Add an environment variable for disabling watchdog

This should only be used when running the Wine process under a separate
namespace.

CHANGELOG.md

@@ -8,6 +8,12 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+### Added
+
+- Added an environment variable to disable the watchdog timer. This allows the
+  Wine process to run under a separate namespace. If you don't know that you
+  need this, then you probably don't need this!
+
 ### Changed
 
 - The audio processing implementation for both VST2 and VST3 plugins has been

README.md

@@ -654,6 +654,11 @@ the yabridge [Discord](https://discord.gg/pyNeweqadf).
   [plugin groups](#plugin-groups) to run multiple instances of your most
   frequently used plugins within a single process.
 
+- If you're using a `WINELOADER` that runs the Wine process under a separate
+  namespace while the host is not sandboxed, then you'll have to use the
+  `YABRIDGE_NO_WATCHDOG` environment variable to disable the watchdog timer. If
+  you know what this means then you probably know what you're doing.
+
 ## Performance tuning
 
 Running Windows plugins under Wine should have a minimal performance overhead,

src/wine-host/utils.cpp

@@ -16,10 +16,23 @@
 
 #include "utils.h"
 
+#include <iostream>
+
+#include <boost/process/environment.hpp>
+
 #include "bridges/common.h"
 
+namespace bp = boost::process;
+
 using namespace std::literals::chrono_literals;
 
+/**
+ * If this environment variable is set to `1`, then we won't enable the watchdog
+ * timer. This is only necessary when running the Wine process under a different
+ * namespace than the host.
+ */
+constexpr char disable_watchdog_timer_env_var[] = "YABRIDGE_NO_WATCHDOG";
+
 uint32_t WINAPI
 win32_thread_trampoline(fu2::unique_function<void()>* entry_point) {
     (*entry_point)();
@@ -81,9 +94,21 @@ MainContext::MainContext()
       events_timer(context),
       watchdog_context(),
       watchdog_timer(watchdog_context) {
+    bp::environment env = boost::this_process::environment();
+
+    // NOTE: We allow disabling the watchdog timer to allow the Wine process to
+    //       be run from a separate namespace. This is not something you'd
+    //       normally want to enable.
+    if (env[disable_watchdog_timer_env_var].to_string() == "1") {
+        std::cerr << "WARNING: Watchdog timer disabled. Not protecting"
+                  << std::endl;
+        std::cerr << "         against dangling processes." << std::endl;
+        return;
+    }
+
     // To account for hosts terminating before the bridged plugin has
-    // initialized, we'll do the first watchdog check five seconds. After this
+    // initialized, we'll do the first watchdog check five seconds. After
-    // we'll run the timer on a 30 second interval.
+    // this we'll run the timer on a 30 second interval.
     async_handle_watchdog_timer(5s);
 
     watchdog_handler = Win32Thread([&]() {