Add a "fork" of musl as //fusl.

fusl/src/network/getservbyport_r.c

Index: fusl/src/network/getservbyport_r.c
diff --git a/fusl/src/network/getservbyport_r.c b/fusl/src/network/getservbyport_r.c
new file mode 100644
index 0000000000000000000000000000000000000000..a0a7caecf77e8dd89bbbc3aa3ee3d3b4112ac08a
--- /dev/null
+++ b/fusl/src/network/getservbyport_r.c
@@ -0,0 +1,55 @@
+#define _GNU_SOURCE
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <inttypes.h>
+#include <errno.h>
+#include <string.h>
+
+int getservbyport_r(int port, const char *prots,
+	struct servent *se, char *buf, size_t buflen, struct servent **res)
+{
+	int i;
+	struct sockaddr_in sin = {
+		.sin_family = AF_INET,
+		.sin_port = port,
+	};
+
+	if (!prots) {
+		int r = getservbyport_r(port, "tcp", se, buf, buflen, res);
+		if (r) r = getservbyport_r(port, "udp", se, buf, buflen, res);
+		return r;
+	}
+
+	/* Align buffer */
+	i = (uintptr_t)buf & sizeof(char *)-1;
+	if (!i) i = sizeof(char *);
+	if (buflen < 3*sizeof(char *)-i)
+		return ERANGE;
+	buf += sizeof(char *)-i;
+	buflen -= sizeof(char *)-i;
+
+	if (strcmp(prots, "tcp") && strcmp(prots, "udp")) return EINVAL;
+
+	se->s_port = port;
+	se->s_proto = (char *)prots;
+	se->s_aliases = (void *)buf;
+	buf += 2*sizeof(char *);
+	buflen -= 2*sizeof(char *);
+	se->s_aliases[1] = 0;
+	se->s_aliases[0] = se->s_name = buf;
+
+	switch (getnameinfo((void *)&sin, sizeof sin, 0, 0, buf, buflen,
+		strcmp(prots, "udp") ? 0 : NI_DGRAM)) {
+	case EAI_MEMORY:
+	case EAI_SYSTEM:
+		return ENOMEM;
+	default:
+		return ENOENT;
+	case 0:
+		break;
+	}
+
+	*res = se;
+	return 0;
+}