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| 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) | |
| download | focaccia-qemu-2525edd85fec53e23fda98974a15e3b3c8957596.tar.gz focaccia-qemu-2525edd85fec53e23fda98974a15e3b3c8957596.zip | |
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 |