sys_mq_open [ipc/mqueue.c]
Creates new POSIX message queue or opens an existing queue. Arguments
eax | 277
ebx | Pointer to a null-terminated string specifying the message queue name.
ecx | Message queue access mode. Which must be include following flags:
`O_RDONLY` | `Open the queue to receive messages only.`
`O_WRONLY` | `Open the queue to send messages only.`
`O_RDWR` | `Open the queue to both send and receive messages.`
And may include also the following flags:
`O_NONBLOCK` | `Open the queue in non-blocking mode.`
`O_CREAT` | `Create the message queue if it does not exist. The owner (user ID) of the message queue is set to the effective user ID of the calling process. The group ownership (group ID) is set to the effective group ID of the calling process.`
`O_EXCL` | `If O_CREAT was specified in ecx, and a queue with the given name already exists, then fail with the error -EEXIST.`
edx | Permissions to be placed on the new queue:
`S_IRUSR - owner has read permission S_IWUSR - owner has write permission S_IRGRP - group has read permission S_IWGRP - group has write permission S_IROTH - others have read permission S_IWOTH - others have write permission`
esi | Pointer to a mq_attr structure specifying attributes for the queue. If esi is NULL, then the queue is created with implementation-defined default attributes. mq_attr defined as follows:
`struc mq_attr { .mq_flags rd 1 .mq_maxmsg rd 1 .mq_msgsize rd 1 .mq_curmsgs rd 1 .__reserved rd 4 }`
`mq_attr members: mq_flags` `Message queue flags.` `mq_maxmsg` `The maximum number of messages allowed.` `mq_msgsize` `The maximum message size.` `mq_curmsg` `Number of messages on the queue.` `__reserved` `Not used.`
Return values If the system call succeeds the return value is a message queue descriptor for use by other message queue functions. If the system call fails the return value is one of the following errno values:
`-EACCESS` | `The queue exists, but the caller does not have permission to open it in the specified mode.`
`-EEXIST` | `Both O_CREAT and O_EXCL were specified in ecx, but a queue with the given name already exists`
`-EMFILE` | `The process already has the maximum number of files and message queues open.`
`-ENAMETOOLONG` | `name was too long.`
`-ENFILE` | `The system limit on the total number of open files and message queues has been reached.`
`-ENOENT` | `The O_CREAT flag was not specified in ecx, and no queue with this name exists.`
`-ENOMEM` | `Insufficient memory.`
`-ENOSPC` | `Insufficient space for the creation of a new message queue. This probably occurred because the queues_max limit was encountered;`
Remarks In kernels before 2.6.14, the process umask was not applied to the permissions specified in edx. See samples/ipc/posix_msg.asm for an example. Compatibility n/a