X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=blobdiff_plain;f=config%2Fuser-libblkid.m4;fp=config%2Fuser-libblkid.m4;h=8934d0ab80edec325fdb01bcf488af41d197d86f;hb=c9c0d073da561bcbefbdf09c87fc75b227415619;hp=0000000000000000000000000000000000000000;hpb=40b84e7aec6392187722e61e5a4a853b530bf60f;p=zfs.git

diff --git a/config/user-libblkid.m4 b/config/user-libblkid.m4
new file mode 100644
index 0000000..8934d0a
--- /dev/null
+++ b/config/user-libblkid.m4
@@ -0,0 +1,94 @@
+dnl #
+dnl # Check for ZFS support in libblkid.  This test needs to check
+dnl # more than if the library exists because we expect there are
+dnl # at least 3 flavors of the library out in the wild:
+dnl #
+dnl #   1) blkid which has no ZFS support
+dnl #   2) blkid with ZFS support and a flawed method of probing
+dnl #   3) blkid with ZFS support and a working method of probing
+dnl #
+dnl # To handle this the check first validates that there is a version
+dnl # of the library installed.  If there is it creates a simulated
+dnl # ZFS filesystem and then links a small test app which attempts
+dnl # to detect the simualated filesystem type.  If it correctly
+dnl # identifies the filesystem as ZFS we can safely assume case 3).
+dnl # Otherwise we disable blkid support and resort to manual probing.
+dnl #
+AC_DEFUN([ZFS_AC_CONFIG_USER_LIBBLKID], [
+	AC_ARG_WITH([blkid],
+		[AS_HELP_STRING([--with-blkid],
+		[support blkid caching @<:@default=check@:>@])],
+		[],
+		[with_blkid=check])
+
+	LIBBLKID=
+	AS_IF([test "x$with_blkid" != xno],
+	[
+		AC_CHECK_LIB([blkid], [blkid_get_cache],
+		[
+			AC_MSG_CHECKING([for blkid zfs support])
+
+			ZFS_DEV=`mktemp`
+			dd if=/dev/zero of=$ZFS_DEV bs=1024k count=8 \
+				>/dev/null 2>/dev/null
+			echo -en "\x0c\xb1\xba\0\0\0\0\0" | \
+				dd of=$ZFS_DEV bs=1k count=8 \
+				seek=132 conv=notrunc &>/dev/null \
+				>/dev/null 2>/dev/null
+
+			saved_LDFLAGS="$LDFLAGS"
+			LDFLAGS="-lblkid"
+
+			AC_RUN_IFELSE(AC_LANG_PROGRAM(
+			[
+				#include <stdio.h>
+				#include <blkid/blkid.h>
+			],
+			[
+				blkid_cache cache;
+				char *value;
+
+			        if (blkid_get_cache(&cache, NULL) < 0)
+					return 1;
+
+				value = blkid_get_tag_value(cache, "TYPE",
+				                            "$ZFS_DEV");
+				if (!value) {
+					blkid_put_cache(cache);
+					return 2;
+				}
+
+				if (strcmp(value, "zfs")) {
+					free(value);
+					blkid_put_cache(cache);
+					return 3;
+				}
+
+				free(value);
+				blkid_put_cache(cache);
+			]),
+			[
+				rm -f $ZFS_DEV
+				AC_MSG_RESULT([yes])
+				AC_SUBST([LIBBLKID], ["-lblkid"])
+				AC_DEFINE([HAVE_LIBBLKID], 1,
+					[Define if you have libblkid])
+			],
+			[
+				rm -f $ZFS_DEV
+				AC_MSG_RESULT([no])
+				AS_IF([test "x$with_blkid" != xcheck],
+					[AC_MSG_FAILURE(
+					[--with-blkid given but unavailable])])
+			])
+
+			LDFLAGS="$saved_LDFLAGS"
+		],
+		[
+			AS_IF([test "x$with_blkid" != xcheck],
+				[AC_MSG_FAILURE(
+				[--with-blkid given but unavailable])])
+		]
+		[])
+	])
+])