path: root/elf/rtld.c

/* Run time dynamic linker.
   Copyright (C) 1995, 1996, 1997 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

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

#include <link.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>		/* Check if MAP_ANON is defined.  */
#include "../stdio-common/_itoa.h"
#include <assert.h>
#include "dynamic-link.h"


/* System-specific function to do initial startup for the dynamic linker.
   After this, file access calls and getenv must work.  This is responsible
   for setting __libc_enable_secure if we need to be secure (e.g. setuid),
   and for setting _dl_argc and _dl_argv, and then calling _dl_main.  */
extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
				    void (*dl_main) (const ElfW(Phdr) *phdr,
						     ElfW(Half) phent,
						     ElfW(Addr) *user_entry));
extern void _dl_sysdep_start_cleanup (void);

/* System-dependent function to read a file's whole contents
   in the most convenient manner available.  */
extern void *_dl_sysdep_read_whole_file (const char *filename,
					 size_t *filesize_ptr,
					 int mmap_prot);

/* Helper function to handle errors while resolving symbols.  */
static void print_unresolved (int errcode, const char *objname,
			      const char *errsting);

/* Helper function to handle errors when a version is missing.  */
static void print_missing_version (int errcode, const char *objname,
				   const char *errsting);


int _dl_argc;
char **_dl_argv;
const char *_dl_rpath;

/* Set nonzero during loading and initialization of executable and
   libraries, cleared before the executable's entry point runs.  This
   must not be initialized to nonzero, because the unused dynamic
   linker loaded in for libc.so's "ld.so.1" dep will provide the
   definition seen by libc.so's initializer; that value must be zero,
   and will be since that dynamic linker's _dl_start and dl_main will
   never be called.  */
int _dl_starting_up;

static void dl_main (const ElfW(Phdr) *phdr,
		     ElfW(Half) phent,
		     ElfW(Addr) *user_entry);

struct link_map _dl_rtld_map;
struct libname_list _dl_rtld_libname;

#ifdef RTLD_START
RTLD_START
#else
#error "sysdeps/MACHINE/dl-machine.h fails to define RTLD_START"
#endif

ElfW(Addr)
_dl_start (void *arg)
{
  struct link_map bootstrap_map;

  /* This #define produces dynamic linking inline functions for
     bootstrap relocation instead of general-purpose relocation.  */
#define RTLD_BOOTSTRAP
#define RESOLVE(sym, version, flags) bootstrap_map.l_addr
#include "dynamic-link.h"

  /* Figure out the run-time load address of the dynamic linker itself.  */
  bootstrap_map.l_addr = elf_machine_load_address ();

  /* Read our own dynamic section and fill in the info array.  */
  bootstrap_map.l_ld = (void *) bootstrap_map.l_addr + elf_machine_dynamic ();
  elf_get_dynamic_info (bootstrap_map.l_ld, bootstrap_map.l_info);

#ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
  ELF_MACHINE_BEFORE_RTLD_RELOC (bootstrap_map.l_info);
#endif

  /* Relocate ourselves so we can do normal function calls and
     data access using the global offset table.  */

  ELF_DYNAMIC_RELOCATE (&bootstrap_map, 0);


  /* Now life is sane; we can call functions and access global data.
     Set up to use the operating system facilities, and find out from
     the operating system's program loader where to find the program
     header table in core.  */


  /* Transfer data about ourselves to the permanent link_map structure.  */
  _dl_rtld_map.l_addr = bootstrap_map.l_addr;
  _dl_rtld_map.l_ld = bootstrap_map.l_ld;
  memcpy (_dl_rtld_map.l_info, bootstrap_map.l_info,
	  sizeof _dl_rtld_map.l_info);
  _dl_setup_hash (&_dl_rtld_map);

  /* Cache the DT_RPATH stored in ld.so itself; this will be
     the default search path.  */
  _dl_rpath = (void *) (_dl_rtld_map.l_addr +
			_dl_rtld_map.l_info[DT_STRTAB]->d_un.d_ptr +
			_