docs/syscalls/port_queue.md

# zx_port_queue

## NAME

port_queue - queue a packet to an port

## SYNOPSIS

```
#include <zircon/syscalls.h>
#include <zircon/syscalls/port.h>

zx_status_t zx_port_queue(zx_handle_t handle, const zx_port_packet_t* packet);

```

## DESCRIPTION

**port_queue**() queues a *packet* to the port specified
by *handle*.

```
typedef struct zx_port_packet {
    uint64_t key;
    uint32_t type;
    int32_t status;
    union {
        zx_packet_user_t user;
        zx_packet_signal_t signal;
    };
} zx_port_packet_t;

```

In *packet* *type* should be **ZX_PKT_TYPE_USER** and only the **user**
union element is considered valid:

```
typedef union zx_packet_user {
    uint64_t u64[4];
    uint32_t u32[8];
    uint16_t u16[16];
    uint8_t   c8[32];
} zx_packet_user_t;

```

## RETURN VALUE

**port_queue**() returns **ZX_OK** on successful queue of a packet.

## ERRORS

**ZX_ERR_BAD_HANDLE** *handle* isn't a valid handle

**ZX_ERR_INVALID_ARGS** *packet* is an invalid pointer.

**ZX_ERR_WRONG_TYPE** *handle* is not a port handle.

**ZX_ERR_ACCESS_DENIED** *handle* does not have **ZX_RIGHT_WRITE**.

**ZX_ERR_SHOULD_WAIT** the port has too many pending packets. Once a thread
has drained some packets a new **port_queue**() call will likely succeed.

## NOTES

The queue is drained by calling **port_wait**().


## SEE ALSO

[port_create](port_create.md).
[port_wait](port_wait.md).