Be consistent in use of multi-path vs multi-index

multi-path is the descriptor extension; multi-index is the index within
a multi-path that is used for derivation/script generation.

Author: jgriffiths

src/bip32.c

@@ -899,7 +899,7 @@ int bip32_key_from_parent_path_str_n(const struct ext_key *hdkey,
                                      struct ext_key *key_out)
 {
     uint32_t path[BIP32_PATH_MAX_LEN], *path_p = path, features;
-    const uint32_t multi_index = 0; /* Multi-index not supported */
+    const uint32_t multi_index = 0; /* Multi-path not supported */
     size_t written;
     if (flags & BIP32_FLAG_STR_MULTIPATH)
         return WALLY_EINVAL; /* Multi-path is not supported for this call */

src/ctest/test_descriptor.c

@@ -1853,7 +1853,7 @@ static const struct address_test {
         "pkh([d34db33f/44'/0'/*]mainnet_xpub/1/*)",
         WALLY_NETWORK_BITCOIN_MAINNET, 0, 0, 0, ADDR("")
     }, {
-        "address errchk - key origin with multi-index",
+        "address errchk - key origin with multi-path",
         "pkh([d34db33f/44'/0'/<0;1>]mainnet_xpub/1/*)",
         WALLY_NETWORK_BITCOIN_MAINNET, 0, 0, 0, ADDR("")
     }, {

src/test/test_bip32.py

@@ -548,16 +548,16 @@ def get_paths(path):
                  ('m/1',          W, 1),          # Non-zero wildcard given for non-wildcard path
                  ('/*',           W, 2147483648), # Hardened wildcard
                  ('1',            0xff, 0),       # Invalid flags
-                 ('/1/<0;1>',     0, 0),          # Multi-index present without flag
-                 ('/1/<0;1>',     M, 0)]          # Multi-index flag present
+                 ('/1/<0;1>',     0, 0),          # Multi-path present without flag
+                 ('/1/<0;1>',     M, 0)]          # Multi-path flag present
 
         for path, flags, wildcard in cases:
             flags = flags | FLAG_KEY_PRIVATE
             ret = bip32_key_from_parent_path_str_n(m, path, len(path or ''),
                                                    wildcard, flags, key_out)
             self.assertEqual(ret, WALLY_EINVAL)
             if flags == M:
-                continue # Multi-index for bip32_path_from_str is tested below
+                continue # Multi-path for bip32_path_from_str is tested below
             ret, written = bip32_path_from_str(path, wildcard, 0, flags,
                                                c_path, len(c_path))
             self.assertEqual((ret, written), (WALLY_EINVAL, 0))