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NetBSD/libexec/ld.elf_so/load.c

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/* $NetBSD: load.c,v 1.35 2007/12/07 20:34:04 ad Exp $ */
/*
* Copyright 1996 John D. Polstra.
* Copyright 1996 Matt Thomas <matt@3am-software.com>
* Copyright 2002 Charles M. Hannum <root@ihack.net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Polstra.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Dynamic linker for ELF.
*
* John Polstra <jdp@polstra.com>.
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: load.c,v 1.35 2007/12/07 20:34:04 ad Exp $");
#endif /* not lint */
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/sysctl.h>
#include <dirent.h>
#include "debug.h"
#include "rtld.h"
static bool _rtld_load_by_name(const char *, Obj_Entry *, Needed_Entry **,
int);
#ifdef RTLD_LOADER
Objlist _rtld_list_main = /* Objects loaded at program startup */
SIMPLEQ_HEAD_INITIALIZER(_rtld_list_main);
Objlist _rtld_list_global = /* Objects dlopened with RTLD_GLOBAL */
SIMPLEQ_HEAD_INITIALIZER(_rtld_list_global);
void
_rtld_objlist_push_head(Objlist *list, Obj_Entry *obj)
{
Objlist_Entry *elm;
elm = NEW(Objlist_Entry);
elm->obj = obj;
SIMPLEQ_INSERT_HEAD(list, elm, link);
}
void
_rtld_objlist_push_tail(Objlist *list, Obj_Entry *obj)
{
Objlist_Entry *elm;
elm = NEW(Objlist_Entry);
elm->obj = obj;
SIMPLEQ_INSERT_TAIL(list, elm, link);
}
Objlist_Entry *
_rtld_objlist_find(Objlist *list, const Obj_Entry *obj)
{
Objlist_Entry *elm;
SIMPLEQ_FOREACH(elm, list, link) {
if (elm->obj == obj)
return elm;
}
return NULL;
}
#endif
/*
* Load a shared object into memory, if it is not already loaded.
*
* Returns a pointer to the Obj_Entry for the object. Returns NULL
* on failure.
*/
Obj_Entry *
_rtld_load_object(const char *filepath, int mode)
{
Obj_Entry *obj;
int fd = -1;
struct stat sb;
size_t pathlen = strlen(filepath);
for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next)
if (pathlen == obj->pathlen && !strcmp(obj->path, filepath))
break;
/*
* If we didn't find a match by pathname, open the file and check
* again by device and inode. This avoids false mismatches caused
* by multiple links or ".." in pathnames.
*
* To avoid a race, we open the file and use fstat() rather than
* using stat().
*/
if (obj == NULL) {
if ((fd = open(filepath, O_RDONLY)) == -1) {
_rtld_error("Cannot open \"%s\"", filepath);
return NULL;
}
if (fstat(fd, &sb) == -1) {
_rtld_error("Cannot fstat \"%s\"", filepath);
close(fd);
return NULL;
}
for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next) {
if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
close(fd);
break;
}
}
}
if (obj == NULL) { /* First use of this object, so we must map it in */
obj = _rtld_map_object(filepath, fd, &sb);
(void)close(fd);
if (obj == NULL)
return NULL;
_rtld_digest_dynamic(filepath, obj);
*_rtld_objtail = obj;
_rtld_objtail = &obj->next;
#ifdef RTLD_LOADER
_rtld_linkmap_add(obj); /* for GDB */
#endif
dbg((" %p .. %p: %s", obj->mapbase,
obj->mapbase + obj->mapsize - 1, obj->path));
if (obj->textrel)
dbg((" WARNING: %s has impure text", obj->path));
}
++obj->refcount;
#ifdef RTLD_LOADER
if (mode & RTLD_MAIN && !obj->mainref) {
obj->mainref = 1;
rdbg(("adding %p (%s) to _rtld_list_main", obj, obj->path));
_rtld_objlist_push_tail(&_rtld_list_main, obj);
}
if (mode & RTLD_GLOBAL && !obj->globalref) {
obj->globalref = 1;
rdbg(("adding %p (%s) to _rtld_list_global", obj, obj->path));
_rtld_objlist_push_tail(&_rtld_list_global, obj);
}
#endif
return obj;
}
static bool
_rtld_load_by_name(const char *name, Obj_Entry *obj, Needed_Entry **needed, int mode)
{
Library_Xform *x = _rtld_xforms;
Obj_Entry *o = NULL;
size_t i, j;
bool got = false;
union {
int i;
u_quad_t q;
char s[16];
} val;
dbg(("load by name %s %p", name, x));
for (; x; x = x->next) {
if (strcmp(x->name, name) != 0)
continue;
j = sizeof(val);
if ((i = _rtld_sysctl(x->ctlname, &val, &j)) == -1) {
xwarnx(_PATH_LD_HINTS ": invalid/unknown sysctl for %s (%d)",
name, errno);
break;
}
switch (i) {
case CTLTYPE_QUAD:
xsnprintf(val.s, sizeof(val.s), "%" PRIu64, val.q);
break;
case CTLTYPE_INT:
xsnprintf(val.s, sizeof(val.s), "%d", val.i);
break;
case CTLTYPE_STRING:
break;
default:
xwarnx("unsupported sysctl type %d", (int)i);
break;
}
dbg(("sysctl returns %s", val.s));
for (i = 0; i < RTLD_MAX_ENTRY && x->entry[i].value != NULL;
i++) {
dbg(("entry %ld", (unsigned long)i));
if (strcmp(x->entry[i].value, val.s) == 0)
break;
}
if (i == RTLD_MAX_ENTRY) {
xwarnx("sysctl value %s not found for lib%s",
val.s, name);
break;
}
/* XXX: This can mess up debuggers, cause we lie about
* what we loaded in the needed objects */
for (j = 0; j < RTLD_MAX_LIBRARY &&
x->entry[i].library[j] != NULL; j++) {
o = _rtld_load_library(x->entry[i].library[j], obj,
mode);
if (o == NULL) {
xwarnx("could not load %s for %s",
x->entry[i].library[j], name);
continue;
}
got = true;
if (j == 0)
(*needed)->obj = o;
else {
/* make a new one and put it in the chain */
Needed_Entry *ne = xmalloc(sizeof(*ne));
ne->name = (*needed)->name;
ne->obj = o;
ne->next = (*needed)->next;
(*needed)->next = ne;
*needed = ne;
}
}
}
if (got)
return true;
return ((*needed)->obj = _rtld_load_library(name, obj, mode)) != NULL;
}
/*
* Given a shared object, traverse its list of needed objects, and load
* each of them. Returns 0 on success. Generates an error message and
* returns -1 on failure.
*/
int
_rtld_load_needed_objects(Obj_Entry *first, int mode)
{
Obj_Entry *obj;
int status = 0;
for (obj = first; obj != NULL; obj = obj->next) {
Needed_Entry *needed;
for (needed = obj->needed; needed != NULL;
needed = needed->next) {
const char *name = obj->strtab + needed->name;
if (!_rtld_load_by_name(name, obj, &needed, mode))
status = -1; /* FIXME - cleanup */
#ifdef RTLD_LOADER
if (status == -1)
return status;
#endif
}
}
return status;
}
#ifdef RTLD_LOADER
int
_rtld_preload(const char *preload_path)
{
const char *path;
char *cp, *buf;
int status = 0;
if (preload_path != NULL && *preload_path != '\0') {
cp = buf = xstrdup(preload_path);
while ((path = strsep(&cp, " :")) != NULL && status == 0) {
if (!_rtld_load_object(path, RTLD_MAIN))
status = -1;
else
dbg((" preloaded \"%s\"", path));
}
xfree(buf);
}
return (status);
}
#endif
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