sessiond: ust: conditionally enable the underscore prefix variant quirk

[lttng-tools.git] / src / bin / lttng-sessiond / ust-app.cpp

diff --git a/src/bin/lttng-sessiond/ust-app.cpp b/src/bin/lttng-sessiond/ust-app.cpp
index 9690115d66c56ca83b06f6adb6e92e888249ec00..11d604ea9a463e7c32126b5189e46707e74f7ce1 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.cpp
+++ b/src/bin/lttng-sessiond/ust-app.cpp
@@ -6430,7 +6430,8 @@ static int handle_app_register_channel_notification(int sock,
                auto app_context_fields = lsu::create_trace_fields_from_ust_ctl_fields(
                                *locked_registry_session, ust_ctl_context_fields.get(),
                                context_field_count,
-                               lst::field_location::root::EVENT_RECORD_COMMON_CONTEXT);
+                               lst::field_location::root::EVENT_RECORD_COMMON_CONTEXT,
+                               lsu::ctl_field_quirks::UNDERSCORE_PREFIXED_VARIANT_TAG_MAPPINGS);
 
                if (!ust_reg_chan.is_registered()) {
                        lst::type::cuptr event_context = app_context_fields.size() ?
@@ -6566,7 +6567,9 @@ static int add_event_ust_registry(int sock, int sobjd, int cobjd, const char *na
                                                                *locked_registry, fields.get(),
                                                                nr_fields,
                                                                lst::field_location::root::
-                                                                               EVENT_RECORD_PAYLOAD),
+                                                                               EVENT_RECORD_PAYLOAD,
+                                                               lsu::ctl_field_quirks::
+                                                                               UNDERSCORE_PREFIXED_VARIANT_TAG_MAPPINGS),
                                                loglevel_value,
                                                model_emf_uri.get() ?
                                                                nonstd::optional<std::string>(
@@ -7892,3 +7895,30 @@ error:
        rcu_read_unlock();
        return ret;
 }
+
+lsu::ctl_field_quirks ust_app::ctl_field_quirks() const
+{
+       /*
+        * Application contexts are expressed as variants. LTTng-UST announces
+        * those by registering an enumeration named `..._tag`. It then registers a
+        * variant as part of the event context that contains the various possible
+        * types.
+        *
+        * Unfortunately, the names used in the enumeration and variant don't
+        * match: the enumeration names are all prefixed with an underscore while
+        * the variant type tag fields aren't.
+        *
+        * While the CTF 1.8.3 specification mentions that
+        * underscores *should* (not *must*) be removed by CTF readers. Babeltrace
+        * 1.x (and possibly others) expect a perfect match between the names used
+        * by tags and variants.
+        *
+        * When the UNDERSCORE_PREFIXED_VARIANT_TAG_MAPPINGS quirk is enabled,
+        * the variant's fields are modified to match the mappings of its tag.
+        *
+        * From ABI version >= 10.x, the variant fields and tag mapping names
+        * correctly match, making this quirk unnecessary.
+        */
+       return v_major <= 9 ? lsu::ctl_field_quirks::UNDERSCORE_PREFIXED_VARIANT_TAG_MAPPINGS :
+               lsu::ctl_field_quirks::NONE;
+}
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