Add support for libtirpc

While OpenSolaris libc and glibc both include XDR support, the musl libc
does not in favor of depending on the BSD-licensed libtirpc library.

Adding support is a simple matter of detecting the library, including
the headers and linking against it.  By default libtirpc will be checked
for and if available used.  Otherwise, configure will fall back to using
the xdr implementation provided by libc if available.  The options
--with-tirpc/--without-tirpc can be used to disable this checking.

In addition, the xdr_control() function has been simplied to only
handle ZFSs specific use case.

Original-patch-by: stf <[email protected]>
Original-patch-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Signed-off-by: Signed-off-by: Carlo Landmeter <[email protected]>
Closes #2254
Closes #4559

3 files changed, 26 insertions, 50 deletions

diff --git a/lib/libspl/include/rpc/Makefile.am b/lib/libspl/include/rpc/Makefile.am
index 7a29aba73..78ee5a29e 100644
--- a/lib/libspl/include/rpc/Makefile.am
+++ b/lib/libspl/include/rpc/Makefile.am
@@ -1,4 +1,3 @@
 libspldir = $(includedir)/libspl/rpc
 libspl_HEADERS = \
-	$(top_srcdir)/lib/libspl/include/rpc/types.h \
 	$(top_srcdir)/lib/libspl/include/rpc/xdr.h
diff --git a/lib/libspl/include/rpc/types.h b/lib/libspl/include/rpc/types.h
deleted file mode 100644
index aa9901fd1..000000000
--- a/lib/libspl/include/rpc/types.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/*
- * CDDL HEADER START
- *
- * The contents of this file are subject to the terms of the
- * Common Development and Distribution License (the "License").
- * You may not use this file except in compliance with the License.
- *
- * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
- * or http://www.opensolaris.org/os/licensing.
- * See the License for the specific language governing permissions
- * and limitations under the License.
- *
- * When distributing Covered Code, include this CDDL HEADER in each
- * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
- * If applicable, add the following below this CDDL HEADER, with the
- * fields enclosed by brackets "[]" replaced with your own identifying
- * information: Portions Copyright [yyyy] [name of copyright owner]
- *
- * CDDL HEADER END
- */
-/*
- * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
- */
-
-#ifndef LIBSPL_RPC_TYPES_H
-#define	LIBSPL_RPC_TYPES_H
-
-#include_next <rpc/types.h>
-#include <sys/kmem.h>
-
-#endif /* LIBSPL_RPC_TYPES_H */
diff --git a/lib/libspl/include/rpc/xdr.h b/lib/libspl/include/rpc/xdr.h
index 99500d657..3c7c53fcc 100644
--- a/lib/libspl/include/rpc/xdr.h
+++ b/lib/libspl/include/rpc/xdr.h
@@ -32,11 +32,20 @@
 #ifndef LIBSPL_RPC_XDR_H
 #define	LIBSPL_RPC_XDR_H
 
-#include_next <rpc/xdr.h>
-
 /*
- * These are XDR control operators
+ * When available prefer libtirpc for xdr functionality.  This library is
+ * mandatory when compiling with musl libc because it does not provide xdr.
  */
+#if defined(HAVE_LIBTIRPC)
+
+#include <tirpc/rpc/xdr.h>
+#ifdef xdr_control
+#undef xdr_control
+#endif
+
+#else
+#include_next <rpc/xdr.h>
+#endif /* HAVE_LIBTIRPC */
 
 #define	XDR_GET_BYTES_AVAIL 1
 
@@ -46,20 +55,20 @@ typedef struct xdr_bytesrec {
 } xdr_bytesrec_t;
 
 /*
- * These are the request arguments to XDR_CONTROL.
- *
- * XDR_PEEK - returns the contents of the next XDR unit on the XDR stream.
- * XDR_SKIPBYTES - skips the next N bytes in the XDR stream.
- * XDR_RDMAGET - for xdr implementation over RDMA, gets private flags from
- *		 the XDR stream being moved over RDMA
- * XDR_RDMANOCHUNK - for xdr implementaion over RDMA, sets private flags in
- *                   the XDR stream moving over RDMA.
+ * This functionality is not required and is disabled in user space.
  */
-#define	XDR_PEEK	2
-#define	XDR_SKIPBYTES	3
-#define	XDR_RDMAGET	4
-#define	XDR_RDMASET	5
+static inline bool_t
+xdr_control(XDR *xdrs, int request, void *info)
+{
+	xdr_bytesrec_t *xptr;
 
-extern bool_t xdr_control(XDR *xdrs, int request, void *info);
+	ASSERT3U(request, ==, XDR_GET_BYTES_AVAIL);
 
-#endif
+	xptr = (xdr_bytesrec_t *)info;
+	xptr->xc_is_last_record = TRUE;
+	xptr->xc_num_avail = xdrs->x_handy;
+
+	return (TRUE);
+}
+
+#endif /* LIBSPL_RPC_XDR_H */