[lldb-dap] Running in server mode does not propagate environment variables

[mateusz-plociennik]

Description

When debugging a program that uses std::getenv() with lldb-dap running in server mode,
the call to std::getenv("HOME") unexpectedly returns nullptr.

---

Environment

• VS Code version: 1.103.2
• Extension version: 0.2.16
• lldb-dap version: 21.1.1
• OS version: macOS 15.6.1 (24G90)

---

settings.json

{
    "lldb-dap.serverMode": true,
    "lldb-dap.executable-path": "/opt/homebrew/opt/llvm/bin/lldb-dap"
}

---

Minimal Reproducible Example

main.cpp

#include <cstdlib>
#include <filesystem>
#include <iostream>
#include <stdexcept>

std::filesystem::path getUserHomeFolder()
{
    if (const char* home = std::getenv("HOME"))
        return home;

    throw std::runtime_error("Could not determine user home directory");
}

int main()
{
    std::cout << getUserHomeFolder() << "\n";
    return 0;
}

---

Steps to Reproduce

1. Enable lldb-dap.serverMode in settings.json.
2. Debug the provided main.cpp with lldb-dap.
3. Observe the result of std::getenv("HOME").

---

Expected Behavior

std::getenv("HOME") should return the user’s home directory path.

---

Actual Behavior

std::getenv("HOME") returns nullptr instead.

[llvmbot]

@llvm/issue-subscribers-lldb-dap

Author: Mateusz Płóciennik (mateusz-plociennik)

### Description

When debugging a program that uses std::getenv() with lldb-dap running in server mode,
the call to std::getenv("HOME") unexpectedly returns nullptr.

---

Environment

• VS Code version: 1.103.2
• Extension version: 0.2.16
• lldb-dap version: 21.1.1
• OS version: macOS 15.6.1 (24G90)

---

settings.json

{
    "lldb-dap.serverMode": true,
    "lldb-dap.executable-path": "/opt/homebrew/opt/llvm/bin/lldb-dap"
}

---

Minimal Reproducible Example

main.cpp

#include <cstdlib>
#include <filesystem>
#include <iostream>
#include <stdexcept>

std::filesystem::path getUserHomeFolder()
{
    if (const char* home = std::getenv("HOME"))
        return home;

    throw std::runtime_error("Could not determine user home directory");
}

int main()
{
    std::cout << getUserHomeFolder() << "\n";
    return 0;
}

---

Steps to Reproduce

1. Enable lldb-dap.serverMode in settings.json.
2. Debug the provided main.cpp with lldb-dap.
3. Observe the result of std::getenv("HOME").

---

Expected Behavior

std::getenv("HOME") should return the user’s home directory path.

---

Actual Behavior

std::getenv("HOME") returns nullptr instead.