libsys: various updates

- move system calls for use by services from libminlib into libsys;
- move srv_fork(2) and srv_kill(2) from RS and into libsys;
- replace getprocnr(2) with sef_self(3);
- rename previous getnprocnr(2) to getprocnr(2);
- clean up getepinfo(2);
- change all libsys calls that used _syscall to use _taskcall, so as
  to avoid going through errno to pass errors; this is already how
  most calls work anyway, and many of the calls previously using
  _syscall were already assumed to return the actual error;
- initialize request messages to zero, for future compatibility
  (note that this does not include PCI calls, which are in need of a
  much bigger overhaul, nor kernel calls);
- clean up more of dead DS code as a side effect.

Change-Id: I8788f54c68598fcf58e23486e270c2d749780ebb

drivers/uds/ioc_uds.c

@@ -166,9 +166,9 @@ do_connect(devminor_t minor, endpoint_t endpt, cp_grant_id_t grant)
 	    sizeof(struct sockaddr_un))) != OK)
 		return rc;
 
-	if (checkperms(uds_fd_table[minor].owner, addr.sun_path,
-	    UNIX_PATH_MAX) != OK)
-		return -errno;
+	if ((rc = checkperms(uds_fd_table[minor].owner, addr.sun_path,
+	    UNIX_PATH_MAX)) != OK)
+		return rc;
 
 	/*
 	 * Look for a socket of the same type that is listening on the
@@ -355,9 +355,9 @@ do_bind(devminor_t minor, endpoint_t endpt, cp_grant_id_t grant)
 	if (addr.sun_path[0] == '\0')
 		return ENOENT;
 
-	if (checkperms(uds_fd_table[minor].owner, addr.sun_path,
-	    UNIX_PATH_MAX) != OK)
-		return -errno;
+	if ((rc = checkperms(uds_fd_table[minor].owner, addr.sun_path,
+	    UNIX_PATH_MAX)) != OK)
+		return rc;
 
 	/* Make sure the address isn't already in use by another socket. */
 	for (i = 0; i < NR_FDS; i++) {
@@ -523,7 +523,7 @@ do_getsockopt_peercred(devminor_t minor, endpoint_t endpt, cp_grant_id_t grant)
 
 	/* Obtain the peer's credentials and copy them out. */
 	if ((rc = getnucred(uds_fd_table[peer_minor].owner, &cred)) < 0)
-		return -errno;
+		return rc;
 
 	return sys_safecopyto(endpt, grant, 0, (vir_bytes) &cred,
 	    sizeof(struct uucred));
@@ -611,9 +611,9 @@ do_sendto(devminor_t minor, endpoint_t endpt, cp_grant_id_t grant)
 	if (addr.sun_family != AF_UNIX || addr.sun_path[0] == '\0')
 		return EINVAL;
 
-	if (checkperms(uds_fd_table[minor].owner, addr.sun_path,
-	    UNIX_PATH_MAX) != OK)
-		return -errno;
+	if ((rc = checkperms(uds_fd_table[minor].owner, addr.sun_path,
+	    UNIX_PATH_MAX)) != OK)
+		return rc;
 
 	memcpy(&uds_fd_table[minor].target, &addr, sizeof(struct sockaddr_un));
 
@@ -645,7 +645,7 @@ send_fds(devminor_t minor, struct msg_control *msg_ctrl,
 
 	/* Obtain this socket's credentials. */
 	if ((rc = getnucred(from_ep, &data->cred)) < 0)
-		return -errno;
+		return rc;
 
 	dprintf(("UDS: minor=%d cred={%d,%d,%d}\n", minor, data->cred.pid,
 	    data->cred.uid, data->cred.gid));
@@ -677,8 +677,6 @@ send_fds(devminor_t minor, struct msg_control *msg_ctrl,
 
 	for (i = data->nfiledes; i < totalfds; i++) {
 		if ((rc = copyfd(from_ep, data->fds[i], COPYFD_FROM)) < 0) {
-			rc = -errno;
-
 			printf("UDS: copyfd(COPYFD_FROM) failed: %d\n", rc);
 
 			/* Revert the successful copyfd() calls made so far. */
@@ -747,8 +745,6 @@ recv_fds(devminor_t minor, struct ancillary *data,
 	/* Copy to the target endpoint. */
 	for (i = 0; i < data->nfiledes; i++) {
 		if ((rc = copyfd(to_ep, data->fds[i], COPYFD_TO)) < 0) {
-			rc = -errno;
-
 			printf("UDS: copyfd(COPYFD_TO) failed: %d\n", rc);
 
 			/* Revert the successful copyfd() calls made so far. */

drivers/vnd/vnd.c

@@ -384,9 +384,10 @@ vnd_ioctl(devminor_t UNUSED(minor), unsigned long request, endpoint_t endpt,
 		 * making the IOCTL call.  The result is either a newly
 		 * allocated file descriptor or an error.
 		 */
-		if ((state.fd = copyfd(user_endpt, vnd.vnd_fildes,
-		    COPYFD_FROM)) == -1)
-			return -errno;
+		if ((r = copyfd(user_endpt, vnd.vnd_fildes, COPYFD_FROM)) < 0)
+			return r;
+
+		state.fd = r;
 
 		/* The target file must be regular. */
 		if (fstat(state.fd, &st) == -1) {