Fixing left over fd on child processes

score/launch_manager/src/daemon/src/main.cpp

@@ -17,12 +17,12 @@
 
 #include "score/mw/launch_manager/common/log.hpp"
 
+#include "score/mw/launch_manager/alive_monitor/details/daemon/AliveMonitorImpl.hpp"
+#include "score/mw/launch_manager/alive_monitor/details/watchdog/WatchdogImpl.hpp"
 #include "score/mw/launch_manager/process_group_manager/alive_monitor_thread.hpp"
 #include "score/mw/launch_manager/process_group_manager/process_group_manager.hpp"
 #include "score/mw/launch_manager/process_state_client/process_state_notifier.hpp"
 #include "score/mw/launch_manager/recovery_client/recovery_client.hpp"
-#include "score/mw/launch_manager/alive_monitor/details/daemon/AliveMonitorImpl.hpp"
-#include "score/mw/launch_manager/alive_monitor/details/watchdog/WatchdogImpl.hpp"
 
 using namespace std;
 using namespace score::lcm::internal;
@@ -67,35 +67,57 @@ bool runLCMDaemon(ProcessGroupManager& process_group_manager)
     }
 }
 
-/// @brief Reserves a file descriptor
-/// @param fd  file descriptor to reserve
+/// @brief Reserves a file descriptor.
+/// @param fd file descriptor to reserve.
+/// @warning This function can abort if system calls fail.
 void reserveFD(int fd)
 {
-    if (fcntl(fd, F_GETFD) != -1 || errno != EBADF)
-    {
+    errno = 0;
+    const int open_fd_flags = ::fcntl(fd, F_GETFD);
+    const bool fd_already_opened = open_fd_flags == 0 && errno == EBADFD;
 
-        std::cerr << "file descriptor already in use\n";
+    if (fd_already_opened)
+    {
+        std::cerr << "Failed to reserve required file descriptor (" << fd
+            << "), file descriptor already in use. " << std::strerror(errno);
         std::abort();
     }
 
     int tmp_fd = open("/dev/null", O_RDWR | O_CLOEXEC);
     if (tmp_fd < 0)
     {
-        std::cerr << "unable to get an unused file descriptor\n";
+        std::cerr << "Failed to reserve required file descriptor (" << fd
+            << "), failed to open temporary file. " << std::strerror(errno);
         std::abort();
     }
 
     if (fd != tmp_fd)
     {
-        if (dup2(tmp_fd, fd) == -1)
+        if (::dup2(tmp_fd, fd) == -1)
+        {
+            ::close(tmp_fd);
+
+            std::cerr << "Failed to reserve required file descriptor (" << fd
+                      << "), couldn't duplicate fd with required number. "
+                      << std::strerror(errno);
+            std::abort();
+        }
+
+        if (::fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
         {
-            close(tmp_fd);
-            std::cerr << std::strerror(errno);
+            ::close(tmp_fd);
+            ::close(fd);
+
+            std::cerr << "Failed to reserve required file descriptor (" << fd
+                      << ") , couldn't set flags on reserved file decriptor. "
+                      << std::strerror(errno);
             std::abort();
         }
-        close(tmp_fd);
+
+        ::close(tmp_fd);
     }
 }
+
 /// @brief Main function to start the LCM daemon.
 /// This function initializes and runs the LCM daemon by creating a ProcessGroupManager,
 /// initializing it, and then running it. It returns the appropriate exit code based on

score/launch_manager/src/daemon/src/process_group_manager/details/process_group_manager.cpp

@@ -151,6 +151,14 @@ inline bool ProcessGroupManager::initializeControlClientHandler()
                 dup2(fd, osal::IpcCommsSync::control_client_handler_nudge_fd);  // always make sure we are using fd=4
             close(fd);
 
+            // dup2 clears the O_CLOEXEC flag so this needs to be set again
+            if (fcntl(fd2, F_SETFD, FD_CLOEXEC) != 0)
+            {
+                ::close(fd2);
+                return false;
+            }
+
+
             if (osal::IpcCommsSync::control_client_handler_nudge_fd == fd2)
             {
                 void* buf = mmap(NULL, sizeof(osal::Semaphore), PROT_WRITE, MAP_SHARED, fd2, 0);

tests/integration/incorrect_config_non_reporting/non_reporting_process.cpp

@@ -26,15 +26,15 @@ TEST(NonReporting, Process)
 {
     using ipc = score::lcm::internal::osal::IpcCommsSync;
 
-    // Map the sync_fd to some shared memory of size 0. With sync_fd=3, this is likely to happen by default
+    // Map the sync_fd to some shared memory of size 0. With sync_fd=111, this is likely to happen by default
     // As there is no comms channel, using sync_fd in this process should not cause a crash.
     auto fd = shm_open("some_shared_memory", O_CREAT | O_RDWR, 0);
     ASSERT_NE(fd, -1) << "Failed to open shared memory: " << strerror(errno);
     shm_unlink("some_shared_memory");
     struct stat res;
     if (fstat(ipc::sync_fd, &res) != 0)
     {  // sync_fd is closed
-        auto dup_res = dup2(ipc::sync_fd, fd);
+        auto dup_res = dup2(fd, ipc::sync_fd);
         ASSERT_NE(dup_res, -1) << "dup2 failed: " << strerror(errno);
     }
 

tests/integration/process_fd_leak/BUILD

@@ -0,0 +1,97 @@
+# *******************************************************************************
+# Copyright (c) 2026 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License Version 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# SPDX-License-Identifier: Apache-2.0
+# *******************************************************************************
+load("@rules_pkg//pkg:mappings.bzl", "pkg_attributes", "pkg_files")
+load("@rules_pkg//pkg:tar.bzl", "pkg_tar")
+load("//:defs.bzl", "launch_manager_config")
+load("//tests/utils/bazel:integration.bzl", "integration_test")
+
+launch_manager_config(
+    name = "lm_process_fd_leak_config",
+    config = "//tests/integration/process_fd_leak:process_fd_leak.json",
+    flatbuffer_out_dir = "etc",
+)
+
+cc_binary(
+    name = "native",
+    srcs = [
+        "get_fds.hpp",
+        "native.cpp",
+    ],
+    deps = [
+        "//tests/utils/test_helper",
+        "@googletest//:gtest_main",
+        "@score_baselibs//score/mw/log",
+    ],
+)
+
+cc_binary(
+    name = "reporting",
+    srcs = [
+        "get_fds.hpp",
+        "reporting.cpp",
+    ],
+    deps = [
+        "//score/launch_manager:lifecycle_cc",
+        "//tests/utils/test_helper",
+        "@googletest//:gtest_main",
+    ],
+)
+
+cc_binary(
+    name = "control_client",
+    srcs = [
+        "control_client.cpp",
+        "get_fds.hpp",
+    ],
+    deps = [
+        "//score/launch_manager:control_cc",
+        "//score/launch_manager:lifecycle_cc",
+        "//tests/utils/test_helper",
+        "@googletest//:gtest_main",
+        "@score_baselibs//score/mw/log",
+    ],
+)
+
+pkg_files(
+    name = "main_files",
+    srcs = [
+        ":control_client",
+        ":native",
+        ":reporting",
+        "//score/launch_manager",
+    ],
+    attributes = pkg_attributes(mode = "0777"),
+    prefix = "tests/process_fd_leak",
+)
+
+pkg_files(
+    name = "configs",
+    srcs = [":lm_process_fd_leak_config"],
+    prefix = "tests/process_fd_leak",
+)
+
+pkg_tar(
+    name = "process_fd_leak_binaries",
+    srcs = [
+        ":configs",
+        ":main_files",
+    ],
+)
+
+integration_test(
+    name = "process_fd_leak",
+    srcs = ["process_fd_leak.py"],
+    tags = ["integration"],
+    test_binaries = ":process_fd_leak_binaries",
+    deps = ["//tests/utils/testing_utils"],
+)

tests/integration/process_fd_leak/control_client.cpp

@@ -0,0 +1,71 @@
+/********************************************************************************
+ * Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ********************************************************************************/
+#include <gtest/gtest.h>
+
+#include <sstream>
+
+#include "get_fds.hpp"
+#include "tests/utils/test_helper/test_helper.hpp"
+#include <score/mw/lifecycle/control_client.h>
+#include <score/mw/lifecycle/report_running.h>
+
+int g_argc;
+char** g_argv;
+
+TEST(ControlClientFDs, FindOpenFDs)
+{
+
+    TEST_STEP("Before Running")
+    {
+        auto open_fds = get_fds();
+        EXPECT_TRUE(filter_fd(open_fds, std::regex("/dev/shm/ipc_shared_mem[0-9]+")));
+        EXPECT_TRUE(filter_fd(open_fds, std::regex("/dev/shm/_nudge~._.~me_")));
+        std::ostringstream oss;
+        oss << open_fds;
+        EXPECT_TRUE(open_fds.empty()) << "Found open files!\n" << oss.str();
+    }
+
+    score::mw::lifecycle::report_running();
+
+    TEST_STEP("After Running")
+    {
+        auto open_fds = get_fds();
+        EXPECT_TRUE(filter_fd(open_fds, std::regex("/dev/shm/ipc_shared_mem[0-9]+")));
+        EXPECT_TRUE(filter_fd(open_fds, std::regex("/dev/shm/_nudge~._.~me_")));
+        std::ostringstream oss;
+        oss << open_fds;
+        EXPECT_TRUE(open_fds.empty()) << "Found open files!\n" << oss.str();
+    }
+
+    score::mw::lifecycle::ControlClient client{};
+
+    TEST_STEP("After Control Client")
+    {
+        auto open_fds = get_fds();
+        EXPECT_TRUE(filter_fd(open_fds, std::regex("/dev/shm/ipc_shared_mem[0-9]+")));
+        EXPECT_TRUE(filter_fd(open_fds, std::regex("/dev/shm/_nudge~._.~me_")));
+        std::ostringstream oss;
+        oss << open_fds;
+        EXPECT_TRUE(open_fds.empty()) << "Found open files!\n" << oss.str();
+    }
+}
+
+int main(int argc, char** argv)
+{
+    g_argc = argc;
+    g_argv = argv;
+
+    TestRunner runner{__FILE__, TerminationBehavior::kContinue, TerminationNotification::kTestEnd};
+
+    return runner.RunTests();
+}