From 1dc8215118ca5b99669c3bf27082a365aef16ea6 Mon Sep 17 00:00:00 2001 From: "Denis V. Lunev" Date: Mon, 17 Jul 2023 16:55:43 +0200 Subject: [PATCH] qemu-nbd: properly report error if qemu_daemon() is failed errno has been overwritten by dup2() just below qemu_daemon() and thus improperly returned to the caller. Fix accordingly. Signed-off-by: Denis V. Lunev CC: Eric Blake CC: Vladimir Sementsov-Ogievskiy Message-ID: <20230717145544.194786-5-den@openvz.org> Reviewed-by: Eric Blake [eblake: reorder patch series] Signed-off-by: Eric Blake --- qemu-nbd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/qemu-nbd.c b/qemu-nbd.c index 186ce9474c..5a8ae1f747 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -932,14 +932,17 @@ int main(int argc, char **argv) error_report("Failed to fork: %s", strerror(errno)); exit(EXIT_FAILURE); } else if (pid == 0) { + int saved_errno; + 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 (ret < 0) { - error_report("Failed to daemonize: %s", strerror(errno)); + error_report("Failed to daemonize: %s", strerror(saved_errno)); exit(EXIT_FAILURE); }