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2016-05-12qapi: Simplify semantics of visit_next_list()Eric Blake
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. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-24-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qapi: Split visit_end_struct() into piecesEric Blake
As mentioned in previous patches, we want to call visit_end_struct() functions unconditionally, so that visitors can release resources tied up since the matching visit_start_struct() without also having to worry about error priority if more than one error occurs. Even though error_propagate() can be safely used to ignore a second error during cleanup caused by a first error, it is simpler if the cleanup cannot set an error. So, split out the error checking portion (basically, input visitors checking for unvisited keys) into a new function visit_check_struct(), which can be safely skipped if any earlier errors are encountered, and leave the cleanup portion (which never fails, but must be called unconditionally if visit_start_struct() succeeded) in visit_end_struct(). Generated code in qapi-visit.c has diffs resembling: |@@ -59,10 +59,12 @@ void visit_type_ACPIOSTInfo(Visitor *v, | goto out_obj; | } | visit_type_ACPIOSTInfo_members(v, obj, &err); |- error_propagate(errp, err); |- err = NULL; |+ if (err) { |+ goto out_obj; |+ } |+ visit_check_struct(v, &err); | out_obj: |- visit_end_struct(v, &err); |+ visit_end_struct(v); | out: and in qapi-event.c: @@ -47,7 +47,10 @@ void qapi_event_send_acpi_device_ost(ACP | goto out; | } | visit_type_q_obj_ACPI_DEVICE_OST_arg_members(v, &param, &err); |- visit_end_struct(v, err ? NULL : &err); |+ if (!err) { |+ visit_check_struct(v, &err); |+ } |+ visit_end_struct(v); | if (err) { | goto out; Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-20-git-send-email-eblake@redhat.com> [Conflict with a doc fixup resolved] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qmp: Support explicit null during visitsEric Blake
Implement the new type_null() callback for the qmp input and output visitors. While we don't yet have a use for this in QAPI input (the generator will need some tweaks first), some potential usages have already been discussed on the list. Meanwhile, the output visitor could already output explicit null via type_any, but this gives us finer control. At any rate, it's easy to test that we can round-trip an explicit null through manual use of visit_type_null() wrapped by a virtual visit_start_struct() walk, even if we can't do the visit in a QAPI type. Repurpose the test_visitor_out_empty test, particularly since a future patch will tighten semantics to forbid use of qmp_output_get_qobject() without at least one intervening visit_type_*. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-16-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qapi: Add visit_type_null() visitorEric Blake
Right now, qmp-output-visitor happens to produce a QNull result if nothing is actually visited between the creation of the visitor and the request for the resulting QObject. A stronger protocol would require that a QMP output visit MUST visit something. But to still be able to produce a JSON 'null' output, we need a new visitor function that states our intentions. Yes, we could say that such a visit must go through visit_type_any(), but that feels clunky. So this patch introduces the new visit_type_null() interface and its no-op interface in the dealloc visitor, and stubs in the qmp visitors (the next patch will finish the implementation). For the visitors that will not implement the callback, document the situation. The code in qapi-visit-core unconditionally dereferences the callback pointer, so that a segfault will inform a developer if they need to implement the callback for their choice of visitor. Note that JSON has a primitive null type, with the single value null; likewise with the QNull type for QObject; but for QAPI, we just have the 'null' value without a null type. We may eventually want to add more support in QAPI for null (most likely, we'd use it via an alternate type that permits 'null' or an object); but we'll create that usage when we need it. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-15-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qmp-input: Refactor when list is advancedEric Blake
In the QMP input visitor, visiting a list traverses two objects: the QAPI GenericList of the caller (which gets advanced in visit_next_list() regardless of this patch), and the QList input that we are converting to QAPI. For consistency with QDict visits, we want to consume elements from the input QList during the visit_type_FOO() for the list element; that is, we want ALL the code for consuming an input to live in qmp_input_get_object(), rather than having it split according to whether we are visiting a dict or a list. Making qmp_input_get_object() the common point of consumption will make it easier for a later patch to refactor visit_start_list() to cover the GenericList * head of a QAPI list, and in turn will get rid of the 'first' flag (which lived in qmp_input_next_list() pre-patch, and is hoisted to StackObject by this patch). This patch is therefore altering the post-condition use of 'entry', while keeping what gets visited unchanged, from: start_list next_list type_ELT ... next_list type_ELT next_list end_list visits 1st elt last elt entry NULL 1st elt 1st elt last elt last elt NULL gone where type_ELT() returns (entry ? entry : 1st elt) and next_list() steps entry to this usage: start_list next_list type_ELT ... next_list type_ELT next_list end_list visits 1st elt last elt entry 1st elt 1nd elt 2nd elt last elt NULL NULL gone where type_ELT() steps entry and returns the old entry, and next_list() leaves entry alone. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-12-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qmp-input: Require struct push to visit members of top dictEric Blake
Don't embed the root of the visit into the stack of current containers being visited. That way, we no longer get confused on whether the first visit of a dictionary is to the dictionary itself or to one of the members of the dictionary, based on whether the caller passed name=NULL; and makes the QMP Input visitor like other visitors where the value of 'name' is now ignored on the root visit. (We may someday want to revisit the rules on what 'name' should be on a top-level visit, rather than just ignoring it; but that would be the topic of another patch). An audit of all qmp_input_visitor_new() call sites shows that there were only two places where callers had previously been visiting to a QDict with a non-NULL name to bypass a call to visit_start_struct(), and those were fixed in prior patches. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-11-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qmp-input: Don't consume input when checking has_memberEric Blake
Commit e8316d7 mistakenly passed consume=true within qmp_input_optional() when checking if an optional member was present, but the mistake was silently ignored since the code happily let us extract a member more than once. Fix qmp_input_optional() to not consume anything, then tighten up the input visitor to ensure that a member is consumed exactly once (all generated code follows this pattern; and the new assert will catch any hand-written code that tries to visit the same key more than once). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-8-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qapi: Consolidate QMP input visitor creationEric Blake
Rather than having two separate ways to create a QMP input visitor, where the safer approach has the more verbose name, it is better to consolidate things into a single function where the caller must explicitly choose whether to be strict or to ignore excess input. This patch is the strictly mechanical conversion; the next patch will then audit which uses can be made stricter. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-6-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qmp-input: Clean up stack handlingEric Blake
Management of the top of stack was a bit verbose; creating a temporary variable and adding some comments makes the existing code more legible before the next few patches improve things. No semantic changes other than asserting that we are always visiting a QObject, and not a NULL value. In particular, the check for 'name && qobject_type(qobj) == QTYPE_QDICT)' is a bit overkill (a dict visit should always have a name); a later patch revisits that, while this patch is only changing one layer of indentation due to dropping 'if (qobj)'. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-5-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qapi: Guarantee NULL obj on input visitor callback errorEric Blake
Our existing input visitors were not very consistent on errors in a function taking 'TYPE **obj'. These are start_struct(), start_alternate(), type_str(), and type_any(). next_list() is similar, but can't fail (see commit 08f9541). 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 input visitors assign '*obj' regardless of success or failure, and that on failure *obj is NULL. Add assertions to enforce consistency in the final setting of err vs. *obj. 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 <eblake@redhat.com> Message-Id: <1461879932-9020-3-git-send-email-eblake@redhat.com> [visit_start_alternate()'s assertion tightened, commit message tweaked] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12qapi-visit: Add visitor.type classificationEric Blake
We have three classes of QAPI visitors: input, output, and dealloc. Currently, all implementations of these visitors have one thing in common based on their visitor type: the implementation used for the visit_type_enum() callback. But since we plan to add more such common behavior, in relation to documenting and further refining the semantics, it makes more sense to have the visitor implementations advertise which class they belong to, so the common qapi-visit-core code can use that information in multiple places. A later patch will better document the types of visitors directly in visitor.h. For this patch, knowing the class of a visitor implementation lets us make input_type_enum() and output_type_enum() become static functions, by replacing the callback function Visitor.type_enum() with the simpler enum member Visitor.type. Share a common assertion in qapi-visit-core as part of the refactoring. Move comments in opts-visitor.c to match the refactored layout. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-2-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-03-22include/qemu/osdep.h: Don't include qapi/error.hMarkus Armbruster
Commit 57cb38b included qapi/error.h into qemu/osdep.h to get the Error typedef. Since then, we've moved to include qemu/osdep.h everywhere. Its file comment explains: "To avoid getting into possible circular include dependencies, this file should not include any other QEMU headers, with the exceptions of config-host.h, compiler.h, os-posix.h and os-win32.h, all of which are doing a similar job to this file and are under similar constraints." qapi/error.h doesn't do a similar job, and it doesn't adhere to similar constraints: it includes qapi-types.h. That's in excess of 100KiB of crap most .c files don't actually need. Add the typedef to qemu/typedefs.h, and include that instead of qapi/error.h. Include qapi/error.h in .c files that need it and don't get it now. Include qapi-types.h in qom/object.h for uint16List. Update scripts/clean-includes accordingly. Update it further to match reality: replace config.h by config-target.h, add sysemu/os-posix.h, sysemu/os-win32.h. Update the list of includes in the qemu/osdep.h comment quoted above similarly. This reduces the number of objects depending on qapi/error.h from "all of them" to less than a third. Unfortunately, the number depending on qapi-types.h shrinks only a little. More work is needed for that one. Signed-off-by: Markus Armbruster <armbru@redhat.com> [Fix compilation without the spice devel packages. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-19qapi: Change visit_start_implicit_struct to visit_start_alternateEric Blake
After recent changes, the only remaining use of visit_start_implicit_struct() is for allocating the space needed when visiting an alternate. Since the term 'implicit struct' is hard to explain, rename the function to its current usage. While at it, we can merge the functionality of visit_get_next_type() into the same function, making it more like visit_start_struct(). Generated code is now slightly smaller: | { | Error *err = NULL; | |- visit_start_implicit_struct(v, (void**) obj, sizeof(BlockdevRef), &err); |+ visit_start_alternate(v, name, (GenericAlternate **)obj, sizeof(**obj), |+ true, &err); | if (err) { | goto out; | } |- visit_get_next_type(v, name, &(*obj)->type, true, &err); |- if (err) { |- goto out_obj; |- } | switch ((*obj)->type) { | case QTYPE_QDICT: | visit_start_struct(v, name, NULL, 0, &err); ... | } |-out_obj: |- visit_end_implicit_struct(v); |+ visit_end_alternate(v); | out: | error_propagate(errp, err); | } Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1455778109-6278-16-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-19qapi: Adjust layout of FooList typesEric Blake
By sticking the next pointer first, we don't need a union with 64-bit padding for smaller types. On 32-bit platforms, this can reduce the size of uint8List from 16 bytes (or 12, depending on whether 64-bit ints can tolerate 4-byte alignment) down to 8. It has no effect on 64-bit platforms (where alignment still dictates a 16-byte struct); but fewer anonymous unions is still a win in my book. It requires visit_next_list() to gain a size parameter, to know what size element to allocate; comparable to the size parameter of visit_start_struct(). I debated about going one step further, to allow for fewer casts, by doing: typedef GenericList GenericList; struct GenericList { GenericList *next; }; struct FooList { GenericList base; Foo *value; }; so that you convert to 'GenericList *' by '&foolist->base', and back by 'container_of(generic, GenericList, base)' (as opposed to the existing '(GenericList *)foolist' and '(FooList *)generic'). But doing that would require hoisting the declaration of GenericList prior to inclusion of qapi-types.h, rather than its current spot in visitor.h; it also makes iteration a bit more verbose through 'foolist->base.next' instead of 'foolist->next'. Note that for lists of objects, the 'value' payload is still hidden behind a boxed pointer. Someday, it would be nice to do: struct FooList { FooList *next; Foo value; }; for one less level of malloc for each list element. This patch is a step in that direction (now that 'next' is no longer at a fixed non-zero offset within the struct, we can store more than just a pointer's-worth of data as the value payload), but the actual conversion would be a task for another series, as it will touch a lot of code. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1455778109-6278-10-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-19qapi: Simplify excess input reporting in input visitorsEric Blake
When reporting that an unvisited member remains at the end of an input visit for a struct, we were using g_hash_table_find() coupled with a callback function that always returns true, to locate an arbitrary member of the hash table. But if all we need is an arbitrary entry, we can get that from a single-use iterator, without needing a tautological callback function. Technically, our cast of &(GQueue *) to (void **) is not strict C (while void * must be able to hold all other pointers, nothing says a void ** has to be the same width or representation as a GQueue **). The kosher way to write it would be the verbose: void *tmp; GQueue *any; if (g_hash_table_iter_next(&iter, NULL, &tmp)) { any = tmp; But our code base (not to mention glib itself) already has other cases of assuming that ALL pointers have the same width and representation, where a compiler would have to go out of its way to mis-compile our borderline behavior. Suggested-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <1455778109-6278-2-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-08qapi: Drop unused error argument for list and implicit structEric Blake
No backend was setting an error when ending the visit of a list or implicit struct, or when moving to the next list node. Make the callers a bit easier to follow by making this a part of the contract, and removing the errp argument - callers can then unconditionally end an object as part of cleanup without having to think about whether a second error is dominated by a first, because there is no second error. A later patch will then tackle the larger task of splitting visit_end_struct(), which can indeed set an error. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1454075341-13658-24-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-08qapi: Tighten qmp_input_end_list()Eric Blake
The only way that qmp_input_pop() will set errp is if a dictionary was the most recent thing pushed. Since we don't have any push(struct)/pop(list) or push(list)/pop(struct) mismatches (such a mismatch is a programming bug), we therefore cannot set errp inside qmp_input_end_list(). Make this obvious by using &error_abort. A later patch will then remove the errp parameter of qmp_input_pop(), but that will first require the larger task of splitting visit_end_struct(). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1454075341-13658-23-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-08qapi: Drop unused 'kind' for struct/enum visitEric Blake
visit_start_struct() and visit_type_enum() had a 'kind' argument that was usually set to either the stringized version of the corresponding qapi type name, or to NULL (although some clients didn't even get that right). But nothing ever used the argument. It's even hard to argue that it would be useful in a debugger, as a stack backtrace also tells which type is being visited. Therefore, drop the 'kind' argument as dead. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <1454075341-13658-22-git-send-email-eblake@redhat.com> [Harmless rebase mistake cleaned up] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-08qapi: Swap 'name' in visit_* callbacks to match public APIEric Blake
As explained in the previous patches, matching argument order of 'name, &value' to JSON's "name":value makes sense. However, while the last two patches were easy with Coccinelle, I ended up doing this one all by hand. Now all the visitor callbacks match the main interface. The compiler is able to enforce that all clients match the changed interface in visitor-impl.h, even where two pointers are being swapped, because only one of the two pointers is const (if that were not the case, then C's looseness on treating 'char *' like 'void *' would have made review a bit harder). Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <1454075341-13658-21-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-08qapi: Make all visitors supply uint64 callbacksEric Blake
Our qapi visitor contract supports multiple integer visitors, but left the type_uint64 visitor as optional (falling back on type_int64); which in turn can lead to awkward behavior with numbers larger than INT64_MAX (the user has to be aware of twos complement, and deal with negatives). This patch does not address the disparity in handling large values as negatives. It merely moves the fallback from uint64 to int64 from the visitor core to the visitors, where the issue can actually be fixed, by implementing the missing type_uint64() callbacks on top of the respective type_int64() callbacks, and with a FIXME comment explaining why that's wrong. With that done, we now have a type_uint64() callback in every driver, so we can make it mandatory from the core. And although the type_int64() callback can cover the entire valid range of type_uint{8,16,32} on valid user input, using type_uint64() to avoid mixed signedness makes more sense. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1454075341-13658-15-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-08qapi: Prefer type_int64 over type_int in visitorsEric Blake
The qapi builtin type 'int' is basically shorthand for the type 'int64'. In fact, since no visitor was providing the optional type_int64() callback, visit_type_int64() was just always falling back to type_int(), cementing the equivalence between the types. However, some visitors are providing a type_uint64() callback. For purposes of code consistency, it is nicer if all visitors use the paired type_int64/type_uint64 names rather than the mismatched type_int/type_uint64. So this patch just renames the signed int callbacks in place, dropping the type_int() callback as redundant, and a later patch will focus on the unsigned int callbacks. Add some FIXMEs to questionable reuse of errp in code touched by the rename, while at it (the reuse works as long as the callbacks don't modify value when setting an error, but it's not a good example to set) - a later patch will then fix those. No change in functionality here, although further cleanups are in the pipeline. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1454075341-13658-14-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-04qapi: Clean up includesPeter Maydell
Clean up includes so that osdep.h is included first and headers which it implies are not included manually. This commit was created with scripts/clean-includes. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Eric Blake <eblake@redhat.com> Message-id: 1454089805-5470-8-git-send-email-peter.maydell@linaro.org
2015-12-17qapi: Simplify visits of optional fieldsEric Blake
None of the visitor callbacks would set an error when testing if an optional field was present; make this part of the interface contract by eliminating the errp argument. The resulting generated code has a nice diff: |- visit_optional(v, &has_fdset_id, "fdset-id", &err); |- if (err) { |- goto out; |- } |+ visit_optional(v, &has_fdset_id, "fdset-id"); | if (has_fdset_id) { | visit_type_int(v, &fdset_id, "fdset-id", &err); | if (err) { | goto out; | } | } Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1449033659-25497-9-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Fix alternates that accept 'number' but not 'int'Eric Blake
The QMP input visitor allows integral values to be assigned by promotion to a QTYPE_QFLOAT. However, when parsing an alternate, we did not take this into account, such that an alternate that accepts 'number' and some other type, but not 'int', would reject integral values. With this patch, we now have the following desirable table: alternate has case selected for 'int' 'number' QTYPE_QINT QTYPE_QFLOAT no no error error no yes 'number' 'number' yes no 'int' error yes yes 'int' 'number' While it is unlikely that we will ever use 'number' in an alternate other than in the testsuite, it never hurts to be more precise in what we allow. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1449033659-25497-8-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Simplify visiting of alternate typesEric Blake
Previously, working with alternates required two lookup arrays and some indirection: for type Foo, we created Foo_qtypes[] which maps each qtype to a value of the generated FooKind enum, then look up that value in FooKind_lookup[] like we do for other union types. This has a couple of subtle bugs. First, the generator was creating a call with a parameter '(int *) &(*obj)->type' where type is an enum type; this is unsafe if the compiler chooses to store the enum type in a different size than int, where assigning through the wrong size pointer can corrupt data or cause a SIGBUS. Related bug, not not fixed in this patch: qapi-visit.py's gen_visit_enum() generates a cast of its enum * argument to int *. Marked FIXME. Second, since the values of the FooKind enum start at zero, all entries of the Foo_qtypes[] array that were not explicitly initialized will map to the same branch of the union as the first member of the alternate, rather than triggering a desired failure in visit_get_next_type(). Fortunately, the bug seldom bites; the very next thing the input visitor does is try to parse the incoming JSON with the wrong parser, which normally fails; the output visitor is not used with a C struct in that state, and the dealloc visitor has nothing to clean up (so there is no leak). However, the second bug IS observable in one case: parsing an integer causes unusual behavior in an alternate that contains at least a 'number' member but no 'int' member, because the 'number' parser accepts QTYPE_QINT in addition to the expected QTYPE_QFLOAT (that is, since 'int' is not a member, the type QTYPE_QINT accidentally maps to FooKind 0; if this enum value is the 'number' branch the integer parses successfully, but if the 'number' branch is not first, some other branch tries to parse the integer and rejects it). A later patch will worry about fixing alternates to always parse all inputs that a non-alternate 'number' would accept, for now this is still marked FIXME in the updated test-qmp-input-visitor.c, to merely point out that new undesired behavior of 'ans' matches the existing undesired behavior of 'asn'. This patch fixes the default-initialization bug by deleting the indirection, and modifying get_next_type() to directly assign a QTypeCode parameter. This in turn fixes the type-casting bug, as we are no longer casting a pointer to enum to a questionable size. There is no longer a need to generate an implicit FooKind enum associated with the alternate type (since the QMP wire format never uses the stringized counterparts of the C union member names). Since the updated visit_get_next_type() does not know which qtypes are expected, the generated visitor is modified to generate an error statement if an unexpected type is encountered. Callers now have to know the QTYPE_* mapping when looking at the discriminator; but so far, only the testsuite was even using the C struct of an alternate types. I considered the possibility of keeping the internal enum FooKind, but initialized differently than most generated arrays, as in: typedef enum FooKind { FOO_KIND_A = QTYPE_QDICT, FOO_KIND_B = QTYPE_QINT, } FooKind; to create nicer aliases for knowing when to use foo->a or foo->b when inspecting foo->type; but it turned out to add too much complexity, especially without a client. There is a user-visible side effect to this change, but I consider it to be an improvement. Previously, the invalid QMP command: {"execute":"blockdev-add", "arguments":{"options": {"driver":"raw", "id":"a", "file":true}}} failed with: {"error": {"class": "GenericError", "desc": "Invalid parameter type for 'file', expected: QDict"}} (visit_get_next_type() succeeded, and the error comes from the visit_type_BlockdevOptions() expecting {}; there is no mention of the fact that a string would also work). Now it fails with: {"error": {"class": "GenericError", "desc": "Invalid parameter type for 'file', expected: BlockdevRef"}} (the error when the next type doesn't match any expected types for the overall alternate). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1449033659-25497-5-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-29qstring: Make conversion from QObject * accept nullMarkus Armbruster
qobject_to_qstring() crashes on null, which is a trap for the unwary. Return null instead, and simplify a few callers. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <1444918537-18107-7-git-send-email-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
2015-10-29qfloat qint: Make conversion from QObject * accept nullMarkus Armbruster
qobject_to_qfloat() and qobject_to_qint() crash on null, which is a trap for the unwary. Return null instead, and simplify a few callers. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <1444918537-18107-5-git-send-email-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
2015-10-29qbool: Make conversion from QObject * accept nullMarkus Armbruster
qobject_to_qbool() crashes on null, which is a trap for the unwary. Return null instead, and simplify a few callers. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <1444918537-18107-3-git-send-email-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
2015-09-21qapi: Introduce a first class 'any' typeMarkus Armbruster
It's first class, because unlike '**', it actually works, i.e. doesn't require 'gen': false. '**' will go away next. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
2015-06-22qerror: Clean up QERR_ macros to expand into a single stringMarkus Armbruster
These macros expand into error class enumeration constant, comma, string. Unclean. Has been that way since commit 13f59ae. The error class is always ERROR_CLASS_GENERIC_ERROR since the previous commit. Clean up as follows: * Prepend every use of a QERR_ macro by ERROR_CLASS_GENERIC_ERROR, and delete it from the QERR_ macro. No change after preprocessing. * Rewrite error_set(ERROR_CLASS_GENERIC_ERROR, ...) into error_setg(...). Again, no change after preprocessing. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
2015-06-22qobject: Use 'bool' for qboolEric Blake
We require a C99 compiler, so let's use 'bool' instead of 'int' when dealing with boolean values. There are few enough clients to fix them all in one pass. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Andreas Färber <afaerber@suse.de> Reviewed-by: Alberto Garcia <berto@igalia.com> Acked-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2014-05-15qapi: Replace start_optional()/end_optional() by optional()Markus Armbruster
Semantics of end_optional() differ subtly from the other end_FOO() callbacks: when start_FOO() succeeds, the matching end_FOO() gets called regardless of what happens in between. end_optional() gets called only when everything in between succeeds as well. Entirely undocumented, like all of the visitor API. The only user of Visitor Callback end_optional() never did anything, and was removed in commit 9f9ab46. I'm about to clean up error handling in the generated visitor code, and end_optional() is in my way. No users mean no test cases, and making non-trivial cleanup transformations without test cases doesn't strike me as a good idea. Drop end_optional(), and rename start_optional() to optional(). We can always go back to a pair of callbacks when we have an actual need. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-04-25qerror.h: Remove QERR defines that are only used onceCole Robinson
Just hardcode them in the callers Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Markus Armbruster <armbru@redhat.com> Signed-off-by: Cole Robinson <crobinso@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2013-07-26qapi: Anonymous unionsKevin Wolf
The discriminator for anonymous unions is the data type. This allows to have a union type that allows both of these: { 'file': 'my_existing_block_device_id' } { 'file': { 'filename': '/tmp/mydisk.qcow2', 'read-only': true } } Unions like this are specified in the schema with an empty dict as discriminator. For this example you could take: { 'union': 'BlockRef', 'discriminator': {}, 'data': { 'definition': 'BlockOptions', 'reference': 'str' } } { 'type': 'ExampleObject', 'data: { 'file': 'BlockRef' } } Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2013-07-26qapi: Add consume argument to qmp_input_get_object()Kevin Wolf
This allows to just look at the next element without actually consuming it. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2013-07-26qapi: Add visitor for implicit structsKevin Wolf
These can be used when an embedded struct is parsed and members not belonging to the struct may be present in the input (e.g. parsing a flat namespace QMP union, where fields from both the base and one of the alternative types are mixed in the JSON object) Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2012-12-19misc: move include files to include/qemu/Paolo Bonzini
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19qapi: move include files to include/qobject/Paolo Bonzini
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-05-14qapi: QMP input visitor, handle floats parsed as intsMichael Roth
JSON numbers can be interpreted as either integers or floating point values depending on their representation. As a result, QMP input visitor might visit a QInt when it was expecting a QFloat, so add handling to account for this. Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Acked-by: Andreas Färber <afaerber@suse.de>
2012-04-23qapi: g_hash_table_find() instead of GHashTableIter.NODA, Kai
GHashTableIter was first introduced in glib 2.16. This patch removes it in favor of older g_hash_table_find() for better compatibility with RHEL5. Signed-off-by: NODA, Kai <nodakai@gmail.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-03-27qapi: add strict mode to input visitorPaolo Bonzini
While QMP in general is designed so that it is possible to ignore unknown arguments, in the case of the QMP server it is better to reject them to detect bad clients. In fact, we're already doing this at the top level in the argument checker. To extend this to complex structures, add a mode to the input visitor where it checks for unvisited keys and raises an error if it finds one. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-03-27qapi: place outermost object on qiv stackPaolo Bonzini
This is a slight change in the implementation of QMPInputVisitor that helps when adding strict mode. Const QObjects cannot be inc/decref-ed, and that's why QMPInputVisitor relies heavily on weak references to inner objects. I'm not removing the weak references now, but since refcount+const is a lost battle in C (C++ has "mutable") I think removing const is fine in this case. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-03-27qapi: untangle next_listPaolo Bonzini
Right now, the semantics of next_list are complicated. The caller must: * call start_list * call next_list for each element *including the first* * on the first call to next_list, the second argument should point to NULL and the result is the head of the list. On subsequent calls, the second argument should point to the last node (last result of next_list) and next_list itself tacks the element at the tail of the list. This works for both input and output visitor, but having the visitor write memory when it is only reading the list is ugly. Plus, relying on *list to detect the first call is tricky and undocumented. We can initialize so->entry in next_list instead of start_list, leaving it NULL in start_list. This way next_list sees clearly whether it is on the first call---as a bonus, it discriminates the cases based on internal state of the visitor rather than external state. We can also pull the assignment of the list head from generated code up to next_list. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-03-27qapi: fix memory leak on errorPaolo Bonzini
QmpInputVisitor would leak the malloced struct if the stack was overflowed. This can be easily fixed using error_propagate. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-03-27qapi: fail hard on stack imbalancePaolo Bonzini
QmpOutputVisitor will segfault if an imbalanced end function is called. So we can abort in QmpInputVisitor too. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-02-21qapi: drop qmp_input_end_optionalPaolo Bonzini
This method is optional, do not implement it if it is empty. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-02-21qapi: allow sharing enum implementation across visitorsPaolo Bonzini
Most visitors will use the same code for enum parsing. Move it to the core. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2011-12-19qapi: protect against NULL QObject in qmp_input_get_objectPaolo Bonzini
A NULL qobj can occur when a parameter is fetched via qdict_get, but the parameter is not in the command. By returning NULL, the caller can choose whether to raise a missing parameter error, an invalid parameter type error, or use a default value. For example, qom-set could can use this to reset a property to its default value, though at this time it will fail with "Invalid parameter type". In any case, anything is better than crashing! Reviewed-by: Anthony Liguori <anthony@codemonkey.ws> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-10-04qapi: modify visitor code generation for list iterationMichael Roth
Modify logic such that we never assign values to the list head argument to progress through the list on subsequent iterations, instead rely only on having our return value passed back in as an argument on the next call. Also update QMP I/O visitors and test cases accordingly, and add a missing test case for QmpOutputVisitor. Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2011-08-20Use glib memory allocation and free functionsAnthony Liguori
qemu_malloc/qemu_free no longer exist after this commit. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>