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KB#00248-Error 0 when OPENing the same file using different naming conventions

Title:

Error 0 when OPENing the same file using different naming conventions

Description:

If the same file is OPENed twice under DOS, each OPEN must use the exact same path/filename. That is, you cannot OPEN it one with just the filename, and then again with the full path. For example, you could not do the following: 

open(1)"TEST.DAT" 
open(2)"Test.dat" 

as it would result in an error 0. However, if you attempt to OPEN it a third time, it may work. 

Resolution:

On single-user Visual PRO/5 products an !ERROR=0 occurs when a file open attempt is made to a file that was already opened on another channel, but the path to the file was different. For example: 

OPEN(1)"file" 
OPEN(2)"./file" 

The OPEN(2) will fail with an !ERROR=0. This has been corrected in P/5 Rev 1.05 through the use of a new SETOPTS bit. The new bit is Byte 7 Bit 1. When this bit is set, Visual PRO/5 behaves in the same manner as the PRO/5 Unix ports. For example: 

OPEN(1)"file" 
OPEN(2)"./file" 

will share the same FCB which prevents an extra user slot being taken on the file and the !ERROR=0 for single user product. The FID() information is that of channel 1 in this case. The file name reported at offset 9 in FID(2) is exactly the same as that of FID(1) (i.e. "file"). Had channel 2 been open first the file name info in the FID(1) would be "./file". As a result of this correction, multiple channels to the same opened file use a single FCB. 



Last Modified: 07/27/1998 Product: Visual PRO/5 Operating System: MS Dos WindowsError Number: 0

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