Re: [Qemu-devel] [RFC 3/3] virtiofsd: add virtiofsctl command-line management tool

[Stefan Hajnoczi]

On Fri, Sep 06, 2019 at 12:03:15AM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Thu, Sep 5, 2019 at 9:13 PM Dr. David Alan Gilbert
> <address@hidden> wrote:
> >
> > * Stefan Hajnoczi (address@hidden) wrote:
> > > virtiofsctl can control a running virtiofsd process:
> > >
> > >   usage: ./virtiofsctl COMMAND [args...]
> > >
> > >   Commands:
> > >     get-log-level       - show current log level
> > >     set-log-level LEVEL - set current log level to one of
> > >                           "err", "warning", "info", "debug"
> > >
> > > Make sure it is running in the same DBus session as virtiofsd.  This may
> > > require setting the DBUS_SESSION_BUS_ADDRESS environment variable to the
> > > same value as used by virtiofsd.
> > >
> > > Signed-off-by: Stefan Hajnoczi <address@hidden>
> > > ---
> > >  Makefile                        |  3 ++
> > >  Makefile.objs                   |  1 +
> > >  contrib/virtiofsd/Makefile.objs |  3 ++
> > >  contrib/virtiofsd/virtiofsctl.c | 55 +++++++++++++++++++++++++++++++++
> > >  4 files changed, 62 insertions(+)
> > >  create mode 100644 contrib/virtiofsd/virtiofsctl.c
> > >
> > > diff --git a/Makefile b/Makefile
> > > index 6b1af33348..d7ed9e7669 100644
> > > --- a/Makefile
> > > +++ b/Makefile
> > > @@ -419,6 +419,7 @@ dummy := $(call unnest-vars,, \
> > >                  ivshmem-client-obj-y \
> > >                  ivshmem-server-obj-y \
> > >                  virtiofsd-obj-y \
> > > +                virtiofsctl-obj-y \
> > >                  rdmacm-mux-obj-y \
> > >                  libvhost-user-obj-y \
> > >                  vhost-user-scsi-obj-y \
> > > @@ -661,6 +662,8 @@ contrib/virtiofsd/gdbus_generated.c-timestamp: 
> > > $(SRC_PATH)/contrib/virtiofsd/org
> > >
> > >  virtiofsd$(EXESUF): $(virtiofsd-obj-y) libvhost-user.a $(COMMON_LDADDS)
> > >       $(call LINK, $^)
> > > +virtiofsctl$(EXESUF): $(virtiofsctl-obj-y)
> > > +     $(call LINK, $^)
> > >  endif
> > >
> > >  vhost-user-gpu$(EXESUF): $(vhost-user-gpu-obj-y) $(libvhost-user-obj-y) 
> > > libqemuutil.a libqemustub.a
> > > diff --git a/Makefile.objs b/Makefile.objs
> > > index dfdd7d56ea..326a8abb8e 100644
> > > --- a/Makefile.objs
> > > +++ b/Makefile.objs
> > > @@ -126,6 +126,7 @@ rdmacm-mux-obj-y = contrib/rdmacm-mux/
> > >  vhost-user-input-obj-y = contrib/vhost-user-input/
> > >  vhost-user-gpu-obj-y = contrib/vhost-user-gpu/
> > >  virtiofsd-obj-y = contrib/virtiofsd/
> > > +virtiofsctl-obj-y = contrib/virtiofsd/
> > >
> > >  ######################################################################
> > >  trace-events-subdirs =
> > > diff --git a/contrib/virtiofsd/Makefile.objs 
> > > b/contrib/virtiofsd/Makefile.objs
> > > index d59ab60f3d..3f944d493e 100644
> > > --- a/contrib/virtiofsd/Makefile.objs
> > > +++ b/contrib/virtiofsd/Makefile.objs
> > > @@ -11,6 +11,9 @@ virtiofsd-obj-y = buffer.o \
> > >                    gdbus_generated.o \
> > >                    dbus.o
> > >
> > > +virtiofsctl-obj-y = virtiofsctl.o \
> > > +                    gdbus_generated.o
> > > +
> > >  seccomp.o-cflags := $(SECCOMP_CFLAGS)
> > >  seccomp.o-libs := $(SECCOMP_LIBS)
> > >
> > > diff --git a/contrib/virtiofsd/virtiofsctl.c 
> > > b/contrib/virtiofsd/virtiofsctl.c
> > > new file mode 100644
> > > index 0000000000..39bee2b881
> > > --- /dev/null
> > > +++ b/contrib/virtiofsd/virtiofsctl.c
> > > @@ -0,0 +1,55 @@
> > > +#include <stdio.h>
> > > +#include "gdbus_generated.h"
> > > +
> > > +static void get_log_level(Virtiofsd *virtiofsd)
> > > +{
> > > +    const char *value = virtiofsd_get_log_level(virtiofsd);
> > > +
> > > +    printf("%s\n", value ? value : "(null)");
> > > +}
> > > +
> > > +static void set_log_level(Virtiofsd *virtiofsd, const char *value)
> > > +{
> > > +    virtiofsd_set_log_level(virtiofsd, value);
> > > +}
> > > +
> > > +static void usage(const char *progname)
> > > +{
> > > +    printf("usage: %s COMMAND [args...]\n", progname);
> > > +    printf("\n");
> > > +    printf("Commands:\n");
> > > +    printf("  get-log-level       - show current log level\n");
> > > +    printf("  set-log-level LEVEL - set current log level to one of\n");
> > > +    printf("                        \"err\", \"warning\", \"info\", 
> > > \"debug\"\n");
> > > +    exit(0);
> > > +}
> > > +
> > > +int main(int argc, char **argv)
> > > +{
> > > +    Virtiofsd *virtiofsd;
> > > +    GError *error = NULL;
> > > +
> > > +    if (argc < 2) {
> > > +        usage(argv[0]);
> > > +    }
> > > +
> > > +    virtiofsd = virtiofsd_proxy_new_for_bus_sync(G_BUS_TYPE_SESSION,
> > > +            G_DBUS_PROXY_FLAGS_NONE, "org.qemu.virtiofsd",
> > > +            "/org/qemu/virtiofsd", NULL, &error);
> > > +    if (error) {
> > > +        fprintf(stderr, "%s\n", error->message);
> > > +        g_error_free(error);
> > > +        return 1;
> > > +    }
> > > +
> > > +    if (strcmp(argv[0], "get-log-level") == 0) {
> >
> > This and the one below works a lot better with argv[1] !
> >
> > (I wonder if a little python script would be better for these type of
> > wrappers).
> 
> Or just plain gdbus/busctl calls (which already has bash completion
> fwiw), and/or eventually a shell script.

A virtiofsctl program is useful because the sub-commands are easily
discoverable and no DBus knowledge is required.  Writing it in Python 3
would be nice.

Stefan

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