Hello,
I am using linux 2.6 and seems it is like you say, close() didn't
release lock.
I have done following test: I have modified "filebuf.c" blocking the
hb_findFile() function... so any use command create a new handle and it
should create problems in POSIX locks.
I created a short programs in order to check it in Linux the programs
give net-error while I try to open TEMP in Exclusive: if I have well
understood, in BSD (POSIX locks) neterr() should return .f.
USE TEMP NEW ALIAS TEMP1 SHARED
USE TEMP NEW ALIAS TEMP2 SHARED
CLOSE
USE TEMP NEW EXCLUSIVE
?NETERR() // equal .t.
Bye, Marco
Przemyslaw Czerpak ha scritto:
On Sat, 18 Jul 2009, be...@alice.it wrote:
Hi,
thank you very much for your detailed answer. Now the situation is clear.
In my programs the duplicate aliases are usually open in READONLY and in
case of update I open the table again in RW, I make the update and I
reclose the alias.
It seems to me that this cannot generate problems, because previous alias
is always in READONLY and therefore there are no lock pending.... le me
know if I am wrong
In Linux kernels AFAIR >= 2.2 is should not cause problems because
FCNTL locks are fully separated from BSD locks and in Linux we are
using BSD locks to simulate DOS DENY flags and BSD locks are not removed
by close() on other file handles because they are bound with file
handle not inode. Anyhow in some other *nixes like real BSD systems or
Darwin BSD locks internally are represented by POSIX locks and can cause
deadlock when both are used so we have to use POSIX locks to emulate
DOS DENY flags. BSD locks are used only in Linux builds so on all other
*nix like systems close on the RW workarea removed lock from RO area which
blocks other processes against opening the table in exclusive mode.
I do not know if it's problem for you.
Anyhow now it is clear to me what can happens....
Like you say, should be better the also in xHarbour the attempt to reopen
a RO table in RW mode generates some kind of error....
I'll commit to Harbour modifications I described in previous message so
it will be possible to reopen file in RW mode and the old RO handle
will be saved in HB_FILE structure to not close file immediately.
best regards,
Przemek
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