From dfd91c6a049d2543c906116777685e45581a3f98 Mon Sep 17 00:00:00 2001
From: Victor Moene <victor.moene@northern.tech>
Date: Tue, 25 Aug 2026 14:52:14 +0200
Subject: [PATCH] Made reactor-plugin into its own forked process

Ticket: ENT-14434
Signed-off-by: Victor Moene <victor.moene@northern.tech>
---
 cf-reactor/cf-reactor.c        | 74 +++++++++++++++++++++++++++++++++-
 libpromises/enterprise_stubs.c |  2 +-
 libpromises/prototypes3.h      |  2 +-
 3 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/cf-reactor/cf-reactor.c b/cf-reactor/cf-reactor.c
index 9e9e87cb12f..b975314dc7f 100644
--- a/cf-reactor/cf-reactor.c
+++ b/cf-reactor/cf-reactor.c
@@ -33,6 +33,10 @@
 #include <man.h>
 #include <cleanup.h>
 #include <prototypes3.h>
+#include <signals.h>            /* HandleSignalsForDaemon, IsPendingTermination */
+#include <unistd.h>             /* sleep */
+#include <signal.h>             /* signal, kill */
+#include <exec_tools.h>
 
 /*****************************************************************************/
 /* Globals                                                                   */
@@ -177,6 +181,15 @@ static GenericAgentConfig *CheckOpts(int argc, char **argv)
     return config;
 }
 
+static void TerminateReactorEnterprise(int pid)
+{
+#ifndef __MINGW32__
+    kill((pid_t) pid, SIGINT);
+#else
+    (void) pid;
+#endif /* !__MINGW32__ */
+}
+
 /*****************************************************************************/
 
 int main(int argc, char *argv[])
@@ -185,10 +198,67 @@ int main(int argc, char *argv[])
     EvalContext *ctx = EvalContextNew();
     GenericAgentConfigApply(ctx, config);
 
-    int ret = ReactorEnterpriseMain(NO_FORK);
+#ifdef __MINGW32__
+
+    if (!NO_FORK)
+    {
+        Log(LOG_LEVEL_VERBOSE, "Windows does not support starting processes in the background - starting in foreground");
+    }
+
+#else /* !__MINGW32__ */
+    pid_t existing_pid = ReadPID("cf-reactor.pid");
+    if ((existing_pid != -1) && (kill(existing_pid, 0) == 0))
+    {
+        Log(LOG_LEVEL_ERR, "Another instance of cf-reactor is already running, terminating");
+        return 1;
+    }
+
+    if ((!NO_FORK) && (fork() != 0))
+    {
+        Log(LOG_LEVEL_INFO, "cf-reactor: starting");
+        _exit(EXIT_SUCCESS);
+    }
+
+    if (!NO_FORK)
+    {
+        ActAsDaemon();
+    }
+
+#endif /* !__MINGW32__ */
+
+    umask(077);
+    WritePID("cf-reactor.pid");
+
+    signal(SIGINT, HandleSignalsForDaemon);
+    signal(SIGTERM, HandleSignalsForDaemon);
+    signal(SIGBUS, HandleSignalsForDaemon);
+    signal(SIGHUP, HandleSignalsForDaemon);
+    signal(SIGPIPE, SIG_IGN);
+    signal(SIGUSR1, HandleSignalsForDaemon);
+    signal(SIGUSR2, HandleSignalsForDaemon);
+
+    int child = ReactorEnterpriseMain();
+    if (child == -1)
+    {
+        return 1;
+    }
+
+    for (int i = 0; !IsPendingTermination(); i++)
+    {
+        /* Do something */
+        Log(LOG_LEVEL_INFO, "cf-reactor: %d", i);
+        sleep(1);
+    }
+
+    /* child == 0 means in this case that no child process was created.
+       It is the default value returned by enterprise stubs */
+    if (child > 0)
+    {
+        TerminateReactorEnterprise(child);
+    }
 
     GenericAgentFinalize(ctx, config);
     CallCleanupFunctions();
 
-    return ret;
+    return 0;
 }
diff --git a/libpromises/enterprise_stubs.c b/libpromises/enterprise_stubs.c
index 98ebe1696df..3c21897517c 100644
--- a/libpromises/enterprise_stubs.c
+++ b/libpromises/enterprise_stubs.c
@@ -232,7 +232,7 @@ ENTERPRISE_VOID_FUNC_2ARG_DEFINE_STUB(void, Nova_ClassHistoryEnable,
 {
 }
 
-ENTERPRISE_FUNC_1ARG_DEFINE_STUB(int, ReactorEnterpriseMain, ARG_UNUSED bool, no_fork)
+ENTERPRISE_FUNC_0ARG_DEFINE_STUB(int, ReactorEnterpriseMain)
 {
     Log(LOG_LEVEL_VERBOSE, "Nova extension library is not available.");
     Log(LOG_LEVEL_VERBOSE, "Running cf-reactor community edition.");
diff --git a/libpromises/prototypes3.h b/libpromises/prototypes3.h
index 7ba1d9f051c..657e5023953 100644
--- a/libpromises/prototypes3.h
+++ b/libpromises/prototypes3.h
@@ -85,7 +85,7 @@ ENTERPRISE_VOID_FUNC_0ARG_DECLARE(void, ReloadHAConfig);
 ENTERPRISE_VOID_FUNC_2ARG_DECLARE(void, Nova_ClassHistoryAddContextName, const StringSet *, list, const char *, context_name);
 ENTERPRISE_VOID_FUNC_2ARG_DECLARE(void, Nova_ClassHistoryEnable, StringSet **, list, bool, enable);
 
-ENTERPRISE_FUNC_1ARG_DECLARE(int, ReactorEnterpriseMain, bool, no_fork);
+ENTERPRISE_FUNC_0ARG_DECLARE(int, ReactorEnterpriseMain);
 
 /* manual.c */