swapon: split swapon-common.c

 swapon    - requires libmount and libblkid
 swapoff   - requires libmount
 swaplabel - requires libblkid

This patch add lib/swapprober.c with blkid stuff for swap. It allows
to use and link libblkid only when necessary.

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

1 files changed, 48 insertions, 0 deletions

diff --git a/lib/swapprober.c b/lib/swapprober.c
new file mode 100644
index 000000000..deb754b8a
--- /dev/null
+++ b/lib/swapprober.c
@@ -0,0 +1,48 @@
+
+#include "c.h"
+#include "nls.h"
+
+#include "swapprober.h"
+
+blkid_probe get_swap_prober(const char *devname)
+{
+	blkid_probe pr;
+	int rc;
+	const char *version = NULL;
+	char *swap_filter[] = { "swap", NULL };
+
+	pr = blkid_new_probe_from_filename(devname);
+	if (!pr) {
+		warn(_("%s: unable to probe device"), devname);
+		return NULL;
+	}
+
+	blkid_probe_enable_superblocks(pr, TRUE);
+	blkid_probe_set_superblocks_flags(pr,
+			BLKID_SUBLKS_LABEL | BLKID_SUBLKS_UUID |
+			BLKID_SUBLKS_VERSION);
+
+	blkid_probe_filter_superblocks_type(pr, BLKID_FLTR_ONLYIN, swap_filter);
+
+	rc = blkid_do_safeprobe(pr);
+	if (rc == -1)
+		warn(_("%s: unable to probe device"), devname);
+	else if (rc == -2)
+		warnx(_("%s: ambivalent probing result, use wipefs(8)"), devname);
+	else if (rc == 1)
+		warnx(_("%s: not a valid swap partition"), devname);
+
+	if (rc == 0) {
+		/* Only the SWAPSPACE2 is supported. */
+		if (blkid_probe_lookup_value(pr, "VERSION", &version, NULL) == 0
+		    && version
+		    && strcmp(version, stringify_value(SWAP_VERSION)))
+			warnx(_("%s: unsupported swap version '%s'"),
+						devname, version);
+		else
+			return pr;
+	}
+
+	blkid_free_probe(pr);
+	return NULL;
+}