i#975 static DR: support setup;detach

Adds support for calling dr_app_setup();dr_app_stop_and_cleanup() with
no start in between.  This is useful to use DR as a decode/encode
library when it's statically linked and also used for instrumentation,
as that setup precludes using drdecodelib, which relies on redirecting
heap allocation via name redirection.

Add a test to api.static_noclient.

Issue: #975

core/synch.c

@@ -2021,6 +2021,17 @@ detach_on_permanent_stack(bool internal, bool do_cleanup, dr_stats_t *drstats)
 
     my_id = get_thread_id();
     my_dcontext = get_thread_private_dcontext();
+    if (my_dcontext == NULL) {
+        /* We support detach after just dr_app_setup() with no start. */
+        ASSERT(!dynamo_started);
+        my_tr = thread_lookup(my_id);
+        ASSERT(my_tr != NULL);
+        my_dcontext = my_tr->dcontext;
+        os_process_under_dynamorio_initiate(my_dcontext);
+        os_process_under_dynamorio_complete(my_dcontext);
+        dynamo_thread_under_dynamo(my_dcontext);
+        ASSERT(get_thread_private_dcontext() == my_dcontext);
+    }
     ASSERT(my_dcontext != NULL);
 
     LOG(GLOBAL, LOG_ALL, 1, "Detach: thread %d starting detach process\n", my_id);

suite/tests/api/static_noclient.c

@@ -1,5 +1,5 @@
 /* **********************************************************
- * Copyright (c) 2016 Google, Inc.  All rights reserved.
+ * Copyright (c) 2016-2018 Google, Inc.  All rights reserved.
  * **********************************************************/
 
 /*
@@ -52,6 +52,20 @@ do_some_work(int seed)
 int
 main(int argc, const char *argv[])
 {
+    /* We test using DR IR routines when statically linked.  We can't use
+     * drdecode when statically linked with DR as drdecode relies on symbol
+     * replacement, so instead we initialize DR and then "detach" to do a full
+     * cleanup (even without an attach) before starting our regular
+     * attach+detach testing.
+     * XXX: When there's a client, this requires a flag to skip the client init
+     * in this first dr_app_setup().
+     */
+    dr_app_setup();
+    instr_t *instr = XINST_CREATE_return(GLOBAL_DCONTEXT);
+    assert(instr_is_return(instr));
+    instr_destroy(GLOBAL_DCONTEXT, instr);
+    dr_app_stop_and_cleanup();
+
     print("pre-DR init\n");
     dr_app_setup();
     assert(!dr_app_running_under_dynamorio());