fix(process): avoid leaking zombies and fds in detached processes (#3379)

src/platform/linux/misc.cpp

@@ -241,22 +241,24 @@ namespace platf {
 
   bp::child
   run_command(bool elevated, bool interactive, const std::string &cmd, boost::filesystem::path &working_dir, const bp::environment &env, FILE *file, std::error_code &ec, bp::group *group) {
+    // clang-format off
     if (!group) {
       if (!file) {
-        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > bp::null, bp::std_err > bp::null, ec);
+        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_in < bp::null, bp::std_out > bp::null, bp::std_err > bp::null, bp::limit_handles, ec);
       }
       else {
-        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > file, bp::std_err > file, ec);
+        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_in < bp::null, bp::std_out > file, bp::std_err > file, bp::limit_handles, ec);
       }
     }
     else {
       if (!file) {
-        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > bp::null, bp::std_err > bp::null, ec, *group);
+        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_in < bp::null, bp::std_out > bp::null, bp::std_err > bp::null, bp::limit_handles, ec, *group);
       }
       else {
-        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > file, bp::std_err > file, ec, *group);
+        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_in < bp::null, bp::std_out > file, bp::std_err > file, bp::limit_handles, ec, *group);
       }
     }
+    // clang-format on
   }
 
   /**

src/platform/macos/misc.mm

@@ -182,22 +182,24 @@ namespace platf {
 
   bp::child
   run_command(bool elevated, bool interactive, const std::string &cmd, boost::filesystem::path &working_dir, const bp::environment &env, FILE *file, std::error_code &ec, bp::group *group) {
+    // clang-format off
     if (!group) {
       if (!file) {
-        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > bp::null, bp::std_err > bp::null, ec);
+        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_in < bp::null, bp::std_out > bp::null, bp::std_err > bp::null, bp::limit_handles, ec);
       }
       else {
-        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > file, bp::std_err > file, ec);
+        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_in < bp::null, bp::std_out > file, bp::std_err > file, bp::limit_handles, ec);
       }
     }
     else {
       if (!file) {
-        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > bp::null, bp::std_err > bp::null, ec, *group);
+        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_in < bp::null, bp::std_out > bp::null, bp::std_err > bp::null, bp::limit_handles, ec, *group);
       }
       else {
-        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > file, bp::std_err > file, ec, *group);
+        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_in < bp::null, bp::std_out > file, bp::std_err > file, bp::limit_handles, ec, *group);
       }
     }
+    // clang-format on
   }
 
   /**

src/process.cpp

@@ -269,6 +269,16 @@ namespace proc {
 
   int
   proc_t::running() {
+#ifndef _WIN32
+    // On POSIX OSes, we must periodically wait for our children to avoid
+    // them becoming zombies. This must be synchronized carefully with
+    // calls to bp::wait() and platf::process_group_running() which both
+    // invoke waitpid() under the hood.
+    auto reaper = util::fail_guard([]() {
+      while (waitpid(-1, nullptr, WNOHANG) > 0);
+    });
+#endif
+
     if (placebo) {
       return _app_id;
     }