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[Qemu-devel] [PULL 40/40] qapi: Detect base class loops
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PULL 40/40] qapi: Detect base class loops |
Date: |
Thu, 17 Dec 2015 09:33:45 +0100 |
From: Eric Blake <address@hidden>
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 <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Markus Armbruster <address@hidden>
---
scripts/qapi.py | 4 +++-
tests/Makefile | 2 ++
tests/qapi-schema/base-cycle-direct.err | 1 +
tests/qapi-schema/base-cycle-direct.exit | 1 +
tests/qapi-schema/base-cycle-direct.json | 2 ++
tests/qapi-schema/base-cycle-direct.out | 0
tests/qapi-schema/base-cycle-indirect.err | 1 +
tests/qapi-schema/base-cycle-indirect.exit | 1 +
tests/qapi-schema/base-cycle-indirect.json | 3 +++
tests/qapi-schema/base-cycle-indirect.out | 0
10 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 tests/qapi-schema/base-cycle-direct.err
create mode 100644 tests/qapi-schema/base-cycle-direct.exit
create mode 100644 tests/qapi-schema/base-cycle-direct.json
create mode 100644 tests/qapi-schema/base-cycle-direct.out
create mode 100644 tests/qapi-schema/base-cycle-indirect.err
create mode 100644 tests/qapi-schema/base-cycle-indirect.exit
create mode 100644 tests/qapi-schema/base-cycle-indirect.json
create mode 100644 tests/qapi-schema/base-cycle-indirect.out
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 8edfd79..7dec611 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -940,7 +940,9 @@ class QAPISchemaObjectType(QAPISchemaType):
self.members = None
def check(self, schema):
- assert self.members is not False # not running in cycles
+ if self.members is False: # check for cycles
+ raise QAPIExprError(self.info,
+ "Object %s contains itself" % self.name)
if self.members:
return
self.members = False # mark as being checked
diff --git a/tests/Makefile b/tests/Makefile
index 69cef77..053c1ae 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -257,6 +257,8 @@ qapi-schema += bad-ident.json
qapi-schema += bad-type-bool.json
qapi-schema += bad-type-dict.json
qapi-schema += bad-type-int.json
+qapi-schema += base-cycle-direct.json
+qapi-schema += base-cycle-indirect.json
qapi-schema += command-int.json
qapi-schema += comments.json
qapi-schema += double-data.json
diff --git a/tests/qapi-schema/base-cycle-direct.err
b/tests/qapi-schema/base-cycle-direct.err
new file mode 100644
index 0000000..9c68f65
--- /dev/null
+++ b/tests/qapi-schema/base-cycle-direct.err
@@ -0,0 +1 @@
+tests/qapi-schema/base-cycle-direct.json:2: Object Loopy contains itself
diff --git a/tests/qapi-schema/base-cycle-direct.exit
b/tests/qapi-schema/base-cycle-direct.exit
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/qapi-schema/base-cycle-direct.exit
@@ -0,0 +1 @@
+1
diff --git a/tests/qapi-schema/base-cycle-direct.json
b/tests/qapi-schema/base-cycle-direct.json
new file mode 100644
index 0000000..4fc66d0
--- /dev/null
+++ b/tests/qapi-schema/base-cycle-direct.json
@@ -0,0 +1,2 @@
+# we reject a loop in base classes
+{ 'struct': 'Loopy', 'base': 'Loopy', 'data': {} }
diff --git a/tests/qapi-schema/base-cycle-direct.out
b/tests/qapi-schema/base-cycle-direct.out
new file mode 100644
index 0000000..e69de29
diff --git a/tests/qapi-schema/base-cycle-indirect.err
b/tests/qapi-schema/base-cycle-indirect.err
new file mode 100644
index 0000000..fc92fe4
--- /dev/null
+++ b/tests/qapi-schema/base-cycle-indirect.err
@@ -0,0 +1 @@
+tests/qapi-schema/base-cycle-indirect.json:2: Object Base1 contains itself
diff --git a/tests/qapi-schema/base-cycle-indirect.exit
b/tests/qapi-schema/base-cycle-indirect.exit
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/qapi-schema/base-cycle-indirect.exit
@@ -0,0 +1 @@
+1
diff --git a/tests/qapi-schema/base-cycle-indirect.json
b/tests/qapi-schema/base-cycle-indirect.json
new file mode 100644
index 0000000..2866772
--- /dev/null
+++ b/tests/qapi-schema/base-cycle-indirect.json
@@ -0,0 +1,3 @@
+# we reject a loop in base classes
+{ 'struct': 'Base1', 'base': 'Base2', 'data': {} }
+{ 'struct': 'Base2', 'base': 'Base1', 'data': {} }
diff --git a/tests/qapi-schema/base-cycle-indirect.out
b/tests/qapi-schema/base-cycle-indirect.out
new file mode 100644
index 0000000..e69de29
--
2.4.3
- [Qemu-devel] [PULL 20/40] blkdebug: Avoid '.' in enum values, (continued)
- [Qemu-devel] [PULL 20/40] blkdebug: Avoid '.' in enum values, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 16/40] qapi: Detect collisions in C member names, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 15/40] qapi: Track owner of each object member, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 28/40] qobject: Rename qtype_code to QType, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 35/40] qapi: Shorter visits of optional fields, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 34/40] qapi: Simplify visits of optional fields, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 27/40] qobject: Simplify QObject, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 39/40] qapi: Move duplicate collision checks to schema check(), Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 29/40] qapi: Convert QType into QAPI built-in enum type, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 37/40] qapi: Track enum values by QAPISchemaMember, not string, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 40/40] qapi: Detect base class loops,
Markus Armbruster <=
- [Qemu-devel] [PULL 33/40] qapi: Fix alternates that accept 'number' but not 'int', Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 38/40] qapi: Enforce (or whitelist) case conventions on qapi members, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 22/40] qapi: Don't let implicit enum MAX member collide, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 26/40] qapi: Change munging of CamelCase enum values, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 36/40] qapi: Prepare new QAPISchemaMember base class, Markus Armbruster, 2015/12/17
- [Qemu-devel] [PULL 30/40] qapi: Simplify visiting of alternate types, Markus Armbruster, 2015/12/17
- Re: [Qemu-devel] [PULL 00/40] QAPI patches for 2015-12-17, Peter Maydell, 2015/12/17