We are trying to temporary redirect stderr of daemonized process to a pipe to report a error and get failed. In that case we could not use error_report() helper, but should write the message directly into the problematic pipe.
Signed-off-by: Denis V. Lunev <[email protected]> CC: Eric Blake <[email protected]> CC: Vladimir Sementsov-Ogievskiy <[email protected]> --- qemu-nbd.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/qemu-nbd.c b/qemu-nbd.c index 186ce9474c..4450cc826b 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -937,7 +937,20 @@ int main(int argc, char **argv) ret = qemu_daemon(1, 0); /* 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)); exit(EXIT_FAILURE); -- 2.34.1
