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/* libthread_db assisted debugging support, generic parts.

   Copyright (C) 1999, 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008

   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "gdb_assert.h"

#include <dlfcn.h>

#include "gdb_proc_service.h"

#include "gdb_thread_db.h"

#include "bfd.h"

#include "exceptions.h"

#include "gdbthread.h"

#include "inferior.h"

#include "symfile.h"

#include "objfiles.h"

#include "target.h"

#include "regcache.h"

#include "solib-svr4.h"

#include "gdbcore.h"

#include "observer.h"

#include "linux-nat.h"

#include <signal.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.  */

/* 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;

/* 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_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);

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)

/* 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";

#ifdef THREAD_DB_HAS_TD_NOTALLOC

    case TD_NOTALLOC:

      return "thread has not yet allocated TLS for given module";

#endif

#ifdef THREAD_DB_HAS_TD_VERSION

    case TD_VERSION:

      return "versions of libpthread and libthread_db do not match";

#endif

#ifdef THREAD_DB_HAS_TD_NOTLS

    case TD_NOTLS:

      return "there is no TLS segment in the given module";

#endif

    default:

      snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);

      return buf;

    }

}

/* Return 1 if any threads have been registered.  There may be none if

   the threading library is not fully initialized yet.  */

static int

have_threads_callback (struct thread_info *thread, void *dummy)

{

  return 1;

}

static int

have_threads (void)

{

  return iterate_over_threads (have_threads_callback, NULL) != NULL;

}

/* 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 = ptid_build (GET_PID (inferior_ptid), ti.ti_lid, ti.ti_tid);

  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);

      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;

}

/* 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 ptid_build (GET_PID (ptid), GET_LWP (ptid),

                     thread_info->private->ti.ti_tid);

}

static ptid_t

lwp_from_thread (ptid_t ptid)

{

  return BUILD_LWP (GET_LWP (ptid), 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;

  /* 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.  */

  gdb_assert (exec_bfd);

  (*bp) = (gdbarch_convert_from_func_ptr_addr

           (current_gdbarch,

            /* Do proper sign extension for the target.  */

            (bfd_get_sign_extend_vma (exec_bfd) > 0

             ? (CORE_ADDR) (intptr_t) notify.u.bptaddr

             : (CORE_ADDR) (uintptr_t) 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

  /* The event reporting facility is broken for TD_DEATH events in

     glibc 2.1.3, so don't enable it if we have glibc but a lower

     version.  */

  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

}

/* 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.  */

void

check_for_thread_db (void)

{

  td_err_e err;

  static int already_loaded;

  /* Do nothing if we couldn't load libthread_db.so.1.  */

  if (td_ta_new_p == NULL)

    return;

  /* 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.  */

  if (!already_loaded)

    {

      Dl_info info;

      const char *library = NULL;

      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;

      if (info_verbose)

        printf_unfiltered (_("Using 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.  */

    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;

  /* Don't attempt to use thread_db for remote targets.  */

  if (!target_can_run (&current_target))

    return;

  /* 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.  */

  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;

    }

}

static void

thread_db_new_objfile (struct objfile *objfile)

{

  if (objfile != NULL)

    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.  */

static void

attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,

               const td_thrinfo_t *ti_p)

{

  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 ();

  if (ti_p->ti_state == TD_THR_UNKNOWN || ti_p->ti_state == TD_THR_ZOMBIE)

    return;                     /* A zombie thread -- do not attach.  */