[binutils-gdb] [gdb] Fix abort in selftest run_on_main_thread with ^C

[Tom de Vries]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=3d36a6396fbfacd7b1941527d84ff6c0f40ff121

commit 3d36a6396fbfacd7b1941527d84ff6c0f40ff121
Author: Tom de Vries <tdevries@suse.de>
Date:   Mon Sep 12 10:05:18 2022 +0200

    [gdb] Fix abort in selftest run_on_main_thread with ^C
    
    When running selftest run_on_main_thread and pressing ^C, we can run into:
    ...
    Running selftest run_on_main_thread.
    terminate called without an active exception
    
    Fatal signal: Aborted
    ...
    
    The selftest function looks like this:
    ...
    static void
    run_tests ()
    {
      std::thread thread;
    
      done = false;
    
      {
        gdb::block_signals blocker;
    
        thread = std::thread (set_done);
      }
    
      while (!done && gdb_do_one_event () >= 0)
        ;
    
      /* Actually the test will just hang, but we want to test
         something.  */
      SELF_CHECK (done);
    
      thread.join ();
    }
    ...
    
    The error message we see is due to the destructor of thread being called while
    thread is joinable.
    
    This is supposed to be taken care of by thread.join (), but the ^C prevents
    that one from being called, while the destructor is still called.
    
    Fix this by ensuring thread.join () is called (if indeed required) before the
    destructor using SCOPE_EXIT.
    
    Tested on x86_64-linux.
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29549

Diff:
---
 gdb/unittests/main-thread-selftests.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/gdb/unittests/main-thread-selftests.c b/gdb/unittests/main-thread-selftests.c
index 7e1a30d7e80..8ab0c445d42 100644
--- a/gdb/unittests/main-thread-selftests.c
+++ b/gdb/unittests/main-thread-selftests.c
@@ -20,6 +20,7 @@
 #include "defs.h"
 #include "gdbsupport/selftest.h"
 #include "gdbsupport/block-signals.h"
+#include "gdbsupport/scope-exit.h"
 #include "run-on-main-thread.h"
 #include "gdbsupport/event-loop.h"
 #if CXX_STD_THREAD
@@ -52,6 +53,11 @@ run_tests ()
   {
     gdb::block_signals blocker;
 
+    SCOPE_EXIT
+      {
+	if (thread.joinable ())
+	  thread.join ();
+      };
     thread = std::thread (set_done);
   }
 
@@ -61,8 +67,6 @@ run_tests ()
   /* Actually the test will just hang, but we want to test
      something.  */
   SELF_CHECK (done);
-
-  thread.join ();
 }
 
 #endif