nptl_db/td_thr_validate.c

   1 /* Validate a thread handle.
   2    Copyright (C) 1999,2001,2002,2003,2004,2007,2008
   3         Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 #include "thread_dbP.h"
  23 #include <stdbool.h>
  24
  25 static td_err_e
  26 check_thread_list (const td_thrhandle_t *th, psaddr_t head, bool *uninit)
  27 {
  28   td_err_e err;
  29   psaddr_t next, ofs;
  30
  31   err = DB_GET_FIELD (next, th->th_ta_p, head, list_t, next, 0);
  32   if (err == TD_OK)
  33     {
  34       if (next == 0)
  35         {
  36           *uninit = true;
  37           return TD_NOTHR;
  38         }
  39       err = DB_GET_FIELD_ADDRESS (ofs, th->th_ta_p, 0, pthread, list, 0);
  40     }
  41
  42   while (err == TD_OK)
  43     {
  44       if (next == head)
  45         return TD_NOTHR;
  46
  47       if (next - (ofs - (psaddr_t) 0) == th->th_unique)
  48         return TD_OK;
  49
  50       err = DB_GET_FIELD (next, th->th_ta_p, next, list_t, next, 0);
  51     }
  52
  53   return err;
  54 }
  55
  56
  57 td_err_e
  58 td_thr_validate (const td_thrhandle_t *th)
  59 {
  60   td_err_e err;
  61   psaddr_t list;
  62
  63   LOG ("td_thr_validate");
  64
  65   /* First check the list with threads using user allocated stacks.  */
  66   bool uninit = false;
  67   err = DB_GET_SYMBOL (list, th->th_ta_p, __stack_user);
  68   if (err == TD_OK)
  69     err = check_thread_list (th, list, &uninit);
  70
  71   /* If our thread is not on this list search the list with stack
  72      using implementation allocated stacks.  */
  73   if (err == TD_NOTHR)
  74     {
  75       err = DB_GET_SYMBOL (list, th->th_ta_p, stack_used);
  76       if (err == TD_OK)
  77         err = check_thread_list (th, list, &uninit);
  78
  79       if (err == TD_NOTHR && uninit && th->th_unique == 0)
  80         /* __pthread_initialize_minimal has not run yet.
  81            There is only the special case thread handle.  */
  82         err = TD_OK;
  83     }
  84
  85   if (err == TD_OK)
  86     {
  87       /* Verify that this is not a stale element in a fork child.  */
  88       pid_t match_pid = ps_getpid (th->th_ta_p->ph);
  89       psaddr_t pid;
  90       err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique, pthread, pid, 0);
  91       if (err == TD_OK && (pid_t) (uintptr_t) pid < 0)
  92         {
  93           /* This was a thread that was about to fork, or it is the new sole
  94              thread in a fork child.  In the latter case, its tid was stored
  95              via CLONE_CHILD_SETTID and so is already the proper child PID.  */
  96           if (-(pid_t) (uintptr_t) pid == match_pid)
  97             /* It is about to do a fork, but is really still the parent PID.  */
  98             pid = (psaddr_t) (uintptr_t) match_pid;
  99           else
 100             /* It must be a fork child, whose new PID is in the tid field.  */
 101             err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique,
 102                                 pthread, tid, 0);
 103         }
 104       if (err == TD_OK && (pid_t) (uintptr_t) pid != match_pid)
 105         err = TD_NOTHR;
 106     }
 107
 108   return err;
 109 }