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libc-start.c

/* Copyright (C) 1998-2003, 2004, 2005 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <bp-start.h>
#include <bp-sym.h>

extern void __libc_init_first (int argc, char **argv, char **envp);

extern int __libc_multiple_libcs;

#include <tls.h>
#ifndef SHARED
# include <dl-osinfo.h>
extern void __pthread_initialize_minimal (void)
# if !(USE_TLS - 0) && !defined NONTLS_INIT_TP
     __attribute__ ((weak))
# endif
     ;
# ifndef THREAD_SET_STACK_GUARD
/* Only exported for architectures that don't store the stack guard canary
   in thread local area.  */
uintptr_t __stack_chk_guard attribute_relro;
# endif
#endif

#ifdef HAVE_PTR_NTHREADS
/* We need atomic operations.  */
# include <atomic.h>
#endif


#ifdef LIBC_START_MAIN
# ifdef LIBC_START_DISABLE_INLINE
#  define STATIC static
# else
#  define STATIC static inline __attribute__ ((always_inline))
# endif
#else
# define STATIC
# define LIBC_START_MAIN BP_SYM (__libc_start_main)
#endif

#ifdef MAIN_AUXVEC_ARG
/* main gets passed a pointer to the auxiliary.  */
# define MAIN_AUXVEC_DECL     , void *
# define MAIN_AUXVEC_PARAM    , auxvec
#else
# define MAIN_AUXVEC_DECL
# define MAIN_AUXVEC_PARAM
#endif

STATIC int LIBC_START_MAIN (int (*main) (int, char **, char **
                               MAIN_AUXVEC_DECL),
                      int argc,
                      char *__unbounded *__unbounded ubp_av,
#ifdef LIBC_START_MAIN_AUXVEC_ARG
                      ElfW(auxv_t) *__unbounded auxvec,
#endif
                      __typeof (main) init,
                      void (*fini) (void),
                      void (*rtld_fini) (void),
                      void *__unbounded stack_end)
     __attribute__ ((noreturn));


/* Note: the fini parameter is ignored here for shared library.  It
   is registered with __cxa_atexit.  This had the disadvantage that
   finalizers were called in more than one place.  */
STATIC int
LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
             int argc, char *__unbounded *__unbounded ubp_av,
#ifdef LIBC_START_MAIN_AUXVEC_ARG
             ElfW(auxv_t) *__unbounded auxvec,
#endif
             __typeof (main) init,
             void (*fini) (void),
             void (*rtld_fini) (void), void *__unbounded stack_end)
{
#if __BOUNDED_POINTERS__
  char **argv;
#else
# define argv ubp_av
#endif

  /* Result of the 'main' function.  */
  int result;

  __libc_multiple_libcs = &_dl_starting_up && !_dl_starting_up;

#ifndef SHARED
  char *__unbounded *__unbounded ubp_ev = &ubp_av[argc + 1];

  INIT_ARGV_and_ENVIRON;

  /* Store the lowest stack address.  This is done in ld.so if this is
     the code for the DSO.  */
  __libc_stack_end = stack_end;

# ifdef HAVE_AUX_VECTOR
  /* First process the auxiliary vector since we need to find the
     program header to locate an eventually present PT_TLS entry.  */
#  ifndef LIBC_START_MAIN_AUXVEC_ARG
  ElfW(auxv_t) *__unbounded auxvec;
  {
    char *__unbounded *__unbounded evp = ubp_ev;
    while (*evp++ != NULL)
      ;
    auxvec = (ElfW(auxv_t) *__unbounded) evp;
  }
#  endif
  _dl_aux_init (auxvec);
# endif
# ifdef DL_SYSDEP_OSCHECK
  if (!__libc_multiple_libcs)
    {
      /* This needs to run to initiliaze _dl_osversion before TLS
       setup might check it.  */
      DL_SYSDEP_OSCHECK (__libc_fatal);
    }
# endif

  /* Initialize the thread library at least a bit since the libgcc
     functions are using thread functions if these are available and
     we need to setup errno.  If there is no thread library and we
     handle TLS the function is defined in the libc to initialized the
     TLS handling.  */
# if !(USE_TLS - 0) && !defined NONTLS_INIT_TP
  if (__pthread_initialize_minimal)
# endif
    __pthread_initialize_minimal ();
#endif

# ifndef SHARED
  /* Set up the stack checker's canary.  */
  uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard ();
#  ifdef THREAD_SET_STACK_GUARD
  THREAD_SET_STACK_GUARD (stack_chk_guard);
#  else
  __stack_chk_guard = stack_chk_guard;
#  endif
#endif

  /* Register the destructor of the dynamic linker if there is any.  */
  if (__builtin_expect (rtld_fini != NULL, 1))
    __cxa_atexit ((void (*) (void *)) rtld_fini, NULL, NULL);

#ifndef SHARED
  /* Call the initializer of the libc.  This is only needed here if we
     are compiling for the static library in which case we haven't
     run the constructors in `_dl_start_user'.  */
  __libc_init_first (argc, argv, __environ);

  /* Register the destructor of the program, if any.  */
  if (fini)
    __cxa_atexit ((void (*) (void *)) fini, NULL, NULL);

  /* Some security at this point.  Prevent starting a SUID binary where
     the standard file descriptors are not opened.  We have to do this
     only for statically linked applications since otherwise the dynamic
     loader did the work already.  */
  if (__builtin_expect (__libc_enable_secure, 0))
    __libc_check_standard_fds ();
#endif

  /* Call the initializer of the program, if any.  */
#ifdef SHARED
  if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
    GLRO(dl_debug_printf) ("\ninitialize program: %s\n\n", argv[0]);
#endif
  if (init)
    (*init) (argc, argv, __environ MAIN_AUXVEC_PARAM);

#ifdef SHARED
  /* Auditing checkpoint: we have a new object.  */
  if (__builtin_expect (GLRO(dl_naudit) > 0, 0))
    {
      struct audit_ifaces *afct = GLRO(dl_audit);
      struct link_map *head = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
      for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
      {
        if (afct->preinit != NULL)
          afct->preinit (&head->l_audit[cnt].cookie);

        afct = afct->next;
      }
    }
#endif

#ifdef SHARED
  if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
    GLRO(dl_debug_printf) ("\ntransferring control: %s\n\n", argv[0]);
#endif

#ifdef HAVE_CLEANUP_JMP_BUF
  /* Memory for the cancellation buffer.  */
  struct pthread_unwind_buf unwind_buf;

  int not_first_call;
  not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
  if (__builtin_expect (! not_first_call, 1))
    {
      struct pthread *self = THREAD_SELF;

      /* Store old info.  */
      unwind_buf.priv.data.prev = THREAD_GETMEM (self, cleanup_jmp_buf);
      unwind_buf.priv.data.cleanup = THREAD_GETMEM (self, cleanup);

      /* Store the new cleanup handler info.  */
      THREAD_SETMEM (self, cleanup_jmp_buf, &unwind_buf);

      /* Run the program.  */
      result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
    }
  else
    {
      /* Remove the thread-local data.  */
# ifdef SHARED
      __libc_pthread_functions.ptr__nptl_deallocate_tsd ();
# else
      extern void __nptl_deallocate_tsd (void) __attribute ((weak));
      __nptl_deallocate_tsd ();
# endif

      /* One less thread.  Decrement the counter.  If it is zero we
       terminate the entire process.  */
      result = 0;
# ifdef SHARED
      unsigned int *const ptr = __libc_pthread_functions.ptr_nthreads;
# else
      extern unsigned int __nptl_nthreads __attribute ((weak));
      unsigned int *const ptr = &__nptl_nthreads;
# endif

      if (! atomic_decrement_and_test (ptr))
      /* Not much left to do but to exit the thread, not the process.  */
      __exit_thread (0);
    }
#else
  /* Nothing fancy, just call the function.  */
  result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
#endif

  exit (result);
}

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