Re: [Qemu-devel] [PATCH v5 05/18] qapi: add QMP input visitor

[Michael Roth <mdroth@linux.vnet.ibm.com>]

On 07/07/2011 09:32 AM, Luiz Capitulino wrote:
> On Tue,  5 Jul 2011 08:02:32 -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>
>> ---
>>   Makefile.objs            |    2 +-
>>   qapi/qmp-input-visitor.c |  264 ++++++++++++++++++++++++++++++++++++++++++++++
>>   qapi/qmp-input-visitor.h |   27 +++++
>>   qerror.h                 |    3 +
>>   4 files changed, 295 insertions(+), 1 deletions(-)
>>   create mode 100644 qapi/qmp-input-visitor.c
>>   create mode 100644 qapi/qmp-input-visitor.h
>>
>> diff --git a/Makefile.objs b/Makefile.objs
>> index 0077014..997ecef 100644
>> --- a/Makefile.objs
>> +++ b/Makefile.objs
>> @@ -375,7 +375,7 @@ libcacard-y = cac.o event.o vcard.o vreader.o vcard_emul_nss.o vcard_emul_type.o
>>   ######################################################################
>>   # qapi
>>
>> -qapi-nested-y = qapi-visit-core.o
>> +qapi-nested-y = qapi-visit-core.o qmp-input-visitor.o
>>   qapi-obj-y = $(addprefix qapi/, $(qapi-nested-y))
>>
>>   vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
>> diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
>> new file mode 100644
>> index 0000000..80912bb
>> --- /dev/null
>> +++ b/qapi/qmp-input-visitor.c
>> @@ -0,0 +1,264 @@
>> +/*
>> + * Input Visitor
>> + *
>> + * 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.
>> + *
>> + */
>> +
>> +#include "qmp-input-visitor.h"
>> +#include "qemu-queue.h"
>> +#include "qemu-common.h"
>> +#include "qemu-objects.h"
>> +#include "qerror.h"
>> +
>> +#define QIV_STACK_SIZE 1024
>> +
>> +typedef struct StackObject
>> +{
>> +    const QObject *obj;
>> +    const  QListEntry *entry;
>> +} StackObject;
>> +
>> +struct QmpInputVisitor
>> +{
>> +    Visitor visitor;
>> +    const QObject *obj;
>> +    StackObject stack[QIV_STACK_SIZE];
>> +    int nb_stack;
>> +};
>> +
>> +static QmpInputVisitor *to_qiv(Visitor *v)
>> +{
>> +    return container_of(v, QmpInputVisitor, visitor);
>> +}
>> +
>> +static const QObject *qmp_input_get_object(QmpInputVisitor *qiv, const char *name)
>> +{
>> +    const 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(QmpInputVisitor *qiv, const QObject *obj, Error **errp)
>> +{
>> +    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++;
>> +
>> +    if (qiv->nb_stack>= QIV_STACK_SIZE) {
>> +        error_set(errp, QERR_BUFFER_OVERRUN);
>> +        return;
>> +    }
>> +}
>> +
>> +static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
>> +{
>> +    qiv->nb_stack--;
>> +    if (qiv->nb_stack<  0) {
>> +        error_set(errp, QERR_BUFFER_OVERRUN);
>> +        return;
>> +    }
>> +}
>> +
>> +static void qmp_input_start_struct(Visitor *v, void **obj, const char *kind, const char *name, size_t size, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
>> +
>> +    if (!qobj || qobject_type(qobj) != QTYPE_QDICT) {
>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null", "QDict");
>> +        return;
>> +    }
>> +
>> +    qmp_input_push(qiv, qobj, errp);
>> +    if (error_is_set(errp)) {
>> +        return;
>> +    }
>> +
>> +    if (obj) {
>> +        *obj = qemu_mallocz(size);
>> +    }
>> +}
>> +
>> +static void qmp_input_end_struct(Visitor *v, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +
>> +    qmp_input_pop(qiv, errp);
>> +}
>> +
>> +static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
>> +
>> +    if (!qobj || qobject_type(qobj) != QTYPE_QLIST) {
>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null", "list");
>> +        return;
>> +    }
>> +
>> +    qmp_input_push(qiv, qobj, errp);
>> +}
>> +
>> +static GenericList *qmp_input_next_list(Visitor *v, GenericList **list, Error **errp)
>> +{
>> +    QmpInputVisitor *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(Visitor *v, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +
>> +    qmp_input_pop(qiv, errp);
>> +}
>> +
>> +static void qmp_input_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
>> +
>> +    if (!qobj || qobject_type(qobj) != QTYPE_QINT) {
>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null", "integer");
>> +        return;
>> +    }
>> +
>> +    *obj = qint_get_int(qobject_to_qint(qobj));
>> +}
>> +
>> +static void qmp_input_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
>> +
>> +    if (!qobj || qobject_type(qobj) != QTYPE_QBOOL) {
>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null", "boolean");
>> +        return;
>> +    }
>> +
>> +    *obj = qbool_get_int(qobject_to_qbool(qobj));
>> +}
>> +
>> +static void qmp_input_type_str(Visitor *v, char **obj, const char *name, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
>> +
>> +    if (!qobj || qobject_type(qobj) != QTYPE_QSTRING) {
>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null", "string");
>> +        return;
>> +    }
>> +
>> +    *obj = qemu_strdup(qstring_get_str(qobject_to_qstring(qobj)));
>> +}
>> +
>> +static void qmp_input_type_number(Visitor *v, double *obj, const char *name, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
>> +
>> +    if (!qobj || qobject_type(qobj) != QTYPE_QFLOAT) {
>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null", "double");
>> +        return;
>> +    }
>> +
>> +    *obj = qfloat_get_double(qobject_to_qfloat(qobj));
>> +}
>> +
>> +static void qmp_input_type_enum(Visitor *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(Visitor *v, bool *present,
>> +                                     const char *name, Error **errp)
>> +{
>> +    QmpInputVisitor *qiv = to_qiv(v);
>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
>> +
>> +    if (!qobj) {
>> +        *present = false;
>> +        return;
>> +    }
>> +
>> +    *present = true;
>> +}
>> +
>> +static void qmp_input_end_optional(Visitor *v, Error **errp)
>> +{
>> +}
>> +
>> +Visitor *qmp_input_get_visitor(QmpInputVisitor *v)
>> +{
>> +    return&v->visitor;
>> +}
>> +
>> +void qmp_input_visitor_cleanup(QmpInputVisitor *v)
>> +{
>
> We talked about doing a qobject_incref(v->obj) in qmp_input_visitor_new() and
> decrefing here.
>

Sorry, remember the discussion but must've missed it when addressing 
comments. Will add it.

>> +    qemu_free(v);
>> +}
>> +
>> +QmpInputVisitor *qmp_input_visitor_new(const QObject *obj)
>> +{
>> +    QmpInputVisitor *v;
>> +
>> +    v = qemu_mallocz(sizeof(*v));
>> +
>> +    v->visitor.start_struct = qmp_input_start_struct;
>> +    v->visitor.end_struct = qmp_input_end_struct;
>> +    v->visitor.start_list = qmp_input_start_list;
>> +    v->visitor.next_list = qmp_input_next_list;
>> +    v->visitor.end_list = qmp_input_end_list;
>> +    v->visitor.type_enum = qmp_input_type_enum;
>> +    v->visitor.type_int = qmp_input_type_int;
>> +    v->visitor.type_bool = qmp_input_type_bool;
>> +    v->visitor.type_str = qmp_input_type_str;
>> +    v->visitor.type_number = qmp_input_type_number;
>> +    v->visitor.start_optional = qmp_input_start_optional;
>> +    v->visitor.end_optional = qmp_input_end_optional;
>> +
>> +    v->obj = obj;
>> +
>> +    return v;
>> +}
>> diff --git a/qapi/qmp-input-visitor.h b/qapi/qmp-input-visitor.h
>> new file mode 100644
>> index 0000000..0f77916
>> --- /dev/null
>> +++ b/qapi/qmp-input-visitor.h
>> @@ -0,0 +1,27 @@
>> +/*
>> + * Input Visitor
>> + *
>> + * 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_VISITOR_H
>> +#define QMP_INPUT_VISITOR_H
>> +
>> +#include "qapi-visit-core.h"
>> +#include "qobject.h"
>> +
>> +typedef struct QmpInputVisitor QmpInputVisitor;
>> +
>> +QmpInputVisitor *qmp_input_visitor_new(const QObject *obj);
>> +void qmp_input_visitor_cleanup(QmpInputVisitor *v);
>> +
>> +Visitor *qmp_input_get_visitor(QmpInputVisitor *v);
>> +
>> +#endif
>> diff --git a/qerror.h b/qerror.h
>> index 16c830d..9a9fa5b 100644
>> --- a/qerror.h
>> +++ b/qerror.h
>> @@ -124,6 +124,9 @@ QError *qobject_to_qerror(const QObject *obj);
>>   #define QERR_JSON_PARSE_ERROR \
>>       "{ 'class': 'JSONParseError', 'data': { 'message': %s } }"
>>
>> +#define QERR_BUFFER_OVERRUN \
>> +    "{ 'class': 'BufferOverrun', 'data': {} }"
>> +
>
> You also have to add an entry in qerror.c. I slightly prefer NotEnoughMemory,
> but BufferOverrrun is probably fine.
>

I like overrun since it doesn't suggest an issue with insufficient 
host/process/guest memory. Will add to qerror.c

>>   #define QERR_KVM_MISSING_CAP \
>>       "{ 'class': 'KVMMissingCap', 'data': { 'capability': %s, 'feature': %s } }"
>>
>