glibc/iconv/gconv_dl.c
Ulrich Drepper dc5efe83c0 Update.
* Versions.def (ld.so): Add GLIBC_2.1.1.
	* elf/Makefile (routines): Add dl-origin.
	(tests): Add origtest.  Add dependencies for the program.
	* elf/Versions (ld.so) [GLIBC_2.1.1]: Add _dl_origin_path,
	_dl_platformlen, _dl_dst_count and _dl_dst_substitute.
	* elf/dl-deps.c (expand_dst): New macro.  Expand DSTs in filename.
	(_dl_map_object_deps): Use expand_dst to expand DSTs in DT_NEEDED,
	DT_AUXILIARY, and DT_FILTER filenames.
	* elf/dl-load.c (expand_dynamic_string_token): Explode into
	two functions and three macros.
	(_dl_dst_count, _dl_dst_substitute): New functions.
	* elf/dl-dst.h: New file.
	* elf/dl-open.c (_dl_open): Take extra parameter with address of
	caller.  Pass address in args structure.
	(dl_open_worker): Recognize and expand DSTs in filename.
	* elf/ldsodefs.h (_dl_open): Adapt prototype.
	* elf/dlopen.c (dlopen_doit): Pass caller address to _dl_open.
	(__dlopen_check): Pass caller address to dlopen_doit in args.
	* elf/dlopendoit.c: Likewise.
	* iconv/gconv_dl.c: Adapt call of _dl_open.
	* nss/nsswitch.c: Likewise.
	* elf/origtest.c: New file.
	* sysdeps/generic/dl-origin.h: Moved to...
	* sysdeps/generic/dl-origin.c: ...here.
	* sysdeps/unix/sysv/linux/dl-origin.h: Moved to...
	* sysdeps/unix/sysv/linux/dl-origin.c: ...here.
1999-05-05 23:29:18 +00:00

276 lines
7.5 KiB
C

/* Handle loading/unloading of shared object for transformation.
Copyright (C) 1997, 1998, 1999 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <dlfcn.h>
#include <inttypes.h>
#include <search.h>
#include <stdlib.h>
#include <string.h>
#include <bits/libc-lock.h>
#include <sys/param.h>
#include <ldsodefs.h>
#include <gconv_int.h>
/* This is a tuning parameter. If a transformation module is not used
anymore it gets not immediately unloaded. Instead we wait a certain
number of load attempts for further modules. If none of the
subsequent load attempts name the same object it finally gets unloaded.
Otherwise it is still available which hopefully is the frequent case.
The following number is the number of unloading attempts we wait
before unloading. */
#define TRIES_BEFORE_UNLOAD 2
/* Array of loaded objects. This is shared by all threads so we have
to use semaphores to access it. */
static void *loaded;
/* Comparison function for searching `loaded_object' tree. */
static int
known_compare (const void *p1, const void *p2)
{
const struct gconv_loaded_object *s1 =
(const struct gconv_loaded_object *) p1;
const struct gconv_loaded_object *s2 =
(const struct gconv_loaded_object *) p2;
return (intptr_t) s1->handle - (intptr_t) s2->handle;
}
static void
do_open (void *a)
{
struct gconv_loaded_object *args = (struct gconv_loaded_object *) a;
/* Open and relocate the shared object. */
args->handle = _dl_open (args->name, RTLD_LAZY, NULL);
}
static int
internal_function
dlerror_run (void (*operate) (void *), void *args)
{
char *last_errstring = NULL;
int result;
(void) _dl_catch_error (&last_errstring, operate, args);
result = last_errstring != NULL;
if (result)
free (last_errstring);
return result;
}
struct get_sym_args
{
/* Arguments to get_sym. */
struct link_map *map;
const char *name;
/* Return values of get_sym. */
ElfW(Addr) loadbase;
const ElfW(Sym) *ref;
};
static void
get_sym (void *a)
{
struct get_sym_args *args = (struct get_sym_args *) a;
args->ref = NULL;
args->loadbase = _dl_lookup_symbol (args->name, &args->ref,
args->map->l_local_scope,
args->map->l_name, 0);
}
void *
internal_function
__gconv_find_func (void *handle, const char *name)
{
struct get_sym_args args;
args.map = handle;
args.name = name;
return (dlerror_run (get_sym, &args) ? NULL
: (void *) (args.loadbase + args.ref->st_value));
}
/* Open the gconv database if necessary. A non-negative return value
means success. */
struct gconv_loaded_object *
internal_function
__gconv_find_shlib (const char *name)
{
struct gconv_loaded_object *found;
void *keyp;
/* Search the tree of shared objects previously requested. Data in
the tree are `loaded_object' structures, whose first member is a
`const char *', the lookup key. The search returns a pointer to
the tree node structure; the first member of the is a pointer to
our structure (i.e. what will be a `loaded_object'); since the
first member of that is the lookup key string, &FCT_NAME is close
enough to a pointer to our structure to use as a lookup key that
will be passed to `known_compare' (above). */
keyp = __tfind (&name, &loaded, known_compare);
if (keyp == NULL)
{
/* This name was not known before. */
found = malloc (sizeof (struct gconv_loaded_object));
if (found != NULL)
{
/* Point the tree node at this new structure. */
found->name = name;
found->counter = -TRIES_BEFORE_UNLOAD - 1;
found->handle = NULL;
if (__tsearch (found, &loaded, known_compare) == NULL)
{
/* Something went wrong while inserting the entry. */
free (found);
found = NULL;
}
}
}
else
found = *(struct gconv_loaded_object **) keyp;
/* Try to load the shared object if the usage count is 0. This
implies that if the shared object is not loadable, the handle is
NULL and the usage count > 0. */
if (found != NULL)
{
if (found->counter < -TRIES_BEFORE_UNLOAD)
{
if (dlerror_run (do_open, found) == 0)
{
found->fct = __gconv_find_func (found->handle, "gconv");
if (found->fct == NULL)
{
/* Argh, no conversion function. There is something
wrong here. */
__gconv_release_shlib (found);
found = NULL;
}
else
{
found->init_fct = __gconv_find_func (found->handle,
"gconv_init");
found->end_fct = __gconv_find_func (found->handle,
"gconv_end");
/* We have succeeded in loading the shared object. */
found->counter = 1;
}
}
else
/* Error while loading the shared object. */
found = NULL;
}
else if (found->handle != NULL)
found->counter = MAX (found->counter + 1, 1);
}
return found;
}
/* This is very ugly but the tsearch functions provide no way to pass
information to the walker function. So we use a global variable.
It is MT safe since we use a lock. */
static struct gconv_loaded_object *release_handle;
static void
do_release_shlib (const void *nodep, VISIT value, int level)
{
struct gconv_loaded_object *obj = *(struct gconv_loaded_object **) nodep;
if (value != preorder && value != leaf)
return;
if (obj == release_handle)
/* This is the object we want to unload. Now set the release
counter to zero. */
obj->counter = 0;
else if (obj->counter <= 0)
{
if (--obj->counter < -TRIES_BEFORE_UNLOAD && obj->handle != NULL)
{
/* Unload the shared object. We don't use the trick to
catch errors since in the case an error is signalled
something is really wrong. */
_dl_close (obj->handle);
obj->handle = NULL;
}
}
}
/* Notify system that a shared object is not longer needed. */
int
internal_function
__gconv_release_shlib (struct gconv_loaded_object *handle)
{
/* Urgh, this is ugly but we have no other possibility. */
release_handle = handle;
/* Process all entries. Please note that we also visit entries
with release counts <= 0. This way we can finally unload them
if necessary. */
__twalk (loaded, do_release_shlib);
return GCONV_OK;
}
/* We run this if we debug the memory allocation. */
static void
do_release_all (void *nodep)
{
struct gconv_loaded_object *obj = (struct gconv_loaded_object *) nodep;
/* Unload the shared object. We don't use the trick to
catch errors since in the case an error is signalled
something is really wrong. */
if (obj->handle != NULL)
_dl_close (obj->handle);
free (obj);
}
static void __attribute__ ((unused))
free_mem (void)
{
__tdestroy (loaded, do_release_all);
}
text_set_element (__libc_subfreeres, free_mem);