nptl_db/td_thr_validate.c

   1 /* Validate a thread handle.
   2    Copyright (C) 1999-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include "thread_dbP.h"
  21 #include <stdbool.h>
  22
  23 static td_err_e
  24 check_thread_list (const td_thrhandle_t *th, psaddr_t head, bool *uninit)
  25 {
  26   td_err_e err;
  27   psaddr_t next, ofs;
  28
  29   err = DB_GET_FIELD (next, th->th_ta_p, head, list_t, next, 0);
  30   if (err == TD_OK)
  31     {
  32       if (next == 0)
  33         {
  34           *uninit = true;
  35           return TD_NOTHR;
  36         }
  37       err = DB_GET_FIELD_ADDRESS (ofs, th->th_ta_p, 0, pthread, list, 0);
  38     }
  39
  40   while (err == TD_OK)
  41     {
  42       if (next == head)
  43         return TD_NOTHR;
  44
  45       if (next - (ofs - (psaddr_t) 0) == th->th_unique)
  46         return TD_OK;
  47
  48       err = DB_GET_FIELD (next, th->th_ta_p, next, list_t, next, 0);
  49     }
  50
  51   return err;
  52 }
  53
  54
  55 td_err_e
  56 td_thr_validate (const td_thrhandle_t *th)
  57 {
  58   td_err_e err;
  59   psaddr_t list;
  60
  61   LOG ("td_thr_validate");
  62
  63   /* First check the list with threads using user allocated stacks.  */
  64   bool uninit = false;
  65   err = DB_GET_SYMBOL (list, th->th_ta_p, __stack_user);
  66   if (err == TD_OK)
  67     err = check_thread_list (th, list, &uninit);
  68
  69   /* If our thread is not on this list search the list with stack
  70      using implementation allocated stacks.  */
  71   if (err == TD_NOTHR)
  72     {
  73       err = DB_GET_SYMBOL (list, th->th_ta_p, stack_used);
  74       if (err == TD_OK)
  75         err = check_thread_list (th, list, &uninit);
  76
  77       if (err == TD_NOTHR && uninit && th->th_unique == 0)
  78         /* __pthread_initialize_minimal has not run yet.
  79            There is only the special case thread handle.  */
  80         err = TD_OK;
  81     }
  82
  83   if (err == TD_OK)
  84     {
  85       /* Verify that this is not a stale element in a fork child.  */
  86       pid_t match_pid = ps_getpid (th->th_ta_p->ph);
  87       psaddr_t pid;
  88       err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique, pthread, pid, 0);
  89       if (err == TD_OK && (pid_t) (uintptr_t) pid < 0)
  90         {
  91           /* This was a thread that was about to fork, or it is the new sole
  92              thread in a fork child.  In the latter case, its tid was stored
  93              via CLONE_CHILD_SETTID and so is already the proper child PID.  */
  94           if (-(pid_t) (uintptr_t) pid == match_pid)
  95             /* It is about to do a fork, but is really still the parent PID.  */
  96             pid = (psaddr_t) (uintptr_t) match_pid;
  97           else
  98             /* It must be a fork child, whose new PID is in the tid field.  */
  99             err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique,
 100                                 pthread, tid, 0);
 101         }
 102       if (err == TD_OK && (pid_t) (uintptr_t) pid != match_pid)
 103         err = TD_NOTHR;
 104     }
 105
 106   return err;
 107 }