Support calling a lua function via a protobuf request.

Previously the only way to call lua code was to call scripts
and parse their output to the stream, which is cumbersome.

NEWS

@@ -1,5 +1,8 @@
 DFHack future
 
+  Internals:
+    - support for calling a lua function via a protobuf request (demonstrated by dfhack-run --lua).
+
   New commands:
     - move the 'grow', 'extirpate' and 'immolate' commands as 'plant' subcommands
     - 'plant create' - spawn a new shrub under the cursor

library/RemoteTools.cpp

@@ -55,6 +55,8 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "modules/Units.h"
 #include "modules/World.h"
 
+#include "LuaTools.h"
+
 #include "DataDefs.h"
 #include "df/ui.h"
 #include "df/ui_advmode.h"
@@ -656,6 +658,8 @@ CoreService::CoreService() {
     addMethod("CoreSuspend", &CoreService::CoreSuspend, SF_DONT_SUSPEND);
     addMethod("CoreResume", &CoreService::CoreResume, SF_DONT_SUSPEND);
 
+    addMethod("RunLua", &CoreService::RunLua);
+
     // Functions:
     addFunction("GetVersion", GetVersion, SF_DONT_SUSPEND);
     addFunction("GetDFVersion", GetDFVersion, SF_DONT_SUSPEND);
@@ -730,3 +734,85 @@ command_result CoreService::CoreResume(color_ostream &stream, const EmptyMessage
     cnt->set_value(--suspend_depth);
     return CR_OK;
 }
+
+namespace {
+    struct LuaFunctionData {
+        command_result rv;
+        const dfproto::CoreRunLuaRequest *in;
+        StringListMessage *out;
+    };
+}
+
+command_result CoreService::RunLua(color_ostream &stream,
+                                   const dfproto::CoreRunLuaRequest *in,
+                                   StringListMessage *out)
+{
+    auto L = Lua::Core::State;
+    LuaFunctionData data = { CR_FAILURE, in, out };
+
+    lua_pushcfunction(L, doRunLuaFunction);
+    lua_pushlightuserdata(L, &data);
+
+    if (!Lua::Core::SafeCall(stream, 1, 0))
+        return CR_FAILURE;
+
+    return data.rv;
+}
+
+int CoreService::doRunLuaFunction(lua_State *L)
+{
+    color_ostream &out = *Lua::GetOutput(L);
+    auto &args = *(LuaFunctionData*)lua_touserdata(L, 1);
+
+    // Verify module name
+    std::string module = args.in->module();
+    size_t len = module.size();
+
+    bool valid = false;
+
+    if (len > 4)
+    {
+        if (module.substr(0,4) == "rpc.")
+            valid = true;
+        else if ((module[len-4] == '.' || module[len-4] == '-') && module.substr(len-3) != "rpc")
+            valid = true;
+    }
+
+    if (!valid)
+    {
+        args.rv = CR_WRONG_USAGE;
+        out.printerr("Only modules named rpc.* or *.rpc or *-rpc may be called.\n");
+        return 0;
+    }
+
+    // Prepare function and arguments
+    lua_settop(L, 0);
+
+    if (!Lua::PushModulePublic(out, L, module.c_str(), args.in->function().c_str())
+        || lua_isnil(L, 1))
+    {
+        args.rv = CR_NOT_FOUND;
+        return 0;
+    }
+
+    luaL_checkstack(L, args.in->arguments_size(), "too many arguments");
+
+    for (int i = 0; i < args.in->arguments_size(); i++)
+        lua_pushstring(L, args.in->arguments(i).c_str());
+
+    // Call
+    lua_call(L, args.in->arguments_size(), LUA_MULTRET);
+
+    // Store results
+    int nresults = lua_gettop(L);
+
+    for (int i = 1; i <= nresults; i++)
+    {
+        size_t len;
+        const char *data = lua_tolstring(L, i, &len);
+        args.out->add_value(std::string(data, len));
+    }
+
+    args.rv = CR_OK;
+    return 0;
+}

library/dfhack-run.cpp

@@ -72,12 +72,49 @@ int main (int argc, char *argv[])
     if (!client.connect())
         return 2;
 
+    command_result rv;
+
+    if (strcmp(argv[1], "--lua") == 0)
+    {
+        if (argc <= 3)
+        {
+            fprintf(stderr, "Usage: dfhack-run --lua <module> <function> [args...]\n");
+            return 2;
+        }
+
+        RemoteFunction<dfproto::CoreRunLuaRequest,dfproto::StringListMessage> run_call;
+
+        if (!run_call.bind(&client, "RunLua"))
+        {
+            fprintf(stderr, "No RunLua protocol function found.");
+            return 3;
+        }
+
+        run_call.in()->set_module(argv[2]);
+        run_call.in()->set_function(argv[3]);
+        for (int i = 4; i < argc; i++)
+            run_call.in()->add_arguments(argv[i]);
+
+        rv = run_call();
+
+        out.flush();
+
+        if (rv == CR_OK)
+        {
+            for (int i = 0; i < run_call.out()->value_size(); i++)
+                printf("%s%s", (i>0?"\t":""), run_call.out()->value(i).c_str());
+            printf("\n");
+        }
+    }
+    else
+    {
         // Call the command
         std::vector<std::string> args;
         for (int i = 2; i < argc; i++)
             args.push_back(argv[i]);
 
-    command_result rv = client.run_command(argv[1], args);
+        rv = client.run_command(argv[1], args);
+    }
 
     out.flush();
 

library/include/RemoteTools.h

@@ -48,6 +48,8 @@ namespace DFHack
     DFHACK_EXPORT void strVectorToRepeatedField(RepeatedPtrField<std::string> *pf,
                                                 const std::vector<std::string> &vec);
 
+    using dfproto::StringListMessage;
+
     /**
      * Represent bitfield bits as a repeated string field.
      */
@@ -131,6 +133,8 @@ namespace DFHack
 
     class CoreService : public RPCService {
         int suspend_depth;
+
+        static int doRunLuaFunction(lua_State *L);
     public:
         CoreService();
         ~CoreService();
@@ -144,5 +148,9 @@ namespace DFHack
         // For batching
         command_result CoreSuspend(color_ostream &stream, const EmptyMessage*, IntMessage *cnt);
         command_result CoreResume(color_ostream &stream, const EmptyMessage*, IntMessage *cnt);
+
+        command_result RunLua(color_ostream &stream,
+                              const dfproto::CoreRunLuaRequest *in,
+                              StringListMessage *out);
     };
 }

library/proto/CoreProtocol.proto

@@ -81,3 +81,10 @@ message CoreRunCommandRequest {
 
 // RPC CoreSuspend : EmptyMessage -> IntMessage
 // RPC CoreResume : EmptyMessage -> IntMessage
+
+// RPC RunLua : CoreRunLuaRequest -> StringListMessage
+message CoreRunLuaRequest {
+    required string module = 1;
+    required string function = 2;
+    repeated string arguments = 3;
+}