qemu/qga-Don-t-daemonize-before-channel-is-initialized.patch

From 752d98d93459c87817be5e02c39257e0fa5934f8 Mon Sep 17 00:00:00 2001
From: qihao_yewu <qihao_yewu@cmss.chinamobile.com>
Date: Fri, 7 Mar 2025 21:07:11 -0500
Subject: [PATCH] qga: Don't daemonize before channel is initialized
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

cheery-pick from c6f5dd7ac8ef62dcdec4cdeda1467c658161afff

If the agent is set to daemonize but for whatever reason fails to
init the channel, the error message is lost. Worse, the agent
daemonizes needlessly and returns success. For instance:

  # qemu-ga -m virtio-serial \
            -p /dev/nonexistent_device \
            -f /run/qemu-ga.pid \
            -t /run \
            -d
  # echo $?
  0

This makes it needlessly hard for init scripts to detect a
failure in qemu-ga startup. Though, they shouldn't pass '-d' in
the first place.

Let's open the channel first and only after that become a daemon.

Related bug: https://bugs.gentoo.org/810628

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Message-ID: <7a42b0cbda5c7e01cf76bc1b29a1210cd018fa78.1736261360.git.mprivozn@redhat.com>
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Signed-off-by: qihao_yewu <qihao_yewu@cmss.chinamobile.com>
---
 qga/main.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/qga/main.c b/qga/main.c
index c4dcbb86be..8d341ffdf1 100644
--- a/qga/main.c
+++ b/qga/main.c
@@ -1407,7 +1407,6 @@ static GAState *initialize_agent(GAConfig *config, int socket_activation)
         if (config->daemonize) {
             /* delay opening/locking of pidfile till filesystems are unfrozen */
             s->deferred_options.pid_filepath = config->pid_filepath;
-            become_daemon(NULL);
         }
         if (config->log_filepath) {
             /* delay opening the log file till filesystems are unfrozen */
@@ -1416,9 +1415,6 @@ static GAState *initialize_agent(GAConfig *config, int socket_activation)
         ga_disable_logging(s);
         qmp_for_each_command(&ga_commands, ga_disable_not_allowed_freeze, NULL);
     } else {
-        if (config->daemonize) {
-            become_daemon(config->pid_filepath);
-        }
         if (config->log_filepath) {
             FILE *log_file = ga_open_logfile(config->log_filepath);
             if (!log_file) {
@@ -1482,6 +1478,20 @@ static GAState *initialize_agent(GAConfig *config, int socket_activation)
     }
 #endif
 
+    if (!channel_init(s, s->config->method, s->config->channel_path,
+                      s->socket_activation ? FIRST_SOCKET_ACTIVATION_FD : -1)) {
+        g_critical("failed to initialize guest agent channel");
+        return NULL;
+    }
+
+    if (config->daemonize) {
+        if (ga_is_frozen(s)) {
+            become_daemon(NULL);
+        } else {
+            become_daemon(config->pid_filepath);
+        }
+    }
+
     ga_state = s;
     return s;
 failed:
@@ -1516,8 +1526,9 @@ static void cleanup_agent(GAState *s)
 
 static int run_agent_once(GAState *s)
 {
-    if (!channel_init(s, s->config->method, s->config->channel_path,
-                      s->socket_activation ? FIRST_SOCKET_ACTIVATION_FD : -1)) {
+    if (!s->channel &&
+        channel_init(s, s->config->method, s->config->channel_path,
+                     s->socket_activation ? FIRST_SOCKET_ACTIVATION_FD : -1)) {
         g_critical("failed to initialize guest agent channel");
         return EXIT_FAILURE;
     }
@@ -1526,6 +1537,7 @@ static int run_agent_once(GAState *s)
 
     if (s->channel) {
         ga_channel_free(s->channel);
+        s->channel = NULL;
     }
 
     return EXIT_SUCCESS;
-- 
2.41.0.windows.1