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[Qemu-devel] [PATCH v15 02/23] qapi: Guarantee NULL obj on input visitor
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH v15 02/23] qapi: Guarantee NULL obj on input visitor callback error |
Date: |
Wed, 27 Apr 2016 18:01:34 -0600 |
Our existing input visitors were not very consistent on errors
in a function taking 'TYPE **obj' (that is, start_struct(),
start_alternate(), next_list(), type_str(), and type_any()).
While all of them set '*obj' to allocated storage on success,
it was not obvious whether '*obj' was guaranteed safe on failure,
or whether it was left uninitialized. But a future patch wants
to guarantee that visit_type_FOO() does not leak a partially-
constructed obj back to the caller; it is easier to implement
this if we can reliably state that '*obj' is assigned on exit,
even on failures. Add assertions to enforce it.
The opts-visitor start_struct() doesn't set an error, but it
also was doing a weird check for 0 size; all callers pass in
non-zero size if obj is non-NULL.
The testsuite has at least one spot where we no longer need
to pre-initialize a variable prior to a visit; valgrind confirms
that the test is still fine with the cleanup.
A later patch will document the design constraint implemented
here.
Signed-off-by: Eric Blake <address@hidden>
---
v15: enhance commit message, hoist assertions from later in series
v14: no change
v13: no change
v12: new patch
---
qapi/qapi-visit-core.c | 34 ++++++++++++++++++++++++++++++----
qapi/opts-visitor.c | 3 ++-
qapi/qmp-input-visitor.c | 4 ++++
qapi/string-input-visitor.c | 1 +
tests/test-qmp-input-strict.c | 2 +-
5 files changed, 38 insertions(+), 6 deletions(-)
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 3cd7edc..3a131ce 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -23,7 +23,13 @@
void visit_start_struct(Visitor *v, const char *name, void **obj,
size_t size, Error **errp)
{
- v->start_struct(v, name, obj, size, errp);
+ Error *err = NULL;
+
+ v->start_struct(v, name, obj, size, &err);
+ if (obj && v->type == VISITOR_INPUT) {
+ assert(err || *obj);
+ }
+ error_propagate(errp, err);
}
void visit_end_struct(Visitor *v, Error **errp)
@@ -51,9 +57,15 @@ void visit_start_alternate(Visitor *v, const char *name,
GenericAlternate **obj, size_t size,
bool promote_int, Error **errp)
{
+ Error *err = NULL;
+
assert(obj && size >= sizeof(GenericAlternate));
if (v->start_alternate) {
- v->start_alternate(v, name, obj, size, promote_int, errp);
+ v->start_alternate(v, name, obj, size, promote_int, &err);
+ if (v->type == VISITOR_INPUT) {
+ assert(err || *obj);
+ }
+ error_propagate(errp, err);
}
}
@@ -188,7 +200,14 @@ void visit_type_bool(Visitor *v, const char *name, bool
*obj, Error **errp)
void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
{
- v->type_str(v, name, obj, errp);
+ Error *err = NULL;
+
+ assert(obj);
+ v->type_str(v, name, obj, &err);
+ if (v->type == VISITOR_INPUT) {
+ assert(err || *obj);
+ }
+ error_propagate(errp, err);
}
void visit_type_number(Visitor *v, const char *name, double *obj,
@@ -199,7 +218,14 @@ void visit_type_number(Visitor *v, const char *name,
double *obj,
void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
{
- v->type_any(v, name, obj, errp);
+ Error *err = NULL;
+
+ assert(obj);
+ v->type_any(v, name, obj, &err);
+ if (v->type == VISITOR_INPUT) {
+ assert(err || *obj);
+ }
+ error_propagate(errp, err);
}
static void output_type_enum(Visitor *v, const char *name, int *obj,
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index 66aeaed..4cb6436 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -133,7 +133,7 @@ opts_start_struct(Visitor *v, const char *name, void **obj,
const QemuOpt *opt;
if (obj) {
- *obj = g_malloc0(size > 0 ? size : 1);
+ *obj = g_malloc0(size);
}
if (ov->depth++ > 0) {
return;
@@ -314,6 +314,7 @@ opts_type_str(Visitor *v, const char *name, char **obj,
Error **errp)
opt = lookup_scalar(ov, name, errp);
if (!opt) {
+ *obj = NULL;
return;
}
*obj = g_strdup(opt->str ? opt->str : "");
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 02d4233..77cce8b 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -120,6 +120,9 @@ static void qmp_input_start_struct(Visitor *v, const char
*name, void **obj,
QObject *qobj = qmp_input_get_object(qiv, name, true);
Error *err = NULL;
+ if (obj) {
+ *obj = NULL;
+ }
if (!qobj || qobject_type(qobj) != QTYPE_QDICT) {
error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
"QDict");
@@ -267,6 +270,7 @@ static void qmp_input_type_str(Visitor *v, const char
*name, char **obj,
QString *qstr = qobject_to_qstring(qmp_input_get_object(qiv, name, true));
if (!qstr) {
+ *obj = NULL;
error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
"string");
return;
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index d604575..797973a 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -293,6 +293,7 @@ static void parse_type_str(Visitor *v, const char *name,
char **obj,
if (siv->string) {
*obj = g_strdup(siv->string);
} else {
+ *obj = NULL;
error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
"string");
}
diff --git a/tests/test-qmp-input-strict.c b/tests/test-qmp-input-strict.c
index d71727e..d5f80ec 100644
--- a/tests/test-qmp-input-strict.c
+++ b/tests/test-qmp-input-strict.c
@@ -263,7 +263,7 @@ static void
test_validate_fail_union_flat_no_discrim(TestInputVisitorData *data,
static void test_validate_fail_alternate(TestInputVisitorData *data,
const void *unused)
{
- UserDefAlternate *tmp = NULL;
+ UserDefAlternate *tmp;
Visitor *v;
Error *err = NULL;
--
2.5.5
- [Qemu-devel] [PATCH v15 07/23] qapi-commands: Wrap argument visit in visit_start_struct, (continued)
- [Qemu-devel] [PATCH v15 07/23] qapi-commands: Wrap argument visit in visit_start_struct, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 03/23] qmp: Drop dead command->type, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 06/23] qmp-input: Don't consume input when checking has_member, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 09/23] qom: Wrap prop visit in visit_start_struct, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 04/23] qmp-input: Clean up stack handling, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 11/23] qmp-input: Refactor when list is advanced, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 13/23] tests: Add check-qnull, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 02/23] qapi: Guarantee NULL obj on input visitor callback error,
Eric Blake <=
- [Qemu-devel] [PATCH v15 02A/23] fixup! qapi: Guarantee NULL obj on input visitor callback error, Eric Blake, 2016/04/28
- [Qemu-devel] [PATCH v15 14/23] qapi: Add visit_type_null() visitor, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 05/23] qapi: Use strict QMP input visitor in more places, Eric Blake, 2016/04/27
- [Qemu-devel] [PATCH v15 08/23] monitor: Let generated code validate arguments, Eric Blake, 2016/04/27