File Open

NTDEV
1

Hi,

In Windows, is there a way to open a file in a non-blocking mode similar to
“O_NONBLOCK or O_NDELAY” in linux?

Thanks,
Sunil

2

> In Windows, is there a way to open a file in a non-blocking mode similar to

“O_NONBLOCK or O_NDELAY” in linux?

The default Windows way is like that. Read about asynchronous I/O:
http://msdn.microsoft.com/en-us/library/aa365683(v=VS.85).aspx .

–
Aram Hăvărneanu

3

If I understand correctly, async IO mentioned below allows to do READ/WRITE
asynchronously. I am interested in OPEN system call that will not block. In
linux, if O_NONBLOCK is set in oflag field of “open(const char **path*, int
*oflag*, … );”, then the *open()* function will return without blocking
for the device to be ready or available.

On Mon, Sep 20, 2010 at 2:33 PM, Aram Hăvărneanu wrote:

> > In Windows, is there a way to open a file in a non-blocking mode similar
> to
> > “O_NONBLOCK or O_NDELAY” in linux?
>
> The default Windows way is like that. Read about asynchronous I/O:
> http://msdn.microsoft.com/en-us/library/aa365683(v=VS.85).aspxhttp:.
>
> –
> Aram Hăvărneanu
>
> —
> NTDEV is sponsored by OSR
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></http:>

4

>In Windows, is there a way to open a file in a non-blocking mode similar to "O_NONBLOCK or

O_NDELAY" in linux?

Only the sockets support this in Windows, and also select() only works for sockets.

Windows has overlapped IO instead, the more flexible replacement of this feature.

–
Maxim S. Shatskih
Windows DDK MVP
xxxxx@storagecraft.com
http://www.storagecraft.com

5

>interested in OPEN system call that will not block

Pre-Vista, the whole MJ_CREATE path is always synchronous and cannot be async.

In Vista+, MJ_CREATE is async to some degree, but mainly to be cancellable only (SMB redir’s creates in Vista+ are cancellable).

I’m not sure that app-exposed MJ_CREATE is supported in Vista+.

–
Maxim S. Shatskih
Windows DDK MVP
xxxxx@storagecraft.com
http://www.storagecraft.com