passed unchanged from the sfi_selfsfn field. If no 
open instance corresponds to this call, this field should be set to 
0xFFFF. 

cat is the category of IOCTL to perform. 

func is the function within the category of IOCTL. 

pParm is the long address to the parameter area. 

cbParm is the length of the parameter area. 

pData is the long address to the data area. 

cbData is the length of the data area. 
  

Returns   

If no error is detected, a zero error code is returned. If an error is 
detected, one of the following error codes is returned: 

oERROR_INVALID_FUNCTION 
indicates the function supplied is incompatible with the category and 
device handle supplied. 

oERROR_INVALID_CATEGORY 
indicates the category supplied is incompatible with the function and 
device handle supplied. 

oDevice driver error code 
  

Remarks   

The only category currently supported for this call is 8, which is for the 
logical disk. FSDs call FSH_DEVIOCTL to control device driver operation 
independently from I/O operations. This is typically in filtering 
DosDevIOCtl requests when passing the request on to the device driver. 

An FSD needs to be careful of pointers to buffers that are passed to it 
from FS_IOCTL, and what it passes to FSH_DEVIOCTL. It is possible that 
such pointers may be real mode pointers if the call was made from the DOS 
mode. In any case, the FSD must indicate whether it initiated the DevIOCtl 
call, in which case the kernel can assume that the pointers are all 
protect mode pointers, or if it is passing user pointers on to the 
FSH_DEVIOCTL call, in which case the mode of the pointers will depend on 
whether this is the DOS mode or not. An important thing to note is that 
the FSD must not mix user pointers with its own pointers when using this 
helper. 

FSH_DEVIOCTL may block. 

Note:   OS/2 does not validate input parameters. Therefore, an FSD should 
call FSH_PROBEBUF where appropriate.