Add multi-process support

[JulianvDoorn]

I have rebased https://github.com/WebFreak001/code-debug/pull/133 to the new master since it hasn't been updated. Then I fixed some things to make the extension more respectable to pausing and continuing individual processes. I think only gdb is supported.

Please let me know if the problems that existed in the past are still present. I did some manual fuzzy testing on a C++ file.

[JulianvDoorn]

There is a simple C++ program that I used to test. In fact I asked ChatGPT to directly translate https://github.com/WebFreak001/code-debug/pull/133#issuecomment-367473724 to C++ as the D code seemed less stable to me when I started testing. Also I added inferior processes that immediately exit, since this is a particular use case I'm interested in.

#include <iostream>
#include <thread>
#include <chrono>
#include <unistd.h>     // fork, sleep
#include <map>
#include <string>
#include <vector>

struct T {
    uint8_t d;
    char e;
    T* child;
};

struct S {
    int a;
    long b;
    std::string c;
    T* f;
};

void fork_and_exit_other();

void secondThread();

int main(int argc, char* argv[]) {
    // Print environment variables
    extern char **environ;
    for (char **env = environ; *env != nullptr; env++) {
        std::string entry = *env;
        auto pos = entry.find('=');
        if (pos != std::string::npos) {
            std::string key = entry.substr(0, pos);
            std::string value = entry.substr(pos + 1);
            std::cout << key << " = " << value << "\n";
        }
    }
    std::cout.flush();

    // Print 0, 1, 2
    for (int i = 0; i < 3; i++) {
        std::cout << i << "\n";
        std::cout.flush();
    }

    // Handle args
    std::vector<std::string> args;
    for (int i = 0; i < argc; i++)
        args.emplace_back(argv[i]);

    if (args.size() > 1 && args[1] == "fork") {
        pid_t origin = getpid();
        pid_t i = fork();

        if (i != 0) {
            secondThread();
        }

        fork_and_exit_other();
        

    } else if (args.size() == 1 || args[1] != "single") {
        std::thread th(secondThread);
        th.detach();
    }

    // Write without newline
    std::cout << "No newline!";
    std::cout.flush();

    int count = 5;
    for (; count < 20; count++) {
        S s;
        s.f = new T();
        s.f->child = new T();
        s.f->child->d = 4;
        s.a = count;
    }

    // Print arguments
    std::cout << "Got Arguments: ";
    for (auto &a : args)
        std::cout << a << " ";
    std::cout << "\n";

    // Main infinite loop
    for (thread_local int i = 0; ; i++) {
        std::cout << "Multithreaded Main thread " << i << "\n";
        std::cout.flush();
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }

    return 0;
}

void fork_and_exit_other() {
    pid_t pid = fork();

    if (pid == 0) {
        exit(1);
    }
}

void secondThread() {
    for (thread_local int i = 0; ; i++) {
        std::cout << "Multithreaded " << i << "\n";
        std::cout.flush();
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }
}

[JulianvDoorn]

There are still some problems in the combination of threads and processes because the threadId is common among threads and processes. I'm looking for a solution.

[JulianvDoorn]

Added initial support for child processes viewer. Worked on auto-discovery of processes and subsequently for each a new 'inferior debug session' is started, necessary for VSCode to create the window as desired. It uses a trick that for every inferior process a new port is opened which redirects events to the original debugger.

[JulianvDoorn]

Thanks for the feedback. Right now the PR is still a WIP, since the scope increased because I went down the rabbit hole of starting multiple debug sessions. I have a very strong feeling that once every works stably, there is a huge opportunity for refactoring which I think is necessary prior to merging.

[JulianvDoorn]

Nevertheless, I have relatively little experience in Node.js and TypeScript so I will welcome feedback on style en conventions. Also I also had to add some features in the VSCode debug adapter to support this PR. Once the changes settle I will open a PR over there as well. So it will take a while before this PR can be merged.

[JulianvDoorn]

I think I have gotten to the point that it works relatively stable. Let's see if I can test drive this in the coming days 😄