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From: Paul Stewart <phorefaux@gmail.com>
Newsgroups: comp.sys.acorn.programmer
Subject: Re: OS_Find &4F
Date: Sun, 22 Feb 2026 17:17:45 GMT
Organization: A noiseless patient Spider
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Message-ID: <97283caf5c.Paul@phorefaux>
References: <b171d8ae5c.Paul@phorefaux> <2b3b10af5c.jmb@jmc.bruck.orange.fr> <5caf1565f8News04@avisoft.f9.co.uk>
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In message <5caf1565f8News04@avisoft.f9.co.uk>
          Martin <News04@avisoft.f9.co.uk> wrote:

> In article <2b3b10af5c.jmb@jmc.bruck.orange.fr>,
>    Jean-Michel <jmc.bruck@orange.fr> wrote:
>> In message <b171d8ae5c.Paul@phorefaux>
>>           Paul Stewart <phorefaux@gmail.com> wrote:

>>> Hi there,

>>> Trying to read a log file when the file is already open by the
>>> the utility that is create it.(downloading a file using WGet and
>>> reading the log file to display percentage downloaded)

>>> Using SYS "XOS_Find",&4F,file$ TO handle%

>>> Now the above works fine on my RO4.42 and RO5 devices.

>>> When I test with VRPC with RO4 and RO6, Error is generated:
>>> Handle is either illegal or has been closed and errors with the
>>> line number the above SYS command is on.

>>> I'm doing
>>> OS_Find command to open the file
>>> getting the size
>>> OS_GBPB to read into buffer
>>> OS_Find to then close the file.

>>> Above all works fine on 4.42 and 5, but generates the Handle is
>>> either illegal or has been closed error on RO4 and RO6.

>>> Any ideas as to why the RO4 and RO6 do not like SYS
>>> "XOS_Find",&4F,file$ TO handle% with a file that is already open
>>> and being updated, where as other OS's are fine with it?

>> Not sure, but osfind must have evolved According to OSLib's SHelp
>> manual, there are 32bit handles, the old ones were 8bit. from
>> version 6.3 the handles are 32 bits. I don't know how to
>> distinguish with Sys "OSfind" on Ro4  ?

>> You can display handle% for comparison. (Reporter is fine!)

> I suspect the differences are more to do with the FileSystem being
> used, rather than the RISC OS version. I have certainly seen
> differences in what can be done to open files on different file
> systems.

Good shout, that had crossed my mind.
In all cases, the file is being read from Wimp$ScrapDir.
On RO4.39, this is set to Memphis, as is the case on RO4/6 (or so I was 
thinking, however, now having checked this, I see I was wrong, it was set 
to !Scrap folder in Resources on HostFS, if I set to Memphis, works as 
expected.  On further testing.  Reading the file works fine with Memphis, 
but errors with IDEFS, HOSTS,ADFS(VRPC),SDFS.

Therefore my next question.
I am using webget and outputting the log file to scrap.  I am trying to 
update a window with percentage of file downloaded, which as I now know 
works fine with Memphis, but not anything else :(.  The file itself is 
open by webget as it is updating it.  I also need to open it for reading 
so I can get the download percentage.

With OS_Find not working apart from on Memphis, is there another way to do 
this?

-- 
Paul Stewart
Sent from A9home running RISC OS 4.42