Re: [PATCH 2/3] qemu: Generate cmd line for pipewire audio backend

On Thu, May 11, 2023 at 02:14:51PM +0200, Michal Privoznik wrote: > This is mostly straightforward, except for a teensy-weensy > detail: usually, there's no system wide daemon running, no system > wide available socket that anybody could connect to. PipeWire > uses a per user daemon approach instead. But this in turn means, I spent some time thinking about this even after I said "just give it runtime dir" and now I'm wondering, is this not similar to the dbus daemon?  When we launch it with a constructed config file for graphics type='dbus' we could also launch pipewire deamon with our config file and let qemu connect to that daemon.  I'm not sure what the audio permissions would look like, but it seems like a less messy approach.

> that the socket location floats between various locations and is > derived from various environment variables (just like the actual > socket name) and thus we must pass the variables to QEMU. > > Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; > --- > src/qemu/qemu_command.c                       | 61 +++++++++++++++++++ > .../audio-many-backends.x86_64-latest.args    |  2 + > .../qemuxml2argvdata/audio-many-backends.xml  |  1 + > .../audio-pipewire-best.x86_64-latest.args    | 36 +++++++++++ > .../audio-pipewire-full.x86_64-latest.args    | 36 +++++++++++ > .../audio-pipewire-minimal.x86_64-latest.args | 36 +++++++++++ > tests/qemuxml2argvtest.c                      | 12 ++++ > 7 files changed, 184 insertions(+) > create mode 100644 > tests/qemuxml2argvdata/audio-pipewire-best.x86_64-latest.args > create mode 100644 > tests/qemuxml2argvdata/audio-pipewire-full.x86_64-latest.args > create mode 100644 > tests/qemuxml2argvdata/audio-pipewire-minimal.x86_64-latest.args > > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > index 3a08cac870..b31f4db6b1 100644 > --- a/src/qemu/qemu_command.c > +++ b/src/qemu/qemu_command.c > @@ -7783,6 +7783,60 @@ qemuBuildAudioSDLProps(virDomainAudioIOSDL *def, > } > > > +static int > +qemuBuildAudioPipewireAudioProps(virDomainAudioIOPipewireAudio *def, > +                                 virJSONValue **props) > +{ > +    return virJSONValueObjectAdd(props, > +                                 "S:name", def->name, > +                                 "S:stream-name", def->streamName, > +                                 "p:latency", def->latency, > +                                 NULL); > +} > + > + > +static void > +qemuBuildAudioPipewireAudioEnv(virCommand *cmd) > +{ > +    const char *envVars[] = { "PIPEWIRE_RUNTIME_DIR", "XDG_RUNTIME_DIR", > +                              "USERPROFILE" }; > +    size_t i; > + > +    /* PipeWire needs access to its daemon socket. The socket name is > +     * configurable (core.name in pipewire.conf, or PIPEWIRE_CORE and > +     * PIPEWIRE_REMOTE env vars). If the socket name is not an absolute > +     * path, then the socket is looked for in the following directories > +     * (in order): > +     * > +     * - PIPEWIRE_RUNTIME_DIR > +     * - XDG_RUNTIME_DIR > +     * - USERPROFILE > +     * > +     * This order is defined in get_runtime_dir() from > +     * src/modules/module-protocol-native/local-socket.c from PipeWire's > +     * codebase. > +     * > +     * Now, PIPEWIRE_CORE and/or PIPEWIRE_REMOTE should be passed > +     * whenever present in the environment. But for the other three > +     * (socket location dirs), we can add just the first existing one > +     * (basically mimic get_runtime_dir() logic). > +     */ > + > +    virCommandAddEnvPass(cmd, "PIPEWIRE_CORE"); > +    virCommandAddEnvPass(cmd, "PIPEWIRE_REMOTE"); > + > +    for (i = 0; i < G_N_ELEMENTS(envVars); i++) { > +        const char *value = getenv(envVars[i]); > + > +        if (!value) > +            continue; > + > +        virCommandAddEnvPair(cmd, envVars[i], value); > +        break; > +    } > +} > + > + > static int > qemuBuildAudioCommandLineArg(virCommand *cmd, >                              virDomainAudioDef *def) > @@ -7889,6 +7943,13 @@ qemuBuildAudioCommandLineArg(virCommand *cmd, >         break; > >     case VIR_DOMAIN_AUDIO_TYPE_PIPEWIRE: > +        if > (qemuBuildAudioPipewireAudioProps(&def->backend.pipewire.input, &in) < > 0 || > +            > qemuBuildAudioPipewireAudioProps(&def->backend.pipewire.output, &out) > < 0) > +            return -1; > + > +        qemuBuildAudioPipewireAudioEnv(cmd); > +        break; > + >     case VIR_DOMAIN_AUDIO_TYPE_LAST: >     default: >         virReportEnumRangeError(virDomainAudioType, def->type); > diff --git > a/tests/qemuxml2argvdata/audio-many-backends.x86_64-latest.args > b/tests/qemuxml2argvdata/audio-many-backends.x86_64-latest.args > index 9caf591daf..13dd55054e 100644 > --- a/tests/qemuxml2argvdata/audio-many-backends.x86_64-latest.args > +++ b/tests/qemuxml2argvdata/audio-many-backends.x86_64-latest.args > @@ -6,6 +6,7 @@ LOGNAME=test \ > XDG_DATA_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.local/share \ > XDG_CACHE_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.cache \ > XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \ > +XDG_RUNTIME_DIR=/bad-test-used-env-xdg-runtime-dir \ This should fail the test suite IIRC.