Re: [Qemu-devel] [PATCH v2][ 10/21] qapi: add QMP input visiter

[Luiz Capitulino <lcapitulino@redhat.com>]

On Thu, 09 Jun 2011 10:41:53 -0500
Michael Roth <mdroth@linux.vnet.ibm.com> wrote:

> On 06/09/2011 10:30 AM, Luiz Capitulino wrote:
> > On Fri,  3 Jun 2011 17:33:08 -0500
> > Michael Roth<mdroth@linux.vnet.ibm.com>  wrote:
> >
> >> A type of Visiter class that is used to walk a qobject's
> >> structure and assign each entry to the corresponding native C type.
> >> Command marshaling function will use this to pull out QMP command
> >> parameters recieved over the wire and pass them as native arguments
> >> to the corresponding C functions.
> >>
> >> Signed-off-by: Michael Roth<mdroth@linux.vnet.ibm.com>
> >> ---
> >>   qapi/qmp-input-visiter.c |  239 ++++++++++++++++++++++++++++++++++++++++++++++
> >>   qapi/qmp-input-visiter.h |   26 +++++
> >>   2 files changed, 265 insertions(+), 0 deletions(-)
> >>   create mode 100644 qapi/qmp-input-visiter.c
> >>   create mode 100644 qapi/qmp-input-visiter.h
> >>
> >> diff --git a/qapi/qmp-input-visiter.c b/qapi/qmp-input-visiter.c
> >> new file mode 100644
> >> index 0000000..6767e39
> >> --- /dev/null
> >> +++ b/qapi/qmp-input-visiter.c
> >> @@ -0,0 +1,239 @@
> >> +#include "qmp-input-visiter.h"
> >> +#include "qemu-queue.h"
> >> +#include "qemu-common.h"
> >> +#include "qemu-objects.h"
> >> +#include "qerror.h"
> >> +
> >> +#define QAPI_OBJECT_SIZE 512
> >> +
> >> +#define QIV_STACK_SIZE 1024
> >> +
> >> +typedef struct StackObject
> >> +{
> >> +    QObject *obj;
> >> +    QListEntry *entry;
> >> +} StackObject;
> >> +
> >> +struct QmpInputVisiter
> >> +{
> >> +    Visiter visiter;
> >> +    QObject *obj;
> >> +    StackObject stack[QIV_STACK_SIZE];
> >> +    int nb_stack;
> >> +};
> >> +
> >> +static QmpInputVisiter *to_qiv(Visiter *v)
> >> +{
> >> +    return container_of(v, QmpInputVisiter, visiter);
> >> +}
> >> +
> >> +static QObject *qmp_input_get_object(QmpInputVisiter *qiv, const char *name)
> >> +{
> >> +    QObject *qobj;
> >> +
> >> +    if (qiv->nb_stack == 0) {
> >> +        qobj = qiv->obj;
> >> +    } else {
> >> +        qobj = qiv->stack[qiv->nb_stack - 1].obj;
> >> +    }
> >> +
> >> +    if (name&&  qobject_type(qobj) == QTYPE_QDICT) {
> >> +        return qdict_get(qobject_to_qdict(qobj), name);
> >> +    } else if (qiv->nb_stack>  0&&  qobject_type(qobj) == QTYPE_QLIST) {
> >> +        return qlist_entry_obj(qiv->stack[qiv->nb_stack - 1].entry);
> >> +    }
> >> +
> >> +    return qobj;
> >> +}
> >> +
> >> +static void qmp_input_push(QmpInputVisiter *qiv, QObject *obj)
> >> +{
> >> +    qiv->stack[qiv->nb_stack].obj = obj;
> >> +    if (qobject_type(obj) == QTYPE_QLIST) {
> >> +        qiv->stack[qiv->nb_stack].entry = qlist_first(qobject_to_qlist(obj));
> >> +    }
> >> +    qiv->nb_stack++;
> >> +
> >> +    assert(qiv->nb_stack<  QIV_STACK_SIZE); // FIXME
> >
> > Can't this limit be reached if a client sends a nested object? Why
> > don't we make it dynamic and/or return an error if a limit is reached?
> >
> 
> Yup, I think that's what the fixme was for. It's been fixed in my tree, 
> just sets an Error and returns instead now.
> 
> In reality the token limit added to the json parser with the set1 
> patches would catch overrun attempts from the client though, so it's 
> just an extra layer of protection.

Isn't this limit only in effect for individual tokens? Or does it also
catches the number of values in a dict?

> 
> >> +}
> >> +
> >> +static void qmp_input_pop(QmpInputVisiter *qiv)
> >> +{
> >> +    qiv->nb_stack--;
> >> +    assert(qiv->nb_stack>= 0); // FIXME
> >> +}
> >> +
> >> +static void qmp_input_start_struct(Visiter *v, void **obj, const char *kind, const char *name, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +    QObject *qobj = qmp_input_get_object(qiv, name);
> >> +
> >> +    if (!qobj || qobject_type(qobj) != QTYPE_QDICT) {
> >> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "object");
> >> +        return;
> >> +    }
> >> +
> >> +    qmp_input_push(qiv, qobj);
> >> +
> >> +    if (obj) {
> >> +        *obj = qemu_mallocz(QAPI_OBJECT_SIZE);
> >
> > I'm not sure I understand how this is being handled. This is allocating
> > the struct size, right? What happens if struct size>  QAPI_OBJECT_SIZE?
> >
> 
> Badness :) We'll need to pick a reasonable value and note it in the 
> schema documentation.

Isn't it possible to pass the struct size to visit_start_struct()? The
object itself is passed... Another (complex) solution would be to walk
through the dictionary's elements and calculate the struct size.

> 
> >> +    }
> >> +}
> >> +
> >> +static void qmp_input_end_struct(Visiter *v, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +
> >> +    qmp_input_pop(qiv);
> >> +}
> >> +
> >> +static void qmp_input_start_list(Visiter *v, const char *name, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +    QObject *qobj = qmp_input_get_object(qiv, name);
> >> +
> >> +    if (!qobj || qobject_type(qobj) != QTYPE_QLIST) {
> >> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "list");
> >> +        return;
> >> +    }
> >> +
> >> +    qmp_input_push(qiv, qobj);
> >> +}
> >> +
> >> +static GenericList *qmp_input_next_list(Visiter *v, GenericList **list, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +    GenericList *entry;
> >> +    StackObject *so =&qiv->stack[qiv->nb_stack - 1];
> >> +
> >> +    if (so->entry == NULL) {
> >> +        return NULL;
> >> +    }
> >> +
> >> +    entry = qemu_mallocz(sizeof(*entry));
> >> +    if (*list) {
> >> +        so->entry = qlist_next(so->entry);
> >> +        if (so->entry == NULL) {
> >> +            qemu_free(entry);
> >> +            return NULL;
> >> +        }
> >> +        (*list)->next = entry;
> >> +    }
> >> +    *list = entry;
> >> +
> >> +
> >> +    return entry;
> >> +}
> >> +
> >> +static void qmp_input_end_list(Visiter *v, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +
> >> +    qmp_input_pop(qiv);
> >> +}
> >> +
> >> +static void qmp_input_type_int(Visiter *v, int64_t *obj, const char *name, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +    QObject *qobj = qmp_input_get_object(qiv, name);
> >> +
> >> +    if (!qobj || qobject_type(qobj) != QTYPE_QINT) {
> >> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "integer");
> >> +        return;
> >> +    }
> >> +
> >> +    *obj = qint_get_int(qobject_to_qint(qobj));
> >> +}
> >> +
> >> +static void qmp_input_type_bool(Visiter *v, bool *obj, const char *name, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +    QObject *qobj = qmp_input_get_object(qiv, name);
> >> +
> >> +    if (!qobj || qobject_type(qobj) != QTYPE_QBOOL) {
> >> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "boolean");
> >> +        return;
> >> +    }
> >> +
> >> +    *obj = qbool_get_int(qobject_to_qbool(qobj));
> >> +}
> >> +
> >> +static void qmp_input_type_str(Visiter *v, char **obj, const char *name, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +    QObject *qobj = qmp_input_get_object(qiv, name);
> >> +
> >> +    if (!qobj || qobject_type(qobj) != QTYPE_QSTRING) {
> >> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "string");
> >> +        return;
> >> +    }
> >> +
> >> +    *obj = qemu_strdup(qstring_get_str(qobject_to_qstring(qobj)));
> >> +}
> >> +
> >> +static void qmp_input_type_number(Visiter *v, double *obj, const char *name, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +    QObject *qobj = qmp_input_get_object(qiv, name);
> >> +
> >> +    if (!qobj || qobject_type(qobj) != QTYPE_QFLOAT) {
> >> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "double");
> >> +        return;
> >> +    }
> >> +
> >> +    *obj = qfloat_get_double(qobject_to_qfloat(qobj));
> >> +}
> >> +
> >> +static void qmp_input_type_enum(Visiter *v, int *obj, const char *kind, const char *name, Error **errp)
> >> +{
> >> +    int64_t value;
> >> +    qmp_input_type_int(v,&value, name, errp);
> >> +    *obj = value;
> >> +}
> >> +
> >> +static void qmp_input_start_optional(Visiter *v, bool *present,
> >> +                                     const char *name, Error **errp)
> >> +{
> >> +    QmpInputVisiter *qiv = to_qiv(v);
> >> +    QObject *qobj = qmp_input_get_object(qiv, name);
> >> +
> >> +    if (!qobj) {
> >> +        *present = false;
> >> +        return;
> >> +    }
> >> +
> >> +    *present = true;
> >> +}
> >> +
> >> +static void qmp_input_end_optional(Visiter *v, Error **errp)
> >> +{
> >> +}
> >> +
> >> +Visiter *qmp_input_get_visiter(QmpInputVisiter *v)
> >> +{
> >> +    return&v->visiter;
> >> +}
> >> +
> >> +QmpInputVisiter *qmp_input_visiter_new(QObject *obj)
> >> +{
> >> +    QmpInputVisiter *v;
> >> +
> >> +    v = qemu_mallocz(sizeof(*v));
> >> +
> >> +    v->visiter.start_struct = qmp_input_start_struct;
> >> +    v->visiter.end_struct = qmp_input_end_struct;
> >> +    v->visiter.start_list = qmp_input_start_list;
> >> +    v->visiter.next_list = qmp_input_next_list;
> >> +    v->visiter.end_list = qmp_input_end_list;
> >> +    v->visiter.type_enum = qmp_input_type_enum;
> >> +    v->visiter.type_int = qmp_input_type_int;
> >> +    v->visiter.type_bool = qmp_input_type_bool;
> >> +    v->visiter.type_str = qmp_input_type_str;
> >> +    v->visiter.type_number = qmp_input_type_number;
> >> +    v->visiter.start_optional = qmp_input_start_optional;
> >> +    v->visiter.end_optional = qmp_input_end_optional;
> >> +
> >> +    v->obj = obj;
> >> +
> >> +    return v;
> >> +}
> >> diff --git a/qapi/qmp-input-visiter.h b/qapi/qmp-input-visiter.h
> >> new file mode 100644
> >> index 0000000..3e4d06f
> >> --- /dev/null
> >> +++ b/qapi/qmp-input-visiter.h
> >> @@ -0,0 +1,26 @@
> >> +/*
> >> + * Input Visiter
> >> + *
> >> + * Copyright IBM, Corp. 2011
> >> + *
> >> + * Authors:
> >> + *  Anthony Liguori<aliguori@us.ibm.com>
> >> + *
> >> + * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
> >> + * See the COPYING.LIB file in the top-level directory.
> >> + *
> >> + */
> >> +
> >> +#ifndef QMP_INPUT_VISITER_H
> >> +#define QMP_INPUT_VISITER_H
> >> +
> >> +#include "qapi-visit-core.h"
> >> +#include "qobject.h"
> >> +
> >> +typedef struct QmpInputVisiter QmpInputVisiter;
> >> +
> >> +QmpInputVisiter *qmp_input_visiter_new(QObject *obj);
> >> +
> >> +Visiter *qmp_input_get_visiter(QmpInputVisiter *v);
> >> +
> >> +#endif
> >
>