uclibc-ng/ldso/libdl/libdl.c

/* vi: set sw=4 ts=4: */
/*
 * Program to load an ELF binary on a linux system, and run it
 * after resolving ELF shared library symbols
 *
 * Copyright (C) 2000-2006 by Erik Andersen <andersen@uclibc.org>
 * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
 *				David Engel, Hongjiu Lu and Mitch D'Souza
 *
 * 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. The name of the above contributors may not be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``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 CONTRIBUTORS 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.
 */


#include <ldso.h>
#include <stdio.h>
#include <string.h> /* Needed for 'strstr' prototype' */
#include <stdbool.h>

#ifdef __UCLIBC_HAS_TLS__
#include <tls.h>
#endif

#if defined(USE_TLS) && USE_TLS
#include <ldsodefs.h>
extern void _dl_add_to_slotinfo(struct link_map  *l);
#endif

#ifdef SHARED
# if defined(USE_TLS) && USE_TLS
# include <dl-tls.h>
extern struct link_map *_dl_update_slotinfo(unsigned long int req_modid);
# endif

/* When libdl is loaded as a shared library, we need to load in
 * and use a pile of symbols from ldso... */
#include <dl-elf.h>
#if 0
extern struct elf_resolve * _dl_load_shared_library(unsigned, struct dyn_elf **,
	struct elf_resolve *, char *, int);
extern int _dl_fixup(struct dyn_elf *rpnt, struct r_scope_elem *scope, int lazy);
extern void _dl_protect_relro(struct elf_resolve * tpnt);
#endif
extern int _dl_errno;
extern struct dyn_elf *_dl_symbol_tables;
extern struct dyn_elf *_dl_handles;
extern struct elf_resolve *_dl_loaded_modules;
extern void _dl_free (void *__ptr);
extern struct r_debug *_dl_debug_addr;
extern unsigned long _dl_error_number;
extern void *(*_dl_malloc_function)(size_t);
extern void (*_dl_free_function) (void *p);
extern void _dl_run_init_array(struct elf_resolve *);
extern void _dl_run_fini_array(struct elf_resolve *);
#ifdef __LDSO_CACHE_SUPPORT__
int _dl_map_cache(void);
int _dl_unmap_cache(void);
#endif
#ifdef __mips__
extern void _dl_perform_mips_global_got_relocations(struct elf_resolve *tpnt, int lazy);
#endif
#ifdef __SUPPORT_LD_DEBUG__
extern char *_dl_debug;
#endif

#else /* !SHARED */

#define _dl_malloc malloc
#define _dl_free free

/* When libdl is linked as a static library, we need to replace all
 * the symbols that otherwise would have been loaded in from ldso... */

#ifdef __SUPPORT_LD_DEBUG__
char *_dl_debug  = NULL;
char *_dl_debug_symbols   = NULL;
char *_dl_debug_move      = NULL;
char *_dl_debug_reloc     = NULL;
char *_dl_debug_detail    = NULL;
char *_dl_debug_nofixups  = NULL;
char *_dl_debug_bindings  = NULL;
int   _dl_debug_file      = 2;
#endif
const char *_dl_progname       = "";        /* Program name */
void *(*_dl_malloc_function)(size_t);
void (*_dl_free_function) (void *p);
#ifdef __LDSO_LD_LIBRARY_PATH__
char *_dl_library_path         = NULL;         /* Where we look for libraries */
#endif
int _dl_errno                  = 0;         /* We can't use the real errno in ldso */
size_t _dl_pagesize            = PAGE_SIZE; /* Store the page size for use later */
/* This global variable is also to communicate with debuggers such as gdb. */
struct r_debug *_dl_debug_addr = NULL;

#include "../ldso/dl-array.c"
#include "../ldso/dl-debug.c"


# if defined(USE_TLS) && USE_TLS
/*
 * Giving this initialized value preallocates some surplus bytes in the
 * static TLS area, see __libc_setup_tls (libc-tls.c).
 */
size_t _dl_tls_static_size = 2048;
# endif
#include LDSO_ELFINTERP
#include "../ldso/dl-hash.c"
#define _dl_trace_loaded_objects    0
#include "../ldso/dl-elf.c"
#endif /* SHARED */

#ifdef __SUPPORT_LD_DEBUG__
# define _dl_if_debug_print(fmt, args...) \
	do { \
	if (_dl_debug) \
		fprintf(stderr, "%s():%i: " fmt, __FUNCTION__, __LINE__, ## args); \
	} while (0)
#else
# define _dl_if_debug_print(fmt, args...)
#endif

static int do_dlclose(void *, int need_fini);


static const char *const dl_error_names[] = {
	"",
	"File not found",
	"Unable to open /dev/zero",
	"Not an ELF file",
#if defined (__i386__)
	"Not i386 binary",
#elif defined (__sparc__)
	"Not sparc binary",
#elif defined (__mc68000__)
	"Not m68k binary",
#else
	"Unrecognized binary type",
#endif
	"Not an ELF shared library",
	"Unable to mmap file",
	"No dynamic section",
	"Library contains unsupported TLS",
#ifdef ELF_USES_RELOCA
	"Unable to process REL relocs",
#else
	"Unable to process RELA relocs",
#endif
	"Bad handle",
	"Unable to resolve symbol"
};


#if defined(USE_TLS) && USE_TLS
#ifdef SHARED
/*
 * Systems which do not have tls_index also probably have to define
 * DONT_USE_TLS_INDEX.
 */

# ifndef __TLS_GET_ADDR
#  define __TLS_GET_ADDR __tls_get_addr
# endif

/*
 * Return the symbol address given the map of the module it is in and
 *  the symbol record.  This is used in dl-sym.c.
 */
static void *
internal_function
_dl_tls_symaddr(struct link_map *map, const Elf32_Addr st_value)
{
# ifndef DONT_USE_TLS_INDEX
	tls_index tmp =
	{
		.ti_module = map->l_tls_modid,
		.ti_offset = st_value
	};

	return __TLS_GET_ADDR (&tmp);
# else
	return __TLS_GET_ADDR (map->l_tls_modid, st_value);
# endif
}
#endif

/* Returns true when a non-empty entry was found.  */
static bool
remove_slotinfo(size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
	 bool should_be_there)
{
	if (idx - disp >= listp->len) {
		if (listp->next == NULL) {
			/*
			 * The index is not actually valid in the slotinfo list,
			 * because this object was closed before it was fully set
			 * up due to some error.
			 */
			_dl_assert(!should_be_there);
		} else {
			if (remove_slotinfo(idx, listp->next, disp + listp->len,
					should_be_there))
				return true;

			/*
			 * No non-empty entry. Search from the end of this element's
			 * slotinfo array.
			 */
			idx = disp + listp->len;
		}
	} else {
		struct link_map *old_map = listp->slotinfo[idx - disp].map;

		/*
		 * The entry might still be in its unused state if we are
		 * closing an object that wasn't fully set up.
		 */
		if (__builtin_expect(old_map != NULL, 1)) {
			_dl_assert(old_map->l_tls_modid == idx);

			/* Mark the entry as unused. */
			listp->slotinfo[idx - disp].gen = _dl_tls_generation + 1;
			listp->slotinfo[idx - disp].map = NULL;
		}

		/*
		 * If this is not the last currently used entry no need to
		 * look further.
		 */
		if (idx != _dl_tls_max_dtv_idx)
			return true;
	}

	while (idx - disp > (disp == 0 ? 1 + _dl_tls_static_nelem : 0)) {
		--idx;

		if (listp->slotinfo[idx - disp].map != NULL) {
			/* Found a new last used index.  */
			_dl_tls_max_dtv_idx = idx;
			return true;
		}
	}

	/* No non-entry in this list element.  */
	return false;
}
#endif

#ifndef __LDSO_NO_CLEANUP__
void dl_cleanup(void) __attribute__ ((destructor));
void dl_cleanup(void)
{
	struct dyn_elf *h, *n;

	for (h = _dl_handles; h; h = n) {
		n = h->next_handle;
		do_dlclose(h, 1);
	}
}
#endif

static ptrdiff_t _dl_build_local_scope (struct elf_resolve **list,
	struct elf_resolve *map)
{
	struct elf_resolve **p = list;
	struct init_fini_list *q;

	*p++ = map;
	map->init_flag |= DL_RESERVED;
	if (map->init_fini)
		for (q = map->init_fini; q; q = q->next)
			if (! (q->tpnt->init_flag & DL_RESERVED))
				p += _dl_build_local_scope (p, q->tpnt);
	return p - list;
}

void *dlopen(const char *libname, int flag)
{
	struct elf_resolve *tpnt, *tfrom;
	struct dyn_elf *dyn_chain, *rpnt = NULL, *dyn_ptr, *relro_ptr, *handle;
	ElfW(Addr) from;
	struct elf_resolve *tpnt1;
	void (*dl_brk) (void);
	int now_flag;
	struct init_fini_list *tmp, *runp, *runp2, *dep_list;
	unsigned int nlist, i;
	struct elf_resolve **init_fini_list;
	static bool _dl_init;
	struct elf_resolve **local_scope;
	struct r_scope_elem *ls;
#if defined(USE_TLS) && USE_TLS
	bool any_tls = false;
#endif

	/* A bit of sanity checking... */
	if (!(flag & (RTLD_LAZY|RTLD_NOW|RTLD_NOLOAD))) {
		_dl_error_number = LD_BAD_HANDLE;
		return NULL;
	}

	from = (ElfW(Addr)) __builtin_return_address(0);

	if (!_dl_init) {
		_dl_init = true;
		_dl_malloc_function = malloc;
		_dl_free_function = free;
	}
	/* Cover the trivial case first */
	if (!libname)
		return _dl_symbol_tables;

#ifndef SHARED
# ifdef __SUPPORT_LD_DEBUG__
	_dl_debug = getenv("LD_DEBUG");
	if (_dl_debug) {
		if (_dl_strstr(_dl_debug, "all")) {
			_dl_debug_detail = _dl_debug_move = _dl_debug_symbols
				= _dl_debug_reloc = _dl_debug_bindings = _dl_debug_nofixups = (void*)1;
		} else {
			_dl_debug_detail   = strstr(_dl_debug, "detail");
			_dl_debug_move     = strstr(_dl_debug, "move");
			_dl_debug_symbols  = strstr(_dl_debug, "sym");
			_dl_debug_reloc    = strstr(_dl_debug, "reloc");
			_dl_debug_nofixups = strstr(_dl_debug, "nofix");
			_dl_debug_bindings = strstr(_dl_debug, "bind");
		}
	}
# endif
#endif

	_dl_map_cache();

	/*
	 * Try and locate the module we were called from - we
	 * need this so that we get the correct RPATH/RUNPATH.  Note that
	 * this is the current behavior under Solaris, but the
	 * ABI+ specifies that we should only use the RPATH from
	 * the application.  Thus this may go away at some time
	 * in the future.
	 */
	{
		struct dyn_elf *dpnt;
		tfrom = NULL;
		for (dpnt = _dl_symbol_tables; dpnt; dpnt = dpnt->next) {
			tpnt = dpnt->dyn;
			if (DL_ADDR_IN_LOADADDR(from, tpnt, tfrom))
				tfrom = tpnt;
		}
	}
	for (rpnt = _dl_symbol_tables; rpnt && rpnt->next; rpnt = rpnt->next)
		continue;

	relro_ptr = rpnt;
	now_flag = (flag & RTLD_NOW) ? RTLD_NOW : 0;
	if (getenv("LD_BIND_NOW"))
		now_flag = RTLD_NOW;

#if !defined SHARED && defined __LDSO_LIBRARY_PATH__
	/* When statically linked, the _dl_library_path is not yet initialized */
	_dl_library_path = getenv("LD_LIBRARY_PATH");
#endif

	/* Try to load the specified library */
	_dl_if_debug_print("Trying to dlopen '%s', RTLD_GLOBAL:%d RTLD_NOW:%d\n",
			(char*)libname, (flag & RTLD_GLOBAL ? 1:0), (now_flag & RTLD_NOW ? 1:0));

	tpnt = _dl_load_shared_library((flag & RTLD_NOLOAD) ? DL_RESOLVE_NOLOAD : 0,
					&rpnt, tfrom, (char*)libname, 0);
	if (tpnt == NULL) {
		_dl_unmap_cache();
		return NULL;
	}
	dyn_chain = (struct dyn_elf *) malloc(sizeof(struct dyn_elf));
	_dl_memset(dyn_chain, 0, sizeof(struct dyn_elf));
	dyn_chain->dyn = tpnt;
	tpnt->rtld_flags |= (flag & RTLD_GLOBAL);

	dyn_chain->next_handle = _dl_handles;
	_dl_handles = dyn_ptr = dyn_chain;

	if (tpnt->usage_count > 1) {
		_dl_if_debug_print("Lib: %s already opened\n", libname);
		/* see if there is a handle from a earlier dlopen */
		for (handle = _dl_handles->next_handle; handle; handle = handle->next_handle) {
			if (handle->dyn == tpnt) {
				dyn_chain->init_fini.init_fini = handle->init_fini.init_fini;
				dyn_chain->init_fini.nlist = handle->init_fini.nlist;
				for (i = 0; i < dyn_chain->init_fini.nlist; i++)
					dyn_chain->init_fini.init_fini[i]->rtld_flags |= (flag & RTLD_GLOBAL);
				dyn_chain->next = handle->next;
				break;
			}
		}
		return dyn_chain;
	}

	tpnt->init_flag |= DL_OPENED;

	_dl_if_debug_print("Looking for needed libraries\n");
	nlist = 0;
	runp = alloca(sizeof(*runp));
	runp->tpnt = tpnt;
	runp->next = NULL;
	dep_list = runp2 = runp;
	for (; runp; runp = runp->next)	{
		ElfW(Dyn) *dpnt;
		char *lpntstr;

		nlist++;
		runp->tpnt->init_fini = NULL; /* clear any previous dependcies */
		for (dpnt = (ElfW(Dyn) *) runp->tpnt->dynamic_addr; dpnt->d_tag; dpnt++) {
			if (dpnt->d_tag == DT_NEEDED) {
				lpntstr = (char*) (runp->tpnt->dynamic_info[DT_STRTAB] +
						dpnt->d_un.d_val);
				_dl_if_debug_print("Trying to load '%s', needed by '%s'\n",
						lpntstr, runp->tpnt->libname);
				tpnt1 = _dl_load_shared_library(0, &rpnt, runp->tpnt, lpntstr, 0);
				if (!tpnt1)
					goto oops;

				tpnt1->rtld_flags |= (flag & RTLD_GLOBAL);

				/* This list is for dlsym() and relocation */
				dyn_ptr->next = (struct dyn_elf *) malloc(sizeof(struct dyn_elf));
				_dl_memset (dyn_ptr->next, 0, sizeof (struct dyn_elf));
				dyn_ptr = dyn_ptr->next;
				dyn_ptr->dyn = tpnt1;
				/* Used to record RTLD_LOCAL scope */
				tmp = alloca(sizeof(struct init_fini_list));
				tmp->tpnt = tpnt1;
				tmp->next = runp->tpnt->init_fini;
				runp->tpnt->init_fini = tmp;

				for (tmp=dep_list; tmp; tmp = tmp->next) {
					if (tpnt1 == tmp->tpnt) { /* if match => cirular dependency, drop it */
						_dl_if_debug_print("Circular dependency, skipping '%s',\n",
								   tmp->tpnt->libname);
						tpnt1->usage_count--;
						break;
					}
				}
				if (!tmp) { /* Don't add if circular dependency detected */
					runp2->next = alloca(sizeof(*runp));
					runp2 = runp2->next;
					runp2->tpnt = tpnt1;
					runp2->next = NULL;
				}
			}
		}
	}
	init_fini_list = malloc(nlist * sizeof(struct elf_resolve *));
	dyn_chain->init_fini.init_fini = init_fini_list;
	dyn_chain->init_fini.nlist = nlist;
	i = 0;
	for (runp2 = dep_list; runp2; runp2 = runp2->next) {
		init_fini_list[i++] = runp2->tpnt;
		for (runp = runp2->tpnt->init_fini; runp; runp = runp->next) {
			if (!(runp->tpnt->rtld_flags & RTLD_GLOBAL)) {
				tmp = malloc(sizeof(struct init_fini_list));
				tmp->tpnt = runp->tpnt;
				tmp->next = runp2->tpnt->rtld_local;
				runp2->tpnt->rtld_local = tmp;
			}
		}

	}
	/* Build the local scope for the dynamically loaded modules. */
	local_scope = _dl_malloc(nlist * sizeof(struct elf_resolve *)); /* Could it allocated on stack? */
	for (i = 0; i < nlist; i++)
		if (init_fini_list[i]->symbol_scope.r_nlist == 0) {
			int k, cnt;
			cnt = _dl_build_local_scope(local_scope, init_fini_list[i]);
			init_fini_list[i]->symbol_scope.r_list = _dl_malloc(cnt * sizeof(struct elf_resolve *));
			init_fini_list[i]->symbol_scope.r_nlist = cnt;
			_dl_memcpy (init_fini_list[i]->symbol_scope.r_list, local_scope,
					cnt * sizeof (struct elf_resolve *));
			/* Restoring the init_flag.*/
			for (k = 0; k < nlist; k++)
				init_fini_list[k]->init_flag &= ~DL_RESERVED;
		}

	_dl_free(local_scope);

	/* Sort the INIT/FINI list in dependency order. */
	for (runp2 = dep_list; runp2; runp2 = runp2->next) {
		unsigned int j, k;
		for (j = 0; init_fini_list[j] != runp2->tpnt; ++j)
			/* Empty */;
		for (k = j + 1; k < nlist; ++k) {
			struct init_fini_list *ele = init_fini_list[k]->init_fini;

			for (; ele; ele = ele->next) {
				if (ele->tpnt == runp2->tpnt) {
					struct elf_resolve *here = init_fini_list[k];
					_dl_if_debug_print("Move %s from pos %d to %d in INIT/FINI list.\n", here->libname, k, j);
					for (i = (k - j); i; --i)
						init_fini_list[i+j] = init_fini_list[i+j-1];
					init_fini_list[j] = here;
					++j;
					break;
				}
			}
		}
	}
#ifdef __SUPPORT_LD_DEBUG__
	if (_dl_debug) {
		fprintf(stderr, "\nINIT/FINI order and dependencies:\n");
		for (i = 0; i < nlist; i++) {
			fprintf(stderr, "lib: %s has deps:\n", init_fini_list[i]->libname);
			runp = init_fini_list[i]->init_fini;
			for (; runp; runp = runp->next)
				fprintf(stderr, " %s ", runp->tpnt->libname);
			fprintf(stderr, "\n");
		}
	}
#endif

	_dl_if_debug_print("Beginning dlopen relocation fixups\n");
	/*
	 * OK, now all of the kids are tucked into bed in their proper addresses.
	 * Now we go through and look for REL and RELA records that indicate fixups
	 * to the GOT tables.  We need to do this in reverse order so that COPY
	 * directives work correctly */
#ifdef __mips__
	/*
	 * Relocation of the GOT entries for MIPS have to be done
	 * after all the libraries have been loaded.
	 */
	_dl_perform_mips_global_got_relocations(tpnt, !now_flag);
#endif
	/* Get the tail of the list */
	for (ls = &_dl_loaded_modules->symbol_scope; ls && ls->next; ls = ls->next);

	/* Extend the global scope by adding the local scope of the dlopened DSO. */
	ls->next = &dyn_chain->dyn->symbol_scope;

	if (_dl_fixup(dyn_chain, &_dl_loaded_modules->symbol_scope, now_flag))
		goto oops;

	if (relro_ptr) {
		for (rpnt = relro_ptr->next; rpnt; rpnt = rpnt->next) {
			if (rpnt->dyn->relro_size)
				_dl_protect_relro(rpnt->dyn);
		}
	}
	/* TODO:  Should we set the protections of all pages back to R/O now ? */


#if defined(USE_TLS) && USE_TLS

	for (i=0; i < nlist; i++) {
		struct elf_resolve *tmp_tpnt = init_fini_list[i];
		/* Only add TLS memory if this object is loaded now and
		   therefore is not yet initialized.  */

		if (!(tmp_tpnt->init_flag & INIT_FUNCS_CALLED)
		/* Only if the module defines thread local data. */
			&& __builtin_expect (tmp_tpnt->l_tls_blocksize > 0, 0)) {

			/* Now that we know the object is loaded successfully add
			modules containing TLS data to the slot info table.  We
			might have to increase its size.  */
			_dl_add_to_slotinfo ((struct link_map*)tmp_tpnt);

			/* It is the case in which we couldn't perform TLS static
			   initialization at relocation time, and we delayed it until
			   the relocation has been completed. */

			if (tmp_tpnt->l_need_tls_init) {
				tmp_tpnt->l_need_tls_init = 0;
# ifdef SHARED
				/* Update the slot information data for at least the
				generation of the DSO we are allocating data for.  */
				_dl_update_slotinfo (tmp_tpnt->l_tls_modid);
# endif

				_dl_init_static_tls((struct link_map*)tmp_tpnt);
				_dl_assert (tmp_tpnt->l_need_tls_init == 0);
		}

		/* We have to bump the generation counter. */
		any_tls = true;
		}
	}

	/* Bump the generation number if necessary.  */
	if (any_tls && __builtin_expect (++_dl_tls_generation == 0, 0)) {
		_dl_debug_early("TLS generation counter wrapped! Please report this.");
		_dl_exit(30);
	}

#endif

	/* Notify the debugger we have added some objects. */
	if (_dl_debug_addr) {
		dl_brk = (void (*)(void)) _dl_debug_addr->r_brk;
		if (dl_brk != NULL) {
			_dl_debug_addr->r_state = RT_ADD;
			(*dl_brk) ();

			_dl_debug_addr->r_state = RT_CONSISTENT;
			(*dl_brk) ();
		}
	}

	/* Run the ctors and setup the dtors */
	for (i = nlist; i; --i) {
		tpnt = init_fini_list[i-1];
		if (tpnt->init_flag & INIT_FUNCS_CALLED)
			continue;
		tpnt->init_flag |= INIT_FUNCS_CALLED;

		if (tpnt->dynamic_info[DT_INIT]) {
			void (*dl_elf_func) (void);
			dl_elf_func = (void (*)(void)) DL_RELOC_ADDR(tpnt->loadaddr, tpnt->dynamic_info[DT_INIT]);
			if (dl_elf_func) {
				_dl_if_debug_print("running ctors for library %s at '%p'\n",
						tpnt->libname, dl_elf_func);
				DL_CALL_FUNC_AT_ADDR (dl_elf_func, tpnt->loadaddr, (void(*)(void)));
			}
		}

		_dl_run_init_array(tpnt);
	}

	_dl_unmap_cache();
	return (void *) dyn_chain;

oops:
	/* Something went wrong.  Clean up and return NULL. */
	_dl_unmap_cache();
	do_dlclose(dyn_chain, 0);
	return NULL;
}

void *dlsym(void *vhandle, const char *name)
{
	struct elf_resolve *tpnt, *tfrom;
	struct dyn_elf *handle;
	ElfW(Addr) from;
	struct dyn_elf *rpnt;
	void *ret;
	struct symbol_ref sym_ref = { NULL, NULL };
	/* Nastiness to support underscore prefixes.  */
#ifdef __UCLIBC_UNDERSCORES__
	char tmp_buf[80];
	char *name2 = tmp_buf;
	size_t nlen = strlen (name) + 1;
	if (nlen + 1 > sizeof (tmp_buf))
		name2 = malloc (nlen + 1);
	if (name2 == 0) {
		_dl_error_number = LD_ERROR_MMAP_FAILED;
		return 0;
	}
	name2[0] = '_';
	memcpy (name2 + 1, name, nlen);
#else
	const char *name2 = name;
#endif
	handle = (struct dyn_elf *) vhandle;

	/* First of all verify that we have a real handle
	   of some kind.  Return NULL if not a valid handle. */

	if (handle == NULL)
		handle = _dl_symbol_tables;
	else if (handle != RTLD_NEXT && handle != _dl_symbol_tables) {
		for (rpnt = _dl_handles; rpnt; rpnt = rpnt->next_handle)
			if (rpnt == handle)
				break;
		if (!rpnt) {
			_dl_error_number = LD_BAD_HANDLE;
			ret = NULL;
			goto out;
		}
	} else if (handle == RTLD_NEXT) {
		/*
		 * Try and locate the module we were called from - we
		 * need this so that we know where to start searching
		 * from.  We never pass RTLD_NEXT down into the actual
		 * dynamic loader itself, as it doesn't know
		 * how to properly treat it.
		 */
		from = (ElfW(Addr)) __builtin_return_address(0);

		tfrom = NULL;
		for (rpnt = _dl_symbol_tables; rpnt; rpnt = rpnt->next) {
			tpnt = rpnt->dyn;
			if (DL_ADDR_IN_LOADADDR(from, tpnt, tfrom)) {
				tfrom = tpnt;
				handle = rpnt->next;
			}
		}
	}
	tpnt = NULL;
	if (handle == _dl_symbol_tables)
		tpnt = handle->dyn; /* Only search RTLD_GLOBAL objs if global object */
	ret = _dl_find_hash(name2, &handle->dyn->symbol_scope, tpnt, ELF_RTYPE_CLASS_DLSYM, &sym_ref);

#if defined(USE_TLS) && USE_TLS && defined SHARED
	if (sym_ref.sym && (ELF_ST_TYPE(sym_ref.sym->st_info) == STT_TLS) && (sym_ref.tpnt)) {
		/* The found symbol is a thread-local storage variable.
		Return its address for the current thread.  */
		ret = _dl_tls_symaddr ((struct link_map *)sym_ref.tpnt, (Elf32_Addr)ret);
	}
#endif

	/*
	 * Nothing found.
	 */
	if (!ret)
		_dl_error_number = LD_NO_SYMBOL;
out:
#ifdef __UCLIBC_UNDERSCORES__
	if (name2 != tmp_buf)
		free (name2);
#endif
	return ret;
}

#if 0
void *dlvsym(void *vhandle, const char *name, const char *version)
{
	return dlsym(vhandle, name);
}
#endif

static int do_dlclose(void *vhandle, int need_fini)
{
	struct dyn_elf *rpnt, *rpnt1, *rpnt1_tmp;
	struct init_fini_list *runp, *tmp;
	ElfW(Phdr) *ppnt;
	struct elf_resolve *tpnt, *run_tpnt;
	int (*dl_elf_fini) (void);
	void (*dl_brk) (void);
	struct dyn_elf *handle;
	unsigned int end;
	unsigned int i, j;
	struct r_scope_elem *ls;
#if defined(USE_TLS) && USE_TLS
	bool any_tls = false;
	size_t tls_free_start = NO_TLS_OFFSET;
	size_t tls_free_end = NO_TLS_OFFSET;
	struct link_map *tls_lmap;
#endif

	handle = (struct dyn_elf *) vhandle;
	if (handle == _dl_symbol_tables)
		return 0;
	rpnt1 = NULL;
	for (rpnt = _dl_handles; rpnt; rpnt = rpnt->next_handle) {
		if (rpnt == handle)
			break;
		rpnt1 = rpnt;
	}

	if (!rpnt) {
		_dl_error_number = LD_BAD_HANDLE;
		return 1;
	}
	if (rpnt1)
		rpnt1->next_handle = rpnt->next_handle;
	else
		_dl_handles = rpnt->next_handle;
	_dl_if_debug_print("%s: usage count: %d\n",
			handle->dyn->libname, handle->dyn->usage_count);
	if (handle->dyn->usage_count != 1 || (handle->dyn->rtld_flags & RTLD_NODELETE)) {
		handle->dyn->usage_count--;
		free(handle);
		return 0;
	}
	/* OK, this is a valid handle - now close out the file */
	for (j = 0; j < handle->init_fini.nlist; ++j) {
		tpnt = handle->init_fini.init_fini[j];
		tpnt->usage_count--;
		if (tpnt->usage_count == 0 && !(tpnt->rtld_flags & RTLD_NODELETE)) {
			if ((tpnt->dynamic_info[DT_FINI]
			     || tpnt->dynamic_info[DT_FINI_ARRAY])
			 && need_fini
			 && !(tpnt->init_flag & FINI_FUNCS_CALLED)
			) {
				tpnt->init_flag |= FINI_FUNCS_CALLED;
				_dl_run_fini_array(tpnt);

				if (tpnt->dynamic_info[DT_FINI]) {
					dl_elf_fini = (int (*)(void)) DL_RELOC_ADDR(tpnt->loadaddr, tpnt->dynamic_info[DT_FINI]);
					_dl_if_debug_print("running dtors for library %s at '%p'\n",
							tpnt->libname, dl_elf_fini);
					DL_CALL_FUNC_AT_ADDR (dl_elf_fini, tpnt->loadaddr, (int (*)(void)));
				}
			}

			_dl_if_debug_print("unmapping: %s\n", tpnt->libname);
			end = 0;
			for (i = 0, ppnt = tpnt->ppnt;
					i < tpnt->n_phent; ppnt++, i++) {
				if (ppnt->p_type != PT_LOAD)
					continue;
				if (end < ppnt->p_vaddr + ppnt->p_memsz)
					end = ppnt->p_vaddr + ppnt->p_memsz;
			}

#if defined(USE_TLS) && USE_TLS
			/* Do the cast to make things easy. */
			tls_lmap = (struct link_map *) tpnt;

			/* Remove the object from the dtv slotinfo array if it uses TLS. */
			if (__builtin_expect (tls_lmap->l_tls_blocksize > 0, 0)) {
				any_tls = true;

				if (_dl_tls_dtv_slotinfo_list != NULL
						&& ! remove_slotinfo (tls_lmap->l_tls_modid,
						_dl_tls_dtv_slotinfo_list, 0,
						(tpnt->init_flag & INIT_FUNCS_CALLED)))
					/* All dynamically loaded modules with TLS are unloaded. */
					_dl_tls_max_dtv_idx = _dl_tls_static_nelem;

				if (tls_lmap->l_tls_offset != NO_TLS_OFFSET) {
					/*
					 * Collect a contiguous chunk built from the objects in
					 * this search list, going in either direction.  When the
					 * whole chunk is at the end of the used area then we can
					 * reclaim it.
					 */
# if defined(TLS_TCB_AT_TP)
					if (tls_free_start == NO_TLS_OFFSET
						|| (size_t) tls_lmap->l_tls_offset == tls_free_start) {
						/* Extend the contiguous chunk being reclaimed. */
						tls_free_start
							= tls_lmap->l_tls_offset -
							  tls_lmap->l_tls_blocksize;

						if (tls_free_end == NO_TLS_OFFSET)
							tls_free_end = tls_lmap->l_tls_offset;
					} else if (tls_lmap->l_tls_offset - tls_lmap->l_tls_blocksize
							== tls_free_end)
						/* Extend the chunk backwards.  */
						tls_free_end = tls_lmap->l_tls_offset;
					else {
						/*
						 * This isn't contiguous with the last chunk freed.
						 * One of them will be leaked unless we can free
						 * one block right away.
						 */
						if (tls_free_end == _dl_tls_static_used) {
							_dl_tls_static_used = tls_free_start;
							tls_free_end = tls_lmap->l_tls_offset;
							tls_free_start
								= tls_free_end - tls_lmap->l_tls_blocksize;
						} else if ((size_t) tls_lmap->l_tls_offset
								== _dl_tls_static_used)
							_dl_tls_static_used = tls_lmap->l_tls_offset -
								tls_lmap->l_tls_blocksize;
						else if (tls_free_end < (size_t) tls_lmap->l_tls_offset) {
							/*
							 * We pick the later block. It has a chance
							 * to be freed.
							 */
							tls_free_end = tls_lmap->l_tls_offset;
							tls_free_start = tls_free_end -
								tls_lmap->l_tls_blocksize;
						}
					}
# elif defined(TLS_DTV_AT_TP)
					if ((size_t) tls_lmap->l_tls_offset == tls_free_end)
						/* Extend the contiguous chunk being reclaimed. */
						tls_free_end -= tls_lmap->l_tls_blocksize;
					else if (tls_lmap->l_tls_offset + tls_lmap->l_tls_blocksize
							== tls_free_start)
						/* Extend the chunk backwards. */
						tls_free_start = tls_lmap->l_tls_offset;
					else {
						/*
						 * This isn't contiguous with the last chunk
						 * freed. One of them will be leaked.
						 */
						if (tls_free_end == _dl_tls_static_used)
							_dl_tls_static_used = tls_free_start;
						tls_free_start = tls_lmap->l_tls_offset;
						tls_free_end = tls_free_start +
							tls_lmap->l_tls_blocksize;
					}
# else
#  error Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined
# endif
				} else {

#define TLS_DTV_UNALLOCATED	((void *) -1l)

					dtv_t *dtv = THREAD_DTV ();

					_dl_assert(!(dtv[tls_lmap->l_tls_modid].pointer.is_static));
					if (dtv[tls_lmap->l_tls_modid].pointer.val != TLS_DTV_UNALLOCATED) {
						/* Note that free is called for NULL is well.  We
						deallocate even if it is this dtv entry we are
						supposed to load.  The reason is that we call
						memalign and not malloc.  */
						_dl_free (dtv[tls_lmap->l_tls_modid].pointer.val);
						dtv[tls_lmap->l_tls_modid].pointer.val = TLS_DTV_UNALLOCATED;
					}
				}
			}
#endif

			DL_LIB_UNMAP (tpnt, end - tpnt->mapaddr);
			/* Free elements in RTLD_LOCAL scope list */
			for (runp = tpnt->rtld_local; runp; runp = tmp) {
				tmp = runp->next;
				free(runp);
			}

			/* Next, remove tpnt from the loaded_module list */
			if (_dl_loaded_modules == tpnt) {
				_dl_loaded_modules = tpnt->next;
				if (_dl_loaded_modules)
					_dl_loaded_modules->prev = 0;
			} else {
				for (run_tpnt = _dl_loaded_modules; run_tpnt; run_tpnt = run_tpnt->next) {
					if (run_tpnt->next == tpnt) {
						_dl_if_debug_print("removing loaded_modules: %s\n", tpnt->libname);
						run_tpnt->next = run_tpnt->next->next;
						if (run_tpnt->next)
							run_tpnt->next->prev = run_tpnt;
						break;
					}
				}
			}

			if (handle->dyn == tpnt) {
				/* Unlink the local scope from global one */
				for (ls = &_dl_loaded_modules->symbol_scope; ls; ls = ls->next)
					if (ls->next->r_list[0] == tpnt) {
						_dl_if_debug_print("removing symbol_scope: %s\n", tpnt->libname);
						break;
					}
				ls->next = ls->next->next;
			}

			/* Next, remove tpnt from the global symbol table list */
			if (_dl_symbol_tables) {
				if (_dl_symbol_tables->dyn == tpnt) {
					_dl_symbol_tables = _dl_symbol_tables->next;
					if (_dl_symbol_tables)
						_dl_symbol_tables->prev = 0;
				} else {
					for (rpnt1 = _dl_symbol_tables; rpnt1->next; rpnt1 = rpnt1->next) {
						if (rpnt1->next->dyn == tpnt) {
							_dl_if_debug_print("removing symbol_tables: %s\n", tpnt->libname);
							rpnt1_tmp = rpnt1->next->next;
							free(rpnt1->next);
							rpnt1->next = rpnt1_tmp;
							if (rpnt1->next)
								rpnt1->next->prev = rpnt1;
							break;
						}
					}
				}
			}
			free(tpnt->libname);
			free(tpnt->symbol_scope.r_list);
			free(tpnt);
		}
	}
	for (rpnt1 = handle->next; rpnt1; rpnt1 = rpnt1_tmp) {
		rpnt1_tmp = rpnt1->next;
		free(rpnt1);
	}
	free(handle->init_fini.init_fini);
	free(handle);

#if defined(USE_TLS) && USE_TLS
	/* If we removed any object which uses TLS bump the generation counter.  */
	if (any_tls) {
		if (__builtin_expect(++_dl_tls_generation == 0, 0)) {
			_dl_debug_early("TLS generation counter wrapped!  Please report to the uClibc mailing list.\n");
			_dl_exit(30);
		}

		if (tls_free_end == _dl_tls_static_used)
			_dl_tls_static_used = tls_free_start;
	}
#endif

	if (_dl_debug_addr) {
		dl_brk = (void (*)(void)) _dl_debug_addr->r_brk;
		if (dl_brk != NULL) {
			_dl_debug_addr->r_state = RT_DELETE;
			(*dl_brk) ();

			_dl_debug_addr->r_state = RT_CONSISTENT;
			(*dl_brk) ();
		}
	}

	return 0;
}

int dlclose(void *vhandle)
{
	return do_dlclose(vhandle, 1);
}

char *dlerror(void)
{
	const char *retval;

	if (!_dl_error_number)
		return NULL;
	retval = dl_error_names[_dl_error_number];
	_dl_error_number = 0;
	return (char *)retval;
}

/*
 * Dump information to stderr about the current loaded modules
 */
#ifdef __USE_GNU
static const char type[][4] = { "Lib", "Exe", "Int", "Mod" };

int dlinfo(void)
{
	struct elf_resolve *tpnt;
	struct dyn_elf *rpnt, *hpnt;

	fprintf(stderr, "List of loaded modules\n");
	/* First start with a complete list of all of the loaded files. */
	for (tpnt = _dl_loaded_modules; tpnt; tpnt = tpnt->next) {
		fprintf(stderr, "\t%p %p %p %s %d %s\n",
		        DL_LOADADDR_BASE(tpnt->loadaddr), tpnt, tpnt->symbol_scope,
		        type[tpnt->libtype],
		        tpnt->usage_count, tpnt->libname);
	}

	/* Next dump the module list for the application itself */
	fprintf(stderr, "\nModules for application (%p):\n", _dl_symbol_tables);
	for (rpnt = _dl_symbol_tables; rpnt; rpnt = rpnt->next)
		fprintf(stderr, "\t%p %s\n", rpnt->dyn, rpnt->dyn->libname);

	for (hpnt = _dl_handles; hpnt; hpnt = hpnt->next_handle) {
		fprintf(stderr, "Modules for handle %p\n", hpnt);
		for (rpnt = hpnt; rpnt; rpnt = rpnt->next)
			fprintf(stderr, "\t%p %s\n", rpnt->dyn, rpnt->dyn->libname);
	}
	return 0;
}

int dladdr(const void *__address, Dl_info * __info)
{
	struct elf_resolve *pelf;
	struct elf_resolve *rpnt;

	_dl_map_cache();

	/*
	 * Try and locate the module address is in
	 */
	pelf = NULL;

	_dl_if_debug_print("__address: %p  __info: %p\n", __address, __info);

	__address = DL_LOOKUP_ADDRESS (__address);

	for (rpnt = _dl_loaded_modules; rpnt; rpnt = rpnt->next) {
		struct elf_resolve *tpnt;

		tpnt = rpnt;

		_dl_if_debug_print("Module \"%s\" at %p\n",
		                   tpnt->libname, DL_LOADADDR_BASE(tpnt->loadaddr));

		if (DL_ADDR_IN_LOADADDR((ElfW(Addr)) __address, tpnt, pelf))
			pelf = tpnt;
	}

	if (!pelf) {
		return 0;
	}

	/*
	 * Try and locate the symbol of address
	 */

	{
		char *strtab;
		ElfW(Sym) *symtab;
		unsigned int hn, si, sn, sf;
		ElfW(Addr) sa = 0;

		/* Set the info for the object the address lies in */
		__info->dli_fname = pelf->libname;
		__info->dli_fbase = (void *)pelf->mapaddr;

		symtab = (ElfW(Sym) *) (pelf->dynamic_info[DT_SYMTAB]);
		strtab = (char *) (pelf->dynamic_info[DT_STRTAB]);

		sf = sn = 0;

#ifdef __LDSO_GNU_HASH_SUPPORT__
		if (pelf->l_gnu_bitmask) {
			for (hn = 0; hn < pelf->nbucket; hn++) {
				si = pelf->l_gnu_buckets[hn];
				if (!si)
					continue;

				const Elf32_Word *hasharr = &pelf->l_gnu_chain_zero[si];
				do {
					ElfW(Addr) symbol_addr;

					symbol_addr = (ElfW(Addr)) DL_RELOC_ADDR(pelf->loadaddr, symtab[si].st_value);
					if ((symtab[si].st_shndx != SHN_UNDEF
						 || symtab[si].st_value != 0)
						&& ELF_ST_TYPE(symtab[si].st_info) != STT_TLS
						&& DL_ADDR_SYM_MATCH(symbol_addr, &symtab[si], sa,
											 (ElfW(Addr)) __address)) {
						sa = symbol_addr;
						sn = si;
						sf = 1;
					}
					_dl_if_debug_print("Symbol \"%s\" at %p\n", strtab + symtab[si].st_name, symbol_addr);
					++si;
				} while ((*hasharr++ & 1u) == 0);
			}
		} else
#endif
		for (hn = 0; hn < pelf->nbucket; hn++) {
			for (si = pelf->elf_buckets[hn]; si; si = pelf->chains[si]) {
				ElfW(Addr) symbol_addr;

				symbol_addr = (ElfW(Addr)) DL_RELOC_ADDR(pelf->loadaddr, symtab[si].st_value);
				if ((symtab[si].st_shndx != SHN_UNDEF
					 || symtab[si].st_value != 0)
					&& ELF_ST_TYPE(symtab[si].st_info) != STT_TLS
					&& DL_ADDR_SYM_MATCH(symbol_addr, &symtab[si], sa,
										 (ElfW(Addr)) __address)) {
					sa = symbol_addr;
					sn = si;
					sf = 1;
				}

				_dl_if_debug_print("Symbol \"%s\" at %p\n",
				                   strtab + symtab[si].st_name, symbol_addr);
			}
		}

		if (sf) {
			/* A nearest symbol has been found; fill the entries */
			__info->dli_sname = strtab + symtab[sn].st_name;
			__info->dli_saddr = (void *)sa;
		} else {
			/* No symbol found, fill entries with NULL value,
			only the containing object will be returned. */
			__info->dli_sname = NULL;
			__info->dli_saddr = NULL;
		}
		return 1;
	}
}
#endif