Start gdb fail when attach debug a program.(Authentication is needed to run `/usr/bin/gdb' as the super user)

Type: Debugger

Describe the bug

• OS and Version: Ubuntu 18.04
• VS Code Version: 1.42
• C/C++ Extension Version: 0.26.3
• Other extensions you installed (and if the issue persists after disabling them): Python
• A clear and concise description of what the bug is:
  I want to mix debug C++ and python code. So I launch my python program with ptvsd. Then I start my python debug configuration and c++ debug configuration . When I launch my gdb debug configuration, there are following failure from debug terminal:

==== AUTHENTICATING FOR org.freedesktop.policykit.exec ===
Authentication is needed to run `/usr/bin/gdb' as the super user
Authenticating as: hanbing
Password: [1] + Stopped (tty output)       /usr/bin/pkexec "/usr/bin/gdb" --interpreter=mi --tty=${DbgTerm} 0<"/tmp/Microsoft-MIEngine-In-zmh829r2.jk4" 1>"/tmp/Microsoft-MIEngine-Out-jh3h8jnd.mmk"
You have stopped jobs.

It's because gdb can't get the root permission when start attach to other program. It's is a known issue in https://code.visualstudio.com/docs/cpp/cpp-debug

Linux:

GDB needs elevated permissions to attach to a process. When using attach to process, you need to provide your password before the debugging session can begin.

But there is no prompt to let me input the password. It raise error directly.
To Reproduce
my c++ extention fputsmodule.cc

#define PY_SSIZE_T_CLEAN
#include <Python.h>

static PyObject *StringTooShortError = NULL;

static PyObject *method_fputs(PyObject *self, PyObject *args, PyObject *kw) {
    char *str, *filename = NULL;
    int bytes_copied = -1;

    /* Parse arguments */
    char *kwlist[] = {"content", "filename", NULL};
    if(!PyArg_ParseTupleAndKeywords(args, kw, "ss", kwlist, &str, &filename)) {
        return NULL;
    }
    if (strlen(str) < 10) {
        /* Passing custom exception */
        PyErr_SetString(StringTooShortError, "String length must be greater than 10");
        return NULL;
    }

    FILE *fp = fopen(filename, "w");
    bytes_copied = fputs(str, fp);
    fclose(fp);

    return (PyObject *)Py_BuildValue("i", bytes_copied);
}

static PyMethodDef FputsMethods[] = {
    {"fputs", (PyCFunction)method_fputs, METH_VARARGS | METH_KEYWORDS, "Python interface for fputs C library function"},
    {NULL, NULL, 0, NULL}
};


static struct PyModuleDef fputsmodule = {
    PyModuleDef_HEAD_INIT,
    "fputs",
    "Python interface for the fputs C library function",
    -1,
    FputsMethods
};


PyMODINIT_FUNC PyInit_fputs(void) {

        /* Assign module value */
    PyObject *module = PyModule_Create(&fputsmodule);

    /* Initialize new exception object */
    StringTooShortError = PyErr_NewException("fputs.StringTooShortError", NULL, NULL);

    /* Add exception object to your module */
    PyModule_AddObject(module, "StringTooShortError", StringTooShortError);

    return module;
}

setup.py

from distutils.core import setup, Extension

def main():
    setup(name="fputs",
          version="1.0.0",
          description="Python interface for the fputs C library function",
          author="hanbing",
          author_email="beatmight@gmail.com",
          ext_modules=[Extension("fputs", ["fputsmodule.cc"], language="c++")])

if __name__ == "__main__":
    main()

fputs_test.py

import argparse

parser = argparse.ArgumentParser()
parser.add_argument("--ptvsd", action="store_true", help="是否启动ptvsd调试。")
args = parser.parse_args()

if args.ptvsd:
    import ptvsd
    ptvsd.enable_attach(address =('127.0.0.1', 10010), redirect_output=True)
    ptvsd.wait_for_attach()

import fputs

fputs.fputs("hello world! You are good!", "hello.txt")

print("hello world!")

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python Attach (local) proc 0",
            "type": "python",
            "request": "attach",
            "pathMappings": [
                {
                    "localRoot": "${workspaceFolder}", // You may also manually specify the directory containing your source code.
                    "remoteRoot": "${workspaceFolder}", // Linux example; adjust as necessary for your OS and situation.
                }
            ],
            "port": 10010,
            "host": "localhost"
        },
        {
            "name": "GDB Attach proc 0",
            "type": "cppdbg",
            "request": "attach",
            "program": "/home/hanbing/anaconda3/bin/python",
            "processId": "${command:pickProcess}",
            "MIMode": "gdb"
        }
    ]
}

First compile the c++ extention

python  setup.py build_ext --inplace

Then start the ptvsd server

python fputs_test.py --ptvsd

Then start "Python Attach (local) proc 0"

Then, start "GDB Attach proc 0", the error raised.

==== AUTHENTICATING FOR org.freedesktop.policykit.exec ===
Authentication is needed to run `/usr/bin/gdb' as the super user
Authenticating as: hanbing
Password: [1] + Stopped (tty output)       /usr/bin/pkexec "/usr/bin/gdb" --interpreter=mi --tty=${DbgTerm} 0<"/tmp/Microsoft-MIEngine-In-zmh829r2.jk4" 1>"/tmp/Microsoft-MIEngine-Out-jh3h8jnd.mmk"
You have stopped jobs.

Reproduce the attach flow using fputsmodule.cc, setup.py, fputs_test.py, and launch.json on Ubuntu 18.04, starting with the GDB attach configuration and its debug terminal output. Investigate why pkexec authentication has no usable password prompt; done means the C++ debugger can attach to the Python process after authentication.