problems with locking

problems with locking

[Siim Vahtre]

Hi.

I need to use some dosemu clients(running old database programs made in
turbo pascal) that read/write paradox databases on linux samba server.
However, it seems that samba and dosemu doesn't share their thoughts about
file locking.

For example, when I open (read-only!) some file (let's say "L:\test.txt"
that is actually "/mnt/samba/test.txt") then I can't open the same file
with another dosemu. (It says "Access denied.")

smbstatus shows:
Pid    DenyMode    R/W  Oplock Name
2347   DENY_NONE   RDRW NONE   /mnt/samba/test.txt

DenyMode is DENY_NONE, so I should be able to at least open the file
read_only from another client aswell, right?

Dosemu version is 1.0.2
Samba version is 2.2.3a-6
The OS on Dosemu is FreeDOS (1.1.24c)

And even if I can get this to work... will I be able to use bytelocking
(for databases) aswell?

Or in general - does anyone know how well one old TPascal program with
paradox databases might work on dosemu?

Any hints/helps are deeply appreciated.

Re: problems with locking

[Siim Vahtre]

> For example, when I open (read-only!) some file (let's say "L:\test.txt"
> that is actually "/mnt/samba/test.txt") then I can't open the same file
> with another dosemu. (It says "Access denied.")

One thing more:
It does not matter HOW I configure the samba. Even if there  is no locking
whatsoever, I STILL cannot look at file someone else is _reading_.

If anyone knows how, please help.

Re: problems with locking

[Michal Samek]

On St, 2002-11-06 at 12:55, Siim Vahtre wrote:
> > For example, when I open (read-only!) some file (let's say "L:\test.txt"
> > that is actually "/mnt/samba/test.txt") then I can't open the same file
> > with another dosemu. (It says "Access denied.")

OK, there ARE 2 locking problems. One with a file lock and another with
a record lock. Try to search archives. Try 1.1.3 version, for some
people it seems to work (not for me and for some clipper users i
think).  But  what do you try with test.txt is maybe ok, when I open for
ex. with NC some file for reading (F3 - view file), it opens the file in
DENY-ALL mode and it should deny other sessions to open the file.

> 
> One thing more:
> It does not matter HOW I configure the samba. Even if there  is no locking
> whatsoever, I STILL cannot look at file someone else is _reading_.
> 
> If anyone knows how, please help.
> 



-- 
Michal Samek <webmaster@tony.cz>

Re: problems with locking

[Siim Vahtre]

> OK, there ARE 2 locking problems. One with a file lock and another with
> a record lock. Try to search archives. Try 1.1.3 version, for some
> people it seems to work (not for me and for some clipper users i
> think).  But  what do you try with test.txt is maybe ok, when I open for
> ex. with NC some file for reading (F3 - view file), it opens the file in
> DENY-ALL mode and it should deny other sessions to open the file.

I tried 1.1.3 aswell. Exactly the same  :(

I also tried to change the os on it. (drdos and various versions of
freedos). No luck whatsoever.

Whatever I do, "DENY_NONE" and "Oplock:" none is unreadable by others.

Re: problems with locking

[Stephen Lee]

On Wed, 2002-11-06 at 06:20, Siim Vahtre wrote:
> > OK, there ARE 2 locking problems. One with a file lock and another with
> > a record lock. Try to search archives. Try 1.1.3 version, for some
> > people it seems to work (not for me and for some clipper users i
> > think).  But  what do you try with test.txt is maybe ok, when I open for
> > ex. with NC some file for reading (F3 - view file), it opens the file in
> > DENY-ALL mode and it should deny other sessions to open the file.
> 
> I tried 1.1.3 aswell. Exactly the same  :(
> 

Try it with the latest patches (1.1.3.7) at
http://www.dosemu.org/testing. I had to use the patches, starting with
1.1.3.3, before Foxpro and Samba would recognize each others locks.

Stephen

Re: problems with locking

[Siim Vahtre]

> Try it with the latest patches (1.1.3.7) at

It works!
I now just hope that this testing version is 'stable' enough.

Thank you!

Re: problems with locking

[Siim Vahtre]

> > Try it with the latest patches (1.1.3.7) at
>
> It works!

*sigh*
It doesn't work :)

The samba has shared everything well. Windows clients get done their
locking correctly. However, when dosemu clients come, they don't care
about locking any more. Even if they are exclusive locks that should
forbid even reading. All the locks are downgraded to DENY_NONE and
everything can always be readed/writed. Alas.

I even tried strict locking aso... nothing worked.

dosemu locking capabilities

[Siim Vahtre]

How much ways dosemu actually knows to lock one file?

As I mentioned already, I need quite special way of locking files (paradox
databases). It must be able to lock one certain record, that is being
changed, and leave every other record readable/writeable.

Can dosemu handle it in any way?
(I'm not sure even if DOS can...)

Atm, I have tried thousands of different ways to do it (many different
versions of samba, dosemu, freedos/drdos, etc) but I have not been able
to (even not for once) get different locking than just this simple
"OpLocks: none" and "DenyMode: DENY_NONE", which basicly is quite
'nothing' for me. (It doesn't forbid anyone to corrupt the data.)

Am I doing something totally wrong or isn't it really possible to be able
to lock files in more complex way? (The Windows boxes using the same
samba fileserver locked correctly, so it must be dosemu's problem, right?)

I'm really sorry if I'm just wasting your time with stupid questions but
all those long hours with 'gain: zero' are getting depressing ;-)

Re: dosemu locking capabilities

[Stephen Lee]

On Wed, 2002-11-06 at 12:58, Siim Vahtre wrote:
> 
> How much ways dosemu actually knows to lock one file?
> 
> As I mentioned already, I need quite special way of locking files (paradox
> databases). It must be able to lock one certain record, that is being
> changed, and leave every other record readable/writeable.
> 
> Can dosemu handle it in any way?
> (I'm not sure even if DOS can...)
> 
> Atm, I have tried thousands of different ways to do it (many different
> versions of samba, dosemu, freedos/drdos, etc) but I have not been able
> to (even not for once) get different locking than just this simple
> "OpLocks: none" and "DenyMode: DENY_NONE", which basicly is quite
> 'nothing' for me. (It doesn't forbid anyone to corrupt the data.)
> 
> Am I doing something totally wrong or isn't it really possible to be able
> to lock files in more complex way? (The Windows boxes using the same
> samba fileserver locked correctly, so it must be dosemu's problem, right?)
> 
> I'm really sorry if I'm just wasting your time with stupid questions but
> all those long hours with 'gain: zero' are getting depressing ;-)

Hang in there ;-) I use Foxpro so the locking requirements look to be
different than for Clipper. Hopefully the developers can chime in and
ask for some diagnostic output.

Stephen

Re: dosemu locking capabilities

[Bart Oldeman]

On Wed, 6 Nov 2002, Siim Vahtre wrote:

> How much ways dosemu actually knows to lock one file?

just a few days ago I wrote down the way how DOSEMU handles file locking 
now (since 1.1.3.3) here:
http://marc.theaimsgroup.com/?l=linux-msdos&m=103627393213889&w=2
see src/dosext/mfs/mfs.c for the implementation.

There is a fundamental problem in that DOS locking is incompatible with 
UNIX locking. Now if you use smbfs and samba you add two extra layers 
where things can go wrong. This makes it complex. If the file server is 
not running Windows then it's probably better to use NFS instead.

The locking mechanism I did not mention was region locking, which however 
can probably be solved now in certain cases by using the 64-bit 
lock functions. See
http://marc.theaimsgroup.com/?l=linux-msdos&m=103626684509236&w=2
(this is not implemented yet; patches are welcome :)

Bart