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mq_open - open a message queue


The mq_open function opens a POSIX message queue, attempting to create it if O_CREAT is specified in the oflag argument. If successful, it returns a message queue descriptor for use in later mq_* calls.

The name argument gives the name of the message queue and mode is the working mode, which is related to the protection of the created message queue. The oflag argument is a flag argument that may be made up of one or more of the following specified in <fcntl.h>:

  • O_RDONLY - Open the message queue for reading only.
  • O_WRONLY - Open the message queue for writing only.
  • O_RDWR - Open the message queue for both reading and writing.
  • O_CREAT - Create the message queue if it does not already exist.
  • O_EXCL - When used with O_CREAT, if the queue already exists, the call fails.

If the O_CREAT is specified in oflag the mode argument specifies the initial permissions of the newly created queue, as in open(2). It is modified by the process's umask in the usual way. The attr argument pointer can be used to set the initial attributes of the queue.


  • name:const char*[KU] - Name of the message queue to be opened. Must begin with a '/' character.
  • oflag:int[KU] - Flag argument used to determine how the queue should be opened.
  • mode:mode_t[KU] - Permission bits used when setting the queue's initial permissions.
  • attr:struct mq_attr*[KU] - Pointer to a structure containing the queue's initial attributes.

Available Tags

  • K - Originated from kernel-space.
  • U - Originated from user space (for example, pointer to user space memory used to get it)
  • TOCTOU - Vulnerable to TOCTOU (time of check, time of use)
  • OPT - Optional argument - might not always be available (passed with null value)






To capture information about when and where the mq_open syscall is invoked.

Example Use Case

Using the mq_open event can be used to monitor the creation and access of message queues, logging any relevant information pertaining to the queue and the process that invoked it.


The mq_open event occurs when the message queue is opened and does not indicate that it was successfully opened.

  • mq_timedsend
  • mq_receive
  • mq_timedreceive

This document was automatically generated by OpenAI and needs review. It might not be accurate and might contain errors. The authors of Tracee recommend that the user reads the "events.go" source file to understand the events and their arguments better.