libblkid: btrfs: prepare for more checksum algorithms

diff --git a/libblkid/src/superblocks/btrfs.c b/libblkid/src/superblocks/btrfs.c
index 4a5f761741d90ac81680fee09b3b2ab2af6db8a3..15817d4e4fedb34c00f21a66b756b26953da8df2 100644 (file)
--- a/libblkid/src/superblocks/btrfs.c
+++ b/libblkid/src/superblocks/btrfs.c
@@ -20,6 +20,10 @@
 #include "superblocks.h"
 #include "crc32c.h"
 
+enum btrfs_super_block_csum_type {
+       BTRFS_SUPER_BLOCK_CSUM_TYPE_CRC32C = 0,
+};
+
 union btrfs_super_block_csum {
        uint8_t bytes[32];
        uint32_t crc32c;
@@ -211,17 +215,20 @@ out:
 
 static int btrfs_verify_csum(blkid_probe pr, const struct btrfs_super_block *bfs)
 {
-       int csum_type = le16_to_cpu(bfs->csum_type);
-       if (csum_type != 0) {
-               DBG(LOWPROBE, ul_debug("(btrfs) unknown checksum type %d, skipping validation",
-                                      csum_type));
-               return 1;
+       uint16_t csum_type = le16_to_cpu(bfs->csum_type);
+       const void *csum_data = (char *) bfs + sizeof(bfs->csum);
+       size_t csum_data_size = sizeof(*bfs) - sizeof(bfs->csum);
+       switch (csum_type) {
+               case BTRFS_SUPER_BLOCK_CSUM_TYPE_CRC32C: {
+                       uint32_t crc = ~crc32c(~0L, csum_data, csum_data_size);
+                       return blkid_probe_verify_csum(pr, crc,
+                                       le32_to_cpu(bfs->csum.crc32c));
+               }
+               default:
+                       DBG(LOWPROBE, ul_debug("(btrfs) unknown checksum type %d, skipping validation",
+                                              csum_type));
+                       return 1;
        }
-       uint32_t crc = crc32c(~0L, (char *) bfs + sizeof(bfs->csum),
-                       sizeof(*bfs) - sizeof(bfs->csum)
-       );
-       crc ^= ~0L;
-       return blkid_probe_verify_csum(pr, crc, le32_to_cpu(bfs->csum.crc32c));
 }
 
 static int probe_btrfs(blkid_probe pr, const struct blkid_idmag *mag)