ldsodefs.h

Newlib 嵌入式 C库 标准实现代码

/* Run-time dynamic linker data structures for loaded ELF shared objects.
   Copyright (C) 1995-1999, 2000, 2001 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.  */

#ifndef	_LDSODEFS_H
#define	_LDSODEFS_H	1

#include <features.h>

#define __need_size_t
#define __need_NULL
#include <stddef.h>
#include <string.h>

#include <elf.h>
#include <link.h>
#include <dl-lookupcfg.h>
#include <bits/libc-lock.h>

#include "dl-local.h"

__BEGIN_DECLS

/* We use this macro to refer to ELF types independent of the native wordsize.
   `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'.  */
#define ELFW(type)	_ElfW (ELF, __ELF_NATIVE_CLASS, type)

#define internal_function 
/* All references to the value of l_info[DT_PLTGOT],
  l_info[DT_STRTAB], l_info[DT_SYMTAB], l_info[DT_RELA],
  l_info[DT_REL], l_info[DT_JMPREL], and l_info[VERSYMIDX (DT_VERSYM)]
  have to be accessed via the D_PTR macro.  The macro is needed since for
  most architectures the entry is already relocated - but for some not
  and we need to relocate at access time.  */
#ifdef DL_RO_DYN_SECTION
# define D_PTR(map,i) (map->i->d_un.d_ptr + map->l_addr)
#else
# define D_PTR(map,i) map->i->d_un.d_ptr
#endif

/* On some platforms more information than just the address of the symbol
   is needed from the lookup functions.  In this case we return the whole
   link map.  */
#ifdef DL_LOOKUP_RETURNS_MAP
typedef struct link_map *lookup_t;
# define LOOKUP_VALUE(map) map
# define LOOKUP_VALUE_ADDRESS(map) (map ? map->l_addr : 0)
#else
typedef ElfW(Addr) lookup_t;
# define LOOKUP_VALUE(map) map->l_addr
# define LOOKUP_VALUE_ADDRESS(address) address
#endif

/* on some architectures a pointer to a function is not just a pointer
   to the actual code of the function but rather an architecture
   specific descriptor. */
#ifndef ELF_FUNCTION_PTR_IS_SPECIAL
# define DL_SYMBOL_ADDRESS(map, ref) \
 (void *) (LOOKUP_VALUE_ADDRESS (map) + ref->st_value)
# define DL_LOOKUP_ADDRESS(addr) ((ElfW(Addr)) (addr))
# define DL_DT_INIT_ADDRESS(map, start) (start)
# define DL_DT_FINI_ADDRESS(map, start) (start)
#endif

/* Unmap a loaded object, called by _dl_close (). */
#ifndef DL_UNMAP_IS_SPECIAL
# define DL_UNMAP(map) \
 __munmap ((void *) (map)->l_map_start,					      \
	   (map)->l_map_end - (map)->l_map_start)
#endif

/* By default we do not need special support to initialize DSOs loaded
   by statically linked binaries.  */
#ifndef DL_STATIC_INIT
# define DL_STATIC_INIT(map)
#endif

/* Reloc type classes as returned by elf_machine_type_class().
   ELF_RTYPE_CLASS_PLT means this reloc should not be satisfied by
   some PLT symbol, ELF_RTYPE_CLASS_COPY means this reloc should not be
   satisfied by any symbol in the executable.  */
#define ELF_RTYPE_CLASS_PLT 1
#define ELF_RTYPE_CLASS_COPY 2

/* ELF uses the PF_x macros to specify the segment permissions, mmap
   uses PROT_xxx.  In most cases the three macros have the values 1, 2,
   and 3 but not in a matching order.  The following macros allows
   converting from the PF_x values to PROT_xxx values.  */
#define PF_TO_PROT \
  ((PROT_READ << (PF_R * 4))						      \
   | (PROT_WRITE << (PF_W * 4))						      \
   | (PROT_EXEC << (PF_X * 4))						      \
   | ((PROT_READ | PROT_WRITE) << ((PF_R | PF_W) * 4))			      \
   | ((PROT_READ | PROT_EXEC) << ((PF_R | PF_X) * 4))			      \
   | ((PROT_WRITE | PROT_EXEC) << (PF_W | PF_X) * 4)			      \
   | ((PROT_READ | PROT_WRITE | PROT_EXEC) << ((PF_R | PF_W | PF_X) * 4)))


/* For the version handling we need an array with only names and their
   hash values.  */
struct r_found_version
  {
    const char *name;
    ElfW(Word) hash;

    int hidden;
    const char *filename;
  };

/* We want to cache information about the searches for shared objects.  */

enum r_dir_status { unknown, nonexisting, existing };

struct r_search_path_elem
  {
    /* This link is only used in the `all_dirs' member of `r_search_path'.  */
    struct r_search_path_elem *next;

    /* Strings saying where the definition came from.  */
    const char *what;
    const char *where;

    /* Basename for this search path element.  The string must end with
       a slash character.  */
    const char *dirname;
    size_t dirnamelen;

    enum r_dir_status status[0];
  };

struct r_strlenpair
  {
    const char *str;
    size_t len;
  };


/* A data structure for a simple single linked list of strings.  */
struct libname_list
  {
    const char *name;		/* Name requested (before search).  */
    struct libname_list *next;	/* Link to next name for this object.  */
    int dont_free;		/* Flag whether this element should be freed
				   if the object is not entirely unloaded.  */
  };


/* Test whether given NAME matches any of the names of the given object.  */
static __inline int
__attribute__ ((unused))
_dl_name_match_p (const char *__name, struct link_map *__map)
{
  int __found = strcmp (__name, __map->l_name) == 0;
  struct libname_list *__runp = __map->l_libname;

  while (! __found && __runp != NULL)
    if (strcmp (__name, __runp->name) == 0)
      __found = 1;
    else
      __runp = __runp->next;

  return __found;
}

/* Function used as argument for `_dl_receive_error' function.  The
   arguments are the error code, error string, and the objname the
   error occurred in.  */
typedef void (*receiver_fct) (int, const char *, const char *);

/* Internal functions of the run-time dynamic linker.
   These can be accessed if you link again the dynamic linker
   as a shared library, as in `-lld' or `/lib/ld.so' explicitly;
   but are not normally of interest to user programs.

   The `-ldl' library functions in <dlfcn.h> provide a simple
   user interface to run-time dynamic linking.  */


/* Parameters passed to the dynamic linker.  */
extern char **_dl_argv;

/* Cached value of `getpagesize ()'.  */
extern size_t _dl_pagesize;

/* OS version.  */
extern unsigned int _dl_osversion;

/* File descriptor referring to the zero-fill device.  */
extern int _dl_zerofd;

/* Name of the shared object to be profiled (if any).  */
extern const char *_dl_profile;
/* Map of shared object to be profiled.  */
extern struct link_map *_dl_profile_map;
/* Filename of the output file.  */
extern const char *_dl_profile_output;

/* If nonzero the appropriate debug information is printed.  */
extern int _dl_debug_mask;
#define DL_DEBUG_LIBS	    (1 << 0)
#define DL_DEBUG_IMPCALLS   (1 << 1)
#define DL_DEBUG_BINDINGS   (1 << 2)
#define DL_DEBUG_SYMBOLS    (1 << 3)
#define DL_DEBUG_VERSIONS   (1 << 4)
#define DL_DEBUG_RELOC      (1 << 5)
#define DL_DEBUG_FILES      (1 << 6)
#define DL_DEBUG_STATISTICS (1 << 7)
/* This one is used only internally.  */
#define DL_DEBUG_HELP       (1 << 8)

/* Expect cache ID.  */
extern int _dl_correct_cache_id;

/* Mask for hardware capabilities that are available.  */
extern unsigned long int _dl_hwcap;

/* Mask for important hardware capabilities we honour. */
extern unsigned long int _dl_hwcap_mask;

/* File descriptor to write debug messages to.  */
extern int _dl_debug_fd;

/* Names of shared object for which the RPATH should be ignored.  */
extern const char *_dl_inhibit_rpath;

/* Nonzero if references should be treated as weak during runtime linking.  */
extern int _dl_dynamic_weak;

/* The array with message we print as a last resort.  */
extern const char _dl_out_of_memory[];

/* Nonzero if runtime lookups should not update the .got/.plt.  */
extern int _dl_bind_not;

/* List of search directories.  */
extern struct r_search_path_elem *_dl_all_dirs;
extern struct r_search_path_elem *_dl_init_all_dirs;

/* OS-dependent function to open the zero-fill device.  */
extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */


/* During the program run we must not modify the global data of
   loaded shared object simultanously in two threads.  Therefore we
   protect `_dl_open' and `_dl_close' in dl-close.c.

   This must be a recursive lock since the initializer function of
   the loaded object might as well require a call to this function.
   At this time it is not anymore a problem to modify the tables.  */
__libc_lock_define_recursive (extern, _dl_load_lock)


/* Write message on the debug file descriptor.  The parameters are
   interpreted as for a `printf' call.  All the lines start with a