Re: USE {table} EXCLUSIVE sometimes opens readonly.

-- Alan Bourke alanpbourke (at) fastmail (dot) fm On Tue, 8 Mar 2016, at 05:46 PM, AndyHC wrote: > As Christof said some years ago: all is not what it seems with Foxpro > file handling - there is a *lot* of smoke and mirrors! > > On 08/03/2016 20:44, Tracy Pearson wrote: > > I have been tracking down a very random occurrence of a table opened with > > the Exclusive flag throwing an error. > > > > #111 Cannot update the cursor "cursor", since it is read-only. > > > > I checked the code, no NOUPDATE flag. > > > > I brought up SysInternals Process Monitor and opened, appended a record, > > and closed a table 10000 times. > > I had suspected multiple anti-virus and on demand backup tools causing > > behavior problems. > > This Windows 7 (virtual machine) has 1 GB RAM, Kaspersky, Bitdefender, and > > Carbonite installed. > > No exclusions, and Carbonite is set to specifically backup the data folder > > on demand. > > > > My test actually does a Try/Catch around the USE statement, wrapped in a DO > > WHILE NOT USED() > > It seems the tools mentioned are not the direct culprit. Instead when things > > fail, Windows Explorer was the direct cause. Windows Explorer opens the > > table Read Only and with Share Read/Write and reads the first 4000 bytes. > > Then closes the file. Why I don't know, I don't care. I do know it only > > happens when the Explorer window is open to the folder where the table > > exist. > > > > Lucky for me, the place I open tables is via a class, so a check with > > ISREADONLY() will prevent this in the future. > > > > So what really happens? In Process Monitor I can clearly see I open a table > > in one session of VFP 9, then in another session of VFP 9 I attempt to open > > it again. First VFP attempts to open the table Read/Write with Share None. > > It gets a Sharing Violation. Then VFP attempts to open the table Read Only > > with Share None. There is that split moment on some machines that VFP is > > successful. > > > > Has anyone else seen this behavior before? > > > > Thank you for reading, > > Tracy > > > > [excessive quoting removed by server]