aboutsummaryrefslogtreecommitdiff
path: root/scripts/qapi-visit.py
AgeCommit message (Collapse)Author
2015-05-14qapi: Factor open_output(), close_output() out of generatorsMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-05-14qapi: Factor parse_command_line() out of the generatorsMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2015-05-14qapi: Support downstream alternatesEric Blake
Enhance the testsuite to cover downstream alternates, including whether the branch name or type is downstream. Update the generator to mangle alternate names in the appropriate places. Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-14qapi: Support downstream flat unionsEric Blake
Enhance the testsuite to cover downstream flat unions, including the base type, discriminator name and type, and branch name and type. Update the generator to mangle the union names in the appropriate places. Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-14qapi: Support downstream simple unionsEric Blake
Enhance the testsuite to cover downstream simple unions, including when a union branch is a downstream name. Update the generator to mangle the union names in the appropriate places. Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-14qapi: Support downstream structsEric Blake
Enhance the testsuite to cover downstream structs, including struct members and base structs. Update the generator to mangle the struct names in the appropriate places. Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-14qapi: Support downstream enumsEric Blake
Enhance the testsuite to cover a downstream enum type and enum string. Update the generator to mangle the enum name in the appropriate places. Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-14qapi: Rename generate_enum_full_value() to c_enum_const()Markus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2015-05-14qapi: Rename identical c_fun()/c_var() into c_name()Eric Blake
Now that the two functions are identical, we only need one of them, and we might as well give it a more descriptive name. Basically, the function serves as the translation from a QAPI name into a (portion of a) C identifier, without regards to whether it is a variable or function name. Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-05qapi: Drop dead visitor code related to nested structsEric Blake
Now that we no longer have nested structs to visit, the use of prefix strings is no longer required. Remove the code that is no longer reachable. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-05qapi: Drop support for inline nested typesEric Blake
A future patch will be using a 'name':{dictionary} entry in the QAPI schema to specify a default value for an optional argument (see previous commit messages for more details why); but existing use of inline nested structs conflicts with that goal. Now that all commands have been changed to avoid inline nested structs, nuke support for them, and turn it into a hard error. Update the testsuite to reflect tighter parsing rules. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-05qapi: Prefer 'struct' over 'type' in generatorEric Blake
Referring to "type" as both a meta-type (built-in, enum, union, alternate, or struct) and a specific type (the name that the schema uses for declaring structs) is confusing. The confusion is only made worse by the fact that the generator mostly already refers to struct even when dealing with expr['type']. This commit changes the generator to consistently refer to it as struct everywhere, plus a single back-compat tweak that allows accepting the existing .json files as-is, so that the meat of this change is separate from the mindless churn of that change. Fix the testsuite fallout for error messages that change, and in some cases, become more legible. Improve comments to better match our intentions where a struct (rather than any complex type) is required. Note that in some cases, an error message now refers to 'struct' while the schema still refers to 'type'; that will be cleaned up in the later commit to the schema. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-05qapi: Use 'alternate' to replace anonymous unionEric Blake
Previous patches have led up to the point where I create the new meta-type "'alternate':'Foo'". See the previous patches for documentation; I intentionally split as much work into earlier patches to minimize the size of this patch, but a lot of it is churn due to testsuite fallout after updating to the new type. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-05qapi: Segregate anonymous unions into alternates in generatorEric Blake
Special-casing 'discriminator == {}' for handling anonymous unions is getting awkward; since this particular type is not always a dictionary on the wire, it is easier to treat it as a completely different class of type, "alternate", so that if a type is listed in the union_types array, we know it is not an anonymous union. This patch just further segregates union handling, to make sure that anonymous unions are not stored in union_types, and splitting up check_union() into separate functions. A future patch will change the qapi grammar, and having the segregation already in place will make it easier to deal with the distinct meta-type. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-05qapi: Forbid base without discriminator in unionsEric Blake
None of the existing QMP or QGA interfaces uses a union with a base type but no discriminator; it is easier to avoid this in the generator to save room for other future extensions more likely to be useful. An earlier commit added a union-base-no-discriminator test to ensure that we eventually give a decent error message; likewise, removing UserDefUnion outright is okay, because we moved all the tests we wish to keep into the tests of the simple union UserDefNativeListUnion in the previous commit. Now is the time to actually forbid simple union with base, and remove the last vestiges from the testsuite. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-05-05qapi: Simplify builtin type handlingEric Blake
There was some redundancy between builtin_types[] and builtin_type_qtypes{}. Merge them into one. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-04-24qapi: Drop dead genlist parameterEric Blake
Defaulting a parameter to True, then having all callers omit or pass an explicit True for that parameter, is pointless. Looks like it has been dead since introduction in commit 06d64c6, more than 4 years ago. Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-09-26qapi: add visit_start_union and visit_end_unionMichael Roth
In some cases an input visitor might bail out on filling out a struct for various reasons, such as missing fields when running in strict mode. In the case of a QAPI Union type, this may lead to cases where the .kind field which encodes the union type is uninitialized. Subsequently, other visitors, such as the dealloc visitor, may use this .kind value as if it were initialized, leading to assumptions about the union type which in this case may lead to segfaults. For example, freeing an integer value. However, we can generally rely on the fact that the always-present .data void * field that we generate for these union types will always be NULL in cases where .kind is uninitialized (at least, there shouldn't be a reason where we'd do this purposefully). So pass this information on to Visitor implementation via these optional start_union/end_union interfaces so this information can be used to guard against the situation above. We will make use of this information in a subsequent patch for the dealloc visitor. Cc: qemu-stable@nongnu.org Reported-by: Fam Zheng <famz@redhat.com> Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-09-22qapi: Allow enums in anonymous unionsMax Reitz
Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-id: 1408557576-14574-3-git-send-email-mreitz@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-06-23qapi: fix coding style in parameters listAmos Kong
A space after * when declaring a pointer type is redundant. Signed-off-by: Amos Kong <akong@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-05-15qapi: Replace uncommon use of the error API by the common oneMarkus Armbruster
We commonly use the error API like this: err = NULL; foo(..., &err); if (err) { goto out; } bar(..., &err); Every error source is checked separately. The second function is only called when the first one succeeds. Both functions are free to pass their argument to error_set(). Because error_set() asserts no error has been set, this effectively means they must not be called with an error set. The qapi-generated code uses the error API differently: // *errp was initialized to NULL somewhere up the call chain frob(..., errp); gnat(..., errp); Errors accumulate in *errp: first error wins, subsequent errors get dropped. To make this work, the second function does nothing when called with an error set. Requires non-null errp, or else the second function can't see the first one fail. This usage has also bled into visitor tests, and two device model object property getters rtc_get_date() and balloon_stats_get_all(). With the "accumulate" technique, you need fewer error checks in callers, and buy that with an error check in every callee. Can be nice. However, mixing the two techniques is confusing. You can't use the "accumulate" technique with functions designed for the "check separately" technique. You can use the "check separately" technique with functions designed for the "accumulate" technique, but then error_set() can't catch you setting an error more than once. Standardize on the "check separately" technique for now, because it's overwhelmingly prevalent. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-05-15qapi: Un-inline visit of implicit structMarkus Armbruster
In preparation of error handling changes. Bonus: generates less duplicated code. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-05-15qapi-visit.py: Clean up a sloppy use of field prefixMarkus Armbruster
generate_visit_struct_fields() generates the base type's struct member name both with and without the field prefix. Harmless, because the field prefix is always empty there: only unboxed complex members have a prefix, and those can't have a base type. Clean it up anyway. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-05-15qapi: Clean up shadowing of parameters and locals in inner scopesMarkus Armbruster
By un-inlining the visit of nested complex types. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-05-15qapi-visit.py: Clean up confusing push_indent() / pop_indent() useMarkus Armbruster
Changing implicit indentation in the middle of generating a block makes following the code being generated unnecessarily hard. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@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>
2014-05-08qapi: Use an explicit input fileLluís Vilanova
Use an explicit input file on the command-line instead of reading from standard input. It also outputs the proper file name when there's an error. Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-03-11qapi script: support enum type as discriminator in unionWenchao Xia
By default, any union will automatically generate a enum type as "[UnionName]Kind" in C code, and it is duplicated when the discriminator is specified as a pre-defined enum type in schema. After this patch, the pre-defined enum type will be really used as the switch case condition in generated C code, if discriminator is an enum field. Signed-off-by: Wenchao Xia <wenchaoqemu@gmail.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-03-11qapi script: use same function to generate enum stringWenchao Xia
Prior to this patch, qapi-visit.py used custom code to generate enum names used for handling a qapi union. Fix it to instead reuse common code, with identical generated results, and allowing future updates to generation to only need to touch one place. Signed-off-by: Wenchao Xia <wenchaoqemu@gmail.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-03-03qapi: Clean up null checking in generated visitorsMarkus Armbruster
Visitors get passed a pointer to the visited object. The generated visitors try to cope with this pointer being null in some places, for instance like this: visit_start_optional(m, obj ? &(*obj)->has_name : NULL, "name", &err); visit_start_optional() passes its second argument to Visitor method start_optional. Three out of three methods dereference it unconditionally. I fail to see how this pointer could legitimately be null. All this useless null checking is highly redundant, which Coverity duly reports. About 200 times. Remove the useless null checks. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-03-03qapi: Drop nonsensical header guard in generated qapi-visit.cMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-03-03qapi: Fix licensing of scriptsMarkus Armbruster
The scripts carry this copyright notice: # This work is licensed under the terms of the GNU GPLv2. # See the COPYING.LIB file in the top-level directory. The sentences contradict each other, as COPYING.LIB contains the LGPL 2.1. Michael Roth says this was a simple pasto, and he meant to refer COPYING. Let's fix that. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2013-11-11Adjust qapi-visit for python-2.4.3Richard Henderson
We say we support python 2.4, but python 2.4.3 does not support the "expr if test else expr" syntax used here. This allows QEMU to compile on RHEL 5.3, the last release for ia64. Signed-off-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2013-10-11qapi-types/visit.py: Inheritance for structsKevin Wolf
This introduces a new 'base' key for struct definitions that refers to another struct type. On the JSON level, the fields of the base type are included directly into the same namespace as the fields of the defined type, like with unions. On the C level, a pointer to a struct of the base type is included. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2013-10-11qapi-types/visit.py: Pass whole expr dict for structsKevin Wolf
Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@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: Flat unions with arbitrary discriminatorKevin Wolf
Instead of the rather verbose syntax that distinguishes base and subclass fields... { "type": "file", "read-only": true, "data": { "filename": "test" } } ...we can now have both in the same namespace, allowing a more direct mapping of the command line, and moving fields between the common base and subclasses without breaking the API: { "driver": "file", "read-only": true, "filename": "test" } Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2013-07-26qapi-visit.py: Implement 'base' for unionsKevin Wolf
This implements the visitor part of base types for unions. Parsed into QMP, this example schema definition... { 'type': 'BlockOptionsBase', 'data': { 'read-only': 'bool' } } { 'type': 'BlockOptionsQcow2, 'data': { 'lazy-refcounts': 'bool' } } { 'union': 'BlockOptions', 'base': 'BlockOptionsBase', 'data': { 'raw': 'BlockOptionsRaw' 'qcow2': 'BlockOptionsQcow2' } } ...would describe the following JSON object: { "type": "qcow2", "read-only": true, "data": { "lazy-refcounts": false } } Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2013-07-26qapi-visit.py: Split off generate_visit_struct_fields()Kevin Wolf
Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2013-05-23qapi: qapi-visit.py, native list supportMichael Roth
Teach visitor generators about native types so they can generate the appropriate visitor routines. Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Amos Kong <akong@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2013-05-23qapi: qapi-visit.py, fix list handling for union typesMichael Roth
Currently we assume non-list types when generating visitor routines for union types. This is broken, since values like ['Type'] need to mapped to 'TypeList'. We already have a type_name() function to handle this that we use for generating struct visitors, so use that here as well. Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Amos Kong <akong@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-12-19qapi: move include files to include/qobject/Paolo Bonzini
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19qapi: move inclusions of qemu-common.h from headers to .c filesPaolo Bonzini
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-09-26qapi: do not protect enum values from namespace pollutionPaolo Bonzini
Enum values are always preceded by the uppercase name of the enum, so they do not conflict with reserved words. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-09-05qapi: Fix potential NULL pointer segfaultStefan Weil
Report from smatch: qapi-visit.c:1640 visit_type_BlockdevAction(8) error: we previously assumed 'obj' could be null (see line 1639) qapi-visit.c:2432 visit_type_NetClientOptions(8) error: we previously assumed 'obj' could be null (see line 2431) Signed-off-by: Stefan Weil <sw@weilnetz.de> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-09-05qapi: generate list struct and visit_list for enumAmos Kong
Currently, if we define an 'enum' and use it in one command's data, list struct for enum could not be generated, but it's used in qmp function. For example: KeyCodesList could not be generated. >>> qapi-schema.json: { 'enum': 'KeyCodes', 'data': [ 'shift', 'alt' ... ] } { 'command': 'sendkey', 'data': { 'keys': ['KeyCodes'], '*hold-time': 'int' } } >>> qmp-command.h: void qmp_sendkey(KeyCodesList * keys, bool has_hold_time, int64_t hold_time, Error **errp); This patch lets qapi generate list struct and visit_list for enum. Signed-off-by: Amos Kong <akong@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-07-23qapi: fix error propagationPaolo Bonzini
Don't overwrite / leak previously set errors. Make traversal cope with missing mandatory sub-structs. Don't try to end a container that could not be started. v1->v2: - unchanged v2->v3: - instead of examining, assert that we never overwrite errors with error_set() - allow visitors to set a NULL struct pointer successfully, so traversal of incomplete objects can continue - check for a NULL "obj" before accessing "(*obj)->has_XXX" (this is not a typo, "obj != NULL" implies "*obj != NULL" here) - fix start_struct / end_struct balance for unions as well Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.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: allow freeing partially-allocated objectsPaolo Bonzini
Objects going through the dealloc visitor can be only partially allocated. Detect the situation and avoid a segfault. This also helps with the input visitor, when there are errors. 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: shortcut visits on errorsPaolo Bonzini
We can exit very soon if we enter a visitor with a preexisting error. This simplifies some cases because we will not have to deal with obj being non-NULL while *obj is NULL. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>