trace: [stderr] add support for dynamically enabling/disabling events

Uses the generic interface provided in "trace/control.h" in order to provide
a programmatic interface as well as command line and monitor controls.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>

trace/stderr.c

@@ -0,0 +1,37 @@
+#include "trace.h"
+#include "trace/control.h"
+
+
+void trace_print_events(FILE *stream, fprintf_function stream_printf)
+{
+    unsigned int i;
+
+    for (i = 0; i < NR_TRACE_EVENTS; i++) {
+        stream_printf(stream, "%s [Event ID %u] : state %u\n",
+                      trace_list[i].tp_name, i, trace_list[i].state);
+    }
+}
+
+bool trace_event_set_state(const char *name, bool state)
+{
+    unsigned int i;
+
+    for (i = 0; i < NR_TRACE_EVENTS; i++) {
+        if (!strcmp(trace_list[i].tp_name, name)) {
+            trace_list[i].state = state;
+            return true;
+        }
+    }
+    return false;
+}
+
+bool trace_backend_init(const char *events, const char *file)
+{
+    if (file) {
+        fprintf(stderr, "error: -trace file=...: "
+                "option not supported by the selected tracing backend\n");
+        return false;
+    }
+    trace_backend_init_events(events);
+    return true;
+}

trace/stderr.h

@@ -0,0 +1,11 @@
+#ifndef TRACE_STDERR_H
+#define TRACE_STDERR_H
+
+typedef uint64_t TraceEventID;
+
+typedef struct {
+    const char *tp_name;
+    bool state;
+} TraceEvent;
+
+#endif /* ! TRACE_STDERR_H */