lib: Recreate the event loop after daemonizing on BSD platforms.

include/fluent-bit/flb_error.h

@@ -26,6 +26,7 @@
 #define FLB_ERR_CFG_FLUSH             20
 #define FLB_ERR_CFG_FLUSH_CREATE      21
 #define FLB_ERR_CFG_FLUSH_REGISTER    22
+#define FLB_ERR_EVENT_LOOP_CREATE     30
 #define FLB_ERR_CUSTOM_INVALID        49
 #define FLB_ERR_INPUT_INVALID         50
 #define FLB_ERR_INPUT_UNDEF           51

include/fluent-bit/flb_lib.h

@@ -49,6 +49,8 @@ typedef struct flb_lib_ctx         flb_ctx_t;
 struct flb_processor;
 
 FLB_EXPORT void flb_init_env();
+FLB_EXPORT int flb_event_loop_create(flb_ctx_t *ctx);
+FLB_EXPORT int flb_event_loop_destroy(flb_ctx_t *ctx);
 FLB_EXPORT flb_ctx_t *flb_create();
 FLB_EXPORT void flb_destroy(flb_ctx_t *ctx);
 FLB_EXPORT int flb_input(flb_ctx_t *ctx, const char *input, void *data);

src/CMakeLists.txt

@@ -8,6 +8,7 @@ set(src
   flb_api.c
   flb_csv.c
   flb_lib.c
+  flb_event_loop.c
   flb_log.c
   flb_env.c
   flb_file.c

src/flb_event_loop.c

@@ -0,0 +1,102 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+/*  Fluent Bit
+ *  ==========
+ *  Copyright (C) 2015-2025 The Fluent Bit Authors
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#include <fluent-bit/flb_lib.h>
+#include <fluent-bit/flb_mem.h>
+
+#include <unistd.h>
+
+int flb_event_loop_create(flb_ctx_t *ctx)
+{
+    int ret;
+    struct flb_config *config;
+
+    if (ctx == NULL || ctx->config == NULL)
+        return FLB_LIB_ERROR;
+
+    config = ctx->config;
+
+    /* Create the event loop to receive notifications */
+    ctx->event_loop = mk_event_loop_create(256);
+    if (!ctx->event_loop)
+        return FLB_LIB_ERROR;
+
+    config->ch_evl = ctx->event_loop;
+
+    /* Prepare the notification channels */
+    ctx->event_channel = flb_calloc(1, sizeof(struct mk_event));
+    if (!ctx->event_channel) {
+        perror("calloc");
+        goto error_1;
+    }
+
+    MK_EVENT_ZERO(ctx->event_channel);
+
+    ret = mk_event_channel_create(config->ch_evl,
+                                  &config->ch_notif[0],
+                                  &config->ch_notif[1],
+                                  ctx->event_channel);
+    if (ret != 0) {
+        flb_error("[lib] could not create notification channels");
+        goto error_2;
+    }
+
+    return 0;
+
+error_2:
+    flb_free(ctx->event_channel);
+    ctx->event_channel = NULL;
+error_1:
+    mk_event_loop_destroy(ctx->event_loop);
+    ctx->event_loop = NULL;
+    return FLB_LIB_ERROR;
+}
+
+int flb_event_loop_destroy(flb_ctx_t *ctx)
+{
+    int ret;
+    struct flb_config *config;
+
+    if (ctx == NULL || ctx->config == NULL)
+        return 0;
+
+    config = ctx->config;
+    if (ctx->event_channel != NULL) {
+        ret = mk_event_channel_destroy(config->ch_evl,
+                                       config->ch_notif[0],
+                                       config->ch_notif[1],
+                                       ctx->event_channel);
+        if (ret != 0) {
+            /* make sure to close file descriptors */
+            close(config->ch_notif[0]);
+            close(config->ch_notif[1]);
+        }
+        flb_free(ctx->event_channel);
+        ctx->event_channel = NULL;
+    }
+
+    if (ctx->event_loop != NULL) {
+        mk_event_loop_destroy(ctx->event_loop);
+        ctx->event_loop = NULL;
+        config->ch_evl = NULL;
+    }
+
+    return 0;
+}
+

src/flb_lib.c

@@ -184,37 +184,13 @@ flb_ctx_t *flb_create()
         return NULL;
     }
 
-    /* Create the event loop to receive notifications */
-    ctx->event_loop = mk_event_loop_create(256);
-    if (!ctx->event_loop) {
-        flb_config_exit(ctx->config);
-        flb_free(ctx);
-        return NULL;
-    }
-    config->ch_evl = ctx->event_loop;
-
-    /* Prepare the notification channels */
-    ctx->event_channel = flb_calloc(1, sizeof(struct mk_event));
-    if (!ctx->event_channel) {
-        perror("calloc");
+    ret = flb_event_loop_create(ctx);
+    if (ret != 0) {
         flb_config_exit(ctx->config);
         flb_free(ctx);
         return NULL;
     }
 
-    MK_EVENT_ZERO(ctx->event_channel);
-
-    ret = mk_event_channel_create(config->ch_evl,
-                                  &config->ch_notif[0],
-                                  &config->ch_notif[1],
-                                  ctx->event_channel);
-    if (ret != 0) {
-        flb_error("[lib] could not create notification channels");
-        flb_stop(ctx);
-        flb_destroy(ctx);
-        return NULL;
-    }
-
     #ifdef FLB_HAVE_AWS_ERROR_REPORTER
     if (is_error_reporting_enabled()) {
         error_reporter = flb_aws_error_reporter_create();

src/flb_utils.c

@@ -89,6 +89,9 @@ void flb_utils_error(int err)
     case FLB_ERR_CFG_FLUSH_REGISTER:
         msg = "could not register timer for flushing";
         break;
+    case FLB_ERR_EVENT_LOOP_CREATE:
+        msg = "could not create event loop";
+        break;
     case FLB_ERR_INPUT_INVALID:
         msg = "invalid input type";
         break;

src/fluent-bit.c

@@ -1415,7 +1415,18 @@ static int flb_main_run(int argc, char **argv)
 #ifdef FLB_HAVE_FORK
     /* Run in background/daemon mode */
     if (config->daemon == FLB_TRUE) {
+#if defined(__FreeBSD__) || defined(__NetBSD__) || \
+    defined(__OpenBSD__) || defined(__DragonFly__)
+        flb_event_loop_destroy(ctx);
+#endif
         flb_utils_set_daemon(config);
+#if defined(__FreeBSD__) || defined(__NetBSD__) || \
+    defined(__OpenBSD__) || defined(__DragonFly__)
+        if (flb_event_loop_create(ctx) != 0) {
+            flb_error("[daemon] failed to recreate event loop after daemonizing");
+            flb_utils_error(FLB_ERR_EVENT_LOOP_CREATE);
+        }
+#endif
     }
 #endif