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Full Discussion: creating a message queue using mq_open
Top Forums Programming creating a message queue using mq_open Post 302471089 by parusasi on Friday 12th of November 2010 12:38:18 AM
Old 11-12-2010
Quote:
Originally Posted by Loic Domaigne
Yeah, now I understand your problem. How do you check that the error returned by mq_open() ? On which OS do you see this problem?
Thank you for time,
I am giving below the code snippet which i use.
Code:
oflags = 0;
  oflags |= (Flags & MQ_READ)?(O_RDONLY):(0);
  oflags |= (Flags & MQ_WRITE)?(O_WRONLY):(0);
  oflags |= (Flags & MQ_READ_WRITE)?(O_RDWR):(0);
  oflags |= (Flags & MQ_NON_BLOCKING)?(O_NONBLOCK):(0);
  oflags |= (O_CREAT | O_EXCL); // try to create it first
  mqAttr.mq_maxmsg = maxMsg;
  mqAttr.mq_msgsize = msgSz + sizeof(MSG_Q_HEADER);
  
  if ((fileDesc = mq_open( "/iothreadNewTest435", oflags,(S_IRUSR | S_IWUSR),NULL)) == -1 )
  {
    rc = mqEvalErrnoOpen(pName))

}

mqEvalErrnoOpen( const char * pName )
{
 MQ_RC rc;
 int err = 0;

  switch ( errno )
  {
  case EACCES:
    rc = MQ_INVALID_ACCESS;
    break;

  case EEXIST:
    rc = MQ_ALREADY_EXISTS;
    break;

  case EFAULT:
    rc = MQ_INVALID_ADDRESS;
    break;

  case EINVAL:
    rc = MQ_INVALID_ACCESS;
    break;

  case EMFILE:
    rc = MQ_TOO_MANY_MSG_Q_DESC;
    break;

  case ENAMETOOLONG:
    rc = MQ_NAME_TOO_LONG;
    break;

  case ENFILE:
    rc = MQ_TOO_MANY_MSG_Q_DESC;
    break;

  case ENOENT:
    rc = MQ_QUEUE_NOT_PRESENT;
    break;

  case ENOMEM:
    rc = MQ_INSUFFICIENT_MEMORY;
    break;

  case ENOSPC:
    rc = MQ_INSUFFICIENT_MEMORY;
    break;

  case ENOTSUP:
    rc = MQ_NOT_SUPPORTED_CHECKPOINT_RESTART_PROC;
    break;

  default:
    rc = MQ_ERRNO;
    err = errno;
    break;
  }

Here rc is returning a value MQ_INVALID Address.
My os details are as follows Fedora Sulphur
Code:
Linux myMachine 2.6.25-14.fc9.i686 #1 SMP Thu May 1 06:28:41 EDT 2008 i686 i686 i386 GNU/Linux

Please help me with this,
Thanks again,
Paru.
Last edited by Scott; 11-15-2010 at 02:52 AM.. Reason: Code tags
 

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LEARN ABOUT HPUX

mq_unlink

mq_unlink(2)							System Calls Manual						      mq_unlink(2)

NAME

       mq_unlink - unlink a message queue

SYNOPSIS

DESCRIPTION

       The system call disassociates the queue name, from a message queue specified by the argument, name.  After a successful call to attempts to
       open a message queue with the same name will fail, if the flag is not set in oflags.

       If there are no processes with existing open descriptors for the message queue, the queue is destroyed. If one or more processes  have  the
       message queue open, the removal of the queue is postponed until all descriptors for the queue have been closed.

       To use this function, link in the realtime library by specifying on the compiler or linker command line.

   Security Restrictions
       Some or all of the actions associated with this system call are subject to compartmentalization restrictions.  See compartments(5) for more
       information.

       Some or all of the actions associated with this system call require privileges.	See privileges(5).

RETURN VALUE

       returns the following values:

	      Successful completion.

	      Failure,
		   is set to indicate the error.

ERRORS

       If fails, is set to one of the following values:

	      [EACCES]	     Permission to unlink the named message queue is denied.

	      [EINVAL]	     The argument name is not a valid message queue name.

	      [ENAMETOOLONG] The length of the name string exceeds bytes, or the length of a (pathname) component of the name string exceeds bytes
			     while is in effect.

	      [ENOENT]	     The named message queue does not exist.

	      [ENOSYS]	     is not supported by the implementation.

SEE ALSO

       mq_open(2), mq_close(2), compartments(5), privileges(5).

STANDARDS CONFORMANCE

																      mq_unlink(2)
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