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/**
* @file
*
* @brief Creates a new POSIX Message Queue or Opens an Existing Queue
* @ingroup POSIXAPI
*/
/*
* NOTE: The structure of the routines is identical to that of POSIX
* Message_queues to leave the option of having unnamed message
* queues at a future date. They are currently not part of the
* POSIX standard but unnamed message_queues are. This is also
* the reason for the apparently unnecessary tracking of
* the process_shared attribute. [In addition to the fact that
* it would be trivial to add pshared to the mq_attr structure
* and have process private message queues.]
*
* This code ignores the O_RDONLY/O_WRONLY/O_RDWR flag at open
* time.
*
* COPYRIGHT (c) 1989-2009.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/posix/mqueueimpl.h>
#include <rtems/score/wkspace.h>
#include <rtems/sysinit.h>
#include <stdarg.h>
#include <fcntl.h>
#define MQ_OPEN_FAILED ((mqd_t) -1)
/*
* There is no real basis for the default values. They will work
* but were not compared against any existing implementation for
* compatibility. See README.mqueue for an example program we
* think will print out the defaults. Report anything you find with it.
*/
static const struct mq_attr _POSIX_Message_queue_Default_attributes = {
.mq_maxmsg = 10,
.mq_msgsize = 16
};
static mqd_t _POSIX_Message_queue_Create(
const char *name_arg,
size_t name_len,
int oflag,
const struct mq_attr *attr
)
{
POSIX_Message_queue_Control *the_mq;
char *name;
/* length of name has already been validated */
if ( attr->mq_maxmsg <= 0 ){
rtems_set_errno_and_return_value( EINVAL, MQ_OPEN_FAILED );
}
if ( attr->mq_msgsize <= 0 ){
rtems_set_errno_and_return_value( EINVAL, MQ_OPEN_FAILED );
}
the_mq = _POSIX_Message_queue_Allocate_unprotected();
if ( !the_mq ) {
rtems_set_errno_and_return_value( ENFILE, MQ_OPEN_FAILED );
}
/*
* Make a copy of the user's string for name just in case it was
* dynamically constructed.
*/
name = _Workspace_String_duplicate( name_arg, name_len );
if ( !name ) {
_POSIX_Message_queue_Free( the_mq );
rtems_set_errno_and_return_value( ENOMEM, MQ_OPEN_FAILED );
}
the_mq->open_count = 1;
the_mq->linked = true;
the_mq->oflag = oflag;
/*
* NOTE: That thread blocking discipline should be based on the
* current scheduling policy.
*
* Joel: Cite POSIX or OpenGroup on above statement so we can determine
* if it is a real requirement.
*/
if (
!_CORE_message_queue_Initialize(
&the_mq->Message_queue,
CORE_MESSAGE_QUEUE_DISCIPLINES_FIFO,
attr->mq_maxmsg,
attr->mq_msgsize
)
) {
_POSIX_Message_queue_Free( the_mq );
_Workspace_Free( name );
rtems_set_errno_and_return_value( ENOSPC, MQ_OPEN_FAILED );
}
_Objects_Open_string(
&_POSIX_Message_queue_Information,
&the_mq->Object,
name
);
return the_mq->Object.id;
}
/*
* 15.2.2 Open a Message Queue, P1003.1b-1993, p. 272
*/
mqd_t mq_open(
const char *name,
int oflag,
...
/* mode_t mode, */
/* struct mq_attr attr */
)
{
POSIX_Message_queue_Control *the_mq;
size_t name_len;
Objects_Get_by_name_error error;
mqd_t status;
_Objects_Allocator_lock();
the_mq = _POSIX_Message_queue_Get_by_name( name, &name_len, &error );
/*
* If the name to id translation worked, then the message queue exists
* and we can just return a pointer to the id. Otherwise we may
* need to check to see if this is a "message queue does not exist"
* or some other miscellaneous error on the name.
*/
if ( the_mq == NULL ) {
va_list ap;
const struct mq_attr *attr;
/*
* Unless provided a valid name that did not already exist
* and we are willing to create then it is an error.
*/
if ( error != OBJECTS_GET_BY_NAME_NO_OBJECT || ( oflag & O_CREAT ) == 0 ) {
_Objects_Allocator_unlock();
rtems_set_errno_and_return_value(
_POSIX_Get_by_name_error( error ),
MQ_OPEN_FAILED
);
}
va_start( ap, oflag );
va_arg( ap, mode_t );
attr = va_arg( ap, const struct mq_attr * );
va_end( ap );
if ( attr == NULL ) {
attr = &_POSIX_Message_queue_Default_attributes;
}
/*
* At this point, the message queue does not exist and everything has been
* checked. We should go ahead and create a message queue.
*/
status = _POSIX_Message_queue_Create( name, name_len, oflag, attr );
} else {
/*
* Check for existence with creation.
*/
if ( ( oflag & ( O_CREAT | O_EXCL ) ) == ( O_CREAT | O_EXCL ) ) {
_Objects_Allocator_unlock();
rtems_set_errno_and_return_value( EEXIST, MQ_OPEN_FAILED );
}
the_mq->open_count += 1;
status = the_mq->Object.id;
}
_Objects_Allocator_unlock();
return status;
}
static void _POSIX_Message_queue_Manager_initialization( void )
{
_Objects_Initialize_information( &_POSIX_Message_queue_Information );
}
RTEMS_SYSINIT_ITEM(
_POSIX_Message_queue_Manager_initialization,
RTEMS_SYSINIT_POSIX_MESSAGE_QUEUE,
RTEMS_SYSINIT_ORDER_MIDDLE
);
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