Add cxx_demangle() and Lua wrapper

docs/dev/Lua API.rst

@@ -2735,6 +2735,11 @@ and are only documented here for completeness:
   The oldval, newval or delta arguments may be used to specify additional constraints.
   Returns: *found_index*, or *nil* if end reached.
 
+* ``dfhack.internal.cxxDemangle(mangled_name)``
+
+  Decodes a mangled C++ symbol name. Returns the demangled name on success, or
+  ``nil, error_message`` on failure.
+
 * ``dfhack.internal.getDir(path)``
 
   Lists files/directories in a directory.

library/LuaApi.cpp

@@ -3333,6 +3333,24 @@ static int internal_diffscan(lua_State *L)
     return 1;
 }
 
+static int internal_cxxDemangle(lua_State *L)
+{
+    std::string mangled = luaL_checkstring(L, 1);
+    std::string status;
+    std::string demangled = cxx_demangle(mangled, &status);
+    if (demangled.length())
+    {
+        lua_pushstring(L, demangled.c_str());
+        return 1;
+    }
+    else
+    {
+        lua_pushnil(L);
+        lua_pushstring(L, status.c_str());
+        return 2;
+    }
+}
+
 static int internal_runCommand(lua_State *L)
 {
     color_ostream *out = NULL;
@@ -3637,6 +3655,7 @@ static const luaL_Reg dfhack_internal_funcs[] = {
     { "memcmp", internal_memcmp },
     { "memscan", internal_memscan },
     { "diffscan", internal_diffscan },
+    { "cxxDemangle", internal_cxxDemangle },
     { "getDir", filesystem_listdir },
     { "runCommand", internal_runCommand },
     { "getModifiers", internal_getModifiers },

library/MiscUtils.cpp

@@ -36,6 +36,7 @@ distribution.
 #else
     #include <sys/time.h>
     #include <ctime>
+    #include <cxxabi.h>
 #endif
 
 #include <ctype.h>
@@ -472,3 +473,29 @@ DFHACK_EXPORT std::string DF2CONSOLE(DFHack::color_ostream &out, const std::stri
 {
     return out.is_console() ? DF2CONSOLE(in) : in;
 }
+
+DFHACK_EXPORT std::string cxx_demangle(const std::string &mangled_name, std::string *status_out)
+{
+#ifdef __GNUC__
+    int status;
+    char *demangled = abi::__cxa_demangle(mangled_name.c_str(), nullptr, nullptr, &status);
+    std::string out;
+    if (demangled) {
+        out = demangled;
+        free(demangled);
+    }
+    if (status_out) {
+        if (status == 0) *status_out = "success";
+        else if (status == -1) *status_out = "memory allocation failure";
+        else if (status == -2) *status_out = "invalid mangled name";
+        else if (status == -3) *status_out = "invalid arguments";
+        else *status_out = "unknown error";
+    }
+    return out;
+#else
+    if (status_out) {
+        *status_out = "not implemented on this platform";
+    }
+    return "";
+#endif
+}

library/include/MiscUtils.h

@@ -474,3 +474,5 @@ DFHACK_EXPORT std::string UTF2DF(const std::string &in);
 DFHACK_EXPORT std::string DF2UTF(const std::string &in);
 DFHACK_EXPORT std::string DF2CONSOLE(const std::string &in);
 DFHACK_EXPORT std::string DF2CONSOLE(DFHack::color_ostream &out, const std::string &in);
+
+DFHACK_EXPORT std::string cxx_demangle(const std::string &mangled_name, std::string *status_out);