blkid: start to use ABI versioning

The library ABI and API is backwardly compatible, so it does not
make sense to change the library SONAME. This patch adds a symbol
versioning, naming paradigm is:

	BLKID_<maj>.<min>

The original libblkid from e2fsprogs uses "1.0" as a .so version and
"libblkid.1" as a SONAME for all time (at least according to stuff in
/lib/libblkid*)

And the original library is without symbols versioning. It means that
many private functions are exported to applications ;-(

Note that the original blkid_get_library_version() returns
E2FSPROGS_VERSION. The version in util-linux-ng returns BLKID_VERSION
which is <maj>.<min>.<rel>. The <maj>.<min> is the same version as we
use for ABI. This concept seems less confusing than mix a library
version and package version.

Summary:

OLD (e2fsprogs):
  ABI versioning:              -none-
  SONAME:                      libblkid.1
  .so version:                 libblkid.so.1.0
  blkid_get_library_version(): @E2FSPROGS_VERSION@ (e.g. 1.41.1)

NEW (util-linux-ng):
  ABI versioning:              BLKID_<maj>.<min>
  SONAME:                      libblkid.1
  .so version:                 libblkid.so.<maj.<min> (e.g. 1.41)
  blkid_get_library_version(): @BLKID_VERSION@ (e.g. 1.41.1)

  (BLKID_VERSION = <maj>.<min>.<rel>)

Signed-off-by: Karel Zak <kzak@redhat.com>

3 files changed, 42 insertions, 20 deletions

diff --git a/configure.ac b/configure.ac
index 2af03d9db..dc8374de0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -10,12 +10,13 @@ AC_CONFIG_SRCDIR(mount/mount.c)
 
 AC_PREFIX_DEFAULT([/usr])
 
-dnl libblkid version definition
-dnl -----------------------------
+dnl blkid version definition (the library SONAME is
+dnl "libblkid.so.$BLKID_VERSION_MAJOR", see blkid/Makefile.am)
+dnl ----------------------------------------------------------
 BLKID_VERSION_MAJOR=1
-BLKID_VERSION_MINOR=41
+BLKID_VERSION_MINOR=42
 BLKID_VERSION_RELEASE=0
-BLKID_DATE="10-Jul-2008"
+BLKID_DATE="10-Feb-2009"
 
 BLKID_VERSION=$BLKID_VERSION_MAJOR.$BLKID_VERSION_MINOR.$BLKID_VERSION_RELEASE
 
diff --git a/libs/blkid/bin/blkid.c b/libs/blkid/bin/blkid.c
index 3d29d03cb..f0852e45e 100644
--- a/libs/blkid/bin/blkid.c
+++ b/libs/blkid/bin/blkid.c
@@ -44,7 +44,8 @@ const char *progname = "blkid";
 
 static void print_version(FILE *out)
 {
-	fprintf(out, "%s %s (%s)\n", progname, BLKID_VERSION, BLKID_DATE);
+	fprintf(out, "%s from %s (libblkid %s, %s)\n",
+		progname, PACKAGE_STRING, BLKID_VERSION, BLKID_DATE);
 }
 
 static void usage(int error)
diff --git a/libs/blkid/src/blkid.sym b/libs/blkid/src/blkid.sym
index 26ecfe582..e08df0f52 100644
--- a/libs/blkid/src/blkid.sym
+++ b/libs/blkid/src/blkid.sym
@@ -1,4 +1,13 @@
-{ global:
+/*
+ * The symbol versioning ensures that a new application requiring symbol foo()
+ * can't run with old libblkid.so not providing foo() - the global SONAME
+ * version info can't enforce this since we never change the SONAME.
+ *
+ * The original libblkid (.so version 1.0) from e2fsprogs does not to use
+ * symbol versioning -- all the original symbols are in BLKID_1.0 now.
+ */
+BLKID_1.0 {
+global:
 	blkid_dev_devname;
 	blkid_dev_has_tag;
 	blkid_dev_iterate_begin;
@@ -6,12 +15,7 @@
 	blkid_dev_next;
 	blkid_devno_to_devname;
 	blkid_dev_set_search;
-	blkid_do_probe;
-	blkid_do_safeprobe;
-	blkid_encode_string;
-	blkid_evaluate_spec;
 	blkid_find_dev_with_tag;
-	blkid_free_probe;
 	blkid_gc_cache;
 	blkid_get_cache;
 	blkid_get_dev;
@@ -20,11 +24,33 @@
 	blkid_get_library_version;
 	blkid_get_tag_value;
 	blkid_known_fstype;
-	blkid_new_probe;
 	blkid_parse_tag_string;
 	blkid_parse_version_string;
 	blkid_probe_all;
 	blkid_probe_all_new;
+	blkid_put_cache;
+	blkid_tag_iterate_begin;
+	blkid_tag_iterate_end;
+	blkid_tag_next;
+	blkid_verify;
+local:
+	*;
+};
+
+
+/*
+ * util-linux-ng version(s)
+ */
+BLKID_1.42 {
+global:
+	blkid_do_probe;
+	blkid_do_safeprobe;
+	blkid_encode_string;
+	blkid_evaluate_spec;
+	blkid_free_probe;
+	blkid_new_probe;
+	blkid_probe_all;
+	blkid_probe_all_new;
 	blkid_probe_filter_types;
 	blkid_probe_filter_usage;
 	blkid_probe_get_value;
@@ -35,14 +61,8 @@
 	blkid_probe_reset_filter;
 	blkid_probe_set_device;
 	blkid_probe_set_request;
-	blkid_put_cache;
 	blkid_reset_probe;
 	blkid_safe_string;
 	blkid_send_uevent;
-	blkid_tag_iterate_begin;
-	blkid_tag_iterate_end;
-	blkid_tag_next;
-	blkid_verify;
-local:
-	*;
-};
+} BLKID_1.0;
+