NetBSD/libexec/ld.elf_so/load.c
junyoung fd1f5e8f1b A bit speedup: in _rtld_load_object(), save the number of calls to
strcmp() by performing path name length comparison first. In the test
with Mozilla, the number was reduced to 1068 from 7182 (yes, we saved
6114 strcmp()!).
2002-12-05 04:56:56 +00:00

320 lines
7.9 KiB
C

/* $NetBSD: load.c,v 1.25 2002/12/05 04:56:56 junyoung 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 <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 __P((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_add(list, obj)
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. The
* argument must be a string allocated on the heap. This function assumes
* responsibility for freeing it when necessary.
*
* Returns a pointer to the Obj_Entry for the object. Returns NULL
* on failure.
*/
Obj_Entry *
_rtld_load_object(filepath, mode)
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) {
free(filepath);
return NULL;
}
_rtld_digest_dynamic(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));
} else
free(filepath);
++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_add(&_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_add(&_rtld_list_global, obj);
}
#endif
return obj;
}
static bool
_rtld_load_by_name(name, obj, needed, mode)
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;
char s[16];
} val;
dbg(("load by name %s %p", name, x));
for (; x; x = x->next) {
if (strcmp(x->name, name) != 0)
continue;
i = sizeof(val);
if (sysctl(x->ctl, x->ctlmax, &val, &i, NULL, 0) == -1) {
xwarnx(_PATH_LD_HINTS ": unknown sysctl for %s", name);
break;
}
switch (x->ctltype[x->ctlmax - 1]) {
case CTLTYPE_INT:
xsnprintf(val.s, sizeof(val.s), "%d", val.i);
break;
case CTLTYPE_STRING:
break;
default:
xwarnx("unsupported sysctl type %d",
x->ctltype[x->ctlmax - 1]);
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(first, mode)
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(preload_path)
const char *preload_path;
{
const char *path;
char *cp, *buf;
int status = 0;
if (preload_path != NULL) {
cp = buf = xstrdup(preload_path);
while ((path = strsep(&cp, " :")) != NULL && status == 0) {
if (!_rtld_load_object(xstrdup(path), RTLD_MAIN))
status = -1;
else
dbg((" preloaded \"%s\"", path));
}
free(buf);
}
return (status);
}
#endif