Status: submitted similar patch 2004-12-08

This patch cleans up the initialization of thread_db.  It works for static

binaries now.  The vsyscall patches hide this problem, since new static

binaries will load the vsyscall DSO and then trigger thread_db; but

this is still a good cleanup.

Index: gdb-6.3/gdb/thread-db.c

===================================================================

--- gdb-6.3.orig/gdb/thread-db.c	2004-10-08 16:29:56.000000000 -0400

+++ gdb-6.3/gdb/thread-db.c	2004-11-10 00:19:30.626530413 -0500

@@ -34,6 +34,7 @@

 #include "target.h"

 #include "regcache.h"

 #include "solib-svr4.h"

+#include "observer.h"

 #ifdef HAVE_GNU_LIBC_VERSION_H

 #include <gnu/libc-version.h>

@@ -627,59 +628,49 @@ check_thread_signals (void)

 #endif

 }

+/* Check whether thread_db is usable.  This function is called when

+   an inferior is created (or otherwise acquired, e.g. attached to)

+   and when new shared libraries are loaded into a running process.  */

+

 static void

-thread_db_new_objfile (struct objfile *objfile)

+check_for_thread_db (void)

 {

   td_err_e err;

+  static int already_loaded;

   /* First time through, report that libthread_db was successfuly

      loaded.  Can't print this in in thread_db_load as, at that stage,

-     the interpreter and it's console haven't started.  The real

-     problem here is that libthread_db is loaded too early - it should

-     only be loaded when there is a program to debug.  */

-  {

-    static int dejavu;

-    if (!dejavu)

-      {

-	Dl_info info;

-	const char *library = NULL;

-	/* Try dladdr.  */

-	if (dladdr ((*td_ta_new_p), &info) != 0)

-	  library = info.dli_fname;

-	/* Try dlinfo?  */

-	if (library == NULL)

-	  /* Paranoid - don't let a NULL path slip through.  */

-	  library = LIBTHREAD_DB_SO;

-	printf_unfiltered ("Using host libthread_db library \"%s\".\n",

-			   library);

-	dejavu = 1;

-      }

-  }

+     the interpreter and it's console haven't started.  */

-  /* Don't attempt to use thread_db on targets which can not run

-     (core files).  */

-  if (objfile == NULL || !target_has_execution)

+  if (!already_loaded)

     {

-      /* All symbols have been discarded.  If the thread_db target is

-         active, deactivate it now.  */

-      if (using_thread_db)

-	{

-	  gdb_assert (proc_handle.pid == 0);

-	  unpush_target (&thread_db_ops);

-	  using_thread_db = 0;

-	}

+      Dl_info info;

+      const char *library = NULL;

+      if (dladdr ((*td_ta_new_p), &info) != 0)

+	library = info.dli_fname;

+

+      /* Try dlinfo?  */

-      goto quit;

+      if (library == NULL)

+	/* Paranoid - don't let a NULL path slip through.  */

+	library = LIBTHREAD_DB_SO;

+

+      printf_unfiltered ("\nUsing host libthread_db library \"%s\".\n",

+			 library);

+      already_loaded = 1;

     }

   if (using_thread_db)

     /* Nothing to do.  The thread library was already detected and the

        target vector was already activated.  */

-    goto quit;

+    return;

+

+  /* Don't attempt to use thread_db on targets which can not run

+     (executables not running yet, core files) for now.  */

+  if (!target_has_execution)

+    return;

-  /* Initialize the structure that identifies the child process.  Note

-     that at this point there is no guarantee that we actually have a

-     child process.  */

+  /* Initialize the structure that identifies the child process.  */

   proc_handle.pid = GET_PID (inferior_ptid);

   /* Now attempt to open a connection to the thread library.  */

@@ -706,12 +697,24 @@ thread_db_new_objfile (struct objfile *o

 	       thread_db_err_str (err));

       break;

     }

+}

+

+static void

+thread_db_new_objfile (struct objfile *objfile)

+{

+  if (objfile != NULL)

+    check_for_thread_db ();

-quit:

   if (target_new_objfile_chain)

     target_new_objfile_chain (objfile);

 }

+static void

+check_for_thread_db_observer (struct target_ops *target, int from_tty)

+{

+  check_for_thread_db ();

+}

+

 /* Attach to a new thread.  This function is called when we receive a

    TD_CREATE event or when we iterate over all threads and find one

    that wasn't already in our list.  */

@@ -1366,5 +1369,8 @@ _initialize_thread_db (void)

       /* Add ourselves to objfile event chain.  */

       target_new_objfile_chain = deprecated_target_new_objfile_hook;

       deprecated_target_new_objfile_hook = thread_db_new_objfile;

+

+      /* Register ourselves for the new inferior observer.  */

+      observer_attach_inferior_created (check_for_thread_db_observer);

     }

 }

Index: gdb-6.3/gdb/Makefile.in

===================================================================

--- gdb-6.3.orig/gdb/Makefile.in	2004-11-09 23:04:57.000000000 -0500

+++ gdb-6.3/gdb/Makefile.in	2004-11-10 00:19:26.440347022 -0500

@@ -2626,7 +2626,8 @@ thread.o: thread.c $(defs_h) $(symtab_h)

 	$(gdbcmd_h) $(regcache_h) $(gdb_h) $(gdb_string_h) $(ui_out_h)

 thread-db.o: thread-db.c $(defs_h) $(gdb_assert_h) $(gdb_proc_service_h) \

 	$(gdb_thread_db_h) $(bfd_h) $(gdbthread_h) $(inferior_h) \

-	$(symfile_h) $(objfiles_h) $(target_h) $(regcache_h) $(solib_svr4_h)

+	$(symfile_h) $(objfiles_h) $(target_h) $(regcache_h) $(solib_svr4_h) \

+	$(observer_h)

 top.o: top.c $(defs_h) $(gdbcmd_h) $(call_cmds_h) $(cli_cmds_h) \

 	$(cli_script_h) $(cli_setshow_h) $(cli_decode_h) $(symtab_h) \

 	$(inferior_h) $(target_h) $(breakpoint_h) $(gdbtypes_h) \