Am 03.03.2022 um 17:48 hat Hanna Reitz geschrieben: > To implement this, we reuse the existing daemonizing functions from the > system emulator, which mainly do the following: > - Fork off a child process, and set up a pipe between parent and child > - The parent process waits until the child sends a status byte over the > pipe (0 means that the child was set up successfully; anything else > (including errors or EOF) means that the child was not set up > successfully), and then exits with an appropriate exit status > - The child process enters a new session (forking off again), changes > the umask, and will ignore terminal signals from then on > - Once set-up is complete, the child will chdir to /, redirect all > standard I/O streams to /dev/null, and tell the parent that set-up has > been completed successfully > > In contrast to qemu-nbd's --fork implementation, during the set up > phase, error messages are not piped through the parent process. > qemu-nbd mainly does this to detect errors, though (while os_daemonize() > has the child explicitly signal success after set up); because we do not > redirect stderr after forking, error messages continue to appear on > whatever the parent's stderr was (until set up is complete). > > Signed-off-by: Hanna Reitz <hre...@redhat.com> > --- > docs/tools/qemu-storage-daemon.rst | 7 +++++++ > storage-daemon/qemu-storage-daemon.c | 15 +++++++++++++++ > 2 files changed, 22 insertions(+) > > diff --git a/docs/tools/qemu-storage-daemon.rst > b/docs/tools/qemu-storage-daemon.rst > index 878e6a5c5c..8b97592663 100644 > --- a/docs/tools/qemu-storage-daemon.rst > +++ b/docs/tools/qemu-storage-daemon.rst > @@ -154,6 +154,13 @@ Standard options: > created but before accepting connections. The daemon has started > successfully > when the pid file is written and clients may begin connecting. > > +.. option:: --daemonize > + > + Daemonize the process. The parent process will exit once startup is > complete > + (i.e., after the pid file has been or would have been written) or failure > + occurs. Its exit code reflects whether the child has started up > successfully > + or failed to do so. > + > Examples > -------- > Launch the daemon with QMP monitor socket ``qmp.sock`` so clients can execute > diff --git a/storage-daemon/qemu-storage-daemon.c > b/storage-daemon/qemu-storage-daemon.c > index b798954edb..9f2c3332bf 100644 > --- a/storage-daemon/qemu-storage-daemon.c > +++ b/storage-daemon/qemu-storage-daemon.c > @@ -137,6 +137,9 @@ static void help(void) > "\n" > " --pidfile <path> write process ID to a file after startup\n" > "\n" > +" --daemonize daemonize the process, and have the parent exit\n" > +" once startup is complete\n" > +"\n"
So far the long options in the help text are sorted alphabetically. Do we want to keep this? Kevin
