implement EXTENT_CSUM

1 files changed, 39 insertions, 0 deletions

diff --git a/pkg/btrfs/btrfsitem/item_extentcsum.go b/pkg/btrfs/btrfsitem/item_extentcsum.go
new file mode 100644
index 0000000..27c7c9b
--- /dev/null
+++ b/pkg/btrfs/btrfsitem/item_extentcsum.go
@@ -0,0 +1,39 @@
+package btrfsitem
+
+import (
+	"fmt"
+
+	"lukeshu.com/btrfs-tools/pkg/btrfs/btrfssum"
+)
+
+// key.objectid = BTRFS_EXTENT_CSUM_OBJECTID
+// key.offset = laddr of checksummed region
+type ExtentCSum struct { // EXTENT_CSUM=128
+	ChecksumSize int
+	// Checksum of each sector starting at key.offset
+	Sums []btrfssum.CSum
+}
+
+func (o *ExtentCSum) UnmarshalBinary(dat []byte) (int, error) {
+	if o.ChecksumSize == 0 {
+		return 0, fmt.Errorf("btrfs.ExtentCSum.UnmarshalBinary: .ChecksumSize must be set")
+	}
+	for len(dat) >= o.ChecksumSize {
+		var csum btrfssum.CSum
+		copy(csum[:], dat[:o.ChecksumSize])
+		dat = dat[o.ChecksumSize:]
+		o.Sums = append(o.Sums, csum)
+	}
+	return len(o.Sums) * o.ChecksumSize, nil
+}
+
+func (o ExtentCSum) MarshalBinary() ([]byte, error) {
+	if o.ChecksumSize == 0 {
+		return nil, fmt.Errorf("btrfs.ExtentCSum.MarshalBinary: .ChecksumSize must be set")
+	}
+	var dat []byte
+	for _, csum := range o.Sums {
+		dat = append(dat, csum[:o.ChecksumSize]...)
+	}
+	return dat, nil
+}