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start-libc.c

/* Initialization code run first thing by the XCOFF startup code.  AIX version.
   Copyright (C) 2001, 2002 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 <unistd.h>
#include <sys/types.h>

/* hack to use uchar's */
typedef unsigned char uchar;
#include <xcoff.h>
#include <rtinit.h>
#include <dlldr.h>
#include <bits/libc-lock.h>

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

/* XXX disable for now
extern int __libc_multiple_libcs; */

/* XXX normally defined in generic/dl-sydep.c, hack it into existance
extern void *__libc_stack_end; */
void *__libc_stack_end;

struct __libc_start_data_rec
{
  void *stack;
  void *toc;
  int argc;
  char **argv;
  char **envp;
  char *data;
  char *text;
  unsigned int mcount;
  unsigned int special;
  int (*main) (int, char **, char **);
  void (*init) (void);
  void (*fini) (void);
  void (*rtld_fini) (void);
};

extern struct __libc_start_data_rec __libc_start_data;
extern int errno;

/* The first piece of initialized data.  */
int __data_start = 0;

#ifndef HAVE_ELF
/* Since gcc/crtstuff.c won't define it unless the ELF format is used
   we will need to define it here.  */
void *__dso_handle = NULL;
#endif

/* AIX kernel function */
extern int __loadx (int flag, void *module, void *arg1, void *arg2,
                void *arg3);
/* Needed by setenv */
char  **__environ;

/*
   Find __rtinit symbol

   __RTINIT *find_rtinit()

   __RTINIT        *rti - pointer to __rtinit data structure
 */

static __RTINIT *
find_rtinit (void)
{
  struct xcoffhdr *xcoff_hdr;
  SCNHDR *sec_hdr;
  SCNHDR *ldr_sec_hdr;
  SCNHDR *data_sec_hdr;
  LDSYM *ldsym_hdr;
  __RTINIT *rtl;

  xcoff_hdr = (struct xcoffhdr *) __libc_start_data.text;
  sec_hdr = (SCNHDR *) ((caddr_t) &xcoff_hdr->aouthdr
                  + xcoff_hdr->filehdr.f_opthdr);
  ldr_sec_hdr = (SCNHDR *) (sec_hdr + (xcoff_hdr->aouthdr.o_snloader - 1));
  ldsym_hdr = (LDSYM  *) ((caddr_t)xcoff_hdr + ldr_sec_hdr->s_scnptr
                    + LDHDRSZ);

  if ( __libc_start_data.mcount <= 0)
    {
      if (!ldr_sec_hdr->s_scnptr)
      return (__RTINIT *) 0;

      if (memcmp (ldsym_hdr, RTINIT_NAME, sizeof (RTINIT_NAME) - 1))
      return (__RTINIT *) 0;
    }

  data_sec_hdr   = (SCNHDR *) (sec_hdr + (xcoff_hdr->aouthdr.o_sndata - 1));
  rtl = (__RTINIT *) (ldsym_hdr->l_value
                  + (__libc_start_data.data - data_sec_hdr->s_vaddr));
  return rtl;
}

/*
   The mod_init1 calls every initialization function for a given module.

    void mod_init1(handler, rti)

    void *handler - if NULL init funtions for modules loaded at exec time
                    are being executed. Otherwise, the handler points to the
                    module loaded.

    __RTINIT *rti - pointer to __rtinit data structure (with rti->init_offset
                    not equal to zero)
 */

static void
mod_init1 (void *handler,__RTINIT *rtl)
{
  __RTINIT_DESCRIPTOR  *descriptor;

  descriptor = (__RTINIT_DESCRIPTOR *) ((caddr_t) &rtl->rtl
                              + rtl->init_offset);
  while (descriptor->f != NULL)
    {
      if (!(descriptor->flags & _RT_CALLED))
      {
        descriptor->flags |= _RT_CALLED;
        (descriptor->f) (handler, rtl, descriptor);  /* execute init/fini */
      }
      descriptor = (__RTINIT_DESCRIPTOR *) ((caddr_t) descriptor
                                  + rtl->__rtinit_descriptor_size);
    }
}

/* The modinit() function performs run-time linking, if enabled, and calling
   the init() function for all loaded modules.  */

#define DL_BUFFER_SIZE 1000

static int
modinit (void)
{
  int *handler = 0;
  __RTINIT *rtinit_info = 0;
  int flag;
  DL_INFO dl_buffer[DL_BUFFER_SIZE];
  DL_INFO *dl_info = dl_buffer;
  int i;

  /* Find __rtinit symbols */
  rtinit_info = find_rtinit ();

  flag = DL_EXECQ;
  if (rtinit_info && rtinit_info->rtl)
    flag |= DL_LOAD_RTL;

  /* Get a list of modules that have __rtinit */
  if (__loadx (flag, dl_info, (void *) sizeof (dl_buffer), NULL, NULL))
    exit (0x90);

  if (dl_info[0].dlinfo_xflags & DL_INFO_OK)
    {
      rtinit_info = find_rtinit ();
      if ((rtinit_info != NULL) & (rtinit_info->rtl != NULL))
      {
        if ((*rtinit_info->rtl) (dl_info, 0))
          exit (0x90);
      }
    }

  /* Initialization each module loaded that has __rtinit. */
  if (dl_info[0].dlinfo_xflags & DL_INFO_OK)
    {
      for (i = 1; i < dl_info[0].dlinfo_arraylen + 1; ++i)
      if (dl_info[i].dlinfo_flags & DL_HAS_RTINIT)
        {
          rtinit_info = find_rtini t();
          if (rtinit_info)
            mod_init1 (handler, rtinit_info);
        }
    }

  return 0;
}


void
__libc_start_init (void)
{
  /* Do run-time linking, if enabled and call the init()
     for all loaded modules. */
  if (__libc_start_data.mcount != __libc_start_data.special)
    modinit ();
}

/* For now these are just stubs. */
void
__libc_start_fini (void)
{
}

void
__libc_start_rtld_fini (void)
{
}


int
__libc_start_main (void)
{
  /* Store the lowest stack address.  */
  __libc_stack_end = __libc_start_data.stack;

  /* Used by setenv */
  __environ = __libc_start_data.envp;

#ifndef SHARED
  /* Clear errno. */
    errno = 0;

  /* 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

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

  /* 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'.  */
#ifndef SHARED
  __libc_init_first (__libc_start_data.argc, __libc_start_data.argv,
                 __libc_start_data.envp);
#endif

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

  /* Call the initializer of the program, if any.  */
  if (__libc_start_data.init)
    (*__libc_start_data.init) ();

  exit ((*__libc_start_data.main) (__libc_start_data.argc,
                           __libc_start_data.argv,
                           __libc_start_data.envp));
}

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