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-rw-r--r--include/linux/ceph/decode.h54
1 files changed, 54 insertions, 0 deletions
diff --git a/include/linux/ceph/decode.h b/include/linux/ceph/decode.h
index e83f3c81ef43..f990f2cc907a 100644
--- a/include/linux/ceph/decode.h
+++ b/include/linux/ceph/decode.h
@@ -218,6 +218,60 @@ static inline void ceph_encode_string(void **p, void *end,
*p += len;
}
+/*
+ * version and length starting block encoders/decoders
+ */
+
+/* current code version (u8) + compat code version (u8) + len of struct (u32) */
+#define CEPH_ENCODING_START_BLK_LEN 6
+
+/**
+ * ceph_start_encoding - start encoding block
+ * @struct_v: current (code) version of the encoding
+ * @struct_compat: oldest code version that can decode it
+ * @struct_len: length of struct encoding
+ */
+static inline void ceph_start_encoding(void **p, u8 struct_v, u8 struct_compat,
+ u32 struct_len)
+{
+ ceph_encode_8(p, struct_v);
+ ceph_encode_8(p, struct_compat);
+ ceph_encode_32(p, struct_len);
+}
+
+/**
+ * ceph_start_decoding - start decoding block
+ * @v: current version of the encoding that the code supports
+ * @name: name of the struct (free-form)
+ * @struct_v: out param for the encoding version
+ * @struct_len: out param for the length of struct encoding
+ *
+ * Validates the length of struct encoding, so unsafe ceph_decode_*
+ * variants can be used for decoding.
+ */
+static inline int ceph_start_decoding(void **p, void *end, u8 v,
+ const char *name, u8 *struct_v,
+ u32 *struct_len)
+{
+ u8 struct_compat;
+
+ ceph_decode_need(p, end, CEPH_ENCODING_START_BLK_LEN, bad);
+ *struct_v = ceph_decode_8(p);
+ struct_compat = ceph_decode_8(p);
+ if (v < struct_compat) {
+ pr_warn("got struct_v %d struct_compat %d > %d of %s\n",
+ *struct_v, struct_compat, v, name);
+ return -EINVAL;
+ }
+
+ *struct_len = ceph_decode_32(p);
+ ceph_decode_need(p, end, *struct_len, bad);
+ return 0;
+
+bad:
+ return -ERANGE;
+}
+
#define ceph_encode_need(p, end, n, bad) \
do { \
if (!likely(ceph_has_room(p, end, n))) \