1  /* pthread initialization called from __libc_early_init.  NPTL version.
       2     Copyright (C) 2021-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _PTHREAD_EARLY_INIT_H
      20  #define _PTHREAD_EARLY_INIT_H 1
      21  
      22  #include <nptl/nptl-stack.h>
      23  #include <pthreadP.h>
      24  #include <pthread_mutex_conf.h>
      25  #include <sys/resource.h>
      26  
      27  static inline void
      28  __pthread_early_init (void)
      29  {
      30    /* Determine the default allowed stack size.  This is the size used
      31       in case the user does not specify one.  */
      32    struct rlimit limit;
      33    if (__getrlimit (RLIMIT_STACK, &limit) != 0
      34        || limit.rlim_cur == RLIM_INFINITY)
      35      /* The system limit is not usable.  Use an architecture-specific
      36         default.  */
      37      limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
      38    else if (limit.rlim_cur < PTHREAD_STACK_MIN)
      39      /* The system limit is unusably small.
      40         Use the minimal size acceptable.  */
      41      limit.rlim_cur = PTHREAD_STACK_MIN;
      42  
      43    /* Make sure it meets the minimum size that allocate_stack
      44       (allocatestack.c) will demand, which depends on the page size.  */
      45    const uintptr_t pagesz = GLRO(dl_pagesize);
      46    const size_t minstack = (pagesz + __nptl_tls_static_size_for_stack ()
      47                             + MINIMAL_REST_STACK);
      48    if (limit.rlim_cur < minstack)
      49      limit.rlim_cur = minstack;
      50  
      51    /* Round the resource limit up to page size.  */
      52    limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
      53    __default_pthread_attr.internal.stacksize = limit.rlim_cur;
      54    __default_pthread_attr.internal.guardsize = GLRO (dl_pagesize);
      55  
      56    __pthread_tunables_init ();
      57  }
      58  
      59  #endif  /* _PTHREAD_EARLY_INIT_H */