Commit Graph

104 Commits

Author SHA1 Message Date
Marc-André Lureau
910d50be6b
qlit: add qobject_from_qlit()
Instantiate a QObject* from a literal QLitObject.

LitObject only supports int64_t for now. uint64_t and double aren't
implemented.

Backports commit 3cf42b8b3af1bd61e736a9ca0f94806c7931ae56 from qemu
2018-03-20 10:30:41 -04:00
Marc-André Lureau
6b2143ad64
qlit: use QType instead of int
Backports commit 3d96ea44d4dde442094b7d9e5b71ef61b4c4ae39 from qemu
2018-03-20 10:28:12 -04:00
Kevin Wolf
025e354370
qdict: Introduce qdict_rename_keys()
A few block drivers will need to rename .bdrv_create options for their
QAPIfication, so let's have a helper function for that.

Backports commit bcebf102ccc3c6db327f341adc379fdf0673ca6b from qemu
2018-03-12 10:11:48 -04:00
Markus Armbruster
3277400723
qapi: Move qapi-schema.json to qapi/, rename generated files
Move qapi-schema.json to qapi/, so it's next to its modules, and all
files get generated to qapi/, not just the ones generated for modules.

Consistently name the generated files qapi-MODULE.EXT:
qmp-commands.[ch] become qapi-commands.[ch], qapi-event.[ch] become
qapi-events.[ch], and qmp-introspect.[ch] become qapi-introspect.[ch].
This gets rid of the temporary hacks in scripts/qapi/commands.py,
scripts/qapi/events.py, and scripts/qapi/common.py.

Backports commit eb815e248f50cde9ab86eddd57eca5019b71ca78 from qemu
2018-03-09 11:35:11 -05:00
Markus Armbruster
5500a5e912
Include less of the generated modular QAPI headers
In my "build everything" tree, a change to the types in
qapi-schema.json triggers a recompile of about 4800 out of 5100
objects.

The previous commit split up qmp-commands.h, qmp-event.h, qmp-visit.h,
qapi-types.h. Each of these headers still includes all its shards.
Reduce compile time by including just the shards we actually need.

To illustrate the benefits: adding a type to qapi/migration.json now
recompiles some 2300 instead of 4800 objects. The next commit will
improve it further.

Backports commit 9af2398977a78d37bf184d6ff6bd04c72bfbf006 from qemu
2018-03-09 10:06:19 -05:00
Markus Armbruster
1496dddeab
Include qapi/qmp/qlist.h exactly where needed
This cleanup makes the number of objects depending on qapi/qmp/qlist.h
drop from 4551 (out of 4743) to 16 in my "build everything" tree.

While there, separate #include from file comment with a blank line.

Backports commit 47e6b297e76007c04a1e9c492006fe093d932cd9 from qemu
2018-03-08 08:50:06 -05:00
Markus Armbruster
801dbfce3d
Include qapi/qmp/qobject.h exactly where needed
Backports commit 5ee9d2fe9e1e15d6e4a112220da3ad8a3512819b from qemu
2018-03-08 08:48:27 -05:00
Max Reitz
b98c4d24d1
qapi: Add qobject_is_equal()
This generic function (along with its implementations for different
types) determines whether two QObjects are equal.

Backports commit b38dd678a21582e03ecd2dec76ccf8290455628a from qemu
2018-03-08 08:41:43 -05:00
Max Reitz
e42e3307f7
qapi/qnull: Add own header
Backports commit 84be629d5545b5ccc5bff2824e4288677e27de9c from qemu
2018-03-08 08:35:23 -05:00
Markus Armbruster
f89de73110
qdict qlist: Make most helper macros functions
The macro expansions of qdict_put_TYPE() and qlist_append_TYPE() need
qbool.h, qnull.h, qnum.h and qstring.h to compile. We include qnull.h
and qnum.h in the headers, but not qbool.h and qstring.h. Works,
because we include those wherever the macros get used.

Open-coding these helpers is of dubious value. Turn them into
functions and drop the includes from the headers.

This cleanup makes the number of objects depending on qapi/qmp/qnum.h
from 4551 (out of 4743) to 46 in my "build everything" tree. For
qapi/qmp/qnull.h, the number drops from 4552 to 21.

Backports commit 15280c360e54a65e2c7be1a47bfbe41dce1ef986 from qemu
2018-03-08 08:30:10 -05:00
Marc-André Lureau
bc2ffe2a71
qlit: add QLIT_QNULL and QLIT_BOOL
As they are going to be used in the following patches.

Backports commit 6c6084c1b0802f5265d5c7dc27f7125d9fd1cceb from qemu
2018-03-07 17:18:56 -05:00
Marc-André Lureau
2833ad4f4c
qlit: make qlit_equal_qobject() take const arguments
Backports commit e2346a19521c6cce417250c75adb0b3a7cd5535a from qemu
2018-03-07 17:17:38 -05:00
Marc-André Lureau
966cac10a7
qlit: make qlit_equal_qobject return a bool
Make it more obvious about the expected return values.

Backports commit d9eba57a6ad6d8fe8cf11bdd8345bbda66deb6d9 from qemu
2018-03-07 17:16:34 -05:00
Marc-André Lureau
c51622c4ce
qlit: rename compare_litqobj_to_qobj() to qlit_equal_qobject()
compare_litqobj_to_qobj() lacks a qlit_ prefix. Moreover, "compare"
suggests -1, 0, +1 for less than, equal and greater than. The
function actually returns non-zero for equal, zero for unequal.
Rename to qlit_equal_qobject().

Its return type will be cleaned up in the next patch.

Backports commit 60cc2eb7afd40b9cbaa35a5e0b54f365ac6e49f1 from qemu
2018-03-07 17:14:55 -05:00
Marc-André Lureau
b462c3929f
qlit: Change compound literals to initializers
The QLIT_QFOO() macros expand into compound literals. Sadly, gcc
doesn't recognizes these as constant expressions (clang does), which
makes the macros useless for initializing objects with static storage
duration.

There is a gcc bug about it:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71713

Change the macros to expand into initializers.

Backports commit d5cd8fbf130312bea91823c41de87d55818d599b from qemu
2018-03-07 17:13:14 -05:00
Marc-André Lureau
a5d527ca72
qlit: use QLit prefix consistently
Rename from LiteralQ to QLit.

Backports commit 082696e767db4d2b6c8c8c233d28291b83fc2b21 from qemu
2018-03-07 17:10:26 -05:00
Marc-André Lureau
c85b87fe06
qlit: move qlit from check-qjson to qobject/
Fix code style issues while at it, to please checkpatch.

Backports commit 28035bcdf4647245743cf87cea3788331bf67a5f from qemu
2018-03-07 17:08:17 -05:00
Marc-André Lureau
101f763077
qdict: Add qdict_put_null() helper, and put it to use
Backports relevant parts of commit 0f9afc2a8b5e78e511d79c936aa7b36deb3508bf from qemu
2018-03-07 17:00:41 -05:00
Markus Armbruster
e1a055bd73
qobject: Explain how QNum works, and why
Backports commit f90cb2846a0b167d47131ba4600dcc816bccb1c6 from qemu
2018-03-07 16:58:46 -05:00
Markus Armbruster
615e361cf2
qapi: Introduce a first class 'null' type
I expect the 'null' type to be useful mostly for members of alternate
types.

Backports commit 4d2d5c41a9e8ee201cda8be8701f7f9fc92e71aa from qemu
2018-03-07 16:52:41 -05:00
Markus Armbruster
4a7abec7c9
qapi: Use QNull for a more regular visit_type_null()
Make visit_type_null() take an @obj argument like its buddies. This
helps keep the next commit simple.

Backports commit d2f95f4d482374485234790a6fc3cca29ebb7355 from qemu
2018-03-07 16:50:16 -05:00
Markus Armbruster
3fd0ff8aa7
qapi: Separate type QNull from QObject
Backports commit 006ca09f3027d86346fce707e9295975c6558f42 from qemu
2018-03-07 16:43:51 -05:00
Markus Armbruster
566b097b85
Eliminate qapi/qmp/types.h
qapi/qmp/types.h is a convenience header to include a number of
qapi/qmp/ headers. Since we rarely need all of the headers
qapi/qmp/types.h includes, we bypass it most of the time. Most of the
places that use it don't need all the headers, either.

Include the necessary headers directly, and drop qapi/qmp/types.h.

Backports commit 6b67395762a4c8b6ca94364e0a0f616a6470c46a from qemu
2018-03-07 12:39:23 -05:00
Markus Armbruster
bbc9bcbb44
Typedef the subtypes of QObject in qemu/typedefs.h, too
This renders many inclusions of qapi/qmp/q*.h superfluous. They'll be
dropped in the next few commits.

Backports commit 9f5c734d591e26186a71f9e36d752f4798df3672 from qemu
2018-03-07 12:29:31 -05:00
Marc-André Lureau
6ca6050206
qnum: add uint type
In order to store integer values between INT64_MAX and UINT64_MAX, add
a uint64_t internal representation.

Backports commit 61a8f418b26a2d974e38e4ae55020aca8d402d88 from qemu
2018-03-03 18:37:56 -05:00
Marc-André Lureau
a57d8a5b50
qapi: Remove visit_start_alternate() parameter promote_int
Before the previous commit, parameter promote_int = true made
visit_start_alternate() with an input visitor avoid QTYPE_QINT
variants and create QTYPE_QFLOAT variants instead. This was used
where QTYPE_QINT variants were invalid.

The previous commit fused QTYPE_QINT with QTYPE_QFLOAT, rendering
promote_int useless and unused.

Backports commit 60390d2dc85ffade8981ca41e02335cb07353a6d from qemu
2018-03-03 18:34:35 -05:00
Marc-André Lureau
dd77730d49
qapi: merge QInt and QFloat in QNum
We would like to use a same QObject type to represent numbers, whether
they are int, uint, or floats. Getters will allow some compatibility
between the various types if the number fits other representations.

Add a few more tests while at it.

Backports commit 01b2ffcedd94ad7b42bc870e4c6936c87ad03429 from qemu
2018-03-03 18:16:28 -05:00
Markus Armbruster
e9174563be
qapi: Document intended use of @name within alternate visits
Backports commit ed0ba0f47e8cb6d924db0a54090bbb7b095fe9ea from qemu
2018-03-03 17:37:12 -05:00
Markus Armbruster
5ab0d5af81
qapi: New QAPI_CLONE_MEMBERS()
QAPI_CLONE() returns a newly allocated QAPI object. Inconvenient when
we want to clone into an existing object. QAPI_CLONE_MEMBERS() does
exactly that.

Backports commit 4626a19c86c30d96cedbac2bd44ef8103303cb37 from qemu
2018-03-03 17:36:02 -05:00
Eric Blake
734778da93
qobject: Add helper macros for common scalar insertions
Rather than making lots of callers wrap a scalar in a QInt, QString,
or QBool, provide helper macros that do the wrapping automatically.

Update the Coccinelle script to make mass conversions easy, although
the conversion itself will be done as a separate patches to ease
review and backport efforts.

Backports commit a92c21591b5bb9543996538f14854ca6b528318b from qemu
2018-03-03 17:33:30 -05:00
Markus Armbruster
8a8dc93945
qapi: Improve qobject visitor documentation
Backports commit aa3a982e674b09ae32502940f93ba98b3a8ad50e from qemu
2018-03-02 12:24:21 -05:00
Markus Armbruster
ac1a61af47
qapi: Make input visitors detect unvisited list tails
Fix the design flaw demonstrated in the previous commit: new method
check_list() lets input visitors report that unvisited input remains
for a list, exactly like check_struct() lets them report that
unvisited input remains for a struct or union.

Implement the method for the qobject input visitor (straightforward),
and the string input visitor (less so, due to the magic list syntax
there). The opts visitor's list magic is even more impenetrable, and
all I can do there today is a stub with a FIXME comment. No worse
than before.

Backports commit a4a1c70dc759e5b81627e96564f344ab43ea86eb from qemu
2018-03-02 12:21:04 -05:00
Markus Armbruster
e0ee098c4a
qapi: Drop unused non-strict qobject input visitor
The split between tests/test-qobject-input-visitor.c and
tests/test-qobject-input-strict.c now makes less sense than ever. The
next commit will take care of that.

Backports commit 048abb7b20c9f822ad9d4b730bade73b3311a47a from qemu
2018-03-02 12:14:52 -05:00
Markus Armbruster
50e3cda49a
qapi: Drop string input visitor method optional()
visit_optional() is to be called only between visit_start_struct() and
visit_end_struct(). Visitors that don't support struct visits,
i.e. don't implement start_struct(), end_struct(), have no use for it.
Clarify documentation.

The string input visitor doesn't support struct visits. Its
parse_optional() is therefore useless. Drop it.

Backports commit a8aec6de2ac1a5e36989fdfba29067b361009b75 from qemu
2018-03-02 12:07:55 -05:00
Markus Armbruster
84e5261cdf
qapi: Improve qobject input visitor error reporting
Error messages refer to nodes of the QObject being visited by name.
Trouble is the names are sometimes less than helpful:

* The name of the root QObject is whatever @name argument got passed
to the visitor, except NULL gets mapped to "null". We commonly pass
NULL. Not good.

Avoiding errors "at the root" mitigates. For instance,
visit_start_struct() can only fail when the visited object is not a
dictionary, and we commonly ensure it is beforehand.

* The name of a QDict's member is the member key. Good enough only
when this happens to be unique.

* The name of a QList's member is "null". Not good.

Improve error messages by referring to nodes by path instead, as
follows:

* The path of the root QObject is whatever @name argument got passed
to the visitor, except NULL gets mapped to "<anonymous>".

* The path of a root QDict's member is the member key.

* The path of a root QList's member is "[%u]", where %u is the list
index, starting at zero.

* The path of a non-root QDict's member is the path of the QDict
concatenated with "." and the member key.

* The path of a non-root QList's member is the path of the QList
concatenated with "[%u]", where %u is the list index.

For example, the incorrect QMP command

{ "execute": "blockdev-add", "arguments": { "node-name": "foo", "driver": "raw", "file": {"driver": "file" } } }

now fails with

{"error": {"class": "GenericError", "desc": "Parameter 'file.filename' is missing"}}

instead of

{"error": {"class": "GenericError", "desc": "Parameter 'filename' is missing"}}

and

{ "execute": "input-send-event", "arguments": { "device": "bar", "events": [ [] ] } }

now fails with

{"error": {"class": "GenericError", "desc": "Invalid parameter type for 'events[0]', expected: object"}}

instead of

{"error": {"class": "GenericError", "desc": "Invalid parameter type for 'null', expected: QDict"}}

Aside: calling the thing "parameter" is suboptimal for QMP, because
the root object is "arguments" there.

The qobject output visitor doesn't have this problem because it should
not fail. Same for dealloc and clone visitors.

The string visitors don't have this problem because they visit just
one value, whose name needs to be passed to the visitor as @name. The
string output visitor shouldn't fail anyway.

The options visitor uses QemuOpts names. Their name space is flat, so
the use of QDict member keys as names is fine. NULL names used with
roots and lists could conceivably result in bad error messages. Left
for another day.

Backports commit a9fc37f6bc3f2ab90585cb16493da9f6dcfbfbcf from qemu
2018-03-02 12:05:53 -05:00
Markus Armbruster
d07bcef231
qmp: Eliminate silly QERR_QMP_* macros
The QERR_ macros are leftovers from the days of "rich" error objects.

QERR_QMP_BAD_INPUT_OBJECT, QERR_QMP_BAD_INPUT_OBJECT_MEMBER,
QERR_QMP_EXTRA_MEMBER are used in just one place now, except for one
use that has crept into qobject-input-visitor.c.

Drop these macros, to make the (bad) error messages more visible.

Backports commit 99fb0c53c038105bae68b02a3d9f1cbf7951ba10 from qemu
2018-03-02 11:28:17 -05:00
Sascha Silbe
11c66029b7
error: error_setg_errno(): errno gets preserved
C11 allows errno to be clobbered by pretty much any library function
call, so in general callers need to take care to save errno before
calling other functions.

However, for error reporting functions this is rather awkward and can
make the code on the caller side more complicated than
necessary. error_setg_errno() already takes care of preserving errno
and some functions rely on that, so just promise that we continue to
do so in the future.

Backports commit 98cb89af4df7e1776ce418ed6167b6e214a64435 from qemu
2018-03-01 23:38:25 -05:00
Daniel P. Berrange
83a5bf2d25
qapi: rename QmpOutputVisitor to QObjectOutputVisitor
The QmpOutputVisitor has no direct dependency on QMP. It is
valid to use it anywhere that one wants a QObject. Rename it
to better reflect its functionality as a generic QAPI
to QObject converter.

The commit before previous renamed the files, this one renames C
identifiers.

Backports commit 7d5e199ade76c53ec316ab6779800581bb47c50a from qemu
2018-02-27 08:05:33 -05:00
Daniel P. Berrange
2949a90977
qapi: rename QmpInputVisitor to QObjectInputVisitor
The QmpInputVisitor has no direct dependency on QMP. It is
valid to use it anywhere that one has a QObject. Rename it
to better reflect its functionality as a generic QObject
to QAPI converter.

The previous commit renamed the files, this one renames C identifiers.

Backports commit 09e68369a88d7de0f988972bf28eec1b80cc47f9 from qemu
2018-02-26 15:54:15 -05:00
Daniel P. Berrange
228f122248
qapi: rename *qmp-*-visitor* to *qobject-*-visitor*
The QMP visitors have no direct dependency on QMP. It is
valid to use them anywhere that one has a QObject. Rename them
to better reflect their functionality as a generic QObject
to QAPI converter.

This is the first of three parts: rename the files. The next two
parts will rename C identifiers. The split is necessary to make git
rename detection work.

Backports commit b3db211f3c80bb996a704d665fe275619f728bd4 from qemu
2018-02-26 15:42:37 -05:00
Markus Armbruster
9ae2fc4d9e
Clean up header guards that don't match their file name
Header guard symbols should match their file name to make guard
collisions less likely. Offenders found with
scripts/clean-header-guards.pl -vn.

Cleaned up with scripts/clean-header-guards.pl, followed by some
renaming of new guard symbols picked by the script to better ones.

Backports commit 121d07125bb6d7079c7ebafdd3efe8c3a01cc440 from qemu
2018-02-25 04:18:42 -05:00
Lioncash
532f840dc3
qapi: Add new clone visitor
We have a couple places in the code base that want to deep-clone
one QAPI object into another, and they were resorting to serializing
the struct out to QObject then reparsing it. A much more efficient
version can be done by adding a new clone visitor.

Since cloning is still relatively uncommon, expose the use of the
new visitor via a QAPI_CLONE() macro that takes care of type-punning
the underlying function pointer, rather than generating lots of
unused functions for types that won't be cloned. And yes, we're
relying on the compiler treating all pointers equally, even though
a strict C program cannot portably do so - but we're not the first
one in the qemu code base to expect it to work (hello, glib!).

The choice of adding a fourth visitor type deserves some explanation.
On the surface, the clone visitor is mostly an input visitor (it
takes arbitrary input - in this case, another QAPI object - and
creates a new QAPI object during the course of the visit). But
ever since commit da72ab0 consolidated enum visits based on the
visitor type, using VISITOR_INPUT would cause us to run
visit_type_str(), even though for cloning there is nothing to do
(we just copy the enum value across, without regards to its mapping
to strings). Also, since our input happens to be a QAPI object,
we can also satisfy the internal checks for VISITOR_OUTPUT. So in
the end, I settled with a new VISITOR_CLONE, and chose its value
such that many internal checks can use 'v->type & mask', sticking
to 'v->type == value' where the difference matters.

Note that we can only clone objects (including alternates) and lists,
not built-ins or enums. The visitor core hides integer width from
the actual visitor (since commit 04e070d), and as long as that's the
case, we can't clone top-level integers. Then again, those can
always be cloned by direct copy, since they are not objects with
deep pointers, so it's no real loss. And restricting cloning to
just objects and lists is cleaner than restricting it to non-integers.
As such, I documented that the clone visitor is for direct use only
by code internal to QAPI, and should not be used on incomplete objects
(other than a hack to work around the fact that we allow NULL in place
of "" in visit_type_str() in other output visitors). Note that as
written, the clone visitor will never fail on a complete object.

Scalars (including enums) not at the root of the clone copy just fine
with no additional effort while visiting the scalar, by virtue of a
g_memdup() each time we push another struct onto the stack. Cloning
a string requires deduplication of a pointer, which means it can also
provide the guarantee of an input visitor of never producing NULL
even when still accepting NULL in place of "" the way the QMP output
visitor does.

Cloning an 'any' type could be possible by incrementing the QObject
refcnt, but it's not obvious whether that is better than implementing
a QObject deep clone. So for now, we document it as unsupported,
and intentionally omit the .type_any() callback to let a developer
know their usage needs implementation.

Add testsuite coverage for several different clone situations, to
ensure that the code is working. I also tested that valgrind was
happy with the test.

Backports commit a15fcc3cf69ee3d408f60d6cc316488d2b0249b4 from qemu
2018-02-25 01:34:12 -05:00
Eric Blake
85af4b2030
qapi: Add new visit_complete() function
Making each output visitor provide its own output collection
function was the only remaining reason for exposing visitor
sub-types to the rest of the code base. Add a polymorphic
visit_complete() function which is a no-op for input visitors,
and which populates an opaque pointer for output visitors. For
maximum type-safety, also add a parameter to the output visitor
constructors with a type-correct version of the output pointer,
and assert that the two uses match.

This approach was considered superior to either passing the
output parameter only during construction (action at a distance
during visit_free() feels awkward) or only during visit_complete()
(defeating type safety makes it easier to use incorrectly).

Most callers were function-local, and therefore a mechanical
conversion; the testsuite was a bit trickier, but the previous
cleanup patch minimized the churn here.

The visit_complete() function may be called at most once; doing
so lets us use transfer semantics rather than duplication or
ref-count semantics to get the just-built output back to the
caller, even though it means our behavior is not idempotent.

Generated code is simplified as follows for events:

|@@ -26,7 +26,7 @@ void qapi_event_send_acpi_device_ost(ACP
| QDict *qmp;
| Error *err = NULL;
| QMPEventFuncEmit emit;
|- QmpOutputVisitor *qov;
|+ QObject *obj;
| Visitor *v;
| q_obj_ACPI_DEVICE_OST_arg param = {
| info
|@@ -39,8 +39,7 @@ void qapi_event_send_acpi_device_ost(ACP
|
| qmp = qmp_event_build_dict("ACPI_DEVICE_OST");
|
|- qov = qmp_output_visitor_new();
|- v = qmp_output_get_visitor(qov);
|+ v = qmp_output_visitor_new(&obj);
|
| visit_start_struct(v, "ACPI_DEVICE_OST", NULL, 0, &err);
| if (err) {
|@@ -55,7 +54,8 @@ void qapi_event_send_acpi_device_ost(ACP
| goto out;
| }
|
|- qdict_put_obj(qmp, "data", qmp_output_get_qobject(qov));
|+ visit_complete(v, &obj);
|+ qdict_put_obj(qmp, "data", obj);
| emit(QAPI_EVENT_ACPI_DEVICE_OST, qmp, &err);

and for commands:

| {
| Error *err = NULL;
|- QmpOutputVisitor *qov = qmp_output_visitor_new();
| Visitor *v;
|
|- v = qmp_output_get_visitor(qov);
|+ v = qmp_output_visitor_new(ret_out);
| visit_type_AddfdInfo(v, "unused", &ret_in, &err);
|- if (err) {
|- goto out;
|+ if (!err) {
|+ visit_complete(v, ret_out);
| }
|- *ret_out = qmp_output_get_qobject(qov);
|-
|-out:
| error_propagate(errp, err);

Backports commit 3b098d56979d2f7fd707c5be85555d114353a28d from qemu
2018-02-25 01:20:03 -05:00
Eric Blake
ec53301cda
qmp-output-visitor: Favor new visit_free() function
Now that we have a polymorphic visit_free(), we no longer need
qmp_output_visitor_cleanup(); however, we still need to
expose the subtype for qmp_output_get_qobject().

Backports commit 1830f22a6777cedaccd67a08f675d30f7a85ebfd from qemu
2018-02-25 01:12:27 -05:00
Eric Blake
f008d93ac0
qmp-input-visitor: Favor new visit_free() function
Now that we have a polymorphic visit_free(), we no longer need
qmp_input_visitor_cleanup(); which in turn means we no longer
need to return a subtype from qmp_input_visitor_new() nor a
public upcast function.

Generated code changes to qmp-marshal.c look like:

|@@ -52,11 +52,10 @@ void qmp_marshal_add_fd(QDict *args, QOb
| {
| Error *err = NULL;
| AddfdInfo *retval;
|- QmpInputVisitor *qiv = qmp_input_visitor_new(QOBJECT(args), true);
| Visitor *v;
| q_obj_add_fd_arg arg = {0};
|
|- v = qmp_input_get_visitor(qiv);
|+ v = qmp_input_visitor_new(QOBJECT(args), true);
| visit_start_struct(v, NULL, NULL, 0, &err);
| if (err) {
| goto out;

Backports commit b70ce1018a251c0c33498d9c927a07cade655a5e from qemu
2018-02-25 01:10:53 -05:00
Eric Blake
e88a7e260b
string-input-visitor: Favor new visit_free() function
Now that we have a polymorphic visit_free(), we no longer need
string_input_visitor_cleanup(); which in turn means we no longer
need to return a subtype from string_input_visitor_new() nor a
public upcast function.

Backports commit 7a0525c7be6b38d32d586e3fd12e7377ded21faa from qemu
2018-02-25 01:08:04 -05:00
Eric Blake
7f741a6c9b
qapi: Add new visit_free() function
Making each visitor provide its own (awkwardly-named) FOO_cleanup()
is unusual, when we can instead have a polymorphic visit_free()
interface. Over the next few patches, we can use the polymorphic
functions to eliminate the need for a FOO_get_visitor() function
for accessing specific visitor functionality, once everything can
be accessed directly through the Visitor* interfaces.

The dealloc visitor is the first one converted to completely use
the new entry point, since qapi_dealloc_visitor_cleanup() was the
only reason that qapi_dealloc_get_visitor() existed, and only
generated and testsuite code was even using it. With the new
visit_free() entry point in place, we no longer need to expose
the QapiDeallocVisitor subtype through qapi_dealloc_visitor_new(),
and can get by with less generated code, with diffs that look like:

| void qapi_free_ACPIOSTInfo(ACPIOSTInfo *obj)
| {
|- QapiDeallocVisitor *qdv;
| Visitor *v;
|
| if (!obj) {
| return;
| }
|
|- qdv = qapi_dealloc_visitor_new();
|- v = qapi_dealloc_get_visitor(qdv);
|+ v = qapi_dealloc_visitor_new();
| visit_type_ACPIOSTInfo(v, NULL, &obj, NULL);
|- qapi_dealloc_visitor_cleanup(qdv);
|+ visit_free(v);
|}

Backports commit 2c0ef9f411ae6081efa9eca5b3eab2dbeee45a6c from qemu
2018-02-25 01:05:41 -05:00
Eric Blake
37ae4dfdfd
qapi: Add parameter to visit_end_*
Rather than making the dealloc visitor track of stack of pointers
remembered during visit_start_* in order to free them during
visit_end_*, it's a lot easier to just make all callers pass the
same pointer to visit_end_*. The generated code has access to the
same pointer, while all other users are doing virtual walks and
can pass NULL. The dealloc visitor is then greatly simplified.

All three visit_end_*() functions intentionally take a void**,
even though the visit_start_*() functions differ between void**,
GenericList**, and GenericAlternate**. This is done for several
reasons: when doing a virtual walk, passing NULL doesn't care
what the type is, but when doing a generated walk, we already
have to cast the caller's specific FOO* to call visit_start,
while using void** lets us use visit_end without a cast. Also,
an upcoming patch will add a clone visitor that wants to use
the same implementation for all three visit_end callbacks,
which is made easier if all three share the same signature.

For visitors with already track per-object state (the QMP visitors
via a stack, and the string visitors which do not allow nesting),
add an assertion that the caller is indeed passing the same
pointer to paired calls.

Backports commit 1158bb2a058fcdd0c8fc3e60dc77f7a57ddbb271 from qemu
2018-02-25 00:57:54 -05:00
Eric Blake
2f42c2c195
qapi: Change visit_type_FOO() to no longer return partial objects
Returning a partial object on error is an invitation for a careless
caller to leak memory. We already fixed things in an earlier
patch to guarantee NULL if visit_start fails ("qapi: Guarantee
NULL obj on input visitor callback error"), but that does not
help the case where visit_start succeeds but some other failure
happens before visit_end, such that we leak a partially constructed
object outside visit_type_FOO(). As no one outside the testsuite
was actually relying on these semantics, it is cleaner to just
document and guarantee that ALL pointer-based visit_type_FOO()
functions always leave a safe value in *obj during an input visitor
(either the new object on success, or NULL if an error is
encountered), so callers can now unconditionally use
qapi_free_FOO() to clean up regardless of whether an error occurred.

The decision is done by adding visit_is_input(), then updating the
generated code to check if additional cleanup is needed based on
the type of visitor in use.

Note that we still leave *obj unchanged after a scalar-based
visit_type_FOO(); I did not feel like auditing all uses of
visit_type_Enum() to see if the callers would tolerate a specific
sentinel value (not to mention having to decide whether it would
be better to use 0 or ENUM__MAX as that sentinel).

Backports commit 68ab47e4b4ecc1c4649362b8cc1e49794d1a6537 from qemu
2018-02-23 19:53:17 -05:00
Eric Blake
0d52542da2
qapi: Simplify semantics of visit_next_list()
The semantics of the list visit are somewhat baroque, with the
following pseudocode when FooList is used:

start()
for (prev = head; cur = next(prev); prev = &cur) {
visit(&cur->value)
}

Note that these semantics (advance before visit) requires that
the first call to next() return the list head, while all other
calls return the next element of the list; that is, every visitor
implementation is required to track extra state to decide whether
to return the input as-is, or to advance. It also requires an
argument of 'GenericList **' to next(), solely because the first
iteration might need to modify the caller's GenericList head, so
that all other calls have to do a layer of dereferencing.

Thankfully, we only have two uses of list visits in the entire
code base: one in spapr_drc (which completely avoids
visit_next_list(), feeding in integers from a different source
than uint8List), and one in qapi-visit.py. That is, all other
list visitors are generated in qapi-visit.c, and share the same
paradigm based on a qapi FooList type, so we can refactor how
lists are laid out with minimal churn among clients.

We can greatly simplify things by hoisting the special case
into the start() routine, and flipping the order in the loop
to visit before advance:

start(head)
for (tail = *head; tail; tail = next(tail)) {
visit(&tail->value)
}

With the simpler semantics, visitors have less state to track,
the argument to next() is reduced to 'GenericList *', and it
also becomes obvious whether an input visitor is allocating a
FooList during visit_start_list() (rather than the old way of
not knowing if an allocation happened until the first
visit_next_list()). As a minor drawback, we now allocate in
two functions instead of one, and have to pass the size to
both functions (unless we were to tweak the input visitors to
cache the size to start_list for reuse during next_list, but
that defeats the goal of less visitor state).

The signature of visit_start_list() is chosen to match
visit_start_struct(), with the new parameters after 'name'.

The spapr_drc case is a virtual visit, done by passing NULL for
list, similarly to how NULL is passed to visit_start_struct()
when a qapi type is not used in those visits. It was easy to
provide these semantics for qmp-output and dealloc visitors,
and a bit harder for qmp-input (several prerequisite patches
refactored things to make this patch straightforward). But it
turned out that the string and opts visitors munge enough other
state during visit_next_list() to make it easier to just
document and require a GenericList visit for now; an assertion
will remind us to adjust things if we need the semantics in the
future.

Several pre-requisite cleanup patches made the reshuffling of
the various visitors easier; particularly the qmp input visitor.

Backports commit d9f62dde1303286b24ac8ce88be27e2b9b9c5f46 from qemu
2018-02-23 19:50:26 -05:00