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mq_getattr(3)
NAME
  mq_getattr - Returns the status and attributes of a message queue
  (P1003.1b)

SYNOPSIS
  #include <mqueue.h>

  int mq_getattr (
  mqd_t mqdes,
  struct mq_attr *mqstat);

LIBRARY
  Realtime Library (librt.so, librt.a)

PARAMETERS
  mqdes
      Specifies the message queue descriptor whose attributes are obtained.

  *mqstat
      Specifies a pointer to a structure that is updated to contain the
      values that were set when the message queue was created or modified by
      a call to the mq_setattr function.

  When the mq_getattr function returns, the following three members of the
  mq_attr structure specified by mqstat will have the values that were set
  when the message queue was created, but with modifications made by
  subsequent calls to the mq_setattr function:

    ·  The mq_maxmsg member specifies the maximum number of messages that can
       be held in the queue specified by the mqdes argument.

    ·  The mq_msgsize member specifies the maximum size of any message in the
       queue.

    ·  The mq_options member specifies whether the message operation is
       blocking or nonblocking (MQ_NONBLOCK).

  The mq_curmsgs member of the mq_attr structure indicates the number of
  messages currently on the queue.

DESCRIPTION
  The mq_getattr function returns the status and attributes of a message
  queue. Use the mq_setattr function to set message queue attributes.

RETURN VALUES
  On successful completion, the function returns the value 0 (zero);
  otherwise, the function returns the value -1 and sets errno to indicate the
  error.

ERRORS
  The mq_getattr function fails under the following conditions:

  [EBADF]
      The fildes argument is an invalid file descriptor.

  [EINVAL]
      The mqstat argument is a null pointer.

SEE ALSO
  Functions: mq_open(3), mq_receive(3), mq_send(3), mq_setattr(3)

  Guide to Realtime Programming

Index for Section 3

Alphabetical listing for M

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