1 files changed, 48 insertions, 20 deletions

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 4276163564..5b2757920c 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -73,7 +73,6 @@
 
 #define MBR_SIZE 512
 
-static int verbose;
 static char *srcpath;
 static SocketAddress *saddr;
 static int persistent = 0;
@@ -272,9 +271,15 @@ static void *show_parts(void *arg)
     return NULL;
 }
 
+struct NbdClientOpts {
+    char *device;
+    bool fork_process;
+    bool verbose;
+};
+
 static void *nbd_client_thread(void *arg)
 {
-    char *device = arg;
+    struct NbdClientOpts *opts = arg;
     NBDExportInfo info = { .request_sizes = false, .name = g_strdup("") };
     QIOChannelSocket *sioc;
     int fd = -1;
@@ -298,10 +303,10 @@ static void *nbd_client_thread(void *arg)
         goto out;
     }
 
-    fd = open(device, O_RDWR);
+    fd = open(opts->device, O_RDWR);
     if (fd < 0) {
         /* Linux-only, we can use %m in printf.  */
-        error_report("Failed to open %s: %m", device);
+        error_report("Failed to open %s: %m", opts->device);
         goto out;
     }
 
@@ -311,14 +316,18 @@ static void *nbd_client_thread(void *arg)
     }
 
     /* update partition table */
-    pthread_create(&show_parts_thread, NULL, show_parts, device);
+    pthread_create(&show_parts_thread, NULL, show_parts, opts->device);
 
-    if (verbose) {
+    if (opts->verbose && !opts->fork_process) {
         fprintf(stderr, "NBD device %s is now connected to %s\n",
-                device, srcpath);
+                opts->device, srcpath);
     } else {
         /* Close stderr so that the qemu-nbd process exits.  */
-        dup2(STDOUT_FILENO, STDERR_FILENO);
+        if (dup2(STDOUT_FILENO, STDERR_FILENO) < 0) {
+            error_report("Could not set stderr to /dev/null: %s",
+                         strerror(errno));
+            exit(EXIT_FAILURE);
+        }
     }
 
     if (nbd_client(fd) < 0) {
@@ -573,9 +582,9 @@ int main(int argc, char **argv)
     const char *tlshostname = NULL;
     bool imageOpts = false;
     bool writethrough = false; /* Client will flush as needed. */
+    bool verbose = false;
     bool fork_process = false;
     bool list = false;
-    int old_stderr = -1;
     unsigned socket_activation;
     const char *pid_file_name = NULL;
     const char *selinux_label = NULL;
@@ -738,7 +747,7 @@ int main(int argc, char **argv)
             }
             break;
         case 'v':
-            verbose = 1;
+            verbose = true;
             break;
         case 'V':
             version(argv[0]);
@@ -928,19 +937,30 @@ int main(int argc, char **argv)
             error_report("Failed to fork: %s", strerror(errno));
             exit(EXIT_FAILURE);
         } else if (pid == 0) {
-            close(stderr_fd[0]);
+            int saved_errno;
 
-            /* Remember parent's stderr if we will be restoring it. */
-            if (fork_process) {
-                old_stderr = dup(STDERR_FILENO);
-            }
+            close(stderr_fd[0]);
 
             ret = qemu_daemon(1, 0);
+            saved_errno = errno;    /* dup2 will overwrite error below */
 
             /* Temporarily redirect stderr to the parent's pipe...  */
-            dup2(stderr_fd[1], STDERR_FILENO);
+            if (dup2(stderr_fd[1], STDERR_FILENO) < 0) {
+                char str[256];
+                snprintf(str, sizeof(str),
+                         "%s: Failed to link stderr to the pipe: %s\n",
+                         g_get_prgname(), strerror(errno));
+                /*
+                 * We are unable to use error_report() here as we need to get
+                 * stderr pointed to the parent's pipe. Write to that pipe
+                 * manually.
+                 */
+                ret = write(stderr_fd[1], str, strlen(str));
+                exit(EXIT_FAILURE);
+            }
+
             if (ret < 0) {
-                error_report("Failed to daemonize: %s", strerror(errno));
+                error_report("Failed to daemonize: %s", strerror(saved_errno));
                 exit(EXIT_FAILURE);
             }
 
@@ -1125,8 +1145,13 @@ int main(int argc, char **argv)
     if (device) {
 #if HAVE_NBD_DEVICE
         int ret;
+        struct NbdClientOpts opts = {
+            .device = device,
+            .fork_process = fork_process,
+            .verbose = verbose,
+        };
 
-        ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
+        ret = pthread_create(&client_thread, NULL, nbd_client_thread, &opts);
         if (ret != 0) {
             error_report("Failed to create client thread: %s", strerror(ret));
             exit(EXIT_FAILURE);
@@ -1152,8 +1177,11 @@ int main(int argc, char **argv)
     }
 
     if (fork_process) {
-        dup2(old_stderr, STDERR_FILENO);
-        close(old_stderr);
+        if (dup2(STDOUT_FILENO, STDERR_FILENO) < 0) {
+            error_report("Could not set stderr to /dev/null: %s",
+                         strerror(errno));
+            exit(EXIT_FAILURE);
+        }
     }
 
     state = RUNNING;