Associates a C run-time file descriptor with an existing operating system file handle.


int _open_osfhandle (
   intptr_t osfhandle,
   int flags


Operating system file handle.

Types of operations allowed.

Return Value

If successful, _open_osfhandle returns a C run-time file descriptor. Otherwise, it returns -1.


The _open_osfhandle function allocates a C run-time file descriptor. It associates this file descriptor with the operating system file handle specified by osfhandle. To avoid a compiler warning, cast the osfhandle argument from HANDLE to intptr_t. The flags argument is an integer expression formed from one or more of the manifest constants defined in <fcntl.h>. You can use the bitwise-OR operator ( | ) to combine two or more manifest constants to form the flags argument.

These manifest constants are defined in <fcntl.h>:

_O_APPEND Positions a file pointer to the end of the file before every write operation.
_O_RDONLY Opens the file for reading only.
_O_TEXT Opens the file in text (translated) mode.
_O_WTEXT Opens the file in Unicode (translated UTF-16) mode.

The _open_osfhandle call transfers ownership of the Win32 file handle to the file descriptor. To close a file opened by using _open_osfhandle, call _close. The underlying OS file handle is also closed by a call to _close. Don't call the Win32 function CloseHandle on the original handle. If the file descriptor is owned by a FILE * stream, then a call to fclose closes both the file descriptor and the underlying handle. In this case, don't call _close on the file descriptor or CloseHandle on the original handle.


Routine Required header
_open_osfhandle <io.h>

For more compatibility information, see Compatibility.

See also

File Handling