glibc/elf/dl-conflict.c

/* Resolve conflicts against already prelinked libraries.
   Copyright (C) 2001-2021 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; see the file COPYING.LIB.  If
   not, see <https://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <errno.h>
#include <libintl.h>
#include <stdlib.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/types.h>
#include "dynamic-link.h"

/* Used at loading time solely for prelink executable.  It is not called
   concurrently so it is be safe to defined as static.  */
static struct link_map *resolve_conflict_map __attribute__ ((__unused__));

    /* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code.  */
#define RESOLVE_MAP(map, scope, ref, version, flags) (*ref = NULL, NULL)
#define RESOLVE(ref, version, flags) (*ref = NULL, 0)
#define RESOLVE_CONFLICT_FIND_MAP(map, r_offset) \
  do {									      \
    while ((resolve_conflict_map->l_map_end < (ElfW(Addr)) (r_offset))	      \
	   || (resolve_conflict_map->l_map_start > (ElfW(Addr)) (r_offset)))  \
      resolve_conflict_map = resolve_conflict_map->l_next;		      \
									      \
    (map) = resolve_conflict_map;					      \
  } while (0)

#include "dynamic-link.h"

void
_dl_resolve_conflicts (struct link_map *l, ElfW(Rela) *conflict,
		       ElfW(Rela) *conflictend)
{
#if ! ELF_MACHINE_NO_RELA
  if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_RELOC))
    _dl_debug_printf ("\nconflict processing: %s\n", DSO_FILENAME (l->l_name));

  {
    /* Do the conflict relocation of the object and library GOT and other
       data.  */

    /* Prelinking makes no sense for anything but the main namespace.  */
    assert (l->l_ns == LM_ID_BASE);
    resolve_conflict_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;

    /* Override these, defined in dynamic-link.h.  */
#undef CHECK_STATIC_TLS
#define CHECK_STATIC_TLS(ref_map, sym_map) ((void) 0)
#undef TRY_STATIC_TLS
#define TRY_STATIC_TLS(ref_map, sym_map) (0)

    GL(dl_num_cache_relocations) += conflictend - conflict;

    for (; conflict < conflictend; ++conflict)
      elf_machine_rela (l, NULL, conflict, NULL, NULL,
			(void *) conflict->r_offset, 0);
  }
#endif
}