csu/libc-start.c

   1 /* Copyright (C) 1998-2006, 2007, 2009 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <stdlib.h>
  20 #include <stdio.h>
  21 #include <unistd.h>
  22 #include <ldsodefs.h>
  23 #include <bp-start.h>
  24 #include <bp-sym.h>
  25
  26 extern void __libc_init_first (int argc, char **argv, char **envp);
  27
  28 extern int __libc_multiple_libcs;
  29
  30 #include <tls.h>
  31 #ifndef SHARED
  32 # include <dl-osinfo.h>
  33 extern void __pthread_initialize_minimal (void);
  34 # ifndef THREAD_SET_STACK_GUARD
  35 /* Only exported for architectures that don't store the stack guard canary
  36    in thread local area.  */
  37 uintptr_t __stack_chk_guard attribute_relro;
  38 # endif
  39 #endif
  40
  41 #ifdef HAVE_PTR_NTHREADS
  42 /* We need atomic operations.  */
  43 # include <atomic.h>
  44 #endif
  45
  46
  47 #ifdef LIBC_START_MAIN
  48 # ifdef LIBC_START_DISABLE_INLINE
  49 #  define STATIC static
  50 # else
  51 #  define STATIC static inline __attribute__ ((always_inline))
  52 # endif
  53 #else
  54 # define STATIC
  55 # define LIBC_START_MAIN BP_SYM (__libc_start_main)
  56 #endif
  57
  58 #ifdef MAIN_AUXVEC_ARG
  59 /* main gets passed a pointer to the auxiliary.  */
  60 # define MAIN_AUXVEC_DECL       , void *
  61 # define MAIN_AUXVEC_PARAM      , auxvec
  62 #else
  63 # define MAIN_AUXVEC_DECL
  64 # define MAIN_AUXVEC_PARAM
  65 #endif
  66
  67 STATIC int LIBC_START_MAIN (int (*main) (int, char **, char **
  68                                          MAIN_AUXVEC_DECL),
  69                             int argc,
  70                             char *__unbounded *__unbounded ubp_av,
  71 #ifdef LIBC_START_MAIN_AUXVEC_ARG
  72                             ElfW(auxv_t) *__unbounded auxvec,
  73 #endif
  74                             __typeof (main) init,
  75                             void (*fini) (void),
  76                             void (*rtld_fini) (void),
  77                             void *__unbounded stack_end)
  78      __attribute__ ((noreturn));
  79
  80
  81 /* Note: the fini parameter is ignored here for shared library.  It
  82    is registered with __cxa_atexit.  This had the disadvantage that
  83    finalizers were called in more than one place.  */
  84 STATIC int
  85 LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
  86                  int argc, char *__unbounded *__unbounded ubp_av,
  87 #ifdef LIBC_START_MAIN_AUXVEC_ARG
  88                  ElfW(auxv_t) *__unbounded auxvec,
  89 #endif
  90                  __typeof (main) init,
  91                  void (*fini) (void),
  92                  void (*rtld_fini) (void), void *__unbounded stack_end)
  93 {
  94 #if __BOUNDED_POINTERS__
  95   char **argv;
  96 #else
  97 # define argv ubp_av
  98 #endif
  99
 100   /* Result of the 'main' function.  */
 101   int result;
 102
 103   __libc_multiple_libcs = &_dl_starting_up && !_dl_starting_up;
 104
 105 #ifndef SHARED
 106   char *__unbounded *__unbounded ubp_ev = &ubp_av[argc + 1];
 107
 108   INIT_ARGV_and_ENVIRON;
 109
 110   /* Store the lowest stack address.  This is done in ld.so if this is
 111      the code for the DSO.  */
 112   __libc_stack_end = stack_end;
 113
 114 # ifdef HAVE_AUX_VECTOR
 115   /* First process the auxiliary vector since we need to find the
 116      program header to locate an eventually present PT_TLS entry.  */
 117 #  ifndef LIBC_START_MAIN_AUXVEC_ARG
 118   ElfW(auxv_t) *__unbounded auxvec;
 119   {
 120     char *__unbounded *__unbounded evp = ubp_ev;
 121     while (*evp++ != NULL)
 122       ;
 123     auxvec = (ElfW(auxv_t) *__unbounded) evp;
 124   }
 125 #  endif
 126   _dl_aux_init (auxvec);
 127 # endif
 128 # ifdef DL_SYSDEP_OSCHECK
 129   if (!__libc_multiple_libcs)
 130     {
 131       /* This needs to run to initiliaze _dl_osversion before TLS
 132          setup might check it.  */
 133       DL_SYSDEP_OSCHECK (__libc_fatal);
 134     }
 135 # endif
 136
 137   /* Initialize the thread library at least a bit since the libgcc
 138      functions are using thread functions if these are available and
 139      we need to setup errno.  */
 140   __pthread_initialize_minimal ();
 141
 142   /* Set up the stack checker's canary.  */
 143   uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
 144 # ifdef THREAD_SET_STACK_GUARD
 145   THREAD_SET_STACK_GUARD (stack_chk_guard);
 146 # else
 147   __stack_chk_guard = stack_chk_guard;
 148 # endif
 149 #endif
 150
 151   /* Register the destructor of the dynamic linker if there is any.  */
 152   if (__builtin_expect (rtld_fini != NULL, 1))
 153     __cxa_atexit ((void (*) (void *)) rtld_fini, NULL, NULL);
 154
 155 #ifndef SHARED
 156   /* Call the initializer of the libc.  This is only needed here if we
 157      are compiling for the static library in which case we haven't
 158      run the constructors in `_dl_start_user'.  */
 159   __libc_init_first (argc, argv, __environ);
 160
 161   /* Register the destructor of the program, if any.  */
 162   if (fini)
 163     __cxa_atexit ((void (*) (void *)) fini, NULL, NULL);
 164
 165   /* Some security at this point.  Prevent starting a SUID binary where
 166      the standard file descriptors are not opened.  We have to do this
 167      only for statically linked applications since otherwise the dynamic
 168      loader did the work already.  */
 169   if (__builtin_expect (__libc_enable_secure, 0))
 170     __libc_check_standard_fds ();
 171 #endif
 172
 173   /* Call the initializer of the program, if any.  */
 174 #ifdef SHARED
 175   if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 176     GLRO(dl_debug_printf) ("\ninitialize program: %s\n\n", argv[0]);
 177 #endif
 178   if (init)
 179     (*init) (argc, argv, __environ MAIN_AUXVEC_PARAM);
 180
 181 #ifdef SHARED
 182   /* Auditing checkpoint: we have a new object.  */
 183   if (__builtin_expect (GLRO(dl_naudit) > 0, 0))
 184     {
 185       struct audit_ifaces *afct = GLRO(dl_audit);
 186       struct link_map *head = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
 187       for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
 188         {
 189           if (afct->preinit != NULL)
 190             afct->preinit (&head->l_audit[cnt].cookie);
 191
 192           afct = afct->next;
 193         }
 194     }
 195 #endif
 196
 197 #ifdef SHARED
 198   if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 199     GLRO(dl_debug_printf) ("\ntransferring control: %s\n\n", argv[0]);
 200 #endif
 201
 202 #ifdef HAVE_CLEANUP_JMP_BUF
 203   /* Memory for the cancellation buffer.  */
 204   struct pthread_unwind_buf unwind_buf;
 205
 206   int not_first_call;
 207   not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
 208   if (__builtin_expect (! not_first_call, 1))
 209     {
 210       struct pthread *self = THREAD_SELF;
 211
 212       /* Store old info.  */
 213       unwind_buf.priv.data.prev = THREAD_GETMEM (self, cleanup_jmp_buf);
 214       unwind_buf.priv.data.cleanup = THREAD_GETMEM (self, cleanup);
 215
 216       /* Store the new cleanup handler info.  */
 217       THREAD_SETMEM (self, cleanup_jmp_buf, &unwind_buf);
 218
 219       /* Run the program.  */
 220       result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
 221     }
 222   else
 223     {
 224       /* Remove the thread-local data.  */
 225 # ifdef SHARED
 226       PTHFCT_CALL (ptr__nptl_deallocate_tsd, ());
 227 # else
 228       extern void __nptl_deallocate_tsd (void) __attribute ((weak));
 229       __nptl_deallocate_tsd ();
 230 # endif
 231
 232       /* One less thread.  Decrement the counter.  If it is zero we
 233          terminate the entire process.  */
 234       result = 0;
 235 # ifdef SHARED
 236       unsigned int *ptr = __libc_pthread_functions.ptr_nthreads;
 237       PTR_DEMANGLE (ptr);
 238 # else
 239       extern unsigned int __nptl_nthreads __attribute ((weak));
 240       unsigned int *const ptr = &__nptl_nthreads;
 241 # endif
 242
 243       if (! atomic_decrement_and_test (ptr))
 244         /* Not much left to do but to exit the thread, not the process.  */
 245         __exit_thread (0);
 246     }
 247 #else
 248   /* Nothing fancy, just call the function.  */
 249   result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
 250 #endif
 251
 252   exit (result);
 253 }