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Module sys/socketpair

sys/socketpair
Stability: unstable — because the two platform behaviours are not the same object. POSIX returns a real `AF_UNIX` pair; Windows has no `socketpair()` at all, so the runtime emulates one with a loopback TCP `listen`/`connect`/`accept` and hands back two TCP sockets, and its failures are negated *WSA* codes, not `errno`. Freezing needs a decision on whether this module promises "two connected fds" (which the emulation satisfies) or "an `AF_UNIX` pair with `AF_UNIX` semantics" (which it does not), plus an error convention that is one thing on every platform. — stable modules only change additively; this one may still change.

Connected socket pair (socketpair) — the raw syscall boundary.

One wrapper over POSIX socketpair(2). No public std module uses it yet (std/net builds its sockets through std/sys/tcp and std/sys/unix); tests/sys/socketpair.test.yo is its only caller in this tree.

Stability

unstable — because the two platform behaviours are not the same object. POSIX returns a real AF_UNIX pair; Windows has no socketpair() at all, so the runtime emulates one with a loopback TCP listen/connect/accept and hands back two TCP sockets, and its failures are negated WSA codes, not errno. Freezing needs a decision on whether this module promises "two connected fds" (which the emulation satisfies) or "an AF_UNIX pair with AF_UNIX semantics" (which it does not), plus an error convention that is one thing on every platform.

Functions

socketpair function
fn(domain : i32, sock_type : i32, protocol : i32, sv : *i32) -> i32

Create a pair of connected sockets and write both descriptors into sv (sv[0] and sv[1], so the buffer must hold two i32s) — POSIX socketpair(2). Both ends are bidirectional; unlike pipe, either can read and write. Returns 0 on success, a negative errno on failure.

Per platform:

  • Linux and macOS — the real syscall, with domain, sock_type and protocol passed straight through.
  • Windows — emulated with a loopback TCP pair, so only SOCK_STREAM is accepted (-WSAESOCKTNOSUPPORT otherwise), domain must be one of AF_UNIX / AF_INET / AF_UNSPEC (-WSAEAFNOSUPPORT otherwise) and protocol must be 0 or IPPROTO_TCP. The failure values are NEGATED WSA codes (e.g. -10047), which IoError.from_errno will not classify — it lands in .Other.
  • wasm — -ENOSYS; Emscripten has no sockets.

Parameters

NameTypeNotes
domaini32
sock_typei32
protocoli32
sv*i32

Returns: i32