aboutsummaryrefslogtreecommitdiff
path: root/tests/qapi-schema
AgeCommit message (Collapse)Author
2016-02-19qapi-visit: Honor prefix of discriminator enumEric Blake
When we added support for a user-specified prefix for an enum type (commit 351d36e), we forgot to teach the qapi-visit code to honor that prefix in the case of using a prefixed enum as the discriminator for a flat union. While there is still some on-list debate on whether we want to keep prefixes, we should at least make it work as long as it is still part of the code base. Reported-by: Daniel P. Berrange <berrange@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1455665965-27638-1-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Detect base class loopsEric Blake
It should be fairly obvious that qapi base classes need to form an acyclic graph, since QMP cannot specify the same key more than once, while base classes are included as flat members alongside other members added by the child. But the old check_member_clash() parser function was not prepared to check for this, and entered an infinite recursion (at least until Python gives up, complaining about nesting too deep). Now that check_member_clash() has been recently removed, attempts at self-inheritance trigger an assertion failure introduced by commit ac88219a. The obvious fix is to turn the assertion into a conditional. This patch includes both the tests (base-cycle-direct and base-cycle-indirect) and the fix, since the .err file output for the unfixed case is not useful (particularly when it was warning about unbounded recursion, as that limit may be platform-specific). We don't need to worry about cycles in flat unions (neither the base type nor the type of a variant can be a union) nor in alternates (alternate branches cannot themselves be an alternate). But if we later allow a union type as a variant, we will still be okay, as QAPISchemaObjectTypeVariants.check() triggers the same QAPISchemaObjectType.check() that will detect any loops. Likewise, we need not worry about the case of diamond inheritance where the same class is used for a flat union base class and one of its variants; either both uses will introduce a collision in trying to insert the same member name twice, or the shared type is empty and changes nothing. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1449033659-25497-16-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Move duplicate collision checks to schema check()Eric Blake
With the recent commit 'qapi: Detect collisions in C member names', we have two different locations for detecting clashes - one at parse time, and another at QAPISchema*.check() time. Remove all of the ad hoc parser checks, and delete associated code (for example, the global check_member_clash() method is no longer needed). Testing this showed that the test union-bad-branch wasn't adding much: union-clash-branches also exposes the error message when branches collide, and we've recently fixed things to avoid an implicit collision with max. Likewise, the error for enum-clash-member changes to report our new detection of upper case in a value name, unless we modify the test to use all lower case. The wording of several error messages has changed, but the change is generally an improvement rather than a regression. No change to generated code. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1449033659-25497-15-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Enforce (or whitelist) case conventions on qapi membersEric Blake
We document that members of enums and objects should be 'lower-case', although we were not enforcing it. We have to whitelist a few pre-existing entities that violate the norms. Add three new tests to expose the new error message, each of which first uses the whitelisted name 'UuidInfo' to prove the whitelist works, then triggers the failure (this is the same pattern used in the existing returns-whitelist.json test). Note that by adding this check, we have effectively forbidden an entity with a case-insensitive clash of member names, for any entity that is not on the whitelist (although there is still the possibility to clash via '-' vs. '_'). Not done here: a future patch should also add naming convention support and whitelist exceptions for command, event, and type names. The additions to QAPISchemaMember.check_clash() check whether info['name'] is in the whitelist (the top-most entity name at the point 'info' tracks), rather than self.owner (the type, possibly implicit, that directly owns the member), because it is easier to maintain the whitelist by the names actually in the user's .json file, rather than worrying about the names of implicit types. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1449033659-25497-14-git-send-email-eblake@redhat.com> [Simplified a bit as per discussion with Eric] 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>
2015-12-17qapi: Convert QType into QAPI built-in enum typeEric Blake
What's more meta than using qapi to define qapi? :) Convert QType into a full-fledged[*] builtin qapi enum type, so that a subsequent patch can then use it as the discriminator type of qapi alternate types. Fortunately, the judicious use of 'prefix' in the qapi definition avoids churn to the spelling of the enum constants. To avoid circular definitions, we have to flip the order of inclusion between "qobject.h" vs. "qapi-types.h". Back in commit 28770e0, we had the latter include the former, so that we could use 'QObject *' for our implementation of 'any'. But that usage also works with only a forward declaration, whereas the definition of QObject requires QType to be a complete type. [*] The type has to be builtin, rather than declared in qapi/common.json, because we want to use it for alternates even when common.json is not included. But since it is the first builtin enum type, we have to add special cases to qapi-types and qapi-visit to only emit definitions once, even when two qapi files are being compiled into the same binary (the way we already handled builtin list types like 'intList'). We may need to revisit how multiple qapi files share common types, but that's a project for another day. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1449033659-25497-4-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Remove obsolete tests for MAX collisionEric Blake
Now that we no longer collide with an implicit _MAX enum member, we no longer need to reject it in the ad hoc parser, and can remove several tests that are no longer needed. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1447836791-369-24-git-send-email-eblake@redhat.com> [Commit message tweaked] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Tighten the regex on valid namesEric Blake
We already documented that qapi names should match specific patterns (such as starting with a letter unless it was an enum value or a downstream extension). Tighten that from a suggestion into a hard requirement, which frees up names beginning with a single underscore for qapi internal usage. The tighter regex doesn't forbid everything insane that a user could provide (for example, a user could name a type 'Foo-lookup' to collide with the generated 'Foo_lookup[]' for an enum 'Foo'), but does a good job at protecting the most obvious uses, and also happens to reserve single leading underscore for later use. The handling of enum values starting with a digit is tricky: commit 9fb081e introduced a subtle bug by using c_name() on a munged value, which would allow an enum to include the member 'q-int' in spite of our reservation. Furthermore, munging with a leading '_' would fail our tighter regex. So fix it by only munging for leading digits (which are never ticklish in c_name()) and by using a different prefix (I picked 'D', although any letter should do). Add new tests, reserved-member-underscore and reserved-enum-q, to demonstrate the tighter checking. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1447836791-369-22-git-send-email-eblake@redhat.com> Message-Id: <1447883135-18020-1-git-send-email-eblake@redhat.com> [Eric's fixup squashed in] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Fix c_name() mungingEric Blake
The method c_name() is supposed to do two different actions: munge '-' into '_', and add a 'q_' prefix to ticklish names. But it did these steps out of order, making it possible to submit input that is not ticklish until after munging, where the output then lacked the desired prefix. The failure is exposed easily if you have a compiler that recognizes C11 keywords, and try to name a member '_Thread-local', as it would result in trying to compile the declaration 'uint64_t _Thread_local;' which is not valid. However, this name violates our conventions (ultimately, want to enforce that no qapi names start with single underscore), so the test is slightly weaker by instead testing 'wchar-t'; the declaration 'uint64_t wchar_t;' is valid in C (where wchar_t is only a typedef) but would fail with a C++ compiler (where it is a keyword). Fix things by reversing the order of actions within c_name(). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1447836791-369-18-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Detect collisions in C member namesEric Blake
Detect attempts to declare two object members that would result in the same C member name, by keying the 'seen' dictionary off of the C name rather than the qapi name. It also requires passing info through the check_clash() methods. This addresses a TODO and fixes the previously-broken args-name-clash test. The resulting error message demonstrates the utility of the .describe() method added previously. No change to generated code. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1447836791-369-17-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Remove outdated tests related to QMP/branch collisionsEric Blake
Now that branches are in a separate C namespace, we can remove the restrictions in the parser that claim a branch name would collide with QMP, and delete the negative tests that are no longer problematic. A separate patch can then add positive tests to qapi-schema-test to test that any corner cases will compile correctly. This reverts the scripts/qapi.py portion of commit 7b2a5c2, now that the assertions that it plugged are no longer possible. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1447836791-369-15-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17qapi: Track simple union tag in object.local_membersEric Blake
We were previously creating all unions with an empty list for local_members. However, it will make it easier to unify struct and union generation if we include the generated tag member in local_members. That way, we can have a common code pattern: visit the base (if any), visit the local members (if any), visit the variants (if any). The local_members of a flat union remains empty (because the discriminator is already visited as part of the base). Then, by visiting tag_member.check() during AlternateType.check(), we no longer need to call it during Variants.check(). The various front end entities now exist as follows: struct: optional base, optional local_members, no variants simple union: no base, one-element local_members, variants with tag_member from local_members flat union: base, no local_members, variants with tag_member from base alternate: no base, no local_members, variants With the new local members, we require a bit of finesse to avoid assertions in the clients. No change to generated code. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1447836791-369-2-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-11-09qapi: Use generated TestStruct machinery in testsEric Blake
Commit d88f5fd and friends first introduced the various test-qmp-* tests in 2011, with duplicated hand-rolled TestStruct machinery, to make sure the qapi visitor interface was tested. Later, commit 4f193e3 in 2013 added a .json file for further testing use by the files, but without consolidating any of the existing hand-rolled visitors. And with four copies, subtle differences have crept in, between the tests themselves (mainly whitespace differences, but also a question of whether to use NULL or "TestStruct" when calling visit_start_struct()) and from what the generator produces (the hand-rolled versions did not cater to partially-allocated objects, because they did not have a deallocation usage). Of course, just because the visitor interface is tested does not mean it is a sane interface; and future patches will be changing some of the visitor contracts. Rather than having to duplicate the cleanup work in each copy of the TestStruct visitor, and keep each hand-rolled copy in sync with what the generator supplies, we might as well just test what the generator should give us in the first place. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1446791754-23823-2-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-11-02qapi: Reserve 'u' member nameEric Blake
Now that we have separated union tag values from colliding with non-variant C names, by naming the union 'u', we should reserve this name for our use. Note that we want to forbid 'u' even in a struct with no variants, because it is possible for a future qemu release to extend QMP in a backwards-compatible manner while converting from a struct to a flat union. Fortunately, no existing clients were using this member name. If we ever find the need for QMP to have a member 'u', we could at that time relax things, perhaps by having c_name() munge the QMP member to 'q_u'. Note that we cannot forbid 'u' everywhere (by adding the rejection code to check_name()), because the existing QKeyCode enum already uses it; therefore we only reserve it as a struct type member name. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1445898903-12082-24-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-11-02qapi: Unbox base membersEric Blake
Rather than storing a base class as a pointer to a box, just store the fields of that base class in the same order, so that a child struct can be directly cast to its parent. This gives less malloc overhead, less pointer dereferencing, and even less generated code. Compare to the earlier commit 1e6c1616a "qapi: Generate a nicer struct for flat unions" (although that patch had fewer places to change, as less of qemu was directly using qapi structs for flat unions). It also allows us to turn on automatic type-safe wrappers for upcasting to the base class of a struct. Changes to the generated code look like this in qapi-types.h: | struct SpiceChannel { |- SpiceBasicInfo *base; |+ /* Members inherited from SpiceBasicInfo: */ |+ char *host; |+ char *port; |+ NetworkAddressFamily family; |+ /* Own members: */ | int64_t connection_id; as well as additional upcast functions like qapi_SpiceChannel_base(). Meanwhile, changes to qapi-visit.c look like: | static void visit_type_SpiceChannel_fields(Visitor *v, SpiceChannel **obj, Error **errp) | { | Error *err = NULL; | |- visit_type_implicit_SpiceBasicInfo(v, &(*obj)->base, &err); |+ visit_type_SpiceBasicInfo_fields(v, (SpiceBasicInfo **)obj, &err); | if (err) { (the cast is necessary, since our upcast wrappers only deal with a single pointer, not pointer-to-pointer); plus the wholesale elimination of some now-unused visit_type_implicit_FOO() functions. Without boxing, the corner case of one empty struct having another empty struct as its base type now requires inserting a dummy member (previously, the 'Base *base' member sufficed). And now that we no longer consume a 'base' member in the generated C struct, we can delete the former negative struct-base-clash-base test. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1445898903-12082-11-git-send-email-eblake@redhat.com> [Commit message tweaked slightly] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-11-02qapi: Reserve 'q_*' and 'has_*' member namesEric Blake
c_name() produces names starting with 'q_' when protecting a dictionary member name that would fail to directly compile, but in doing so can cause clashes with any member name already beginning with 'q-' or 'q_'. Likewise, we create a C name 'has_' for any optional member that can clash with any member name beginning with 'has-' or 'has_'. Technically, rather than blindly reserving the namespace, we could try to complain about user names only when an actual collision occurs, or even teach c_name() how to munge names to avoid collisions. But it is not trivial, especially when collisions can occur across multiple types (such as via inheritance or flat unions). Besides, no existing .json files are trying to use these names. So it's easier to just outright forbid the potential for collision. We can always relax things in the future if a real need arises for QMP to express member names that have been forbidden here. 'has_' only has to be reserved for struct/union member names, while 'q_' is reserved everywhere (matching the fact that only members can be optional, while we use c_name() for munging both members and entities). Note that we could relax 'q_' restrictions on entities independently from member names; for example, c_name('qmp_' + 'unix') would result in a different function name than our current 'qmp_' + c_name('unix'). Update and add tests to cover the new error messages. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1445898903-12082-6-git-send-email-eblake@redhat.com> [Consistently pass protect=False to c_name(); commit message tweaked slightly] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-11-02qapi: Reserve '*List' type names for list typesEric Blake
Type names ending in 'List' can clash with qapi list types in generated C. We don't currently use such names. It is easier to outlaw them now than to worry about how to resolve such a clash in the future. For precedence, see commit 4dc2e69, which did the same for names ending in 'Kind' versus implicit enum types for qapi unions. Update the testsuite to match. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1445898903-12082-5-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-11-02tests/qapi-schema: Test for reserved names, empty structEric Blake
Add some testsuite coverage to ensure future patches are on the right track: Our current C representation of qapi arrays is done by appending 'List' to the element name; but we are not preventing the creation of an object type with the same name. Add reserved-type-list.json to test this. Then rename enum-union-clash.json to reserved-type-kind.json to cover the reservation that we DO detect, and shorten it to match the fact that the name is reserved even if there is no clash. We are failing to detect a collision between a dictionary member and the implicit 'has_*' flag for another optional member. The easiest fix would be for a future patch to reserve the entire "has[-_]" namespace for member names (the collision is also possible for branch names within flat unions, but only as long as branch names can collide with (non-variant) members; however, since future patches are about to remove that, it is not worth testing here). Add reserved-member-has.json to test this. A similar collision exists between a dictionary member where c_name() munges what might otherwise be a reserved name to start with 'q_', and another member explicitly starts with "q[-_]". Again, the easiest solution for a future patch will be reserving the entire namespace, but here for commands as well as members. Add reserved-member-q.json and reserved-command-q.json to test this; separate tests since arguably our munging of command 'unix' to 'qmp_q_unix()' could be done without a q_, which is different than the munging of a member 'unix' to 'foo.q_unix'. Finally, our testsuite does not have any compilation coverage of struct inheritance with empty qapi structs. Update qapi-schema-test.json to test this. Note that there is currently no technical reason to forbid type name patterns from member names, or member name patterns from types, since the two are not in the same namespace in C and won't collide; but it's not worth adding positive tests of these corner cases at this time, especially while there is other churn pending in patches that rearrange which collisions actually happen. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1445898903-12082-2-git-send-email-eblake@redhat.com> [Commit message tweaked slightly] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-15qapi: Lazy creation of array typesEric Blake
Commit ac88219a had several TODO markers about whether we needed to automatically create the corresponding array type alongside any other type. It turns out that most of the time, we don't! There are a few exceptions: 1) We have a few situations where we use an array type in internal code but do not expose that type through QMP; fix it by declaring a dummy type that forces the generator to see that we want to use the array type. 2) The builtin arrays (such as intList for QAPI ['int']) must always be generated, because of the way our QAPI_TYPES_BUILTIN compile guard works: we have situations (at the very least tests/test-qmp-output-visitor.c) that include both top-level "qapi-types.h" (via "error.h") and a secondary "test-qapi-types.h". If we were to only emit the builtin types when used locally, then the first .h file would not include all types, but the second .h does not declare anything at all because the first .h set QAPI_TYPES_BUILTIN, and we would end up with compilation error due to things like unknown type 'int8List'. Actually, we may need to revisit how we do type guards, and change from a single QAPI_TYPES_BUILTIN over to a different usage pattern that does one #ifdef per qapi type - right now, the only types that are declared multiple times between two qapi .json files for inclusion by a single .c file happen to be the builtin arrays. But now that we have QAPI 'include' statements, it is logical to assume that we will soon reach a point where we want to reuse non-builtin types (yes, I'm thinking about what it will take to add introspection to QGA, where we will want to reuse the SchemaInfo type and friends). One #ifdef per type will help ensure that generating the same qapi type into more than one qapi-types.h won't cause collisions when both are included in the same .c file; but we also have to solve how to avoid creating duplicate qapi-types.c entry points. So that is a problem left for another day. Generated code for qapi-types and qapi-visit is drastically reduced; less than a third of the arrays that were blindly created were actually needed (a quick grep shows we dropped from 219 to 69 *List types), and the .o files lost more than 30% of their bulk. [For best results, diff the generated files with 'git diff --patience --no-index pre post'.] Interestingly, the introspection output is unchanged - this is because we already cull all types that are not indirectly reachable from a command or event, so introspection was already using only a subset of array types. The subset of types introspected is now a much larger percentage of the overall set of array types emitted in qapi-types.h (since the larger set shrunk), but still not 100% (evidence that the array types emitted for our new Dummy structs, and the new struct itself, don't affect QMP). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1444710158-8723-9-git-send-email-eblake@redhat.com> [Moved array info tracking to a later patch] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-15qapi: Drop redundant args-member-array testEric Blake
qapi-schema-test already ensures that we can correctly compile an array of enums (__org.qemu_x-command), an array of builtins (UserDefNativeListUnion), and an array of structs (again __org.qemu_x-command). That means args-member-array is not adding any additional parse-only test coverage, so drop it. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1444760807-11307-1-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-15qapi: Drop redundant flat-union-reverse-define testEric Blake
As of commit 8c3f8e77, we test compilation of forward references for a struct base type (UserDefOne), flat union base type (UserDefUnionBase), and flat union branch type (UserDefFlatUnion2). The only remaining forward reference being tested for parsing in flat-union-reverse-define was a forward enum declaration. Once we make sure that always compiles, the smaller parse-only test is redundant and can be deleted. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1444710158-8723-7-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-15qapi: Drop redundant returns-int testEric Blake
qapi-schema-test was already testing that we could have a command returning int, but burned a command name in the whitelist. Merge the redundant positive test returns-int, and pick a name that reduces the whitelist size. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1444710158-8723-6-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-15qapi: Move empty-enum to compile-time testEric Blake
Rather than just asserting that we can parse an empty enum, let's also make sure we can compile it, by including it in qapi-schema-test. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1444710158-8723-5-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-15qapi: Drop redundant alternate-good testEric Blake
The alternate-good.json test was already covered by qapi-schema-test.json. As future commits will be tweaking how alternates are laid out, removing the duplicate test now reduces churn. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1444710158-8723-4-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-12qapi: Reuse code for flat union base validationEric Blake
Rather than open-code the check for a valid base type, we should reuse the common functionality. This allows for consistent error messages, and also makes it easier for a later patch to turn on support for inline anonymous base structures. Test flat-union-inline is updated to test only one feature (anonymous branch dictionaries), which can be implemented independently (test flat-union-bad-base already covers the idea of an anonymous base dictionary). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1443565276-4535-10-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-12qapi: Test use of 'number' within alternatesEric Blake
Add some testsuite exposure for use of a 'number' as part of an alternate. The current state of the tree has a few bugs exposed by this: our input parser depends on the ordering of how the qapi schema declared the alternate, and the parser does not accept integers for a 'number' in an alternate even though it does for numbers outside of an alternate. Mixing 'int' and 'number' in the same alternate is unusual, since both are supplied by json-numbers, but there does not seem to be a technical reason to forbid it given that our json lexer distinguishes between json-numbers that can be represented as an int vs. those that cannot. Improve the existing test_visitor_in_alternate() to match the style of the new test_visitor_in_alternate_number(), and to ensure full coverage of all possible qtype parsing. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1443565276-4535-9-git-send-email-eblake@redhat.com> [Eric's follow-up fixes squashed in] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-12qapi: Add tests for empty unionsEric Blake
The documentation claims that alternates are useful for allowing two or more types, although nothing enforces this. Meanwhile, it is silent on whether empty unions are allowed. In practice, the generated code will compile, in part because we have a 'void *data' branch; but attempting to visit such a type will cause an abort(). While there's no technical reason that a degenerate union could not be made to work, it's harder to justify the time spent in chasing known (the current abort() during visit) and unknown corner cases, than it would be to just outlaw them. A future patch will probably take the approach of forbidding them; in the meantime, we can at least add testsuite coverage to make it obvious where things stand. In addition to adding tests to expose the problems, we also need to adjust existing tests that are meant to test something else, but which could fail for the wrong reason if we reject degenerate alternates/unions. Note that empty structs are explicitly supported (for example, right now they are the only way to specify that one branch of a flat union adds no additional members), and empty enums are covered by the testsuite as working (even if they do not seem to have much use). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1443565276-4535-8-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-12qapi: Avoid assertion failure on union 'type' collisionEric Blake
The previous commit added two tests that triggered an assertion failure. It's fairly straightforward to avoid the failure by just outright forbidding the collision between a union's tag values and its discriminator name (including the implicit name 'kind' supplied for simple unions [*]). Ultimately, we'd like to move the collision detection into QAPISchema*.check(), but for now it is easier just to enhance the existing checks. [*] Of course, down the road, we have plans to rename the simple union tag name to 'type' to match the QMP wire name, but the idea of the collision will still be present even then. Technically, we could avoid the collision by naming the C union members representing each enum value as '_case_value' rather than 'value'; but until we have an actual qapi client (and not just our testsuite) that has a legitimate reason to match a case label to the name of a QMP key and needs the name munging to satisfy the compiler, it's easier to just reject the qapi as invalid. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1443565276-4535-7-git-send-email-eblake@redhat.com> [Polished a few comments] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-12qapi: Test for various name collisionsEric Blake
Expose some weaknesses in the generator: we don't always forbid the generation of structs that contain multiple members that map to the same C or QMP name. This has already been marked FIXME in qapi.py in commit d90675f, but having more tests will make sure future patches produce desired behavior; and updating existing patches to better document things doesn't hurt, either. Some of these collisions are already caught in the old-style parser checks, but ultimately we want all collisions to be caught in the new-style QAPISchema*.check() methods. This patch focuses on C struct members, and does not consider collisions between commands and events (affecting C function names), or even collisions between generated C type names with user type names (for things like automatic FOOList struct representing array types or FOOKind for an implicit enum). There are two types of struct collisions we want to catch: 1) Collision between two keys in a JSON object. qapi.py prevents that within a single struct (see test duplicate-key), but it is possible to have collisions between a type's members and its base type's members (existing tests struct-base-clash, struct-base-clash-deep), and its flat union variant members (renamed test flat-union-clash-member). 2) Collision between two members of the C struct that is generated for a given QAPI type: a) Multiple QAPI names map to the same C name (new test args-name-clash) b) A QAPI name maps to a C name that is used for another purpose (new tests flat-union-clash-branch, struct-base-clash-base, union-clash-data). We already fixed some such cases in commit 0f61af3e and 1e6c1616, but more remain. c) Two C names generated for other purposes clash (updated test alternate-clash, new test union-clash-branches, union-clash-type, flat-union-clash-type) Ultimately, if we need to have a flat union where a tag value clashes with a base member name, we could change the generator to name the union (using 'foo.u.value' rather than 'foo.value') or otherwise munge the C name corresponding to tag values. But unless such a need arises, it will probably be easier to just forbid these collisions. Some of these negative tests will be deleted later, and positive tests added to qapi-schema-test.json in their place, when the generator code is reworked to avoid particular code generation collisions in class 2). [Note that viewing this patch with git rename detection enabled may see some confusion due to renaming some tests while adding others, but where the content is similar enough that git picks the wrong pre- and post-patch files to associate] Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1443565276-4535-6-git-send-email-eblake@redhat.com> [Improve commit message and comments a bit, drop an unrelated test] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-10-12qapi: Improve 'include' error messageEric Blake
Use of '"...%s" % include' to print non-strings can lead to ugly messages, such as this (if the .json change is applied without the qapi.py change): Expected a file name (string), got: OrderedDict() Better is to just omit the actual non-string value in the message. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1443565276-4535-3-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-09-21qapi: New QMP command query-qmp-schema for QMP introspectionMarkus Armbruster
qapi/introspect.json defines the introspection schema. It's designed for QMP introspection, but should do for similar uses, such as QGA. The introspection schema does not reflect all the rules and restrictions that apply to QAPI schemata. A valid QAPI schema has an introspection value conforming to the introspection schema, but the converse is not true. Introspection lowers away a number of schema details, and makes implicit things explicit: * The built-in types are declared with their JSON type. All integer types are mapped to 'int', because how many bits we use internally is an implementation detail. It could be pressed into external interface service as very approximate range information, but that's a bad idea. If we need range information, we better do it properly. * Implicit type definitions are made explicit, and given auto-generated names: - Array types, named by appending "List" to the name of their element type, like in generated C. - The enumeration types implicitly defined by simple union types, named by appending "Kind" to the name of their simple union type, like in generated C. - Types that don't occur in generated C. Their names start with ':' so they don't clash with the user's names. * All type references are by name. * The struct and union types are generalized into an object type. * Base types are flattened. * Commands take a single argument and return a single result. Dictionary argument or list result is an implicit type definition. The empty object type is used when a command takes no arguments or produces no results. The argument is always of object type, but the introspection schema doesn't reflect that. The 'gen': false directive is omitted as implementation detail. The 'success-response' directive is omitted as well for now, even though it's not an implementation detail, because it's not used by QMP. * Events carry a single data value. Implicit type definition and empty object type use, just like for commands. The value is of object type, but the introspection schema doesn't reflect that. * Types not used by commands or events are omitted. Indirect use counts as use. * Optional members have a default, which can only be null right now Instead of a mandatory "optional" flag, we have an optional default. No default means mandatory, default null means optional without default value. Non-null is available for optional with default (possible future extension). * Clients should *not* look up types by name, because type names are not ABI. Look up the command or event you're interested in, then follow the references. TODO Should we hide the type names to eliminate the temptation? New generator scripts/qapi-introspect.py computes an introspection value for its input, and generates a C variable holding it. It can generate awfully long lines. Marked TODO. A new test-qmp-input-visitor test case feeds its result for both tests/qapi-schema/qapi-schema-test.json and qapi-schema.json to a QmpInputVisitor to verify it actually conforms to the schema. New QMP command query-qmp-schema takes its return value from that variable. Its reply is some 85KiBytes for me right now. If this turns out to be too much, we have a couple of options: * We can use shorter names in the JSON. Not the QMP style. * Optionally return the sub-schema for commands and events given as arguments. Right now qmp_query_schema() sends the string literal computed by qmp-introspect.py. To compute sub-schema at run time, we'd have to duplicate parts of qapi-introspect.py in C. Unattractive. * Let clients cache the output of query-qmp-schema. It changes only on QEMU upgrades, i.e. rarely. Provide a command query-qmp-schema-hash. Clients can have a cache indexed by hash, and re-query the schema only when they don't have it cached. Even simpler: put the hash in the QMP greeting. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-21qapi: Pseudo-type '**' is now unused, drop itMarkus Armbruster
'gen': false needs to stay for now, because netdev_add is still using it. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Message-Id: <1442401589-24189-25-git-send-email-armbru@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>
2015-09-21qapi-event: Convert to QAPISchemaVisitor, fixing data with baseMarkus Armbruster
Fixes events whose data is struct with base to include the struct's base members. Test case is qapi-schema-test.json's event __org.qemu_x-command: { 'event': '__ORG.QEMU_X-EVENT', 'data': '__org.qemu_x-Struct' } { 'struct': '__org.qemu_x-Struct', 'base': '__org.qemu_x-Base', 'data': { '__org.qemu_x-member2': 'str' } } { 'struct': '__org.qemu_x-Base', 'data': { '__org.qemu_x-member1': '__org.qemu_x-Enum' } } Patch's effect on generated qapi_event_send___org_qemu_x_event(): -void qapi_event_send___org_qemu_x_event(const char *__org_qemu_x_member2, +void qapi_event_send___org_qemu_x_event(__org_qemu_x_Enum __org_qemu_x_member1, + const char *__org_qemu_x_member2, Error **errp) { QDict *qmp; @@ -224,6 +225,10 @@ void qapi_event_send___org_qemu_x_event( goto clean; } + visit_type___org_qemu_x_Enum(v, &__org_qemu_x_member1, "__org.qemu_x-member1", &local_err); + if (local_err) { + goto clean; + } visit_type_str(v, (char **)&__org_qemu_x_member2, "__org.qemu_x-member2", &local_err); if (local_err) { goto clean; Code is generated in a different order now, but that doesn't matter. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
2015-09-21qapi-visit: Convert to QAPISchemaVisitor, fixing bugsMarkus Armbruster
Fixes flat unions to visit the base's base members (the previous commit merely added them to the struct). Same test case. Patch's effect on visit_type_UserDefFlatUnion(): static void visit_type_UserDefFlatUnion_fields(Visitor *m, UserDefFlatUnion **obj, Error **errp) { Error *err = NULL; + visit_type_int(m, &(*obj)->integer, "integer", &err); + if (err) { + goto out; + } visit_type_str(m, &(*obj)->string, "string", &err); if (err) { goto out; Test cases updated for the bug fix. Fixes alternates to generate a visitor for their implicit enumeration type. None of them are currently used, obviously. Example: block-core.json's BlockdevRef now generates visit_type_BlockdevRefKind(). Code is generated in a different order now, and therefore has got a few new forward declarations. Doesn't matter. The guard QAPI_VISIT_BUILTIN_VISITOR_DECL is renamed to QAPI_VISIT_BUILTIN. The previous commit's two ugly special cases exist here, too. Mark both TODO. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-21qapi-types: Convert to QAPISchemaVisitor, fixing flat unionsMarkus Armbruster
Fixes flat unions to get the base's base members. Test case is from commit 2fc0043, in qapi-schema-test.json: { 'union': 'UserDefFlatUnion', 'base': 'UserDefUnionBase', 'discriminator': 'enum1', 'data': { 'value1' : 'UserDefA', 'value2' : 'UserDefB', 'value3' : 'UserDefB' } } { 'struct': 'UserDefUnionBase', 'base': 'UserDefZero', 'data': { 'string': 'str', 'enum1': 'EnumOne' } } { 'struct': 'UserDefZero', 'data': { 'integer': 'int' } } Patch's effect on UserDefFlatUnion: struct UserDefFlatUnion { /* Members inherited from UserDefUnionBase: */ + int64_t integer; char *string; EnumOne enum1; /* Own members: */ union { /* union tag is @enum1 */ void *data; UserDefA *value1; UserDefB *value2; UserDefB *value3; }; }; Flat union visitors remain broken. They'll be fixed next. Code is generated in a different order now, but that doesn't matter. The two guards QAPI_TYPES_BUILTIN_STRUCT_DECL and QAPI_TYPES_BUILTIN_CLEANUP_DECL are replaced by just QAPI_TYPES_BUILTIN. Two ugly special cases for simple unions now stand out like sore thumbs: 1. The type tag is named 'type' everywhere, except in generated C, where it's 'kind'. 2. QAPISchema lowers simple unions to semantically equivalent flat unions. However, the C generated for a simple unions differs from the C generated for its equivalent flat union, and we therefore need special code to preserve that pointless difference for now. Mark both TODO. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-21tests/qapi-schema: Convert test harness to QAPISchemaVisitorMarkus Armbruster
The old code prints the result of parsing (list of expression dictionaries), and partial results of semantic analysis (list of enum dictionaries, list of struct dictionaries). The new code prints a trace of a schema visit, i.e. what the back-ends are going to use. Built-in and array types are omitted, because they're boring. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-21qapi: New QAPISchema intermediate reperesentationMarkus Armbruster
The QAPI code generators work with a syntax tree (nested dictionaries) plus a few symbol tables (also dictionaries) on the side. They have clearly outgrown these simple data structures. There's lots of rummaging around in dictionaries, and information is recomputed on the fly. For the work I'm going to do, I want more clearly defined and more convenient interfaces. Going forward, I also want less coupling between the back-ends and the syntax tree, to make messing with the syntax easier. Create a bunch of classes to represent QAPI schemata. Have the QAPISchema initializer call the parser, then walk the syntax tree to create the new internal representation, and finally perform semantic analysis. Shortcut: the semantic analysis still relies on existing check_exprs() to do the actual semantic checking. All this code needs to move into the classes. Mark as TODO. Simple unions are lowered to flat unions. Flat unions and structs are represented as a more general object type. Catching name collisions in generated code would be nice. Mark as TODO. We generate array types eagerly, even though most of them aren't used. Mark as TODO. Nothing uses the new intermediate representation just yet, thus no change to generated files. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-15qapi: allow override of default enum prefix namingDaniel P. Berrange
The camel_to_upper() method applies some heuristics to turn a mixed case type name into an all-uppercase name. This is used for example, to generate enum constant name prefixes. The heuristics don't also generate a satisfactory name though. eg { 'enum': 'QCryptoTLSCredsEndpoint', 'data': ['client', 'server']} Results in Q_CRYPTOTLS_CREDS_ENDPOINT_CLIENT. This has an undesirable _ after the initial Q and is missing an _ between the CRYPTO & TLS strings. Rather than try to add more and more heuristics to try to cope with this, simply allow the QAPI schema to specify the desired enum constant prefix explicitly. eg { 'enum': 'QCryptoTLSCredsEndpoint', 'prefix': 'QCRYPTO_TLS_CREDS_ENDPOINT', 'data': ['client', 'server']} Now gives the QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT name. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2015-09-04qapi: Simplify error reporting for array typesMarkus Armbruster
check_type() first checks and peels off the array type, then checks the element type. For two out of four error messages, it takes pains to report errors for "array of T" instead of just T. Odd. Let's examine the errors. * Unknown element type, e.g. tests/qapi-schema/args-array-unknown.json: Member 'array' of 'data' for command 'oops' uses unknown type 'array of NoSuchType' To make sense of this, you need to know that 'array of NoSuchType' refers to '[NoSuchType]'. Easy enough. However, simply reporting Member 'array' of 'data' for command 'oops' uses unknown type 'NoSuchType' is at least as easy to understand. * Element type's meta-type is inadmissible, e.g. tests/qapi-schema/returns-whitelist.json: 'returns' for command 'no-way-this-will-get-whitelisted' cannot use built-in type 'array of int' 'array of int' is technically not a built-in type, but that's pedantry. However, simply reporting 'returns' for command 'no-way-this-will-get-whitelisted' cannot use built-in type 'int' avoids the issue, and is at least as easy to understand. * The remaining two errors are unreachable, because the array checking ensures that value is a string. Thus, reporting some errors for "array of T" instead of just T works, but doesn't really improve things. Drop it. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04qapi: Fix errors for non-string, non-dictionary membersMarkus Armbruster
Fixes the errors demonstrated by the previous commit. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04tests/qapi-schema: Cover non-string, non-dictionary membersMarkus Armbruster
We always report "should be a dictionary" then. This is misleading: when allow_dict, it can be a dictionary or a type name string, else it can only be a type name. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04tests/qapi-schema: Cover two more syntax errorsMarkus Armbruster
Syntax error coverage should now be complete. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04qapi: Drop one of two "simple union must not have base" checksMarkus Armbruster
The first check ensures the second one can't trigger. Drop the first one, because the second one is in a more logical place, and emits a nicer error message. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04qapi: Command returning anonymous type doesn't work, outlawMarkus Armbruster
Reproducer: with { 'command': 'user_def_cmd4', 'returns': { 'a': 'int' } } added to qapi-schema-test.json, qapi-commands.py dies when it tries to generate the command handler function Traceback (most recent call last): File "/work/armbru/qemu/scripts/qapi-commands.py", line 359, in <module> ret = generate_command_decl(cmd['command'], arglist, ret_type) + "\n" File "/work/armbru/qemu/scripts/qapi-commands.py", line 29, in generate_command_decl ret_type=c_type(ret_type), name=c_name(name), File "/work/armbru/qemu/scripts/qapi.py", line 927, in c_type assert isinstance(value, str) and value != "" AssertionError because the return type doesn't exist. Simply outlaw this usage, and drop or dumb down test cases accordingly. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04qapi: Fix to reject union command and event argumentsMarkus Armbruster
A command's or event's 'data' must be a struct type, given either as a dictionary, or as struct type name. Commit dd883c6 tightened the checking there, but not enough: we still accept 'union'. Fix to reject it. We may want to support union types there, but we'll have to extend qapi-commands.py and qapi-events.py for it. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04qapi-tests: New tests for union, alternate command argumentsMarkus Armbruster
A command's 'data' must be a struct type, given either as a dictionary, or as struct type name. Existing test case data-int.json covers simple type 'int'. Add test cases for type names referring to union and alternate types. The latter is caught (good), but the former is not (bug). Events have the same problem, but since they get checked by the same code, we don't bother to duplicate the tests. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04tests/qapi-schema: Rename tests from data- to args-Markus Armbruster
Since every schema entity has 'data', the data- prefix conveys no information. These tests actually exercise commands. Only commands have arguments, so change the prefix to to args-. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04tests/qapi-schema: Restore test case for flat union base bugMarkus Armbruster
Test case added in commit 2fc0043, and messed up in commit 5223070. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-04tests/qapi-schema: Document events with base don't workMarkus Armbruster
When event FOO's 'data' is a struct with a base, we consider only the struct's direct members, and ignore its base. The generated qapi_event_send_foo() doesn't take arguments for base members. No such events currently exist in the QMP schema. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>