config: better libtirpc detection

Improve the autoconf code for finding libtirpc and do not assume the
headers are in /usr/include/tirpc.

Also remove this assumption from the `rpc/xdr.h` header in libspl and
use the same `#include_next` mechanism that is used for other libspl
headers.

Include pkg.m4 from pkg-config in config/ for PKG_CHECK_MODULES(), the
file license allows this.

Include ax_save_flags.m4 and ax_restore_flags.m4 from autoconf-archive,
the file licenses are compatible. Use the 2012 versions so as not rely
on a more recent autoconf feature AS_VAR_COPY(), which breaks some build
slaves.

Add new macro library `config/find_system_library.m4` which defines the
FIND_SYSTEM_LIBRARY() macro which is a convenience wrapper over using
PKG_CHECK_MODULES() with a fallback to standard library locations and
some sanity checks.

The parameters are:

```
FIND_SYSTEM_LIBRARY(VARIABLE-PREFIX, MODULE, HEADER, HEADER-PREFIXES,
    LIBRARY, FUNCTIONS, [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
```

`HEADER-PREFIXES` and `FUNCTIONS` are comma-separated m4 lists.

For libtirpc we are using:

```
FIND_SYSTEM_LIBRARY(LIBTIRPC, [libtirpc], [rpc/xdr.h], [tirpc], [tirpc],
    [xdrmem_create], [], [...])
```

The headers are first checked for without the prefixes and then with.

This system works with pkg-config and falls back on checking standard
header/library locations, it can be easily overridden by the user by
setting the `PREFIX_CFLAGS` and `PREFIX_LIBS` variables which are
automatically added to the `./configure --help` output.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Rafael Kitover <[email protected]>
Closes #7422 
Closes #8313 

1 files changed, 18 insertions, 18 deletions

diff --git a/config/user-libtirpc.m4 b/config/user-libtirpc.m4
index 5f929061f..19c02c9d5 100644
--- a/config/user-libtirpc.m4
+++ b/config/user-libtirpc.m4
@@ -4,27 +4,27 @@ dnl #
 AC_DEFUN([ZFS_AC_CONFIG_USER_LIBTIRPC], [
 	AC_ARG_WITH([tirpc],
 	    [AS_HELP_STRING([--with-tirpc],
-	        [use tirpc for xdr encoding @<:@default=check@:>@])],
+		[use tirpc for xdr encoding @<:@default=check@:>@])],
 	    [],
 	    [with_tirpc=check])
 
-	LIBTIRPC=
-	LIBTIRPC_CFLAGS=
+	have_xdr=
 
-	AS_IF([test "x$with_tirpc" != xno],
-	    [AC_CHECK_LIB([tirpc], [xdrmem_create],
-		[AC_SUBST([LIBTIRPC], [-ltirpc])
-		 AC_SUBST([LIBTIRPC_CFLAGS], [-I/usr/include/tirpc])
-		 AC_DEFINE([HAVE_LIBTIRPC], [1], [Define if you have libtirpc])
-		],
-		[if test "x$with_tirpc" != xcheck; then
-		    AC_MSG_FAILURE(
-			[--with-tirpc was given, but test for tirpc failed])
-		 fi
-		AC_SEARCH_LIBS([xdrmem_create], [tirpc], [], [
-		    AC_MSG_FAILURE([xdrmem_create() requires tirpc or libc])])
-		])],
-	    [AC_SEARCH_LIBS([xdrmem_create], [tirpc], [], [
-		AC_MSG_FAILURE([xdrmem_create() requires libc])])
+        AS_IF([test "x$with_tirpc" != "xyes"], [
+	    AC_SEARCH_LIBS([xdrmem_create], [], [have_xdr=1], [
+		AS_IF([test "x$with_tirpc" = "xno"], [
+		    AC_MSG_FAILURE([xdrmem_create() requires sunrpc support in libc if not using libtirpc])
+		])
 	    ])
+        ])
+
+	AS_IF([test "x$have_xdr" = "x"], [
+            FIND_SYSTEM_LIBRARY(LIBTIRPC, [libtirpc], [rpc/xdr.h], [tirpc], [tirpc], [xdrmem_create], [], [
+		AS_IF([test "x$with_tirpc" = "xyes"], [
+		    AC_MSG_FAILURE([--with-tirpc was given, but libtirpc is not available, try installing libtirpc-devel])
+		],[dnl ELSE
+		    AC_MSG_FAILURE([neither libc sunrpc support nor libtirpc is available, try installing libtirpc-devel])
+		])
+	    ])
+	])
 ])