Segfault on incorrect coordinates

[krassowski]

Not really a huge issues, just something nice to have:

Sometimes incorrect coordinates (row/col) can lead to segmentation fault (noticed during work on an lsp client). This is unlikely to happen in well-behaved clients, but it might happen, so ideally the off by one errors in indexing would be caught rather than leading to a segfault.

 *** caught segfault ***
address 0x80000000, cause 'memory not mapped'

Traceback:
 1: find_unbalanced_bracket(self$content, row, col - 1)
 2: document$detect_call(point)
 3: completion_reply(id, uri, self$workspace, document, point, self$ClientCapabilities$textDocument$completion)
 4: self$deliver(completion_reply(id, uri, self$workspace, document,     point, self$ClientCapabilities$textDocument$completion))
 5: dispatch(self, id, params)
 6: eval(expr, env)
 7: eval(expr, env)
 8: withCallingHandlers(eval(expr, env), error = capture_calls)
 9: doTryCatch(return(expr), name, parentenv, handler)
10: tryCatchOne(expr, names, parentenv, handlers[[1L]])
11: tryCatchList(expr, classes, parentenv, handlers)
12: tryCatch(withCallingHandlers(eval(expr, env), error = capture_calls),     ...)
13: tryCatchStack({    dispatch <- self$request_handlers[[method]]    dispatch(self, id, params)}, error = function(e) {    logger$info("internal error:", e)    self$deliver(ResponseErrorMessage$new(id, "InternalError",         to_string(e)))})
14: self$handle_request(payload)
15: self$handle_raw(data)
16: eval(expr, env)
17: eval(expr, env)
18: withCallingHandlers(eval(expr, env), error = capture_calls)
19: doTryCatch(return(expr), name, parentenv, handler)
20: tryCatchOne(expr, names, parentenv, handlers[[1L]])
21: tryCatchList(expr, classes, parentenv, handlers)
22: tryCatch(withCallingHandlers(eval(expr, env), error = capture_calls),     ...)
23: tryCatchStack({    if (isTRUE(self$exit_flag)) {        logger$info("exiting")        break    }    self$process_events()    data <- self$fetch(blocking = FALSE)    if (is.null(data)) {        Sys.sleep(0.1)        next    }    self$handle_raw(data)}, error = function(e) e)
24: langserver$run()
25: languageserver::run()

I think this is due to a complete request with col = 6 instead of col = 5 (edited):

{
  "jsonrpc": "2.0",
  "id": 11,
  "method": "textDocument/completion",
   "params": {
      "textDocument": {"uri":"file:///.../file.R"},
      "position": {"line": 0,"character": 6},
      "context": {"triggerKind": 1,"triggerCharacter": "r"}
  }
}

[randy3k]

Would you mind telling me the content of file.R? I cannot reproduce it on my end.

[randy3k]

Wait, the offending argument is not col, it is actually line.