ctf: add tracer version extraction function

This commit adds a utility function to extract tracer version of a given
trace.

Because, it was discovered that some tracers may produce non-compliant
CTF traces more-or-less frequently. To accommodate those external tools,
we will add ad-hoc fixes for the affected version. We thus need a way to
check the tracer versions of the traces.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I67e73a5928dfac0cebc1135552f5525af930ebfc
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1418
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>

diff --git a/src/plugins/ctf/fs-src/fs.c b/src/plugins/ctf/fs-src/fs.c
index 38878f18e2829a5c202b8fc2c1a2a3589ed55883..e33107aea4d661e00d5d2432223024e933e3a6d3 100644 (file)
--- a/src/plugins/ctf/fs-src/fs.c
+++ b/src/plugins/ctf/fs-src/fs.c
@@ -46,6 +46,13 @@
 #include "../common/msg-iter/msg-iter.h"
 #include "query.h"
 
+struct tracer_info {
+       const char *name;
+       int64_t major;
+       int64_t minor;
+       int64_t patch;
+};
+
 static
 int msg_iter_data_set_current_ds_file(struct ctf_fs_msg_iter_data *msg_iter_data)
 {
@@ -1696,6 +1703,83 @@ end:
        return ret;
 }
 
+/*
+ * Extract the tracer information necessary to compare versions.
+ * Returns 0 on success, and -1 if the extraction is not successful because the
+ * necessary fields are absents in the trace metadata.
+ */
+static
+int extract_tracer_info(struct ctf_fs_trace *trace,
+               struct tracer_info *current_tracer_info) __attribute__((unused));
+static
+int extract_tracer_info(struct ctf_fs_trace *trace,
+               struct tracer_info *current_tracer_info)
+{
+       int ret = 0;
+       struct ctf_trace_class_env_entry *entry;
+
+       /* Clear the current_tracer_info struct */
+       memset(current_tracer_info, 0, sizeof(*current_tracer_info));
+
+       /*
+        * To compare 2 tracer versions, at least the tracer name and it's
+        * major version are needed. If one of these is missing, consider it an
+        * extraction failure.
+        */
+       entry = ctf_trace_class_borrow_env_entry_by_name(
+               trace->metadata->tc, "tracer_name");
+       if (!entry || entry->type != CTF_TRACE_CLASS_ENV_ENTRY_TYPE_STR) {
+               goto missing_bare_minimum;
+       }
+
+       /* Set tracer name. */
+       current_tracer_info->name = entry->value.str->str;
+
+       entry = ctf_trace_class_borrow_env_entry_by_name(
+               trace->metadata->tc, "tracer_major");
+       if (!entry || entry->type != CTF_TRACE_CLASS_ENV_ENTRY_TYPE_INT) {
+               goto missing_bare_minimum;
+       }
+
+       /* Set major version number. */
+       current_tracer_info->major = entry->value.i;
+
+       entry = ctf_trace_class_borrow_env_entry_by_name(
+               trace->metadata->tc, "tracer_minor");
+       if (!entry || entry->type != CTF_TRACE_CLASS_ENV_ENTRY_TYPE_INT) {
+               goto end;
+       }
+
+       /* Set minor version number. */
+       current_tracer_info->minor = entry->value.i;
+
+       entry = ctf_trace_class_borrow_env_entry_by_name(
+               trace->metadata->tc, "tracer_patch");
+       if (!entry) {
+               /*
+                * If `tracer_patch` doesn't exist `tracer_patchlevel` might.
+                * For example, `lttng-modules` uses entry name
+                * `tracer_patchlevel`.
+                */
+               entry = ctf_trace_class_borrow_env_entry_by_name(
+                       trace->metadata->tc, "tracer_patchlevel");
+       }
+
+       if (!entry || entry->type != CTF_TRACE_CLASS_ENV_ENTRY_TYPE_INT) {
+               goto end;
+       }
+
+       /* Set patch version number. */
+       current_tracer_info->patch = entry->value.i;
+
+       goto end;
+
+missing_bare_minimum:
+       ret = -1;
+end:
+       return ret;
+}
+
 int ctf_fs_component_create_ctf_fs_traces(bt_self_component_source *self_comp,
                struct ctf_fs_component *ctf_fs,
                const bt_value *paths_value)