xref: /src/libexec/ld.elf_so/load.c

/*	$NetBSD: load.c,v 1.5 1999/11/07 00:21:12 mycroft Exp $	 */

/*
 * Copyright 1996 John D. Polstra.
 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com>
 * 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 (at) 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/mman.h>
#include <dirent.h>

#include "debug.h"
#include "rtld.h"

/*
 * 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, dodebug)
	char *filepath;
	bool dodebug;
{
	Obj_Entry *obj;
	int fd = -1;
	struct stat sb;

	for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next)
		if (strcmp(obj->path, filepath) == 0)
			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;
		}
		obj->path = filepath;
		_rtld_digest_dynamic(obj);

		*_rtld_objtail = obj;
		_rtld_objtail = &obj->next;
#ifdef RTLD_LOADER
		_rtld_linkmap_add(obj);	/* for GDB */
#endif
		if (dodebug) {
			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;
	return obj;
}

/*
 * 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)
	Obj_Entry *first;
{
	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;
			char *libpath = _rtld_find_library(name, obj);

			if (libpath == NULL) {
				status = -1;
			} else {
				needed->obj = _rtld_load_object(libpath, true);
				if (needed->obj == NULL)
					status = -1;	/* FIXME - cleanup */
			}
#ifdef RTLD_LOADER
			if (status == -1)
				return status;
#endif
		}
	}

	return status;
}

#ifdef RTLD_LOADER
int
_rtld_preload(preload_path, dodebug)
	const char *preload_path;
	bool dodebug;
{
	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), dodebug) == NULL)
				status = -1;
			else if (dodebug)
				dbg((" preloaded \"%s\"", path));
		}
		free(buf);
	}

	return (status);
}
#endif