sdbus++: support 'readonly' flag
The previous documentation of 'const' did not match the
specification at a D-Bus level nor the implementation in sdbus++.
Correct the documentation for 'const' and add a new 'readonly' flag
which enables the previously documented behavior for 'const.
This was reported by a user outside of the openbmc project which had
already been using the 'readonly' flag in their YAML to identify this
condition. Previously, sdbus++ silently ignored flags it didn't
explicitly support but as of 20255a5fce55a0743dc3d307d1168f18ed553751
this turned into an error.
There are cases of interfaces in 'phosphor-dbus-interfaces' currently
using 'const' where they likely desire a 'readonly' instead. We are
not changing the behavior of 'const' with this commit, so there would
be no regressions induced by this code change.
Resolves openbmc/sdbusplus#48.
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I690cb424f5fd00da190343a345ae57ccae393041
diff --git a/docs/interface.md b/docs/interface.md
index 01e7f8a..13a5f7a 100644
--- a/docs/interface.md
+++ b/docs/interface.md
@@ -157,16 +157,25 @@
default value of the property. See the `Methods` section above for more
information on errors.
-The supported values for `flags` are `deprecated`, `hidden`, `unprivileged`,
-`const`, `emits_change`, `emits_invalidation`, `explicit` , which corresponds to
-`SD_BUS_VTABLE_DEPRECATED`, `SD_BUS_VTABLE_HIDDEN`,
-`SD_BUS_VTABLE_UNPRIVILEGED`, `SD_BUS_VTABLE_PROPERTY_CONST`,
-`SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE`,
-`SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION` and
-`SD_BUS_VTABLE_PROPERTY_EXPLICIT`, respectively. The flag `const ` makes the
-property read-only via D-Bus but still writable by the app implementing
-it. Moreover, if no flags have been specified for a property, `emits_change`
-will be added by default.
+The supported values for `flags` are and their equivalent sd-bus flag setting:
+
+* `deprecated` - SD_BUS_VTABLE_DEPRECATED
+* `hidden` - SD_BUS_VTABLE_HIDDEN
+* `unprivileged` - SD_BUS_VTABLE_UNPRIVILEGED
+* `const` - SD_BUS_VTABLE_PROPERTY_CONST
+* `emits_change` - SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE
+* `emits_invalidation` - SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION
+* `explicit` - SD_BUS_VTABLE_PROPERTY_EXPLICIT
+* `readonly` - (N/A)
+
+If no flag is given, a property will default to `emits_change`.
+
+Both `const` and `readonly` prevent D-Bus clients from being able to write
+to a property. `const` is a D-Bus indication that the property can never
+change, while `readonly` properties can be changed by the D-Bus server itself.
+As examples, the `Version` property on a software object might be appropriate
+to be `const` and the `Value` property on a sensor object would likely be
+`readonly`.
Example:
```
diff --git a/test/server/Test.interface.yaml b/test/server/Test.interface.yaml
index d015c99..7daea7d 100644
--- a/test/server/Test.interface.yaml
+++ b/test/server/Test.interface.yaml
@@ -3,3 +3,12 @@
properties:
- name: SomeValue
type: int64
+ - name: ReadonlyValue
+ type: int64
+ flags:
+ - readonly
+ - emits_change
+ - name: ConstValue
+ type: int64
+ flags:
+ - const
diff --git a/tools/sdbusplus/property.py b/tools/sdbusplus/property.py
index 75fcff9..e412b60 100644
--- a/tools/sdbusplus/property.py
+++ b/tools/sdbusplus/property.py
@@ -195,18 +195,21 @@
def or_cpp_flags(self, flags):
"""Return the corresponding ORed cpp flags."""
flags_dict = {
- "deprecated": "vtable::common_::deprecated",
- "hidden": "vtable::common_::hidden",
- "unprivileged": "vtable::common_::unprivileged",
"const": "vtable::property_::const_",
+ "deprecated": "vtable::common_::deprecated",
"emits_change": "vtable::property_::emits_change",
"emits_invalidation": "vtable::property_::emits_invalidation",
- "explicit": "vtable::property_::explicit_"}
+ "explicit": "vtable::property_::explicit_",
+ "hidden": "vtable::common_::hidden",
+ "readonly": False,
+ "unprivileged": "vtable::common_::unprivileged",
+ }
cpp_flags = []
for flag in flags:
try:
- cpp_flags.append(flags_dict[flag])
+ if flags_dict[flag]:
+ cpp_flags.append(flags_dict[flag])
except KeyError:
raise ValueError("Invalid flag \"{}\"".format(flag))
diff --git a/tools/sdbusplus/templates/interface.server.cpp.mako b/tools/sdbusplus/templates/interface.server.cpp.mako
index 9acfa2f..c936151 100644
--- a/tools/sdbusplus/templates/interface.server.cpp.mako
+++ b/tools/sdbusplus/templates/interface.server.cpp.mako
@@ -148,7 +148,7 @@
details::${classname}::_property_${p.name}
.data(),
_callback_get_${p.name},
- % if 'const' not in p.flags:
+ % if 'const' not in p.flags and 'readonly' not in p.flags:
_callback_set_${p.name},
% endif
% if not p.cpp_flags: