Cancels all pending input and output (I/O) operations that are issued by the calling thread for the specified file. The function does not cancel I/O operations that other threads issue for a file handle.
To cancel I/O operations from another thread, use the CancelIoEx function.
BOOL CancelIo( HANDLE hFile );
A handle to the file.
The function cancels all pending I/O operations for this file handle.
If the function succeeds, the return value is nonzero. The cancel operation for all pending I/O operations issued by the calling thread for the specified file handle was successfully requested. The thread can use the GetOverlappedResult function to determine when the I/O operations themselves have been completed.
If the function fails, the return value is zero (0). To get extended error information, call the GetLastError function.
If there are any pending I/O operations in progress for the specified file handle, and they are issued by the calling thread, the CancelIo function cancels them. CancelIo cancels only outstanding I/O on the handle, it does not change the state of the handle; this means that you cannot rely on the state of the handle because you cannot know whether the operation was completed successfully or canceled.
The I/O operations must be issued as overlapped I/O. If they are not, the I/O operations do not return to allow the thread to call the CancelIo function. Calling the CancelIo function with a file handle that is not opened with FILE_FLAG_OVERLAPPED does nothing.
All I/O operations that are canceled complete with the error ERROR_OPERATION_ABORTED, and all completion notifications for the I/O operations occur normally.
In Windows 8 and Windows Server 2012, this function is supported by the following technologies.
|Server Message Block (SMB) 3.0 protocol||Yes|
|SMB 3.0 Transparent Failover (TFO)||Yes|
|SMB 3.0 with Scale-out File Shares (SO)||Yes|
|Cluster Shared Volume File System (CsvFS)||Yes|
|Resilient File System (ReFS)||Yes|
|Minimum supported client||Windows XP [desktop apps | UWP apps]|
|Minimum supported server||Windows Server 2003 [desktop apps | UWP apps]|
|Header||ioapiset.h (include Windows.h)|