225 lines
6.7 KiB
C
225 lines
6.7 KiB
C
/* $NetBSD: reloc.c,v 1.103 2010/12/24 12:41:43 skrll Exp $ */
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/*
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* Copyright 1996 John D. Polstra.
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* Copyright 1996 Matt Thomas <matt@3am-software.com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Polstra.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Dynamic linker for ELF.
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*
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* John Polstra <jdp@polstra.com>.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: reloc.c,v 1.103 2010/12/24 12:41:43 skrll Exp $");
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#endif /* not lint */
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <sys/bitops.h>
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#include <dirent.h>
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#include "debug.h"
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#include "rtld.h"
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#ifndef RTLD_INHIBIT_COPY_RELOCS
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static int _rtld_do_copy_relocation(const Obj_Entry *, const Elf_Rela *);
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static int
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_rtld_do_copy_relocation(const Obj_Entry *dstobj, const Elf_Rela *rela)
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{
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void *dstaddr = (void *)(dstobj->relocbase + rela->r_offset);
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const Elf_Sym *dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
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const char *name = dstobj->strtab + dstsym->st_name;
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unsigned long hash = _rtld_elf_hash(name);
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size_t size = dstsym->st_size;
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const void *srcaddr;
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const Elf_Sym *srcsym = NULL;
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Obj_Entry *srcobj;
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for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next)
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if ((srcsym = _rtld_symlook_obj(name, hash, srcobj, false)) != NULL)
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break;
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if (srcobj == NULL) {
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_rtld_error("Undefined symbol \"%s\" referenced from COPY"
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" relocation in %s", name, dstobj->path);
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return (-1);
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}
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srcaddr = (const void *)(srcobj->relocbase + srcsym->st_value);
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(void)memcpy(dstaddr, srcaddr, size);
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rdbg(("COPY %s %s %s --> src=%p dst=%p size %ld",
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dstobj->path, srcobj->path, name, srcaddr,
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(void *)dstaddr, (long)size));
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return (0);
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}
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#endif /* RTLD_INHIBIT_COPY_RELOCS */
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/*
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* Process the special R_xxx_COPY relocations in the main program. These
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* copy data from a shared object into a region in the main program's BSS
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* segment.
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*
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* Returns 0 on success, -1 on failure.
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*/
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int
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_rtld_do_copy_relocations(const Obj_Entry *dstobj)
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{
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#ifndef RTLD_INHIBIT_COPY_RELOCS
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/* COPY relocations are invalid elsewhere */
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assert(!dstobj->isdynamic);
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if (dstobj->rel != NULL) {
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const Elf_Rel *rel;
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for (rel = dstobj->rel; rel < dstobj->rellim; ++rel) {
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if (ELF_R_TYPE(rel->r_info) == R_TYPE(COPY)) {
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Elf_Rela ourrela;
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ourrela.r_info = rel->r_info;
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ourrela.r_offset = rel->r_offset;
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ourrela.r_addend = 0;
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if (_rtld_do_copy_relocation(dstobj,
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&ourrela) < 0)
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return (-1);
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}
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}
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}
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if (dstobj->rela != NULL) {
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const Elf_Rela *rela;
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for (rela = dstobj->rela; rela < dstobj->relalim; ++rela) {
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if (ELF_R_TYPE(rela->r_info) == R_TYPE(COPY)) {
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if (_rtld_do_copy_relocation(dstobj, rela) < 0)
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return (-1);
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}
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}
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}
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#endif /* RTLD_INHIBIT_COPY_RELOCS */
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return (0);
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}
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/*
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* Relocate newly-loaded shared objects. The argument is a pointer to
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* the Obj_Entry for the first such object. All objects from the first
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* to the end of the list of objects are relocated. Returns 0 on success,
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* or -1 on failure.
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*/
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int
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_rtld_relocate_objects(Obj_Entry *first, bool bind_now)
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{
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Obj_Entry *obj;
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int ok = 1;
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for (obj = first; obj != NULL; obj = obj->next) {
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if (obj->nbuckets == 0 || obj->nchains == 0 ||
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obj->buckets == NULL || obj->symtab == NULL ||
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obj->strtab == NULL) {
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_rtld_error("%s: Shared object has no run-time"
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" symbol table", obj->path);
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return -1;
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}
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if (obj->nbuckets == UINT32_MAX) {
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_rtld_error("%s: Symbol table too large", obj->path);
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return -1;
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}
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rdbg((" relocating %s (%ld/%ld rel/rela, %ld/%ld plt rel/rela)",
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obj->path,
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(long)(obj->rellim - obj->rel),
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(long)(obj->relalim - obj->rela),
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(long)(obj->pltrellim - obj->pltrel),
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(long)(obj->pltrelalim - obj->pltrela)));
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if (obj->textrel) {
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/*
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* There are relocations to the write-protected text
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* segment.
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*/
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if (mprotect(obj->mapbase, obj->textsize,
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PROT_READ | PROT_WRITE | PROT_EXEC) == -1) {
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_rtld_error("%s: Cannot write-enable text "
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"segment: %s", obj->path, xstrerror(errno));
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return -1;
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}
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}
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dbg(("doing non-PLT relocations"));
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if (_rtld_relocate_nonplt_objects(obj) < 0)
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ok = 0;
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if (obj->textrel) { /* Re-protected the text segment. */
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if (mprotect(obj->mapbase, obj->textsize,
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PROT_READ | PROT_EXEC) == -1) {
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_rtld_error("%s: Cannot write-protect text "
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"segment: %s", obj->path, xstrerror(errno));
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return -1;
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}
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}
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dbg(("doing lazy PLT binding"));
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if (_rtld_relocate_plt_lazy(obj) < 0)
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ok = 0;
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#if defined(__hppa__)
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bind_now = 1;
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#endif
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if (obj->z_now || bind_now) {
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dbg(("doing immediate PLT binding"));
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if (_rtld_relocate_plt_objects(obj) < 0)
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ok = 0;
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}
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if (!ok)
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return -1;
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/* Set some sanity-checking numbers in the Obj_Entry. */
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obj->magic = RTLD_MAGIC;
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obj->version = RTLD_VERSION;
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/* Fill in the dynamic linker entry points. */
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obj->dlopen = dlopen;
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obj->dlsym = dlsym;
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obj->dlerror = dlerror;
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obj->dlclose = dlclose;
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obj->dladdr = dladdr;
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dbg(("fixing up PLTGOT"));
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/* Set the special PLTGOT entries. */
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if (obj->pltgot != NULL)
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_rtld_setup_pltgot(obj);
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}
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return 0;
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}
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