Socket

NAME

Socket - Bidirectional streaming IPC transport

SYNOPSIS

Sockets are a bidirectional stream transport. Unlike channels, sockets only move data (not handles).

DESCRIPTION

Data is written into one end of a socket via zx_socket_write() and read from the opposing end via zx_socket_read().

Upon creation, both ends of the socket are writable. Using the zx_socket_set_disposition() system call, each end of the socket can be enabled or disabled independently, using the ZX_SOCKET_DISPOSITION_WRITE_ENABLED and ZX_SOCKET_DISPOSITION_WRITE_DISABLED.

PROPERTIES

The following properties may be queried from a socket object:

ZX_PROP_SOCKET_RX_THRESHOLD size of the read threshold of a socket, in bytes. When the bytes queued on the socket (available for reading) is equal to or greater than this value, the ZX_SOCKET_READ_THRESHOLD signal is asserted. Read threshold signalling is disabled by default (and when set, writing a value of 0 for this property disables it).

ZX_PROP_SOCKET_TX_THRESHOLD size of the write threshold of a socket, in bytes. When the space available for writing on the socket is equal to or greater than this value, the ZX_SOCKET_WRITE_THRESHOLD signal is asserted. Write threshold signalling is disabled by default (and when set, writing a value of 0 for this property disables it).

From the point of view of a socket handle, the receive buffer contains the data that is readable via zx_socket_read() from that handle (having been written from the opposing handle), and the transmit buffer contains the data that is written via zx_socket_write() to that handle (and readable from the opposing handle).

SIGNALS

The following signals may be set for a socket object:

ZX_SOCKET_READABLE data is available to read from the socket

ZX_SOCKET_WRITABLE data may be written to the socket

ZX_SOCKET_PEER_CLOSED the other endpoint of this socket has been closed.

ZX_SOCKET_PEER_WRITE_DISABLED writing is disabled for the other endpoint because its disposition was set to ZX_SOCKET_DISPOSITION_WRITE_DISABLED. Reads on a socket endpoint with this signal raised will succeed so long as there is data in the socket that was written before writing was disabled.

ZX_SOCKET_WRITE_DISABLED writing is disabled for this endpoint because its disposition was set to ZX_SOCKET_DISPOSITION_WRITE_DISABLED. Writes on a socket endpoint with this signal raised will fail.

ZX_SOCKET_READ_THRESHOLD data queued up on socket for reading exceeds the read threshold.

ZX_SOCKET_WRITE_THRESHOLD space available on the socket for writing exceeds the write threshold.

SYSCALLS