+/*
+ * The same as WPACKET_allocate_bytes() except the reserved bytes are not
+ * actually counted as written. Typically this will be for when we don't know
+ * how big arbitrary data is going to be up front, but we do know what the
+ * maximum size will be. If this function is used, then it should be immediately
+ * followed by a WPACKET_allocate_bytes() call before any other WPACKET
+ * functions are called (unless the write to the allocated bytes is abandoned).
+ *
+ * For example: If we are generating a signature, then the size of that
+ * signature may not be known in advance. We can use WPACKET_reserve_bytes() to
+ * handle this:
+ *
+ * if (!WPACKET_sub_reserve_bytes_u16(&pkt, EVP_PKEY_size(pkey), &sigbytes1)
+ * || EVP_SignFinal(md_ctx, sigbytes1, &siglen, pkey) <= 0
+ * || !WPACKET_sub_allocate_bytes_u16(&pkt, siglen, &sigbytes2)
+ * || sigbytes1 != sigbytes2)
+ * goto err;
+ */
+int WPACKET_reserve_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes);
+
+/*
+ * The "reserve_bytes" equivalent of WPACKET_sub_allocate_bytes__()
+ */
+int WPACKET_sub_reserve_bytes__(WPACKET *pkt, size_t len,
+ unsigned char **allocbytes, size_t lenbytes);
+
+/*
+ * Convenience macros for WPACKET_sub_reserve_bytes with different lengths
+ */
+#define WPACKET_sub_reserve_bytes_u8(pkt, len, bytes) \
+ WPACKET_reserve_bytes__((pkt), (len), (bytes), 1)
+#define WPACKET_sub_reserve_bytes_u16(pkt, len, bytes) \
+ WPACKET_sub_reserve_bytes__((pkt), (len), (bytes), 2)
+#define WPACKET_sub_reserve_bytes_u24(pkt, len, bytes) \
+ WPACKET_sub_reserve_bytes__((pkt), (len), (bytes), 3)
+#define WPACKET_sub_reserve_bytes_u32(pkt, len, bytes) \
+ WPACKET_sub_reserve_bytes__((pkt), (len), (bytes), 4)
+