libdl.c

Axis 221 camera embedded programing interface

/* 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) 2000-2004 by Erik Andersen <[e-mail]>
 * 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.
 */


#define _GNU_SOURCE
#include <ldso.h>
#include <stdio.h>


#if defined (__LIBDL_SHARED__)

/* When libdl is loaded as a shared library, we need to load in
 * and use a pile of symbols from ldso... */

extern char *_dl_find_hash(const char *, struct dyn_elf *, struct elf_resolve *, int)
	__attribute__ ((__weak__));
extern struct elf_resolve * _dl_load_shared_library(int, struct dyn_elf **,
	struct elf_resolve *, char *, int) __attribute__ ((__weak__));
extern struct elf_resolve * _dl_check_if_named_library_is_loaded(const char *, int)
	__attribute__ ((__weak__));
extern int _dl_fixup(struct dyn_elf *rpnt, int lazy)
	 __attribute__ ((__weak__));
extern void _dl_protect_relro(struct elf_resolve * tpnt)
	__attribute__ ((__weak__));
extern int _dl_errno __attribute__ ((__weak__));
extern struct dyn_elf *_dl_symbol_tables __attribute__ ((__weak__));
extern struct dyn_elf *_dl_handles __attribute__ ((__weak__));
extern struct elf_resolve *_dl_loaded_modules __attribute__ ((__weak__));
extern struct r_debug *_dl_debug_addr __attribute__ ((__weak__));
extern unsigned long _dl_error_number __attribute__ ((__weak__));
extern void *(*_dl_malloc_function)(size_t) __attribute__ ((__weak__));
#ifdef __LDSO_CACHE_SUPPORT__
int _dl_map_cache(void) __attribute__ ((__weak__));
int _dl_unmap_cache(void) __attribute__ ((__weak__));
#endif
#ifdef __mips__
extern void _dl_perform_mips_global_got_relocations(struct elf_resolve *tpnt, int lazy)
	__attribute__ ((__weak__));
#endif
#ifdef __SUPPORT_LD_DEBUG__
extern char *_dl_debug __attribute__ ((__weak__));
#endif


#else /* __LIBDL_SHARED__ */

/* 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  = 0;
#endif
char *_dl_library_path         = 0;		    /* Where we look for libraries */
char *_dl_ldsopath             = 0;		    /* Location of the shared lib loader */
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;
#define _dl_malloc malloc
#include "dl-progname.h"
#include "../ldso/dl-hash.c"
#define _dl_trace_loaded_objects    0
#include "../ldso/dl-elf.c"
#endif

static int do_dlclose(void *, int need_fini);


static const char *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",
#ifdef ELF_USES_RELOCA
	"Unable to process REL relocs",
#else
	"Unable to process RELA relocs",
#endif
	"Bad handle",
	"Unable to resolve symbol"
};

void __attribute__ ((destructor)) dl_cleanup(void)
{
	struct dyn_elf *d;
	for (d = _dl_handles; d; d = d->next_handle) {
		do_dlclose(d, 1);
	}
}

void *dlopen(const char *libname, int flag)
{
	struct elf_resolve *tpnt, *tfrom, *tcurr;
	struct dyn_elf *dyn_chain, *rpnt = NULL, *dyn_ptr, *relro_ptr;
	struct dyn_elf *dpnt;
	ElfW(Addr) from;
	struct elf_resolve *tpnt1;
	void (*dl_brk) (void);
	int now_flag;
	struct init_fini_list *tmp, *runp;
	int nlist, i;
	struct elf_resolve **init_fini_list;

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

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

	/* Cover the trivial case first */
	if (!libname)
		return _dl_symbol_tables;

	_dl_map_cache();

	/*
	 * Try and locate the module we were called from - we
	 * need this so that we get the correct RPATH.  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.
	 */
	tfrom = NULL;
	for (dpnt = _dl_symbol_tables; dpnt; dpnt = dpnt->next) {
		tpnt = dpnt->dyn;
		if (tpnt->loadaddr < from
				&& (tfrom == NULL || tfrom->loadaddr < tpnt->loadaddr))
			tfrom = tpnt;
	}
	for(rpnt = _dl_symbol_tables; rpnt->next; rpnt=rpnt->next);

	relro_ptr = rpnt;
	/* Try to load the specified library */
#ifdef __SUPPORT_LD_DEBUG__
	if(_dl_debug)
		fprintf(stderr, "Trying to dlopen '%s'\n", (char*)libname);
#endif
	tpnt = _dl_check_if_named_library_is_loaded((char *)libname, 0);
	if (!(tpnt))
		tpnt = _dl_load_shared_library(0, &rpnt, tfrom, (char*)libname, 0);
	else
		tpnt->usage_count++;
	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;

#ifdef __SUPPORT_LD_DEBUG__
	if(_dl_debug)
		fprintf(stderr, "Looking for needed libraries\n");
#endif
	nlist = 0;
	for (tcurr = tpnt; tcurr; tcurr = tcurr->next)
	{
		Elf32_Dyn *dpnt;
		char *lpntstr;

		nlist++;
		tcurr->init_fini = NULL; /* clear any previous dependcies */
		for (dpnt = (Elf32_Dyn *) tcurr->dynamic_addr; dpnt->d_tag; dpnt++) {
			if (dpnt->d_tag == DT_NEEDED) {
				char *name;

				lpntstr = (char*) (tcurr->loadaddr + tcurr->dynamic_info[DT_STRTAB] +
						dpnt->d_un.d_val);
				name = _dl_get_last_path_component(lpntstr);
				tpnt1 = _dl_check_if_named_library_is_loaded(name, 0);
#ifdef __SUPPORT_LD_DEBUG__
				if(_dl_debug)
					fprintf(stderr, "Trying to load '%s', needed by '%s'\n",
							lpntstr, tcurr->libname);
#endif
				if (tpnt1) {
					tpnt1->usage_count++;
				} else {
					tpnt1 = _dl_load_shared_library(0, &rpnt, tcurr, lpntstr, 0);
					if (!tpnt1)
						goto oops;
				}
				tpnt1->rtld_flags |= (flag & RTLD_GLOBAL);
				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;

				tmp = alloca(sizeof(struct init_fini_list)); /* Allocates on stack, no need to free this memory */
				tmp->tpnt = tpnt1;
				tmp->next = tcurr->init_fini;
				tcurr->init_fini = tmp;
			}
		}
	}
	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 (tcurr = tpnt; tcurr; tcurr = tcurr->next) {
		init_fini_list[i++] = tcurr;
		for(runp = tcurr->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 = tcurr->rtld_local;
				tcurr->rtld_local = tmp;
			}
		}

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

			for (; runp; runp = runp->next) {
				if (runp->tpnt == tcurr) {
					struct elf_resolve *here = init_fini_list[k];
#ifdef __SUPPORT_LD_DEBUG__
					if(_dl_debug)
						fprintf(stderr, "Move %s from pos %d to %d in INIT/FINI list.\n", here->libname, k, j);
#endif
					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)
				printf(" %s ", runp->tpnt->libname);
			printf("\n");
		}
	}
#endif

	if (dyn_chain->dyn->init_flag & INIT_FUNCS_CALLED) {
		/* If the init and fini stuff has already been run, that means
		 * the dlopen'd library has already been loaded, and nothing
		 * further needs to be done. */
		return (void *) dyn_chain;
	}

#ifdef __SUPPORT_LD_DEBUG__
	if(_dl_debug)
		fprintf(stderr, "Beginning dlopen relocation fixups\n");
#endif
	/*
	 * 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 */
	now_flag = (flag & RTLD_NOW) ? RTLD_NOW : 0;
	if (getenv("LD_BIND_NOW"))
		now_flag = RTLD_NOW;

#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

	if (_dl_fixup(dyn_chain, now_flag))
		goto oops;

	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 ? */


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