DosProtectSetFileSize

Changes the size of a file.

Syntax

DosProtectSetFileSize(hFile, cbSize, fhFileHandleLockID)

Parameters

hFile (HFILE) - input

Handle of the file whose size to be changed.

cbSize (ULONG) - input

New size, in bytes, of the file.

fhFileHandleLockID (FHLOCK) - input

The filehandle lockid obtained from DosProtectOpen.

Return Code

ulrc (APIRET) - returns

DosProtectSetFileSize returns one of the following values:

• 0 NO_ERROR
• 5 ERROR_ACCESS_DENIED
• 6 ERROR_INVALID_HANDLE
• 26 ERROR_NOT_DOS_DISK
• 33 ERROR_LOCK_VIOLATION
• 87 ERROR_INVALID_PARAMETER
• 112 ERROR_DISK_FULL

Remarks

When DosProtectSetFileSize is issued, the file must be open in a mode that allows write access.

The size of the open file can be truncated or extended. If the file size is being extended, the file system tries to allocate additional bytes in a contiguous (or nearly contiguous) space on the medium. The values of the new bytes are undefined.

Example Code

This example writes to a file named "DOSPMAN.DAT", resets the buffer, and changes the size of the file using DosProtect functions.

#define INCL_DOSFILEMGR          /* File Manager values */
#define INCL_DOSERRORS           /* DOS Error values    */
#include <os2.h>
#include <stdio.h>
#include <string.h>

int main(VOID) {
   HFILE  hfFileHandle   = 0L;     /* Handle for file being manipulated */
   ULONG  ulAction       = 0;      /* Action taken by DosOpen */
   FHLOCK FileHandleLock = 0;      /* File handle lock   */

   ULONG  ulWrote        = 0;      /* Number of bytes written by DosWrite */
   UCHAR  uchFileName[20]  = "dospman.dat",     /* Name of file */
          uchFileData[4]   = "DATA";            /* Data to write to file */
   APIRET rc             = NO_ERROR;            /* Return code */

   /* Open the file dosman.dat.  Use an existing file or create a new */
   /* one if it doesn't exist.                                      */
   rc = DosProtectOpen(uchFileName, &hfFileHandle, &ulAction, 4L,
              FILE_ARCHIVED | FILE_NORMAL,
              OPEN_ACTION_CREATE_IF_NEW | OPEN_ACTION_OPEN_IF_EXISTS,
              OPEN_FLAGS_NOINHERIT | OPEN_SHARE_DENYNONE  |
              OPEN_ACCESS_READWRITE, 0L, &FileHandleLock);
   if (rc != NO_ERROR) {
      printf("DosOpen error: return code = %u\n", rc);
      return 1;
   }

   rc = DosProtectWrite (hfFileHandle, (PVOID) uchFileData,
                  sizeof (uchFileData), &ulWrote, FileHandleLock);
   if (rc != NO_ERROR) {
      printf("DosWrite error: return code = %u\n", rc);
      return 1;
   }

   rc = DosResetBuffer (hfFileHandle);
   if (rc != NO_ERROR) {
      printf("DosResetBuffer error: return code = %u\n", rc);
      return 1;
   } /* endif */

   rc = DosProtectSetFileSize (hfFileHandle, 8L, FileHandleLock);
   if (rc != NO_ERROR) {
      printf("DosSetFileSize error: return code = %u\n", rc);
      return 1;
   }

   return NO_ERROR;
}

Related Functions

• DosProtectOpen
• DosProtectQueryFileInfo
• DosQueryPathInfo