Message queue support

[Jose Miguel Goncalves]

OK Jeff, I agree with you.

José Gonçalves

J. Johnston wrote:
> Thanks Jose,
> 
>   The first part regarding the "created" flag is correct, however, I do 
> not agree
> with the 2nd part of your change.  That code ensures that the creator of 
> the shared memory file also
> owns the semaphores.  Once the "created" flag has been set correctly, it 
> should work for
> your test.
> 
> -- Jeff J.
> 
> Jose Miguel Goncalves wrote:
> 
>> Jeff,
>>
>> I have found another bug in mq_open(). When called more than once (for 
>> the same queue) with O_CREAT flag set, it fails. Sugested patch:
>>
>> ===================================================================
>> RCS file: /cvs/src/src/newlib/libc/sys/linux/mq_open.c,v
>> retrieving revision 1.3
>> diff -p -u -r1.3 mq_open.c
>> --- mq_open.c    27 Jun 2003 00:00:48 -0000    1.3
>> +++ mq_open.c    27 Jun 2003 14:53:04 -0000
>> @@ -98,7 +98,8 @@ mq_open (const char *name, int oflag, ..
>>        return (mqd_t)-1;
>>      }
>>        errno = saved_errno;
>> -      created = 1;
>> +      if (fd >= 0)
>> +        created = 1;
>>      }
>>        if (fd < 0)
>> @@ -132,9 +133,12 @@ mq_open (const char *name, int oflag, ..
>>        saved_errno = errno;
>>        semid = semget (key, 6, IPC_CREAT | IPC_EXCL | mode);
>>        errno = saved_errno;
>> -      /* now that we have created the semaphore, we should initialize 
>> it */
>>        if (semid != -1)
>> +        /* now that we have created the semaphore, we should 
>> initialize it */
>>          semctl (semid, 0, SETVAL, arg);
>> +          else
>> +        /* semaphore already exists, so we get only it's id */
>> +        semid = semget (key, 6, 0);
>>      }
>>        else
>>      {
>>
>> Regards,
>> José Gonçalves
>>
>> J. Johnston wrote:
>>
>>> Jose,
>>>
>>>   I found a serious problem with opening an existing queue for read 
>>> whereby the
>>> read/write buffers were not being allocated.  A patch has been 
>>> committed to the
>>> sources.  With that patch applied I was able to run your test case 
>>> successfully.
>>>
>>> -- Jeff J.
>>>
>>> Jose Miguel Goncalves wrote:
>>>
>>>> Jeff,
>>>>
>>>> After setting up /dev/shm I could create a queue with mq_open(), and 
>>>> send messages with mq_send(), but calling to mq_receive() returns 
>>>> errors - "Bad address".
>>>> I attach the source code for the simple mqueue test application that 
>>>> I'm using. I am compiling in a 2.4.21 linux kernel with:
>>>>
>>>> $ gcc -static -nostdlib -g -Wall -D_REENTRANT 
>>>> -I/usr/local/newlib/i686-pc-linux-gnu/include 
>>>> /usr/local/newlib/i686-pc-linux-gnu/lib/crt0.o test_thread_queue.c 
>>>> -L/usr/local/newlib/i686-pc-linux-gnu/lib -lpthread -lc -lgcc -o 
>>>> test_thread_queue
>>>>
>>>> The same source compiled in a Sun Solaris 8 machine (with native 
>>>> support for pthreads and mqueues) works fine.
>>>>
>>>> Regards,
>>>> José Gonçalves
>>>>
>>
>>
> 
>