DosDupHandle

This call returns a new file handle for an open file, which refers to the same position in the file as the old file handle.

DosDupHandle

(OldFileHandle, NewFileHandle)

OldFileHandle (HFILE) - input

Current file handle.
NewFileHandle (PHFILE) - input/output
Address of a Word. On input, values and their meanings are:

Value

Definition
FFFFH
Allocate a new file handle and return it here.
<>FFFFH
Assign this value as the new file handle. A valid value is any of the handles assigned to standard I/O, or the handle of a file currently opened by the process.

On output, a value of FFFFH returns a value for NewFileHandle, allocated by OS/2.

rc (USHORT) - return
Return code descriptions are:
• NO_ERROR 4
  ERROR_TOO_MANY_OPEN_FILES
  6
  ERROR_INVALID_HANDLE
  114
  ERROR_INVALID_TARGET_HANDLE
  Remarks

  Duplicating the handle duplicates and ties all handle-specific information between OldFileHandle and NewFileHandle. For example, if you move the read/write pointer of either handle by a DosRead, DosWrite, or DosChgFilePtr function call, the pointer for the other handle is also changed.

  The valid values for NewFileHandle include the following handles for standard I/O, which are always available to the process:

  0000H

  Standard input
  0001H
  Standard output
  0002H
  Standard error.

  If a file handle value of a currently open file is specified in NewFileHandle, the file handle is closed before it is redefined as the duplicate of OldFileHandle. Avoid using arbitrary values for NewFileHandle.

  Issuing a DosClose against a file handle does not affect the duplicate handle.

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