| # 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 |
| |
| - [`zx_socket_create()`] - create a new socket |
| - [`zx_socket_read()`] - read data from a socket |
| - [`zx_socket_set_disposition()`] - set disposition of a socket |
| - [`zx_socket_write()`] - write data to a socket |
| |
| [`zx_socket_create()`]: /reference/syscalls/socket_create.md |
| [`zx_socket_read()`]: /reference/syscalls/socket_read.md |
| [`zx_socket_set_disposition()`]: /reference/syscalls/socket_set_disposition.md |
| [`zx_socket_write()`]: /reference/syscalls/socket_write.md |