crtl: BSD socket wrappers over PAL IPv4 sockets

• Type: feature
• Status: done
• Track: B (lib/crtl) with C/pin handoff
• Opened: 2026-06-27

Goal

Expose the minimal BSD C socket surface in lib/crtl without importing libc: sys/socket.h, netinet/in.h, arpa/inet.h, and a socket.c veneer that converts C sockaddr_in to the existing PAL IPv4 socket primitives.

This mirrors the stdio/file bridge: C code should call a C-shaped API, while the actual platform work remains in lib/rtl/platform.pas and its selected backend.

Acceptance

• C headers declare IPv4 socket types/constants and the common calls: socket, bind, connect, listen, accept, send, recv, sendto, recvfrom, shutdown, setsockopt, getsockopt, getsockname.
• lib/crtl/src/socket.c implements those calls through pxxcio PAL bridges, not libc imports.
• Regression test/csocket_loopback_b88.c performs a TCP loopback connect, accept, send, recv, and close, returning 42.

Log

• 2026-06-27 — Implemented in working tree (commit pending): added sys/socket.h, netinet/in.h, arpa/inet.h, lib/crtl/src/socket.c, pxxcio bridge functions, and Makefile test wiring. Regression test/csocket_loopback_b88.c covers TCP loopback (socket/setsockopt/ bind/listen/connect/accept/send/recv/close) and UDP loopback (getsockname/sendto/recvfrom). Verified with: stable_linux_amd64/default/pinned compiler/compiler.pas /tmp/pxx-socket-g1 then /tmp/pxx-socket-g1 -Ilib/crtl/include -Ilib/crtl/src test/csocket_loopback_b88.c /tmp/csocket_loopback_b88_g1; the binary returns 42. Pinned v81 itself still needs the bridge re-pin ticket before this can be a pinned gate.