Fix macOS build for sensor-proxy and improve hot-dev script

cmd/pulse-sensor-proxy/peer_creds_linux.go

@@ -0,0 +1,44 @@
+//go:build linux
+
+package main
+
+import (
+	"fmt"
+	"net"
+	"syscall"
+
+	"github.com/rs/zerolog/log"
+)
+
+// extractPeerCredentials extracts peer credentials via SO_PEERCRED
+func extractPeerCredentials(conn net.Conn) (*peerCredentials, error) {
+	unixConn, ok := conn.(*net.UnixConn)
+	if !ok {
+		return nil, fmt.Errorf("not a unix connection")
+	}
+
+	file, err := unixConn.File()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get file descriptor: %w", err)
+	}
+	defer file.Close()
+
+	fd := int(file.Fd())
+
+	cred, err := syscall.GetsockoptUcred(fd, syscall.SOL_SOCKET, syscall.SO_PEERCRED)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get peer credentials: %w", err)
+	}
+
+	log.Debug().
+		Int32("pid", cred.Pid).
+		Uint32("uid", cred.Uid).
+		Uint32("gid", cred.Gid).
+		Msg("Peer credentials")
+
+	return &peerCredentials{
+		uid: cred.Uid,
+		pid: uint32(cred.Pid),
+		gid: cred.Gid,
+	}, nil
+}