Add build system

[mirror_zfs-debian.git] / config / user-libblkid.m4

diff --git a/config/user-libblkid.m4 b/config/user-libblkid.m4
new file mode 100644 (file)
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])])
+               ]
+               [])
+       ])
+])