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, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include "thread_dbP.h"
  22 #include <stdbool.h>
  23
  24 static td_err_e
  25 check_thread_list (const td_thrhandle_t *th, psaddr_t head, bool *uninit)
  26 {
  27   td_err_e err;
  28   psaddr_t next, ofs;
  29
  30   err = DB_GET_FIELD (next, th->th_ta_p, head, list_t, next, 0);
  31   if (err == TD_OK)
  32     {
  33       if (next == 0)
  34         {
  35           *uninit = true;
  36           return TD_NOTHR;
  37         }
  38       err = DB_GET_FIELD_ADDRESS (ofs, th->th_ta_p, 0, pthread, list, 0);
  39     }
  40
  41   while (err == TD_OK)
  42     {
  43       if (next == head)
  44         return TD_NOTHR;
  45
  46       if (next - (ofs - (psaddr_t) 0) == th->th_unique)
  47         return TD_OK;
  48
  49       err = DB_GET_FIELD (next, th->th_ta_p, next, list_t, next, 0);
  50     }
  51
  52   return err;
  53 }
  54
  55
  56 td_err_e
  57 td_thr_validate (const td_thrhandle_t *th)
  58 {
  59   td_err_e err;
  60   psaddr_t list;
  61
  62   LOG ("td_thr_validate");
  63
  64   /* First check the list with threads using user allocated stacks.  */
  65   bool uninit = false;
  66   err = DB_GET_SYMBOL (list, th->th_ta_p, __stack_user);
  67   if (err == TD_OK)
  68     err = check_thread_list (th, list, &uninit);
  69
  70   /* If our thread is not on this list search the list with stack
  71      using implementation allocated stacks.  */
  72   if (err == TD_NOTHR)
  73     {
  74       err = DB_GET_SYMBOL (list, th->th_ta_p, stack_used);
  75       if (err == TD_OK)
  76         err = check_thread_list (th, list, &uninit);
  77
  78       if (err == TD_NOTHR && uninit && th->th_unique == 0)
  79         /* __pthread_initialize_minimal has not run yet.
  80            There is only the special case thread handle.  */
  81         err = TD_OK;
  82     }
  83
  84   if (err == TD_OK)
  85     {
  86       /* Verify that this is not a stale element in a fork child.  */
  87       pid_t match_pid = ps_getpid (th->th_ta_p->ph);
  88       psaddr_t pid;
  89       err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique, pthread, pid, 0);
  90       if (err == TD_OK && (pid_t) (uintptr_t) pid < 0)
  91         {
  92           /* This was a thread that was about to fork, or it is the new sole
  93              thread in a fork child.  In the latter case, its tid was stored
  94              via CLONE_CHILD_SETTID and so is already the proper child PID.  */
  95           if (-(pid_t) (uintptr_t) pid == match_pid)
  96             /* It is about to do a fork, but is really still the parent PID.  */
  97             pid = (psaddr_t) (uintptr_t) match_pid;
  98           else
  99             /* It must be a fork child, whose new PID is in the tid field.  */
 100             err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique,
 101                                 pthread, tid, 0);
 102         }
 103       if (err == TD_OK && (pid_t) (uintptr_t) pid != match_pid)
 104         err = TD_NOTHR;
 105     }
 106
 107   return err;
 108 }