If I write a DOS file from my app (with OSBWrite) and afterwards open it with Word, I get a warning the file is in use by a different user. How can I let my app really let go of the file? I do a OSClose, but that doesn't seem to be enough. Should it?

- Oystein -

Oystein,

AFAIK doing an OSClose should be enough.

[email protected]

SRP Computer Solutions

Don,

Would you be so kind and check if the rest is OK? Perhaps there's something dodgy with the way I create the file.

- Oystein -

/* delete the file if it already exists */

OSOpen OutputFileName to OutputFileHandle then

	OSClose OutputFileHandle

	OSDelete OutputFileName

end 

/* create the file */

OSWrite "" to OutputFileName

/* create file handle */

OSOpen OutputFileName to OutputFileHandle else

	...error handling...

end

/* init write */

OutputFilePos=0

... ... ...

Line=... : CrLf

/* write line to file */

OSBWrite Line on OutputFileHandle at OutputFilePos

if Status()  0 then

	...error handling...

end else

	OutputFilePos += len(Line)

end

... ... ...

/* close file */

OSClose OutputFileHandle

Oystein ..

A couple of possibilities:

1. The file is non-sharable or there are some ownership issues regarding access by another user that cause the file to be opened in read-only mode.

2. If you are using Netware, check the file's properties by doing FLAG . This will list both the DOS and Netware attributes for the file.

A possible solution would be not to delete the file but to simply clear its contents (OSWRITE "" on FILE_HANDLE if it exists). In this way, the ownership and rights would not be changed assuming that it was created properly in the first place (Sharable / Read-Write, etc.)

Just a thought ..

Don Miller

C3 Inc.

Oystein,

I don't know if this will resolve your problem, but here are a couple of thoughts I had from looking at your code:

<code> /* delete the file if it already exists */ OSOpen OutputFileName to OutputFileHandle then OSClose OutputFileHandle OSDelete OutputFileName end </code>

This seems redundant, especially since you are OSWriting a null to the file in the next line.

<code> /* create the file */ OSWrite "" to OutputFileName /* create file handle */ OSOpen OutputFileName to OutputFileHandle else …error handling… end </code>

Shouldn't the above be reversed? You are OSWriting before your OSOpen. Because of this, one of your OSCloses might not be working correctly.

[email protected]

SRP Computer Solutions

Oystein ..

Don has sharp eyes.

Don Miller

C3 Inc.

What you are seeing is probably (a) what Don Bakke identified and (b) that you should perform a FLUSH after each OS I/O group of statements.

Steve

Steve/Don/Don,

Admit my code looks like two functions crashed and merged and got their lines rearranged. Sort of Basic+ scar tissue. It's a long story.

I reverted to the code in the OSWrite online help, but without success:

OSOpen "OSTEST" To file_var Else

• Create an operating system file.

OSWrite "" To "OSTEST"

• Create the necessary file handle.

OSOpen "OSTEST" To file_var Else

  * error handling

End

End

Then I added a Flush statement before my OSClose and the problem went away. Thanks, Steve! But why exactly does Flush help?

- Oystein -

Oystein - Lucky guess.

A FLUSH is designed to put all the buffered stuff to disk. Some is buffered by the network itself and some by the BFS itself. And it would have to close the files to get the buffer contents to disk.

So any caching that's happening would in part be resolved by a flush, otherwise you may be operating on an open file, or trying to share a handle (=error material)

Steve

Steve,

I still don't understand why OSClose cannot finish the file properly. But thanks again!

- Oystein -

Don,

]]/* delete the file if it already exists */

]]OSOpen OutputFileName to OutputFileHandle then

]]OSClose OutputFileHandle

]]OSDelete OutputFileName

]]end

]This seems redundant, especially since you are

]OSWriting a null to the file in the next line.

Now I remember why I did it - to clear the file. Else if I write to an existing file, and the new content is shorter than the old, I get old data at the end. So what is the proper way to clear an existing file, or to set a new EOF?

- Oystein -

Oystein,

I could be wrong but OSWriting a null should clear the file. OSBWriting a null will only clear the byte you are pointing to.

If this is not the case then there are a few routines I need to double check .

[email protected]

SRP Computer Solutions

Don,

You're right about OSWrite "". I always used OSWrite, but I've had a case were it wasn't executed. I also discovered another thing that must have confused me earlier. Final (?) version:

/* try to open the output file */

OSOpen FileName to FileVar then

/* the file exists. clear it */

OSWrite "" to FileName

end else

/* the file does not exist. create it */

OSWrite "" to FileName

/* open the file */ 

OSOpen FileName to FileVar then

	...error handling...

end

end

(Btw - I said in a different post I quoted the help text on OSWrite. It's actually in the help for OSBRead.)

- Oystein -

View this thread on the forum...