How to check if a file is opened by another process

[portoon]

Dear friends

Is there any one know that how to check if a file is opened by another process?
I want to READ a file when the file is writing by another process with SHARE='DENYNONE' in OPEN statement.
It is sometimes OK but sometimes is NOT though both process has SHARE='DENYNONE'.
So, I would like to read the file after the writing process is done.
Please give me some comments.

Thanks a lot.

[DavidWhite]

Quoting - portoon

Dear friends

Is there any one know that how to check if a file is opened by another process?
I want to READ a file when the file is writing by another process with SHARE='DENYNONE' in OPEN statement.
It is sometimes OK but sometimes is NOT though both process has SHARE='DENYNONE'.
So, I would like to read the file after the writing process is done.
Please give me some comments.

Thanks a lot.

the Process which is writing probably should prevent any other process from accessing the file until it has finished - I think the risk of corrupting a file is high.

the process which needs to read the file probably should use DENYWR and put this into a timer loop until you the process successfully opens the file -- suggest also a maximum number of times this can occur before issuing a diagnostic error.

My 2c worth!

David

[Paul_Curtis]

Quoting - portoon

... check if a file is opened by another process?

It's easy to do this using the Win32 API functions:

[cpp]    ntry = 0
 10  ihandl = CreateFile (fullpath,					&
						 access,					&
						 IOR(FILE_SHARE_READ,FILE_SHARE_WRITE),	&
						 NULL_SECURITY_ATTRIBUTES,	& 
						 OPEN_ALWAYS,				&
						 FILE_ATTRIBUTE_NORMAL,		&
						 NULL						)

	IF (ihandl == INVALID_HANDLE_VALUE) THEN
	    IF (GetLastError() == ERROR_SHARING_VIOLATION) THEN
	        ntry = ntry + 1
	        IF (ntry > max_try) RETURN
	        CALL delay_ms (5)
	        GO TO 10
	    END IF
       END IF
[/cpp]