[Lazarus] semaphore

[Sven Barth]

Am 16.02.2012 17:04, schrieb Antonio Fortuny:
> Hi all.
>
> On an OpenSuse 12.1, Lazarus 0.9.31, FPC 2.4.4 I can't create a semaphore
> Code:
>
> LockerS: Integer;
> SemKey: Integer;
>
>
> SemKey := strToIntDef(ESemaphoreKey.Text, -1);
> if SemKey = -1 then
> Break;
> LockerS := semget(SemKey, 1, 0666 + IPC_CREAT + IPC_EXCL);
> if LockerS >= 0 then begin
> // got the semaphore: initialize it
> Args.Val := 1;
> Ret := semctl(LockerS, 0, SEM_SETVAL, Args);
> if Ret >= 0 then begin
> // semaphore locked; get out
> Operation.sem_op := -1; //reduce the semaphore count to lock
> Operation.sem_num := 0; //signifies 0th semaphore
> Operation.sem_flg := IPC_EXCL; // fail if key exists
> Ret := semop(LockerS, @Operation,1);
> if Ret >= 0 then
> Break;
> end
> end else begin
> LastError := errno;
> LastErrorText := strerror(LastError);
> Memo1.Lines.Add(Format('semaphore locker not created errno:%d-%s',
> [LastError, LastErrorText]));
> end
>
> *semget *always returns -1 with errno set to 2 (?) whatever the contents
> of *SemKey* could be.
>
> What is wrong ?

According to 
http://pubs.opengroup.org/onlinepubs/7908799/xsh/semget.html error 2 
means the following:

[ENOENT]
     A semaphore identifier does not exist for the argument key and 
(semflg&IPC_CREAT) is equal to 0.

Can you try to use "or" instead of "+"? Also you're trying to pass a C 
style octal number. Replace the leading zero by a "&" which is the 
equivalent declaration for Free Pascal (see also here: 
http://www.freepascal.org/docs-html/ref/refse6.html ).

Regards,
Sven