config/user-libblkid.m4

   1 dnl #
   2 dnl # Check for ZFS support in libblkid.  This test needs to check
   3 dnl # more than if the library exists because we expect there are
   4 dnl # at least 3 flavors of the library out in the wild:
   5 dnl #
   6 dnl #   1) blkid which has no ZFS support
   7 dnl #   2) blkid with ZFS support and a flawed method of probing
   8 dnl #   3) blkid with ZFS support and a working method of probing
   9 dnl #
  10 dnl # To handle this the check first validates that there is a version
  11 dnl # of the library installed.  If there is it creates a simulated
  12 dnl # ZFS filesystem and then links a small test app which attempts
  13 dnl # to detect the simualated filesystem type.  If it correctly
  14 dnl # identifies the filesystem as ZFS we can safely assume case 3).
  15 dnl # Otherwise we disable blkid support and resort to manual probing.
  16 dnl #
  17 AC_DEFUN([ZFS_AC_CONFIG_USER_LIBBLKID], [
  18         AC_ARG_WITH([blkid],
  19                 [AS_HELP_STRING([--with-blkid],
  20                 [support blkid caching @<:@default=check@:>@])],
  21                 [],
  22                 [with_blkid=check])
  23
  24         LIBBLKID=
  25         AS_IF([test "x$with_blkid" != xno],
  26         [
  27                 AC_CHECK_LIB([blkid], [blkid_get_cache],
  28                 [
  29                         AC_MSG_CHECKING([for blkid zfs support])
  30
  31                         ZFS_DEV=`mktemp`
  32                         dd if=/dev/zero of=$ZFS_DEV bs=1024k count=8 \
  33                                 >/dev/null 2>/dev/null
  34                         echo -en "\x0c\xb1\xba\0\0\0\0\0" | \
  35                                 dd of=$ZFS_DEV bs=1k count=8 \
  36                                 seek=132 conv=notrunc &>/dev/null \
  37                                 >/dev/null 2>/dev/null
  38
  39                         saved_LDFLAGS="$LDFLAGS"
  40                         LDFLAGS="-lblkid"
  41
  42                         AC_RUN_IFELSE(AC_LANG_PROGRAM(
  43                         [
  44                                 #include <stdio.h>
  45                                 #include <blkid/blkid.h>
  46                         ],
  47                         [
  48                                 blkid_cache cache;
  49                                 char *value;
  50
  51                                 if (blkid_get_cache(&cache, NULL) < 0)
  52                                         return 1;
  53
  54                                 value = blkid_get_tag_value(cache, "TYPE",
  55                                                             "$ZFS_DEV");
  56                                 if (!value) {
  57                                         blkid_put_cache(cache);
  58                                         return 2;
  59                                 }
  60
  61                                 if (strcmp(value, "zfs")) {
  62                                         free(value);
  63                                         blkid_put_cache(cache);
  64                                         return 3;
  65                                 }
  66
  67                                 free(value);
  68                                 blkid_put_cache(cache);
  69                         ]),
  70                         [
  71                                 rm -f $ZFS_DEV
  72                                 AC_MSG_RESULT([yes])
  73                                 AC_SUBST([LIBBLKID], ["-lblkid"])
  74                                 AC_DEFINE([HAVE_LIBBLKID], 1,
  75                                         [Define if you have libblkid])
  76                         ],
  77                         [
  78                                 rm -f $ZFS_DEV
  79                                 AC_MSG_RESULT([no])
  80                                 AS_IF([test "x$with_blkid" != xcheck],
  81                                         [AC_MSG_FAILURE(
  82                                         [--with-blkid given but unavailable])])
  83                         ])
  84
  85                         LDFLAGS="$saved_LDFLAGS"
  86                 ],
  87                 [
  88                         AS_IF([test "x$with_blkid" != xcheck],
  89                                 [AC_MSG_FAILURE(
  90                                 [--with-blkid given but unavailable])])
  91                 ]
  92                 [])
  93         ])
  94 ])