FS32_CHGFILEPTRL - Move a file's position pointer

Purpose   

Move a file's logical read/write position pointer. Version for 32-bit 
IFS'es, uses a 64-bit file pointer and size. 

Calling Sequence   

int _cdecl FS32_CHGFILEPTRL(psffsi, psffsd, offset, type, IOflag)

struct sffsi * psffsi;
struct sffsd * psffsd;
long long offset;
unsigned long type;
unsigned long IOflag;

Where   

psffsi is a pointer to the file-system-independent portion of an open file 
instance. 

The FSD uses the current file size or sfi_position along with offset and 
type to compute a new sfi_position. This is updated by the system. 

psffsd is a pointer to the file-system-dependent portion of an open file 
instance. The FSD may store or adjust data as appropriate in this 
structure. 

offset is the signed offset to be added to the current file size or 
position to form the new position within the file. 

type indicates the basis of a seek operation. 

type == 0 indicates seek relative to beginning of file. 
type == 1 indicates seek relative to current position within the file. 
type == 2 indicates seek relative to end of file. 

The value of type passed to the FSD will be valid. 

IOflag indicates information about the operation on the handle. 

IOflag == 0x0010 indicates write-through. 
IOflag == 0x0020 indicates no-cache. 
  

Remarks   

The file system may want to take the seek operation as a hint that an I/O 
operation is about to take place at the new position and initiate a 
positioning operation on sequential access media or read-ahead operation 
on other media. 

Some DOS mode programs expect to be able to do a negative seek. OS/2 
passes these requests on to the FSD and returns an error for OS/2 mode 
negative seek requests. Because a seek to a negative position is, 
effectively, a seek to a very large offset, it is suggested that the FSD 
return end-of-file for subsequent read requests. 

FSDs must allow seeks to positions beyond end-of-file. 

The information passed in IOflag is what was set for the handle during a 
DosOpen/DosOpen2 operation, or by a DosSetFHandState call.