On 03 May 2009, at 14:51, Jonas Maebe wrote:
On 03 May 2009, at 14:09, ajv wrote:
With Region Do Begin
l_type := F_WRLCK; l_whence := SEEK_SET;
l_start := 10; l_len := 20
End;
If FpFcntl (F, F_SETLK, Region) = -1 Then
WriteLn ('unable to apply writelock'); // <-- OK
Sleep (20000); // Sleep 20 Sec
FpClose (F);
End.
--------------------------------------------------------------------------------------
Then within 20 seconds i start test to obtain a readlock on 80.
This fails. Why? What am I doing wrong?
Your test works fine under Solaris. It's a bug somewhere in the FPC
Linux units. strace shows this for your first program:
fcntl(3, F_SETLK, {type=F_WRLCK, whence=SEEK_SET, start=10, len=0})
= 0
As you can see, "len=0" is passed to the system call (instead of
len=20), so it locks the entire file. That's the reason why the
other program is unable to lock anything else.
It's similar to http://bugs.freepascal.org/view.php?id=13363 : the
kernel's off_t is 32 bit on 32 bit systems. It's defined as 64 bit in
the Linux rtl for all platforms.
Jonas
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