[Qemu-devel] [PATCH 3/8] qapi script: check correctness of discriminator values in union

[Wenchao Xia]

It will check whether the values specified are written correctly when
discriminator is a pre-defined enum type, which help check whether the
schema is in good form.

It is allowed, that not every value in enum is used, so does not check
that case.

Signed-off-by: Wenchao Xia <address@hidden>
---
 scripts/qapi-visit.py |   11 +++++++++++
 scripts/qapi.py       |   33 +++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index b3d3af8..612dc4d 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -251,6 +251,17 @@ def generate_visit_union(expr):
         assert not base
         return generate_visit_anon_union(name, members)
 
+    # If discriminator is specified and it is a pre-defined enum in schema,
+    # check its correctness
+    enum_define = discriminator_find_enum_define(expr)
+    if enum_define:
+        for key in members:
+            if not key in enum_define["enum_values"]:
+                sys.stderr.write("Discriminator value '%s' not found in "
+                                 "enum '%s'\n" %
+                                 (key, enum_define["enum_name"]))
+                sys.exit(1)
+
     ret = generate_visit_enum('%sKind' % name, members.keys())
 
     if base:
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 82f586e..f93bda1 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -383,3 +383,36 @@ def guardend(name):
 
 ''',
                  name=guardname(name))
+
+# This function can be used to check whether "base" is valid
+def find_base_fields(base):
+    base_struct_define = find_struct(base)
+    if not base_struct_define:
+        return None
+    return base_struct_define.get('data')
+
+# Return the discriminator enum define, if discriminator is specified in
+# @expr and it is a pre-defined enum type
+def discriminator_find_enum_define(expr):
+    discriminator = expr.get('discriminator')
+    base = expr.get('base')
+
+    # Only support discriminator when base present
+    if not (discriminator and base):
+        return None
+
+    base_fields = find_base_fields(base)
+
+    if not base_fields:
+        sys.stderr.write("Base '%s' is not a valid type\n"
+                         % base)
+        sys.exit(1)
+
+    discriminator_type = base_fields.get(discriminator)
+
+    if not discriminator_type:
+        sys.stderr.write("Discriminator '%s' not found in schema\n"
+                         % discriminator)
+        sys.exit(1)
+
+    return find_enum(discriminator_type)
-- 
1.7.1