diff mbox

[v4,03/10] qemu-nbd: add support for --object command line arg

Message ID 1453815262-13440-4-git-send-email-berrange@redhat.com
State New
Headers show

Commit Message

Daniel P. Berrangé Jan. 26, 2016, 1:34 p.m. UTC 
Allow creation of user creatable object types with qemu-nbd
via a new --object command line arg. This will be used to supply
passwords and/or encryption keys to the various block driver
backends via the recently added 'secret' object type.

 # printf letmein > mypasswd.txt
 # qemu-nbd --object secret,id=sec0,file=mypasswd.txt \
      ...other nbd args...

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 qemu-nbd.c    | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qemu-nbd.texi |  6 ++++++
 2 files changed, 60 insertions(+)

Comments

Kevin Wolf Jan. 27, 2016, 1:57 p.m. UTC | #1 
Am 26.01.2016 um 14:34 hat Daniel P. Berrange geschrieben:
> Allow creation of user creatable object types with qemu-nbd
> via a new --object command line arg. This will be used to supply
> passwords and/or encryption keys to the various block driver
> backends via the recently added 'secret' object type.
> 
>  # printf letmein > mypasswd.txt
>  # qemu-nbd --object secret,id=sec0,file=mypasswd.txt \
>       ...other nbd args...
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
>  qemu-nbd.c    | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  qemu-nbd.texi |  6 ++++++
>  2 files changed, 60 insertions(+)
> 
> diff --git a/qemu-nbd.c b/qemu-nbd.c
> index ede4a54..8e5d36c 100644
> --- a/qemu-nbd.c
> +++ b/qemu-nbd.c
> @@ -23,9 +23,12 @@
>  #include "qemu/main-loop.h"
>  #include "qemu/sockets.h"
>  #include "qemu/error-report.h"
> +#include "qemu/config-file.h"
>  #include "block/snapshot.h"
>  #include "qapi/util.h"
>  #include "qapi/qmp/qstring.h"
> +#include "qapi/opts-visitor.h"
> +#include "qom/object_interfaces.h"
>  
>  #include <stdarg.h>
>  #include <stdio.h>
> @@ -44,6 +47,7 @@
>  #define QEMU_NBD_OPT_AIO           2
>  #define QEMU_NBD_OPT_DISCARD       3
>  #define QEMU_NBD_OPT_DETECT_ZEROES 4
> +#define QEMU_NBD_OPT_OBJECT        5
>  
>  static NBDExport *exp;
>  static int verbose;
> @@ -77,6 +81,9 @@ static void usage(const char *name)
>  "  -o, --offset=OFFSET       offset into the image\n"
>  "  -P, --partition=NUM       only expose partition NUM\n"
>  "\n"
> +"General purpose options:\n"
> +"  --object type,id=ID,...   define an object such as 'secret' for providing\n"
> +"                            passwords and/or encryption keys\n"
>  #ifdef __linux__
>  "Kernel NBD client support:\n"
>  "  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"
> @@ -374,6 +381,35 @@ static SocketAddress *nbd_build_socket_address(const char *sockpath,
>  }
>  
>  
> +static QemuOptsList qemu_object_opts = {
> +    .name = "object",
> +    .implied_opt_name = "qom-type",
> +    .head = QTAILQ_HEAD_INITIALIZER(qemu_object_opts.head),
> +    .desc = {
> +        { }
> +    },
> +};
> +
> +static int object_create(void *opaque, QemuOpts *opts, Error **errp)
> +{
> +    Error *err = NULL;
> +    OptsVisitor *ov;
> +    QDict *pdict;
> +
> +    ov = opts_visitor_new(opts);
> +    pdict = qemu_opts_to_qdict(opts, NULL);
> +
> +    user_creatable_add(pdict, opts_get_visitor(ov), &err);
> +    opts_visitor_cleanup(ov);
> +    QDECREF(pdict);
> +
> +    if (err) {
> +        error_propagate(errp, err);
> +        return -1;
> +    }
> +    return 0;
> +}

Hm... This looks very similar to the same function in qemu-img.c. And
actually, vl.c is a bit different, but not too much either. Wouldn't it
make sense to share this code?

Also, now that I compared this to vl.c, there seem to be two differences
compared to the tools: Support for filtering (the tools don't seem to
need this; passing NULL as the callback could skip it) and an additional
obj_unref(obj).

I don't understand much of QOM, so I don't know what the obj_unref() is
for, but I'm wondering whether we need to do the same in the tools. Can
you explain?

>  int main(int argc, char **argv)
>  {
>      BlockBackend *blk;
> @@ -411,6 +447,7 @@ int main(int argc, char **argv)
>          { "format", 1, NULL, 'f' },
>          { "persistent", 0, NULL, 't' },
>          { "verbose", 0, NULL, 'v' },
> +        { "object", 1, NULL, QEMU_NBD_OPT_OBJECT },
>          { NULL, 0, NULL, 0 }
>      };
>      int ch;
> @@ -428,6 +465,7 @@ int main(int argc, char **argv)
>      Error *local_err = NULL;
>      BlockdevDetectZeroesOptions detect_zeroes = BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF;
>      QDict *options = NULL;
> +    QemuOpts *opts;
>  
>      /* The client thread uses SIGTERM to interrupt the server.  A signal
>       * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
> @@ -436,6 +474,8 @@ int main(int argc, char **argv)
>      memset(&sa_sigterm, 0, sizeof(sa_sigterm));
>      sa_sigterm.sa_handler = termsig_handler;
>      sigaction(SIGTERM, &sa_sigterm, NULL);
> +    module_call_init(MODULE_INIT_QOM);
> +    qemu_add_opts(&qemu_object_opts);

Like in qemu-img, I'd prefer directly using the pointer.

Kevin
Daniel P. Berrangé Feb. 2, 2016, 11:40 a.m. UTC | #2 
On Wed, Jan 27, 2016 at 02:57:51PM +0100, Kevin Wolf wrote:
> Am 26.01.2016 um 14:34 hat Daniel P. Berrange geschrieben:
> > Allow creation of user creatable object types with qemu-nbd
> > via a new --object command line arg. This will be used to supply
> > passwords and/or encryption keys to the various block driver
> > backends via the recently added 'secret' object type.
> > 
> >  # printf letmein > mypasswd.txt
> >  # qemu-nbd --object secret,id=sec0,file=mypasswd.txt \
> >       ...other nbd args...
> > 
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> > ---
> >  qemu-nbd.c    | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  qemu-nbd.texi |  6 ++++++
> >  2 files changed, 60 insertions(+)
> > 
> > diff --git a/qemu-nbd.c b/qemu-nbd.c
> > index ede4a54..8e5d36c 100644
> > --- a/qemu-nbd.c
> > +++ b/qemu-nbd.c
> > @@ -23,9 +23,12 @@
> >  #include "qemu/main-loop.h"
> >  #include "qemu/sockets.h"
> >  #include "qemu/error-report.h"
> > +#include "qemu/config-file.h"
> >  #include "block/snapshot.h"
> >  #include "qapi/util.h"
> >  #include "qapi/qmp/qstring.h"
> > +#include "qapi/opts-visitor.h"
> > +#include "qom/object_interfaces.h"
> >  
> >  #include <stdarg.h>
> >  #include <stdio.h>
> > @@ -44,6 +47,7 @@
> >  #define QEMU_NBD_OPT_AIO           2
> >  #define QEMU_NBD_OPT_DISCARD       3
> >  #define QEMU_NBD_OPT_DETECT_ZEROES 4
> > +#define QEMU_NBD_OPT_OBJECT        5
> >  
> >  static NBDExport *exp;
> >  static int verbose;
> > @@ -77,6 +81,9 @@ static void usage(const char *name)
> >  "  -o, --offset=OFFSET       offset into the image\n"
> >  "  -P, --partition=NUM       only expose partition NUM\n"
> >  "\n"
> > +"General purpose options:\n"
> > +"  --object type,id=ID,...   define an object such as 'secret' for providing\n"
> > +"                            passwords and/or encryption keys\n"
> >  #ifdef __linux__
> >  "Kernel NBD client support:\n"
> >  "  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"
> > @@ -374,6 +381,35 @@ static SocketAddress *nbd_build_socket_address(const char *sockpath,
> >  }
> >  
> >  
> > +static QemuOptsList qemu_object_opts = {
> > +    .name = "object",
> > +    .implied_opt_name = "qom-type",
> > +    .head = QTAILQ_HEAD_INITIALIZER(qemu_object_opts.head),
> > +    .desc = {
> > +        { }
> > +    },
> > +};
> > +
> > +static int object_create(void *opaque, QemuOpts *opts, Error **errp)
> > +{
> > +    Error *err = NULL;
> > +    OptsVisitor *ov;
> > +    QDict *pdict;
> > +
> > +    ov = opts_visitor_new(opts);
> > +    pdict = qemu_opts_to_qdict(opts, NULL);
> > +
> > +    user_creatable_add(pdict, opts_get_visitor(ov), &err);
> > +    opts_visitor_cleanup(ov);
> > +    QDECREF(pdict);
> > +
> > +    if (err) {
> > +        error_propagate(errp, err);
> > +        return -1;
> > +    }
> > +    return 0;
> > +}
> 
> Hm... This looks very similar to the same function in qemu-img.c. And
> actually, vl.c is a bit different, but not too much either. Wouldn't it
> make sense to share this code?
> 
> Also, now that I compared this to vl.c, there seem to be two differences
> compared to the tools: Support for filtering (the tools don't seem to
> need this; passing NULL as the callback could skip it) and an additional
> obj_unref(obj).

Ok, I'll push more of this into qom/object_interfaces.c to allow
more sharing.

> I don't understand much of QOM, so I don't know what the obj_unref() is
> for, but I'm wondering whether we need to do the same in the tools. Can
> you explain?

Yes, we ought to have the obj_unref too from a technical correctness
POV, even though its harmless since we need the object around forever
anyway.

> > @@ -436,6 +474,8 @@ int main(int argc, char **argv)
> >      memset(&sa_sigterm, 0, sizeof(sa_sigterm));
> >      sa_sigterm.sa_handler = termsig_handler;
> >      sigaction(SIGTERM, &sa_sigterm, NULL);
> > +    module_call_init(MODULE_INIT_QOM);
> > +    qemu_add_opts(&qemu_object_opts);
> 
> Like in qemu-img, I'd prefer directly using the pointer.

Yes, will fix

Regards,
Daniel
diff mbox

Patch

diff --git a/qemu-nbd.c b/qemu-nbd.c
index ede4a54..8e5d36c 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -23,9 +23,12 @@ 
 #include "qemu/main-loop.h"
 #include "qemu/sockets.h"
 #include "qemu/error-report.h"
+#include "qemu/config-file.h"
 #include "block/snapshot.h"
 #include "qapi/util.h"
 #include "qapi/qmp/qstring.h"
+#include "qapi/opts-visitor.h"
+#include "qom/object_interfaces.h"
 
 #include <stdarg.h>
 #include <stdio.h>
@@ -44,6 +47,7 @@ 
 #define QEMU_NBD_OPT_AIO           2
 #define QEMU_NBD_OPT_DISCARD       3
 #define QEMU_NBD_OPT_DETECT_ZEROES 4
+#define QEMU_NBD_OPT_OBJECT        5
 
 static NBDExport *exp;
 static int verbose;
@@ -77,6 +81,9 @@  static void usage(const char *name)
 "  -o, --offset=OFFSET       offset into the image\n"
 "  -P, --partition=NUM       only expose partition NUM\n"
 "\n"
+"General purpose options:\n"
+"  --object type,id=ID,...   define an object such as 'secret' for providing\n"
+"                            passwords and/or encryption keys\n"
 #ifdef __linux__
 "Kernel NBD client support:\n"
 "  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"
@@ -374,6 +381,35 @@  static SocketAddress *nbd_build_socket_address(const char *sockpath,
 }
 
 
+static QemuOptsList qemu_object_opts = {
+    .name = "object",
+    .implied_opt_name = "qom-type",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_object_opts.head),
+    .desc = {
+        { }
+    },
+};
+
+static int object_create(void *opaque, QemuOpts *opts, Error **errp)
+{
+    Error *err = NULL;
+    OptsVisitor *ov;
+    QDict *pdict;
+
+    ov = opts_visitor_new(opts);
+    pdict = qemu_opts_to_qdict(opts, NULL);
+
+    user_creatable_add(pdict, opts_get_visitor(ov), &err);
+    opts_visitor_cleanup(ov);
+    QDECREF(pdict);
+
+    if (err) {
+        error_propagate(errp, err);
+        return -1;
+    }
+    return 0;
+}
+
 int main(int argc, char **argv)
 {
     BlockBackend *blk;
@@ -411,6 +447,7 @@  int main(int argc, char **argv)
         { "format", 1, NULL, 'f' },
         { "persistent", 0, NULL, 't' },
         { "verbose", 0, NULL, 'v' },
+        { "object", 1, NULL, QEMU_NBD_OPT_OBJECT },
         { NULL, 0, NULL, 0 }
     };
     int ch;
@@ -428,6 +465,7 @@  int main(int argc, char **argv)
     Error *local_err = NULL;
     BlockdevDetectZeroesOptions detect_zeroes = BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF;
     QDict *options = NULL;
+    QemuOpts *opts;
 
     /* The client thread uses SIGTERM to interrupt the server.  A signal
      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
@@ -436,6 +474,8 @@  int main(int argc, char **argv)
     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
     sa_sigterm.sa_handler = termsig_handler;
     sigaction(SIGTERM, &sa_sigterm, NULL);
+    module_call_init(MODULE_INIT_QOM);
+    qemu_add_opts(&qemu_object_opts);
     qemu_init_exec_dir(argv[0]);
 
     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
@@ -588,6 +628,13 @@  int main(int argc, char **argv)
             usage(argv[0]);
             exit(0);
             break;
+        case QEMU_NBD_OPT_OBJECT:
+            opts = qemu_opts_parse_noisily(qemu_find_opts("object"),
+                                           optarg, true);
+            if (!opts) {
+                exit(1);
+            }
+            break;
         case '?':
             error_report("Try `%s --help' for more information.", argv[0]);
             exit(EXIT_FAILURE);
@@ -600,6 +647,13 @@  int main(int argc, char **argv)
         exit(EXIT_FAILURE);
     }
 
+    if (qemu_opts_foreach(qemu_find_opts("object"),
+                          object_create,
+                          NULL, &local_err)) {
+        error_report_err(local_err);
+        exit(1);
+    }
+
     if (disconnect) {
         fd = open(argv[optind], O_RDWR);
         if (fd < 0) {
diff --git a/qemu-nbd.texi b/qemu-nbd.texi
index 46fd483..9f9daca 100644
--- a/qemu-nbd.texi
+++ b/qemu-nbd.texi
@@ -14,6 +14,12 @@  Export QEMU disk image using NBD protocol.
 @table @option
 @item @var{filename}
  is a disk image filename
+@item --object type,id=@var{id},...props...
+  define a new instance of the @var{type} object class identified by @var{id}.
+  See the @code{qemu(1)} manual page for full details of the properties
+  supported. The common object type that it makes sense to define is the
+  @code{secret} object, which is used to supply passwords and/or encryption
+  keys.
 @item -p, --port=@var{port}
   port to listen on (default @samp{10809})
 @item -o, --offset=@var{offset}