[Qemu-devel] [PATCH RFC 03/10] qapi script: check correctness of discriminator values in union

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

It will check whether the values specfied are wrotten 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 do not check
that case.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
---
 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 c39e628..803d3eb 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -249,6 +249,17 @@ 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 = descriminator_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..235df4f 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 descriminator enum define, if discriminator is specified in
+# @expr and it is a pre-defined enum type
+def descriminator_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)
+
+    descriminator_type = base_fields.get(discriminator)
+
+    if not descriminator_type:
+        sys.stderr.write("Discriminator '%s' not found in schema\n"
+                         % discriminator)
+        sys.exit(1)
+
+    return find_enum(descriminator_type)
-- 
1.7.1