* linux-thread-db.c: New file, renamed from thread-db.c.

	* thread-db.c: Remove.
	* Makefile.in (linux-thread-db.o): Rename from thread-db.o rule.
	* config/alpha/alpha-linux.mh (NATDEPFILES): Rename thread-db.o
	to linux-thread-db.o.
	* config/arm/linux.mh (NATDEPFILES): Likewise.
	* config/i386/linux.mh (NATDEPFILES): Likewise.
	* config/i386/linux64.mh (NATDEPFILES): Likewise.
	* config/ia64/linux.mh (NATDEPFILES): Likewise.
	* config/m32r/linux.mh (NATDEPFILES): Likewise.
	* config/m68k/linux.mh (NATDEPFILES): Likewise.
	* config/mips/linux.mh (NATDEPFILES): Likewise.
	* config/pa/linux.mh (NATDEPFILES): Likewise.
	* config/powerpc/linux.mh (NATDEPFILES): Likewise.
	* config/powerpc/ppc64-linux.mh (NATDEPFILES): Likewise.
	* config/s390/s390.mh (NATDEPFILES): Likewise.
	* config/sparc/linux.mh (NATDEPFILES): Likewise.
	* config/sparc/linux64.mh (NATDEPFILES): Likewise.

1 files changed, 1370 insertions, 0 deletions

diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
new file mode 100644
index 0000000..65d9fd5
--- /dev/null
+++ b/gdb/linux-thread-db.c
@@ -0,0 +1,1370 @@
+/* libthread_db assisted debugging support, generic parts.
+
+   Copyright 1999, 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include "defs.h"
+
+#include "gdb_assert.h"
+#include <dlfcn.h>
+#include "gdb_proc_service.h"
+#include "gdb_thread_db.h"
+
+#include "bfd.h"
+#include "gdbthread.h"
+#include "inferior.h"
+#include "symfile.h"
+#include "objfiles.h"
+#include "target.h"
+#include "regcache.h"
+#include "solib-svr4.h"
+
+#ifdef HAVE_GNU_LIBC_VERSION_H
+#include <gnu/libc-version.h>
+#endif
+
+#ifndef LIBTHREAD_DB_SO
+#define LIBTHREAD_DB_SO "libthread_db.so.1"
+#endif
+
+/* If we're running on GNU/Linux, we must explicitly attach to any new
+   threads.  */
+
+/* FIXME: There is certainly some room for improvements:
+   - Cache LWP ids.
+   - Bypass libthread_db when fetching or storing registers for
+   threads bound to a LWP.  */
+
+/* This module's target vector.  */
+static struct target_ops thread_db_ops;
+
+/* The target vector that we call for things this module can't handle.  */
+static struct target_ops *target_beneath;
+
+/* Pointer to the next function on the objfile event chain.  */
+static void (*target_new_objfile_chain) (struct objfile * objfile);
+
+/* Non-zero if we're using this module's target vector.  */
+static int using_thread_db;
+
+/* Non-zero if we have determined the signals used by the threads
+   library.  */
+static int thread_signals;
+static sigset_t thread_stop_set;
+static sigset_t thread_print_set;
+
+/* Structure that identifies the child process for the
+   <proc_service.h> interface.  */
+static struct ps_prochandle proc_handle;
+
+/* Connection to the libthread_db library.  */
+static td_thragent_t *thread_agent;
+
+/* Pointers to the libthread_db functions.  */
+
+static td_err_e (*td_init_p) (void);
+
+static td_err_e (*td_ta_new_p) (struct ps_prochandle * ps,
+				td_thragent_t **ta);
+static td_err_e (*td_ta_map_id2thr_p) (const td_thragent_t *ta, thread_t pt,
+				       td_thrhandle_t *__th);
+static td_err_e (*td_ta_map_lwp2thr_p) (const td_thragent_t *ta,
+					lwpid_t lwpid, td_thrhandle_t *th);
+static td_err_e (*td_ta_thr_iter_p) (const td_thragent_t *ta,
+				     td_thr_iter_f *callback, void *cbdata_p,
+				     td_thr_state_e state, int ti_pri,
+				     sigset_t *ti_sigmask_p,
+				     unsigned int ti_user_flags);
+static td_err_e (*td_ta_event_addr_p) (const td_thragent_t *ta,
+				       td_event_e event, td_notify_t *ptr);
+static td_err_e (*td_ta_set_event_p) (const td_thragent_t *ta,
+				      td_thr_events_t *event);
+static td_err_e (*td_ta_event_getmsg_p) (const td_thragent_t *ta,
+					 td_event_msg_t *msg);
+
+static td_err_e (*td_thr_validate_p) (const td_thrhandle_t *th);
+static td_err_e (*td_thr_get_info_p) (const td_thrhandle_t *th,
+				      td_thrinfo_t *infop);
+static td_err_e (*td_thr_getfpregs_p) (const td_thrhandle_t *th,
+				       gdb_prfpregset_t *regset);
+static td_err_e (*td_thr_getgregs_p) (const td_thrhandle_t *th,
+				      prgregset_t gregs);
+static td_err_e (*td_thr_setfpregs_p) (const td_thrhandle_t *th,
+				       const gdb_prfpregset_t *fpregs);
+static td_err_e (*td_thr_setgregs_p) (const td_thrhandle_t *th,
+				      prgregset_t gregs);
+static td_err_e (*td_thr_event_enable_p) (const td_thrhandle_t *th,
+					  int event);
+
+static td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
+					  void *map_address,
+					  size_t offset, void **address);
+
+/* Location of the thread creation event breakpoint.  The code at this
+   location in the child process will be called by the pthread library
+   whenever a new thread is created.  By setting a special breakpoint
+   at this location, GDB can detect when a new thread is created.  We
+   obtain this location via the td_ta_event_addr call.  */
+static CORE_ADDR td_create_bp_addr;
+
+/* Location of the thread death event breakpoint.  */
+static CORE_ADDR td_death_bp_addr;
+
+/* Prototypes for local functions.  */
+static void thread_db_find_new_threads (void);
+static void attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
+			   const td_thrinfo_t *ti_p, int verbose);
+static void detach_thread (ptid_t ptid, int verbose);
+
+
+/* Building process ids.  */
+
+#define GET_PID(ptid)		ptid_get_pid (ptid)
+#define GET_LWP(ptid)		ptid_get_lwp (ptid)
+#define GET_THREAD(ptid)	ptid_get_tid (ptid)
+
+#define is_lwp(ptid)		(GET_LWP (ptid) != 0)
+#define is_thread(ptid)		(GET_THREAD (ptid) != 0)
+
+#define BUILD_LWP(lwp, pid)	ptid_build (pid, lwp, 0)
+#define BUILD_THREAD(tid, pid)	ptid_build (pid, 0, tid)
+
+
+/* Use "struct private_thread_info" to cache thread state.  This is
+   a substantial optimization.  */
+
+struct private_thread_info
+{
+  /* Flag set when we see a TD_DEATH event for this thread.  */
+  unsigned int dying:1;
+
+  /* Cached thread state.  */
+  unsigned int th_valid:1;
+  unsigned int ti_valid:1;
+
+  td_thrhandle_t th;
+  td_thrinfo_t ti;
+};
+
+
+static char *
+thread_db_err_str (td_err_e err)
+{
+  static char buf[64];
+
+  switch (err)
+    {
+    case TD_OK:
+      return "generic 'call succeeded'";
+    case TD_ERR:
+      return "generic error";
+    case TD_NOTHR:
+      return "no thread to satisfy query";
+    case TD_NOSV:
+      return "no sync handle to satisfy query";
+    case TD_NOLWP:
+      return "no LWP to satisfy query";
+    case TD_BADPH:
+      return "invalid process handle";
+    case TD_BADTH:
+      return "invalid thread handle";
+    case TD_BADSH:
+      return "invalid synchronization handle";
+    case TD_BADTA:
+      return "invalid thread agent";
+    case TD_BADKEY:
+      return "invalid key";
+    case TD_NOMSG:
+      return "no event message for getmsg";
+    case TD_NOFPREGS:
+      return "FPU register set not available";
+    case TD_NOLIBTHREAD:
+      return "application not linked with libthread";
+    case TD_NOEVENT:
+      return "requested event is not supported";
+    case TD_NOCAPAB:
+      return "capability not available";
+    case TD_DBERR:
+      return "debugger service failed";
+    case TD_NOAPLIC:
+      return "operation not applicable to";
+    case TD_NOTSD:
+      return "no thread-specific data for this thread";
+    case TD_MALLOC:
+      return "malloc failed";
+    case TD_PARTIALREG:
+      return "only part of register set was written/read";
+    case TD_NOXREGS:
+      return "X register set not available for this thread";
+    default:
+      snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
+      return buf;
+    }
+}
+
+static char *
+thread_db_state_str (td_thr_state_e state)
+{
+  static char buf[64];
+
+  switch (state)
+    {
+    case TD_THR_STOPPED:
+      return "stopped by debugger";
+    case TD_THR_RUN:
+      return "runnable";
+    case TD_THR_ACTIVE:
+      return "active";
+    case TD_THR_ZOMBIE:
+      return "zombie";
+    case TD_THR_SLEEP:
+      return "sleeping";
+    case TD_THR_STOPPED_ASLEEP:
+      return "stopped by debugger AND blocked";
+    default:
+      snprintf (buf, sizeof (buf), "unknown thread_db state %d", state);
+      return buf;
+    }
+}
+
+/* A callback function for td_ta_thr_iter, which we use to map all
+   threads to LWPs.
+
+   THP is a handle to the current thread; if INFOP is not NULL, the
+   struct thread_info associated with this thread is returned in
+   *INFOP.
+
+   If the thread is a zombie, TD_THR_ZOMBIE is returned.  Otherwise,
+   zero is returned to indicate success.  */
+
+static int
+thread_get_info_callback (const td_thrhandle_t *thp, void *infop)
+{
+  td_thrinfo_t ti;
+  td_err_e err;
+  struct thread_info *thread_info;
+  ptid_t thread_ptid;
+
+  err = td_thr_get_info_p (thp, &ti);
+  if (err != TD_OK)
+    error ("thread_get_info_callback: cannot get thread info: %s",
+	   thread_db_err_str (err));
+
+  /* Fill the cache.  */
+  thread_ptid = BUILD_THREAD (ti.ti_tid, GET_PID (inferior_ptid));
+  thread_info = find_thread_pid (thread_ptid);
+
+  /* In the case of a zombie thread, don't continue.  We don't want to
+     attach to it thinking it is a new thread.  */
+  if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
+    {
+      if (infop != NULL)
+        *(struct thread_info **) infop = thread_info;
+      if (thread_info != NULL)
+	{
+	  memcpy (&thread_info->private->th, thp, sizeof (*thp));
+	  thread_info->private->th_valid = 1;
+	  memcpy (&thread_info->private->ti, &ti, sizeof (ti));
+	  thread_info->private->ti_valid = 1;
+	}
+      return TD_THR_ZOMBIE;
+    }
+
+  if (thread_info == NULL)
+    {
+      /* New thread.  Attach to it now (why wait?).  */
+      attach_thread (thread_ptid, thp, &ti, 1);
+      thread_info = find_thread_pid (thread_ptid);
+      gdb_assert (thread_info != NULL);
+    }
+
+  memcpy (&thread_info->private->th, thp, sizeof (*thp));
+  thread_info->private->th_valid = 1;
+  memcpy (&thread_info->private->ti, &ti, sizeof (ti));
+  thread_info->private->ti_valid = 1;
+
+  if (infop != NULL)
+    *(struct thread_info **) infop = thread_info;
+
+  return 0;
+}
+
+/* Accessor functions for the thread_db information, with caching.  */
+
+static void
+thread_db_map_id2thr (struct thread_info *thread_info, int fatal)
+{
+  td_err_e err;
+
+  if (thread_info->private->th_valid)
+    return;
+
+  err = td_ta_map_id2thr_p (thread_agent, GET_THREAD (thread_info->ptid),
+			    &thread_info->private->th);
+  if (err != TD_OK)
+    {
+      if (fatal)
+	error ("Cannot find thread %ld: %s",
+	       (long) GET_THREAD (thread_info->ptid),
+	       thread_db_err_str (err));
+    }
+  else
+    thread_info->private->th_valid = 1;
+}
+
+static td_thrinfo_t *
+thread_db_get_info (struct thread_info *thread_info)
+{
+  td_err_e err;
+
+  if (thread_info->private->ti_valid)
+    return &thread_info->private->ti;
+
+  if (!thread_info->private->th_valid)
+    thread_db_map_id2thr (thread_info, 1);
+
+  err =
+    td_thr_get_info_p (&thread_info->private->th, &thread_info->private->ti);
+  if (err != TD_OK)
+    error ("thread_db_get_info: cannot get thread info: %s",
+	   thread_db_err_str (err));
+
+  thread_info->private->ti_valid = 1;
+  return &thread_info->private->ti;
+}
+
+/* Convert between user-level thread ids and LWP ids.  */
+
+static ptid_t
+thread_from_lwp (ptid_t ptid)
+{
+  td_thrhandle_t th;
+  td_err_e err;
+  struct thread_info *thread_info;
+  ptid_t thread_ptid;
+
+  if (GET_LWP (ptid) == 0)
+    ptid = BUILD_LWP (GET_PID (ptid), GET_PID (ptid));
+
+  gdb_assert (is_lwp (ptid));
+
+  err = td_ta_map_lwp2thr_p (thread_agent, GET_LWP (ptid), &th);
+  if (err != TD_OK)
+    error ("Cannot find user-level thread for LWP %ld: %s",
+	   GET_LWP (ptid), thread_db_err_str (err));
+
+  thread_info = NULL;
+
+  /* Fetch the thread info.  If we get back TD_THR_ZOMBIE, then the
+     event thread has already died.  If another gdb interface has called
+     thread_alive() previously, the thread won't be found on the thread list
+     anymore.  In that case, we don't want to process this ptid anymore
+     to avoid the possibility of later treating it as a newly
+     discovered thread id that we should add to the list.  Thus,
+     we return a -1 ptid which is also how the thread list marks a
+     dead thread.  */
+  if (thread_get_info_callback (&th, &thread_info) == TD_THR_ZOMBIE
+      && thread_info == NULL)
+    return pid_to_ptid (-1);
+
+  gdb_assert (thread_info && thread_info->private->ti_valid);
+
+  return BUILD_THREAD (thread_info->private->ti.ti_tid, GET_PID (ptid));
+}
+
+static ptid_t
+lwp_from_thread (ptid_t ptid)
+{
+  struct thread_info *thread_info;
+  ptid_t thread_ptid;
+
+  if (!is_thread (ptid))
+    return ptid;
+
+  thread_info = find_thread_pid (ptid);
+  thread_db_get_info (thread_info);
+
+  return BUILD_LWP (thread_info->private->ti.ti_lid, GET_PID (ptid));
+}
+
+
+void
+thread_db_init (struct target_ops *target)
+{
+  target_beneath = target;
+}
+
+static void *
+verbose_dlsym (void *handle, const char *name)
+{
+  void *sym = dlsym (handle, name);
+  if (sym == NULL)
+    warning ("Symbol \"%s\" not found in libthread_db: %s", name, dlerror ());
+  return sym;
+}
+
+static int
+thread_db_load (void)
+{
+  void *handle;
+  td_err_e err;
+
+  handle = dlopen (LIBTHREAD_DB_SO, RTLD_NOW);
+  if (handle == NULL)
+    {
+      fprintf_filtered (gdb_stderr, "\n\ndlopen failed on '%s' - %s\n",
+			LIBTHREAD_DB_SO, dlerror ());
+      fprintf_filtered (gdb_stderr,
+			"GDB will not be able to debug pthreads.\n\n");
+      return 0;
+    }
+
+  /* Initialize pointers to the dynamic library functions we will use.
+     Essential functions first.  */
+
+  td_init_p = verbose_dlsym (handle, "td_init");
+  if (td_init_p == NULL)
+    return 0;
+
+  td_ta_new_p = verbose_dlsym (handle, "td_ta_new");
+  if (td_ta_new_p == NULL)
+    return 0;
+
+  td_ta_map_id2thr_p = verbose_dlsym (handle, "td_ta_map_id2thr");
+  if (td_ta_map_id2thr_p == NULL)
+    return 0;
+
+  td_ta_map_lwp2thr_p = verbose_dlsym (handle, "td_ta_map_lwp2thr");
+  if (td_ta_map_lwp2thr_p == NULL)
+    return 0;
+
+  td_ta_thr_iter_p = verbose_dlsym (handle, "td_ta_thr_iter");
+  if (td_ta_thr_iter_p == NULL)
+    return 0;
+
+  td_thr_validate_p = verbose_dlsym (handle, "td_thr_validate");
+  if (td_thr_validate_p == NULL)
+    return 0;
+
+  td_thr_get_info_p = verbose_dlsym (handle, "td_thr_get_info");
+  if (td_thr_get_info_p == NULL)
+    return 0;
+
+  td_thr_getfpregs_p = verbose_dlsym (handle, "td_thr_getfpregs");
+  if (td_thr_getfpregs_p == NULL)
+    return 0;
+
+  td_thr_getgregs_p = verbose_dlsym (handle, "td_thr_getgregs");
+  if (td_thr_getgregs_p == NULL)
+    return 0;
+
+  td_thr_setfpregs_p = verbose_dlsym (handle, "td_thr_setfpregs");
+  if (td_thr_setfpregs_p == NULL)
+    return 0;
+
+  td_thr_setgregs_p = verbose_dlsym (handle, "td_thr_setgregs");
+  if (td_thr_setgregs_p == NULL)
+    return 0;
+
+  /* Initialize the library.  */
+  err = td_init_p ();
+  if (err != TD_OK)
+    {
+      warning ("Cannot initialize libthread_db: %s", thread_db_err_str (err));
+      return 0;
+    }
+
+  /* These are not essential.  */
+  td_ta_event_addr_p = dlsym (handle, "td_ta_event_addr");
+  td_ta_set_event_p = dlsym (handle, "td_ta_set_event");
+  td_ta_event_getmsg_p = dlsym (handle, "td_ta_event_getmsg");
+  td_thr_event_enable_p = dlsym (handle, "td_thr_event_enable");
+  td_thr_tls_get_addr_p = dlsym (handle, "td_thr_tls_get_addr");
+
+  return 1;
+}
+
+static td_err_e
+enable_thread_event (td_thragent_t *thread_agent, int event, CORE_ADDR *bp)
+{
+  td_notify_t notify;
+  td_err_e err;
+
+  /* Get the breakpoint address for thread EVENT.  */
+  err = td_ta_event_addr_p (thread_agent, event, &notify);
+  if (err != TD_OK)
+    return err;
+
+  /* Set up the breakpoint.  */
+  (*bp) = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
+					      (CORE_ADDR) notify.u.bptaddr,
+					      &current_target);
+  create_thread_event_breakpoint ((*bp));
+
+  return TD_OK;
+}
+
+static void
+enable_thread_event_reporting (void)
+{
+  td_thr_events_t events;
+  td_notify_t notify;
+  td_err_e err;
+#ifdef HAVE_GNU_LIBC_VERSION_H
+  const char *libc_version;
+  int libc_major, libc_minor;
+#endif
+
+  /* We cannot use the thread event reporting facility if these
+     functions aren't available.  */
+  if (td_ta_event_addr_p == NULL || td_ta_set_event_p == NULL
+      || td_ta_event_getmsg_p == NULL || td_thr_event_enable_p == NULL)
+    return;
+
+  /* Set the process wide mask saying which events we're interested in.  */
+  td_event_emptyset (&events);
+  td_event_addset (&events, TD_CREATE);
+
+#ifdef HAVE_GNU_LIBC_VERSION_H
+  /* FIXME: kettenis/2000-04-23: The event reporting facility is
+     broken for TD_DEATH events in glibc 2.1.3, so don't enable it for
+     now.  */
+  libc_version = gnu_get_libc_version ();
+  if (sscanf (libc_version, "%d.%d", &libc_major, &libc_minor) == 2
+      && (libc_major > 2 || (libc_major == 2 && libc_minor > 1)))
+#endif
+    td_event_addset (&events, TD_DEATH);
+
+  err = td_ta_set_event_p (thread_agent, &events);
+  if (err != TD_OK)
+    {
+      warning ("Unable to set global thread event mask: %s",
+	       thread_db_err_str (err));
+      return;
+    }
+
+  /* Delete previous thread event breakpoints, if any.  */
+  remove_thread_event_breakpoints ();
+  td_create_bp_addr = 0;
+  td_death_bp_addr = 0;
+
+  /* Set up the thread creation event.  */
+  err = enable_thread_event (thread_agent, TD_CREATE, &td_create_bp_addr);
+  if (err != TD_OK)
+    {
+      warning ("Unable to get location for thread creation breakpoint: %s",
+	       thread_db_err_str (err));
+      return;
+    }
+
+  /* Set up the thread death event.  */
+  err = enable_thread_event (thread_agent, TD_DEATH, &td_death_bp_addr);
+  if (err != TD_OK)
+    {
+      warning ("Unable to get location for thread death breakpoint: %s",
+	       thread_db_err_str (err));
+      return;
+    }
+}
+
+static void
+disable_thread_event_reporting (void)
+{
+  td_thr_events_t events;
+
+  /* Set the process wide mask saying we aren't interested in any
+     events anymore.  */
+  td_event_emptyset (&events);
+  td_ta_set_event_p (thread_agent, &events);
+
+  /* Delete thread event breakpoints, if any.  */
+  remove_thread_event_breakpoints ();
+  td_create_bp_addr = 0;
+  td_death_bp_addr = 0;
+}
+
+static void
+check_thread_signals (void)
+{
+#ifdef GET_THREAD_SIGNALS
+  if (!thread_signals)
+    {
+      sigset_t mask;
+      int i;
+
+      GET_THREAD_SIGNALS (&mask);
+      sigemptyset (&thread_stop_set);
+      sigemptyset (&thread_print_set);
+
+      for (i = 1; i < NSIG; i++)
+	{
+	  if (sigismember (&mask, i))
+	    {
+	      if (signal_stop_update (target_signal_from_host (i), 0))
+		sigaddset (&thread_stop_set, i);
+	      if (signal_print_update (target_signal_from_host (i), 0))
+		sigaddset (&thread_print_set, i);
+	      thread_signals = 1;
+	    }
+	}
+    }
+#endif
+}
+
+static void
+thread_db_new_objfile (struct objfile *objfile)
+{
+  td_err_e err;
+
+  /* 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;
+      }
+  }
+
+  /* Don't attempt to use thread_db on targets which can not run
+     (core files).  */
+  if (objfile == NULL || !target_has_execution)
+    {
+      /* 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;
+	}
+
+      goto quit;
+    }
+
+  if (using_thread_db)
+    /* Nothing to do.  The thread library was already detected and the
+       target vector was already activated.  */
+    goto quit;
+
+  /* Initialize the structure that identifies the child process.  Note
+     that at this point there is no guarantee that we actually have a
+     child process.  */
+  proc_handle.pid = GET_PID (inferior_ptid);
+
+  /* Now attempt to open a connection to the thread library.  */
+  err = td_ta_new_p (&proc_handle, &thread_agent);
+  switch (err)
+    {
+    case TD_NOLIBTHREAD:
+      /* No thread library was detected.  */
+      break;
+
+    case TD_OK:
+      printf_unfiltered ("[Thread debugging using libthread_db enabled]\n");
+
+      /* The thread library was detected.  Activate the thread_db target.  */
+      push_target (&thread_db_ops);
+      using_thread_db = 1;
+
+      enable_thread_event_reporting ();
+      thread_db_find_new_threads ();
+      break;
+
+    default:
+      warning ("Cannot initialize thread debugging library: %s",
+	       thread_db_err_str (err));
+      break;
+    }
+
+quit:
+  if (target_new_objfile_chain)
+    target_new_objfile_chain (objfile);
+}
+
+/* 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.  */
+
+static void
+attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
+	       const td_thrinfo_t *ti_p, int verbose)
+{
+  struct thread_info *tp;
+  td_err_e err;
+
+  /* If we're being called after a TD_CREATE event, we may already
+     know about this thread.  There are two ways this can happen.  We
+     may have iterated over all threads between the thread creation
+     and the TD_CREATE event, for instance when the user has issued
+     the `info threads' command before the SIGTRAP for hitting the
+     thread creation breakpoint was reported.  Alternatively, the
+     thread may have exited and a new one been created with the same
+     thread ID.  In the first case we don't need to do anything; in
+     the second case we should discard information about the dead
+     thread and attach to the new one.  */
+  if (in_thread_list (ptid))
+    {
+      tp = find_thread_pid (ptid);
+      gdb_assert (tp != NULL);
+
+      if (!tp->private->dying)
+        return;
+
+      delete_thread (ptid);
+    }
+
+  check_thread_signals ();
+
+  /* Add the thread to GDB's thread list.  */
+  tp = add_thread (ptid);
+  tp->private = xmalloc (sizeof (struct private_thread_info));
+  memset (tp->private, 0, sizeof (struct private_thread_info));
+
+  if (verbose)
+    printf_unfiltered ("[New %s]\n", target_pid_to_str (ptid));
+
+  if (ti_p->ti_state == TD_THR_UNKNOWN || ti_p->ti_state == TD_THR_ZOMBIE)
+    return;			/* A zombie thread -- do not attach.  */
+
+  /* Under GNU/Linux, we have to attach to each and every thread.  */
+#ifdef ATTACH_LWP
+  ATTACH_LWP (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid)), 0);
+#endif
+
+  /* Enable thread event reporting for this thread.  */
+  err = td_thr_event_enable_p (th_p, 1);
+  if (err != TD_OK)
+    error ("Cannot enable thread event reporting for %s: %s",
+	   target_pid_to_str (ptid), thread_db_err_str (err));
+}
+
+static void
+thread_db_attach (char *args, int from_tty)
+{
+  target_beneath->to_attach (args, from_tty);
+
+  /* Destroy thread info; it's no longer valid.  */
+  init_thread_list ();
+
+  /* The child process is now the actual multi-threaded
+     program.  Snatch its process ID...  */
+  proc_handle.pid = GET_PID (inferior_ptid);
+
+  /* ...and perform the remaining initialization steps.  */
+  enable_thread_event_reporting ();
+  thread_db_find_new_threads ();
+}
+
+static void
+detach_thread (ptid_t ptid, int verbose)
+{
+  struct thread_info *thread_info;
+
+  if (verbose)
+    printf_unfiltered ("[%s exited]\n", target_pid_to_str (ptid));
+
+  /* Don't delete the thread now, because it still reports as active
+     until it has executed a few instructions after the event
+     breakpoint - if we deleted it now, "info threads" would cause us
+     to re-attach to it.  Just mark it as having had a TD_DEATH
+     event.  This means that we won't delete it from our thread list
+     until we notice that it's dead (via prune_threads), or until
+     something re-uses its thread ID.  */
+  thread_info = find_thread_pid (ptid);
+  gdb_assert (thread_info != NULL);
+  thread_info->private->dying = 1;
+}
+
+static void
+thread_db_detach (char *args, int from_tty)
+{
+  disable_thread_event_reporting ();
+
+  /* There's no need to save & restore inferior_ptid here, since the
+     inferior is supposed to be survive this function call.  */
+  inferior_ptid = lwp_from_thread (inferior_ptid);
+
+  /* Forget about the child's process ID.  We shouldn't need it
+     anymore.  */
+  proc_handle.pid = 0;
+
+  target_beneath->to_detach (args, from_tty);
+}
+
+static int
+clear_lwpid_callback (struct thread_info *thread, void *dummy)
+{
+  /* If we know that our thread implementation is 1-to-1, we could save
+     a certain amount of information; it's not clear how much, so we
+     are always conservative.  */
+
+  thread->private->th_valid = 0;
+  thread->private->ti_valid = 0;
+
+  return 0;
+}
+
+static void
+thread_db_resume (ptid_t ptid, int step, enum target_signal signo)
+{
+  struct cleanup *old_chain = save_inferior_ptid ();
+
+  if (GET_PID (ptid) == -1)
+    inferior_ptid = lwp_from_thread (inferior_ptid);
+  else if (is_thread (ptid))
+    ptid = lwp_from_thread (ptid);
+
+  /* Clear cached data which may not be valid after the resume.  */
+  iterate_over_threads (clear_lwpid_callback, NULL);
+
+  target_beneath->to_resume (ptid, step, signo);
+
+  do_cleanups (old_chain);
+}
+
+/* Check if PID is currently stopped at the location of a thread event
+   breakpoint location.  If it is, read the event message and act upon
+   the event.  */
+
+static void
+check_event (ptid_t ptid)
+{
+  td_event_msg_t msg;
+  td_thrinfo_t ti;
+  td_err_e err;
+  CORE_ADDR stop_pc;
+  int loop = 0;
+
+  /* Bail out early if we're not at a thread event breakpoint.  */
+  stop_pc = read_pc_pid (ptid) - DECR_PC_AFTER_BREAK;
+  if (stop_pc != td_create_bp_addr && stop_pc != td_death_bp_addr)
+    return;
+
+  /* If we are at a create breakpoint, we do not know what new lwp
+     was created and cannot specifically locate the event message for it.
+     We have to call td_ta_event_getmsg() to get
+     the latest message.  Since we have no way of correlating whether
+     the event message we get back corresponds to our breakpoint, we must
+     loop and read all event messages, processing them appropriately.
+     This guarantees we will process the correct message before continuing
+     from the breakpoint.
+
+     Currently, death events are not enabled.  If they are enabled,
+     the death event can use the td_thr_event_getmsg() interface to
+     get the message specifically for that lwp and avoid looping
+     below.  */
+
+  loop = 1;
+
+  do
+    {
+      err = td_ta_event_getmsg_p (thread_agent, &msg);
+      if (err != TD_OK)
+	{
+	  if (err == TD_NOMSG)
+	    return;
+
+	  error ("Cannot get thread event message: %s",
+		 thread_db_err_str (err));
+	}
+
+      err = td_thr_get_info_p (msg.th_p, &ti);
+      if (err != TD_OK)
+	error ("Cannot get thread info: %s", thread_db_err_str (err));
+
+      ptid = BUILD_THREAD (ti.ti_tid, GET_PID (ptid));
+
+      switch (msg.event)
+	{
+	case TD_CREATE:
+	  /* Call attach_thread whether or not we already know about a
+	     thread with this thread ID.  */
+	  attach_thread (ptid, msg.th_p, &ti, 1);
+
+	  break;
+
+	case TD_DEATH:
+
+	  if (!in_thread_list (ptid))
+	    error ("Spurious thread death event.");
+
+	  detach_thread (ptid, 1);
+
+	  break;
+
+	default:
+	  error ("Spurious thread event.");
+	}
+    }
+  while (loop);
+}
+
+static ptid_t
+thread_db_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
+{
+  extern ptid_t trap_ptid;
+
+  if (GET_PID (ptid) != -1 && is_thread (ptid))
+    ptid = lwp_from_thread (ptid);
+
+  ptid = target_beneath->to_wait (ptid, ourstatus);
+
+  if (proc_handle.pid == 0)
+    /* The current child process isn't the actual multi-threaded
+       program yet, so don't try to do any special thread-specific
+       post-processing and bail out early.  */
+    return ptid;
+
+  if (ourstatus->kind == TARGET_WAITKIND_EXITED)
+    return pid_to_ptid (-1);
+
+  if (ourstatus->kind == TARGET_WAITKIND_STOPPED
+      && ourstatus->value.sig == TARGET_SIGNAL_TRAP)
+    /* Check for a thread event.  */
+    check_event (ptid);
+
+  if (!ptid_equal (trap_ptid, null_ptid))
+    trap_ptid = thread_from_lwp (trap_ptid);
+
+  /* Change the ptid back into the higher level PID + TID format.
+     If the thread is dead and no longer on the thread list, we will 
+     get back a dead ptid.  This can occur if the thread death event
+     gets postponed by other simultaneous events.  In such a case, 
+     we want to just ignore the event and continue on.  */
+  ptid = thread_from_lwp (ptid);
+  if (GET_PID (ptid) == -1)
+    ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
+  
+  return ptid;
+}
+
+static int
+thread_db_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write,
+		       struct mem_attrib *attrib, struct target_ops *target)
+{
+  struct cleanup *old_chain = save_inferior_ptid ();
+  int xfer;
+
+  if (is_thread (inferior_ptid))
+    {
+      /* FIXME: This seems to be necessary to make sure breakpoints
+         are removed.  */
+      if (!target_thread_alive (inferior_ptid))
+	inferior_ptid = pid_to_ptid (GET_PID (inferior_ptid));
+      else
+	inferior_ptid = lwp_from_thread (inferior_ptid);
+    }
+
+  xfer =
+    target_beneath->deprecated_xfer_memory (memaddr, myaddr, len, write,
+					    attrib, target);
+
+  do_cleanups (old_chain);
+  return xfer;
+}
+
+static void
+thread_db_fetch_registers (int regno)
+{
+  struct thread_info *thread_info;
+  prgregset_t gregset;
+  gdb_prfpregset_t fpregset;
+  td_err_e err;
+
+  if (!is_thread (inferior_ptid))
+    {
+      /* Pass the request to the target beneath us.  */
+      target_beneath->to_fetch_registers (regno);
+      return;
+    }
+
+  thread_info = find_thread_pid (inferior_ptid);
+  thread_db_map_id2thr (thread_info, 1);
+
+  err = td_thr_getgregs_p (&thread_info->private->th, gregset);
+  if (err != TD_OK)
+    error ("Cannot fetch general-purpose registers for thread %ld: %s",
+	   (long) GET_THREAD (inferior_ptid), thread_db_err_str (err));
+
+  err = td_thr_getfpregs_p (&thread_info->private->th, &fpregset);
+  if (err != TD_OK)
+    error ("Cannot get floating-point registers for thread %ld: %s",
+	   (long) GET_THREAD (inferior_ptid), thread_db_err_str (err));
+
+  /* Note that we must call supply_gregset after calling the thread_db
+     routines because the thread_db routines call ps_lgetgregs and
+     friends which clobber GDB's register cache.  */
+  supply_gregset ((gdb_gregset_t *) gregset);
+  supply_fpregset (&fpregset);
+}
+
+static void
+thread_db_store_registers (int regno)
+{
+  prgregset_t gregset;
+  gdb_prfpregset_t fpregset;
+  td_err_e err;
+  struct thread_info *thread_info;
+
+  if (!is_thread (inferior_ptid))
+    {
+      /* Pass the request to the target beneath us.  */
+      target_beneath->to_store_registers (regno);
+      return;
+    }
+
+  thread_info = find_thread_pid (inferior_ptid);
+  thread_db_map_id2thr (thread_info, 1);
+
+  if (regno != -1)
+    {
+      char raw[MAX_REGISTER_SIZE];
+
+      deprecated_read_register_gen (regno, raw);
+      thread_db_fetch_registers (-1);
+      regcache_raw_supply (current_regcache, regno, raw);
+    }
+
+  fill_gregset ((gdb_gregset_t *) gregset, -1);
+  fill_fpregset (&fpregset, -1);
+
+  err = td_thr_setgregs_p (&thread_info->private->th, gregset);
+  if (err != TD_OK)
+    error ("Cannot store general-purpose registers for thread %ld: %s",
+	   (long) GET_THREAD (inferior_ptid), thread_db_err_str (err));
+  err = td_thr_setfpregs_p (&thread_info->private->th, &fpregset);
+  if (err != TD_OK)
+    error ("Cannot store floating-point registers  for thread %ld: %s",
+	   (long) GET_THREAD (inferior_ptid), thread_db_err_str (err));
+}
+
+static void
+thread_db_kill (void)
+{
+  /* There's no need to save & restore inferior_ptid here, since the
+     inferior isn't supposed to survive this function call.  */
+  inferior_ptid = lwp_from_thread (inferior_ptid);
+  target_beneath->to_kill ();
+}
+
+static void
+thread_db_create_inferior (char *exec_file, char *allargs, char **env,
+			   int from_tty)
+{
+  unpush_target (&thread_db_ops);
+  using_thread_db = 0;
+  target_beneath->to_create_inferior (exec_file, allargs, env, from_tty);
+}
+
+static void
+thread_db_post_startup_inferior (ptid_t ptid)
+{
+  if (proc_handle.pid == 0)
+    {
+      /* The child process is now the actual multi-threaded
+         program.  Snatch its process ID...  */
+      proc_handle.pid = GET_PID (ptid);
+
+      /* ...and perform the remaining initialization steps.  */
+      enable_thread_event_reporting ();
+      thread_db_find_new_threads ();
+    }
+}
+
+static void
+thread_db_mourn_inferior (void)
+{
+  remove_thread_event_breakpoints ();
+
+  /* Forget about the child's process ID.  We shouldn't need it
+     anymore.  */
+  proc_handle.pid = 0;
+
+  target_beneath->to_mourn_inferior ();
+
+  /* Detach thread_db target ops.  */
+  unpush_target (&thread_db_ops);
+  using_thread_db = 0;
+}
+
+static int
+thread_db_thread_alive (ptid_t ptid)
+{
+  td_thrhandle_t th;
+  td_err_e err;
+
+  if (is_thread (ptid))
+    {
+      struct thread_info *thread_info;
+      thread_info = find_thread_pid (ptid);
+
+      thread_db_map_id2thr (thread_info, 0);
+      if (!thread_info->private->th_valid)
+	return 0;
+
+      err = td_thr_validate_p (&thread_info->private->th);
+      if (err != TD_OK)
+	return 0;
+
+      if (!thread_info->private->ti_valid)
+	{
+	  err =
+	    td_thr_get_info_p (&thread_info->private->th,
+			       &thread_info->private->ti);
+	  if (err != TD_OK)
+	    return 0;
+	  thread_info->private->ti_valid = 1;
+	}
+
+      if (thread_info->private->ti.ti_state == TD_THR_UNKNOWN
+	  || thread_info->private->ti.ti_state == TD_THR_ZOMBIE)
+	return 0;		/* A zombie thread.  */
+
+      return 1;
+    }
+
+  if (target_beneath->to_thread_alive)
+    return target_beneath->to_thread_alive (ptid);
+
+  return 0;
+}
+
+static int
+find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
+{
+  td_thrinfo_t ti;
+  td_err_e err;
+  ptid_t ptid;
+
+  err = td_thr_get_info_p (th_p, &ti);
+  if (err != TD_OK)
+    error ("find_new_threads_callback: cannot get thread info: %s",
+	   thread_db_err_str (err));
+
+  if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
+    return 0;			/* A zombie -- ignore.  */
+
+  ptid = BUILD_THREAD (ti.ti_tid, GET_PID (inferior_ptid));
+
+  if (!in_thread_list (ptid))
+    attach_thread (ptid, th_p, &ti, 1);
+
+  return 0;
+}
+
+static void
+thread_db_find_new_threads (void)
+{
+  td_err_e err;
+
+  /* Iterate over all user-space threads to discover new threads.  */
+  err = td_ta_thr_iter_p (thread_agent, find_new_threads_callback, NULL,
+			  TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
+			  TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
+  if (err != TD_OK)
+    error ("Cannot find new threads: %s", thread_db_err_str (err));
+}
+
+static char *
+thread_db_pid_to_str (ptid_t ptid)
+{
+  if (is_thread (ptid))
+    {
+      static char buf[64];
+      td_thrinfo_t *ti_p;
+      td_err_e err;
+      struct thread_info *thread_info;
+
+      thread_info = find_thread_pid (ptid);
+      thread_db_map_id2thr (thread_info, 0);
+      if (!thread_info->private->th_valid)
+	{
+	  snprintf (buf, sizeof (buf), "Thread %ld (Missing)",
+		    GET_THREAD (ptid));
+	  return buf;
+	}
+
+      ti_p = thread_db_get_info (thread_info);
+
+      if (ti_p->ti_state == TD_THR_ACTIVE && ti_p->ti_lid != 0)
+	{
+	  snprintf (buf, sizeof (buf), "Thread %ld (LWP %d)",
+		    (long) ti_p->ti_tid, ti_p->ti_lid);
+	}
+      else
+	{
+	  snprintf (buf, sizeof (buf), "Thread %ld (%s)",
+		    (long) ti_p->ti_tid,
+		    thread_db_state_str (ti_p->ti_state));
+	}
+
+      return buf;
+    }
+
+  if (target_beneath->to_pid_to_str (ptid))
+    return target_beneath->to_pid_to_str (ptid);
+
+  return normal_pid_to_str (ptid);
+}
+
+/* Get the address of the thread local variable in OBJFILE which is
+   stored at OFFSET within the thread local storage for thread PTID.  */
+
+static CORE_ADDR
+thread_db_get_thread_local_address (ptid_t ptid, struct objfile *objfile,
+				    CORE_ADDR offset)
+{
+  if (is_thread (ptid))
+    {
+      int objfile_is_library = (objfile->flags & OBJF_SHARED);
+      td_err_e err;
+      void *address;
+      CORE_ADDR lm;
+      struct thread_info *thread_info;
+
+      /* glibc doesn't provide the needed interface.  */
+      if (!td_thr_tls_get_addr_p)
+	error ("Cannot find thread-local variables in this thread library.");
+
+      /* Get the address of the link map for this objfile.  */
+      lm = svr4_fetch_objfile_link_map (objfile);
+
+      /* Whoops, we couldn't find one. Bail out.  */
+      if (!lm)
+	{
+	  if (objfile_is_library)
+	    error ("Cannot find shared library `%s' link_map in dynamic"
+		   " linker's module list", objfile->name);
+	  else
+	    error ("Cannot find executable file `%s' link_map in dynamic"
+		   " linker's module list", objfile->name);
+	}
+
+      /* Get info about the thread.  */
+      thread_info = find_thread_pid (ptid);
+      thread_db_map_id2thr (thread_info, 1);
+
+      /* Finally, get the address of the variable.  */
+      err = td_thr_tls_get_addr_p (&thread_info->private->th, (void *) lm,
+				   offset, &address);
+
+#ifdef THREAD_DB_HAS_TD_NOTALLOC
+      /* The memory hasn't been allocated, yet.  */
+      if (err == TD_NOTALLOC)
+	{
+	  /* Now, if libthread_db provided the initialization image's
+	     address, we *could* try to build a non-lvalue value from
+	     the initialization image.  */
+	  if (objfile_is_library)
+	    error ("The inferior has not yet allocated storage for"
+		   " thread-local variables in\n"
+		   "the shared library `%s'\n"
+		   "for the thread %ld",
+		   objfile->name, (long) GET_THREAD (ptid));
+	  else
+	    error ("The inferior has not yet allocated storage for"
+		   " thread-local variables in\n"
+		   "the executable `%s'\n"
+		   "for the thread %ld",
+		   objfile->name, (long) GET_THREAD (ptid));
+	}
+#endif
+
+      /* Something else went wrong.  */
+      if (err != TD_OK)
+	{
+	  if (objfile_is_library)
+	    error ("Cannot find thread-local storage for thread %ld, "
+		   "shared library %s:\n%s",
+		   (long) GET_THREAD (ptid),
+		   objfile->name, thread_db_err_str (err));
+	  else
+	    error ("Cannot find thread-local storage for thread %ld, "
+		   "executable file %s:\n%s",
+		   (long) GET_THREAD (ptid),
+		   objfile->name, thread_db_err_str (err));
+	}
+
+      /* Cast assuming host == target.  Joy.  */
+      return (CORE_ADDR) address;
+    }
+
+  if (target_beneath->to_get_thread_local_address)
+    return target_beneath->to_get_thread_local_address (ptid, objfile,
+							offset);
+
+  error ("Cannot find thread-local values on this target.");
+}
+
+static void
+init_thread_db_ops (void)
+{
+  thread_db_ops.to_shortname = "multi-thread";
+  thread_db_ops.to_longname = "multi-threaded child process.";
+  thread_db_ops.to_doc = "Threads and pthreads support.";
+  thread_db_ops.to_attach = thread_db_attach;
+  thread_db_ops.to_detach = thread_db_detach;
+  thread_db_ops.to_resume = thread_db_resume;
+  thread_db_ops.to_wait = thread_db_wait;
+  thread_db_ops.to_fetch_registers = thread_db_fetch_registers;
+  thread_db_ops.to_store_registers = thread_db_store_registers;
+  thread_db_ops.deprecated_xfer_memory = thread_db_xfer_memory;
+  thread_db_ops.to_kill = thread_db_kill;
+  thread_db_ops.to_create_inferior = thread_db_create_inferior;
+  thread_db_ops.to_post_startup_inferior = thread_db_post_startup_inferior;
+  thread_db_ops.to_mourn_inferior = thread_db_mourn_inferior;
+  thread_db_ops.to_thread_alive = thread_db_thread_alive;
+  thread_db_ops.to_find_new_threads = thread_db_find_new_threads;
+  thread_db_ops.to_pid_to_str = thread_db_pid_to_str;
+  thread_db_ops.to_stratum = thread_stratum;
+  thread_db_ops.to_has_thread_control = tc_schedlock;
+  thread_db_ops.to_get_thread_local_address
+    = thread_db_get_thread_local_address;
+  thread_db_ops.to_magic = OPS_MAGIC;
+}
+
+void
+_initialize_thread_db (void)
+{
+  /* Only initialize the module if we can load libthread_db.  */
+  if (thread_db_load ())
+    {
+      init_thread_db_ops ();
+      add_target (&thread_db_ops);
+
+      /* Add ourselves to objfile event chain.  */
+      target_new_objfile_chain = deprecated_target_new_objfile_hook;
+      deprecated_target_new_objfile_hook = thread_db_new_objfile;
+    }
+}