diff options
| author | Hanna Reitz <hreitz@redhat.com> | 2022-03-03 17:48:13 +0100 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2022-03-04 18:14:40 +0100 |
| commit | 2525edd85fec53e23fda98974a15e3b3c8957596 (patch) | |
| tree | d27ad4f3ee0f0d3a238f23bbfc2e2553d647abdc /docs/tools | |
| parent | 79d51d7317c204dedd220793950a50f46a4e5bd9 (diff) | |
qsd: Add --daemonize
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 <hreitz@redhat.com>
Message-Id: <20220303164814.284974-4-hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'docs/tools')
| -rw-r--r-- | docs/tools/qemu-storage-daemon.rst | 7 |
1 files changed, 7 insertions, 0 deletions
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 |