Add WriteHDKeypath function and move *HDKeypath to util/bip32.{h,cpp}

Creates new files util/bip32.h and util/bip32.cpp for containing
BIP 32 stuff.
Moves FormatKeyPath from descriptor.cpp to util/bip32.
Adds a wrapper around it to prepent the 'm' for when just the
BIP 32 style keypath is needed.

1 files changed, 4 insertions, 13 deletions

diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index 41e0f2e117..532a8028a2 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -10,6 +10,7 @@
 #include <script/standard.h>
 
 #include <span.h>
+#include <util/bip32.h>
 #include <util/system.h>
 #include <util/strencodings.h>
 
@@ -25,16 +26,6 @@ namespace {
 
 typedef std::vector<uint32_t> KeyPath;
 
-std::string FormatKeyPath(const KeyPath& path)
-{
-    std::string ret;
-    for (auto i : path) {
-        ret += strprintf("/%i", (i << 1) >> 1);
-        if (i >> 31) ret += '\'';
-    }
-    return ret;
-}
-
 /** Interface for public key objects in descriptors. */
 struct PubkeyProvider
 {
@@ -63,7 +54,7 @@ class OriginPubkeyProvider final : public PubkeyProvider
 
     std::string OriginString() const
     {
-        return HexStr(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint)) + FormatKeyPath(m_origin.path);
+        return HexStr(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint)) + FormatHDKeypath(m_origin.path);
     }
 
 public:
@@ -184,7 +175,7 @@ public:
     }
     std::string ToString() const override
     {
-        std::string ret = EncodeExtPubKey(m_extkey) + FormatKeyPath(m_path);
+        std::string ret = EncodeExtPubKey(m_extkey) + FormatHDKeypath(m_path);
         if (IsRange()) {
             ret += "/*";
             if (m_derive == DeriveType::HARDENED) ret += '\'';
@@ -195,7 +186,7 @@ public:
     {
         CExtKey key;
         if (!GetExtKey(arg, key)) return false;
-        out = EncodeExtKey(key) + FormatKeyPath(m_path);
+        out = EncodeExtKey(key) + FormatHDKeypath(m_path);
         if (IsRange()) {
             out += "/*";
             if (m_derive == DeriveType::HARDENED) out += '\'';