Avoid deadlocks after fork

score/launch_manager/src/daemon/BUILD

@@ -26,6 +26,7 @@ cc_binary(
     visibility = ["//score/launch_manager:__subpackages__"],
     deps = [
         "//score/launch_manager/src/daemon/src/alive_monitor",
+        "//score/launch_manager/src/daemon/src/common:assertion_handler",
         "//score/launch_manager/src/daemon/src/common:log",
         "//score/launch_manager/src/daemon/src/osal:ipc_comms",
         "//score/launch_manager/src/daemon/src/process_group_manager",

score/launch_manager/src/daemon/src/common/BUILD

@@ -13,6 +13,16 @@
 load("@rules_cc//cc:defs.bzl", "cc_test")
 load("//config:common_cc.bzl", "cc_binary_with_common_opts", "cc_library_with_common_opts")
 
+cc_library(
+    name = "assertion_handler",
+    srcs = ["assertion_handler.cpp"],
+    hdrs = ["assertion_handler.hpp"],
+    include_prefix = "score/mw/launch_manager/common",
+    strip_include_prefix = "/score/launch_manager/src/daemon/src/common",
+    visibility = ["//score:__subpackages__"],
+    deps = ["@score_baselibs//score/language/futurecpp"],
+)
+
 cc_library(
     name = "identifier_hash",
     srcs = [

score/launch_manager/src/daemon/src/common/assertion_handler.cpp

@@ -0,0 +1,102 @@
+/********************************************************************************
+ * 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 <charconv>
+#include <unistd.h>
+#include <cerrno>
+#include <cstdlib>
+#include <cstring>
+
+#include "score/language/futurecpp/include/score/assert.hpp"
+
+namespace score
+{
+namespace lcm
+{
+namespace internal
+{
+
+/*
+ * The assertion handler may be called from any context, therefore, it must
+ * be async signal safe.
+ *
+ * If we encounter an error simply abort, as we are already in the assertion
+ * handler so there is nothing else to do.
+ */
+
+void stderr_print(const char* message)
+{
+    auto offset = 0;
+    const auto length = strlen(message);
+
+    while (offset < length)
+    {
+        const auto result = write(2, &message[offset], length - offset);
+
+        if (result == -1)
+        {
+            if (errno != EINTR)
+                std::abort();
+        }
+        else
+        {
+            offset += result;
+        }
+    }
+}
+
+void assertion_handler(const cpp::handler_parameters& params)
+{
+    stderr_print("Assertion failed:");
+
+    if (params.file != nullptr)
+    {
+        stderr_print("\n  In: ");
+        stderr_print(params.file);
+    }
+
+    if (params.function != nullptr)
+    {
+        stderr_print("\n  In: ");
+        stderr_print(params.function);
+    }
+
+    if (params.line != 0)
+    {
+        stderr_print("\n  Line: ");
+        char buffer[5] = {0};
+        const auto result = std::to_chars(buffer, &buffer[3], params.line);
+        if (result.ec == std::errc())
+            stderr_print(buffer);
+        else
+            stderr_print(">9999");
+    }
+
+    if (params.condition != nullptr)
+    {
+        stderr_print("\n  Condition: ");
+        stderr_print(params.condition);
+    }
+
+    if (params.message != nullptr)
+    {
+        stderr_print("\n  ");
+        stderr_print(params.message);
+    }
+
+    stderr_print("\n");
+}
+
+}  // namespace internal
+}  // namespace lcm
+}  // namespace score

score/launch_manager/src/daemon/src/common/assertion_handler.hpp

@@ -0,0 +1,30 @@
+/********************************************************************************
+ * 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 <unistd.h>
+#include <cstring>
+
+#include "score/language/futurecpp/include/score/assert.hpp"
+
+namespace score
+{
+namespace lcm
+{
+namespace internal
+{
+
+void assertion_handler(const cpp::handler_parameters& params);
+
+}  // namespace internal
+}  // namespace lcm
+}  // namespace score

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

@@ -14,10 +14,10 @@
 #include <unistd.h>
 #include <cstring>
 #include <iostream>
-#include <sstream>
 
 #include <score/assert.hpp>
 
+#include "score/mw/launch_manager/common/assertion_handler.hpp"
 #include "score/mw/launch_manager/common/log.hpp"
 
 #include "score/mw/launch_manager/alive_monitor/details/daemon/AliveMonitorImpl.hpp"
@@ -161,19 +161,7 @@ int main(int argc, const char* argv[])
 int main([[maybe_unused]] int argc, [[maybe_unused]] const char* argv[])
 {
 #endif
-    score::cpp::set_assertion_handler([](const score::cpp::handler_parameters& params) {
-        std::ostringstream msg;
-        msg << "Assertion failed: " << (params.condition != nullptr ? params.condition : "")
-            << "\n  Location: " << (params.file != nullptr ? params.file : "?") << ":" << params.line
-            << " (" << (params.function != nullptr ? params.function : "?") << ")";
-        if (params.message != nullptr)
-        {
-            msg << "\n  Message:  " << params.message;
-        }
-        msg << "\n";
-        std::cerr << msg.str();
-    });
-
+    score::cpp::set_assertion_handler(assertion_handler);
 
     // reserve files descriptor osal::IpcCommsSync::sync_fd (fd3) and
     // osal::IpcCommsSync::control_client_handler_nudge_fd (fd4) for communication tpyes: kNoComms !fd3 & !fd4

score/launch_manager/src/daemon/src/process_group_manager/details/BUILD

@@ -12,6 +12,23 @@
 # *******************************************************************************
 load("@rules_cc//cc:defs.bzl", "cc_library")
 
+cc_library(
+    name = "configure_process",
+    srcs = ["configure_process.cpp"],
+    hdrs = ["configure_process.hpp"],
+    include_prefix = "score/mw/launch_manager/process_group_manager/details",
+    strip_include_prefix = "/score/launch_manager/src/daemon/src/process_group_manager/details",
+    visibility = ["//score/launch_manager/src/daemon/src/process_group_manager:__pkg__"],
+    deps = [
+        "//score/launch_manager/src/daemon/src/osal:return_types",
+        "//score/launch_manager/src/daemon/src/osal:security_policy",
+        "//score/launch_manager/src/daemon/src/osal:set_affinity",
+        "//score/launch_manager/src/daemon/src/osal:set_groups",
+        "//score/launch_manager/src/daemon/src/osal:sys_exit",
+        "//score/launch_manager/src/daemon/src/process_group_manager:iprocess",
+    ],
+)
+
 cc_library(
     name = "process_info_node",
     hdrs = ["process_info_node.hpp"],
@@ -108,13 +125,10 @@ cc_library(
     srcs = ["process_launcher.cpp"],
     visibility = ["//score/launch_manager/src/daemon/src/process_group_manager:__pkg__"],
     deps = [
+        ":configure_process",
         "//score/launch_manager/src/daemon/src/common:log",
         "//score/launch_manager/src/daemon/src/control:control_client_channel",
         "//score/launch_manager/src/daemon/src/osal:ipc_comms",
-        "//score/launch_manager/src/daemon/src/osal:security_policy",
-        "//score/launch_manager/src/daemon/src/osal:set_affinity",
-        "//score/launch_manager/src/daemon/src/osal:set_groups",
-        "//score/launch_manager/src/daemon/src/osal:sys_exit",
         "//score/launch_manager/src/daemon/src/process_group_manager:iprocess",
     ],
 )
@@ -135,6 +149,7 @@ cc_library(
     }),
     visibility = ["//score/launch_manager/src/daemon/src/process_group_manager:__pkg__"],
     deps = [
+        ":configure_process",
         ":graph",
         ":os_handler",
         ":process_info_node",

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

@@ -0,0 +1,157 @@
+/********************************************************************************
+ * 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 <limits.h>
+
+#include <libgen.h>
+#include <sys/resource.h>
+#include <cerrno>
+#include <cstring>
+#include <string>
+#include <string_view>
+
+#include "score/launch_manager/src/daemon/src/osal/return_types.hpp"
+#include "score/mw/launch_manager/osal/security_policy.hpp"
+#include "score/mw/launch_manager/osal/set_affinity.hpp"
+#include "score/mw/launch_manager/osal/set_groups.hpp"
+#include "score/mw/launch_manager/process_group_manager/iprocess.hpp"
+
+/*
+ * In this file only async signal safe functions can be used, as these functions
+ * are used between `fork` and `execve`.
+ *
+ * This is necessary because `fork` only copies the current thread, so any locks
+ * which were held at that time will never be released. See `man 2 fork`.
+ *
+ * A big implication is that we must use assertions rather than log messages,
+ * and the assertion handler itself must follow these rules.
+ */
+
+namespace score
+{
+
+namespace lcm
+{
+
+namespace internal
+{
+
+void setLimit(const int resource, const std::size_t amount, const std::string_view rlimit_name)
+{
+    if (amount == 0)
+        return;
+
+    const struct rlimit limit{
+        .rlim_cur = amount,
+        .rlim_max = amount,
+    };
+
+    const auto result = ::setrlimit(resource, &limit);
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(
+        result != -1, ("Failed to set rlimit " + std::string(rlimit_name) + ": " + std::strerror(errno)).c_str());
+}
+
+void setSchedulingAndSecurity(const osal::OsalConfig& config)
+{
+    int result;  // Used for return value from system calls
+
+    // Set process group id to be equal to the pid
+    // setpgid will fail if called by a session leader (which LCMd is), so skip
+    if (config.comms_type_ != osal::CommsType::kLaunchManager)
+    {
+        result = setpgid(0, getpid());
+        SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(result == 0, std::strerror(errno));
+    }
+
+    // Set scheduling policy with sched_setscheduler
+    sched_param sch_param{};
+
+    sch_param.sched_priority = config.scheduling_priority_;
+
+    // TODO: Clamping should be done when the config is loaded
+    // https://github.com/eclipse-score/lifecycle/issues/304
+    if (sch_param.sched_priority < sched_get_priority_min(config.scheduling_policy_))
+    {
+        sch_param.sched_priority = sched_get_priority_min(config.scheduling_policy_);
+    }
+    else if (sch_param.sched_priority > sched_get_priority_max(config.scheduling_policy_))
+    {
+        sch_param.sched_priority = sched_get_priority_max(config.scheduling_policy_);
+    }
+
+    result = sched_setscheduler(0, config.scheduling_policy_, &sch_param);
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(result != -1, std::strerror(errno));
+
+    result = osal::setaffinity(config.cpu_mask_);
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(result != -1, std::strerror(errno));
+
+    result = setgid(config.gid_);
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(result != -1, std::strerror(errno));
+
+    // Note: the type of the first parameter of setgroups() differs in Linux and QNX, so we use osal
+    const auto gids_size = config.supplementary_gids_.size();
+    if (gids_size > 0)
+    {
+        const auto gids_data = config.supplementary_gids_.data();
+        result = osal::setgroups(gids_size, gids_data);
+        SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(result != -1, std::strerror(errno));
+    }
+
+    result = setuid(config.uid_);
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(result != -1, std::strerror(errno));
+}
+
+void changeCurrentWorkingDirectory(const osal::OsalConfig& config)
+{
+    // Notice that this next static variable is duplicated by the fork() and so does not need
+    // any protection by a mutex although at first sight you may think it could need one.
+    static char path_copy[PATH_MAX + 1U] = {0};
+
+    // TODO: This should be validated when the config is loaded
+    // https://github.com/eclipse-score/lifecycle/issues/304
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(config.executable_path_.size() < PATH_MAX,
+                                                "Executable path is too long");
+
+    const auto result = chdir(dirname(strncpy(path_copy, config.executable_path_.c_str(), PATH_MAX)));
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(result != -1, std::strerror(errno));
+}
+
+void implementMemoryResourceLimits(const osal::OsalConfig& config)
+{
+    setLimit(RLIMIT_DATA, config.resource_limits_.data_, "RLIMIT_DATA");
+    setLimit(RLIMIT_AS, config.resource_limits_.as_, "RLIMIT_AS");
+    setLimit(RLIMIT_STACK, config.resource_limits_.stack_, "RLIMIT_STACK");
+
+    // Note about cpu limit:
+    // Using setrlimit, this imposes a maximum time that a process will run for, which might not be
+    // what you intend? Probably you'll want a maximum time in a time-slice, but you don't get that
+    // with limits set by setrlimit...
+    setLimit(RLIMIT_CPU, config.resource_limits_.cpu_, "RLIMIT_CPU");
+}
+
+void changeSecurityPolicy(const osal::OsalConfig& config)
+{
+    if (config.security_policy_ == "")
+        return;
+
+    const auto result = osal::setSecurityPolicy(config.security_policy_.c_str());
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(
+        result == 0,
+        ("Failed to set security policy " + config.security_policy_ + ": " + std::strerror(errno)).c_str());
+}
+
+}  // namespace internal
+
+}  // namespace lcm
+
+}  // namespace score