Script debugging problem

coderm4ster · December 5, 2021, 12:25pm

If the path to a script is too long, the position of the step is not visible during debugging. I attach an example project and screenshots of the problem.

Normally, the position is indicated by a frame at a breakpoint:

If the path is too long, the frame is not visible at the breakpoint, it can only be debugged blindly in the given script:

ScriptPathTooLong.zip (2.7 KB)

Mathias_Westerdahl · December 5, 2021, 12:30pm

Please add it to the github issues

AarrrBee · December 5, 2021, 1:01pm

It’s a known issue dating back to 2019: https://github.com/defold/defold/issues/3835

coderm4ster · December 14, 2021, 11:11pm

I’ve been investigating what’s causing the problem. There is a limit to the length of Lua source paths in the bob and editor source. In both places, the paths are limited to 59 characters during the build.

github.com

defold/defold/blob/dev/com.dynamo.cr/com.dynamo.cr.bob/src/com/dynamo/bob/pipeline/LuaBuilder.java#L130

    
      
          //
          // See implementation of luaO_chunkid and why a prefix '=' is used; it is to pass through the filename without modifications.
          //
          // We will also limit the chunkname (the identifying part of a script/source chunk) to 59 chars.
          // Lua has a maximum length of chunknames, by default defined to 60 chars.
          //
          // If a script error occurs in runtime we want Lua to report the end of the filepath
          // associated with the chunk, since this is where the filename is visible.
          //
          String chunkName = task.input(0).getPath();
          if (chunkName.length() >= 59) {
              chunkName = chunkName.substring(chunkName.length() - 59);
          }
          chunkName = "=" + chunkName;
          ProcessBuilder pb = new ProcessBuilder(new String[] { Bob.getExe(Platform.getHostPlatform(), luajitExe), "-bgf", chunkName, inputFile.getAbsolutePath(), outputFile.getAbsolutePath() }).redirectErrorStream(true);
          
          
java.util.Map<String, String> env = pb.environment();
          env.put("LUA_PATH", Bob.getPath("share/luajit/") + "/?.lua");
          
          
Process p = pb.start();
          InputStream is = null;

github.com

defold/defold/blob/c2cf0b6131777465a03c71a41308ed2b49876ade/editor/src/clj/editor/luajit.clj#L32

    
      
            (str (system/defold-unpack-path) "/" (.getPair (Platform/getJavaPlatform)) (str (case arch
                                                                                                  :32-bit "/bin/luajit-32"
                                                                                                  :64-bit "/bin/luajit-64"))))
          
          
(defn- luajit-lua-path
            []
            (str (system/defold-unpack-path) "/shared/luajit"))
          
          
(defn luajit-path-to-chunk
            [^String s]
            (subs s (max 0 (- (count s) 59))))
          
          
(defn- compile-file
            [proj-path ^File input ^File output arch]
            (let [{:keys [exit out err]} (shell/sh (luajit-exec-path arch)
                                                   "-bgf"
                                                   ; Take the last 59 chars from the path as Lua chunkname.
                                                   ; Prefix "=" which tells Lua this is a literal file path,
                                                   ; the total length is now at maximum 60 chars (which is the
                                                   ; maximum length of chunknames in Lua).
                                                   (str "=" (luajit-path-to-chunk proj-path))

There is also a note in the bob source code about this:

// We will also limit the chunkname (the identifying part of a script/source chunk) to 59 chars.
// Lua has a maximum length of chunknames, by default defined to 60 chars.

It seems to me that something misunderstood may have happened here. During debugging, the editor uses mobdebug to retrieve current debug status information. Mobdebug uses the debug.getinfo(i, “Snl”) function call to determine the current source, line number, and so on. If you read the lua_getinfo function and its lua_Debug structure in the Lua documentation (Lua 5.1 Reference Manual), you can see that the 60 character limit (LUA_IDSIZE) only applies to printable source names (short_src). Since the editor does not use the short_src attribute (but the content of the source attribute that has no character constraint), I don’t think the 59 long character constraint above makes sense. Developers could say more about that.

I removed this restriction in the bob and editor source and then build the engine and editor as well. During testing, the long path was no longer a problem.

I’d love to do PR for this, but my bad English and the fact that I’ve never done PR prevents me from doing so. Anyway, if anyone feels the urge to fix this problem based on the information above, I would thank you!

I apologize if my reasoning is not correct on the forum.

britzl · December 14, 2021, 11:15pm

Interesting find @coderm4ster ! We should take a closer look at this. Could you please add this info to the GitHub issue?

coderm4ster · December 14, 2021, 11:34pm

Of course I will add the information. This feature is very important to me because I use the debugger built into the editor intensively and it is very inconvenient if this problem occurs. Maybe something else is like that.
Thank you @britzl if this problem is officially resolved in a relatively short time! I really like Defold and the community whose reaction time is unbeatable