bsd-user: Implement fork(2) and vfork(2) system calls.

[mirror_qemu.git] / qemu-nbd.c

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 7c4e22def1788dc31db2812925f18b26d36baa6d..54faa87a0c0ebaf363dcb40170f27c2ef3895005 100644 (file)
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -255,18 +255,23 @@ struct NbdClientOpts {
     char *device;
     char *srcpath;
     SocketAddress *saddr;
+    int old_stderr;
     bool fork_process;
     bool verbose;
 };
 
-static void nbd_client_release_pipe(void)
+static void nbd_client_release_pipe(int old_stderr)
 {
     /* Close stderr so that the qemu-nbd process exits.  */
-    if (dup2(STDOUT_FILENO, STDERR_FILENO) < 0) {
+    if (dup2(old_stderr, STDERR_FILENO) < 0) {
         error_report("Could not release pipe to parent: %s",
                      strerror(errno));
         exit(EXIT_FAILURE);
     }
+    if (old_stderr != STDOUT_FILENO && close(old_stderr) < 0) {
+        error_report("Could not release qemu-nbd: %s", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
 }
 
 #if HAVE_NBD_DEVICE
@@ -290,7 +295,9 @@ static void *show_parts(void *arg)
 static void *nbd_client_thread(void *arg)
 {
     struct NbdClientOpts *opts = arg;
-    NBDExportInfo info = { .request_sizes = false, .name = g_strdup("") };
+    /* TODO: Revisit this if nbd.ko ever gains support for structured reply */
+    NBDExportInfo info = { .request_sizes = false, .name = g_strdup(""),
+                           .mode = NBD_MODE_SIMPLE };
     QIOChannelSocket *sioc;
     int fd = -1;
     int ret = EXIT_FAILURE;
@@ -332,7 +339,7 @@ static void *nbd_client_thread(void *arg)
         fprintf(stderr, "NBD device %s is now connected to %s\n",
                 opts->device, opts->srcpath);
     } else {
-        nbd_client_release_pipe();
+        nbd_client_release_pipe(opts->old_stderr);
     }
 
     if (nbd_client(fd) < 0) {
@@ -597,6 +604,7 @@ int main(int argc, char **argv)
         .device = NULL,
         .srcpath = NULL,
         .saddr = NULL,
+        .old_stderr = STDOUT_FILENO,
     };
 
 #ifdef CONFIG_POSIX
@@ -931,7 +939,6 @@ int main(int argc, char **argv)
         g_autoptr(GError) err = NULL;
         int stderr_fd[2];
         pid_t pid;
-        int ret;
 
         if (!g_unix_open_pipe(stderr_fd, FD_CLOEXEC, &err)) {
             error_report("Error setting up communication pipe: %s",
@@ -951,6 +958,16 @@ int main(int argc, char **argv)
 
             close(stderr_fd[0]);
 
+            /* Remember parent's stderr if we will be restoring it. */
+            if (opts.verbose /* fork_process is set */) {
+                opts.old_stderr = dup(STDERR_FILENO);
+                if (opts.old_stderr < 0) {
+                    error_report("Could not dup original stderr: %s",
+                                 strerror(errno));
+                    exit(EXIT_FAILURE);
+                }
+            }
+
             ret = qemu_daemon(1, 0);
             saved_errno = errno;    /* dup2 will overwrite error below */
 
@@ -1154,7 +1171,6 @@ int main(int argc, char **argv)
 
     if (opts.device) {
 #if HAVE_NBD_DEVICE
-        int ret;
         ret = pthread_create(&client_thread, NULL, nbd_client_thread, &opts);
         if (ret != 0) {
             error_report("Failed to create client thread: %s", strerror(ret));
@@ -1181,7 +1197,7 @@ int main(int argc, char **argv)
     }
 
     if (opts.fork_process) {
-        nbd_client_release_pipe();
+        nbd_client_release_pipe(opts.old_stderr);
     }
 
     state = RUNNING;
@@ -1201,9 +1217,10 @@ int main(int argc, char **argv)
     qemu_opts_del(sn_opts);
 
     if (opts.device) {
-        void *ret;
-        pthread_join(client_thread, &ret);
-        exit(ret != NULL);
+        void *result;
+        pthread_join(client_thread, &result);
+        ret = (intptr_t)result;
+        exit(ret);
     } else {
         exit(EXIT_SUCCESS);
     }