From: Thomas Weißschuh <thomas@t-8ch.de>
Date: Sat, 30 Dec 2023 23:26:22 +0000 (+0100)
Subject: libblkid: introduce helper to get offset for idmag
X-Git-Tag: v2.40-rc1~89
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0928e6ed566bc05218851f084915bde9cfaa42e0;p=thirdparty%2Futil-linux.git

libblkid: introduce helper to get offset for idmag

As idmag->kboff can be negative to refer to an offset from the end of
the device, introduce a helper so probers don't have to worry about this
detail.

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---

diff --git a/libblkid/src/blkidP.h b/libblkid/src/blkidP.h
index 63d1946f9b..cb263ef65f 100644
--- a/libblkid/src/blkidP.h
+++ b/libblkid/src/blkidP.h
@@ -443,6 +443,9 @@ extern const unsigned char *blkid_probe_get_sb_buffer(blkid_probe pr, const stru
 #define blkid_probe_get_sb(_pr, _mag, type) \
 			((type *) blkid_probe_get_sb_buffer((_pr), _mag, sizeof(type)))
 
+extern uint64_t blkid_probe_get_idmag_off(blkid_probe pr, const struct blkid_idmag *mag)
+			__attribute__((nonnull));
+
 extern blkid_partlist blkid_probe_get_partlist(blkid_probe pr)
 			__attribute__((nonnull))
 			__attribute__((warn_unused_result));
diff --git a/libblkid/src/probe.c b/libblkid/src/probe.c
index 27085b473d..64e794467a 100644
--- a/libblkid/src/probe.c
+++ b/libblkid/src/probe.c
@@ -1247,6 +1247,14 @@ const unsigned char *blkid_probe_get_sb_buffer(blkid_probe pr, const struct blki
 	return blkid_probe_get_buffer(pr, off, size);
 }
 
+uint64_t blkid_probe_get_idmag_off(blkid_probe pr, const struct blkid_idmag *mag)
+{
+	if (mag->kboff >= 0)
+		return mag->kboff << 10;
+	else
+		return pr->size - (-mag->kboff << 10);
+}
+
 /*
  * Check for matching magic value.
  * Returns BLKID_PROBE_OK if found, BLKID_PROBE_NONE if not found