Implement ldconfig functionality for ELF. The hints are stored in

a different file than the a.out hints, namely, "/var/run/ld-elf.so.hints".
These hints consist only of the directory search path.  There is
no hash table as in the a.out hints, because ELF doesn't have to
search for the file with the highest minor version number.  (It
doesn't have minor version numbers at all.)

A single run of ldconfig updates either the a.out hints or the ELF
hints, but not both.  The set of hints to process is selected in
the usual way, via /etc/objformat, or ${OBJFORMAT}, or the "-aout"
or "-elf" command line option.  The rationale is that you probably
want to search different directories for ELF than for a.out.

"ldconfig -r" is faked up to produce output like we are used to,
except that for ELF there are no minor version numbers.  This should
enable "ldconfig -r" to be used for checking LIB_DEPENDS in ports
even for ELF.

I implemented the ELF functionality in a new source file, with an
eye toward eliminating the a.out code entirely at some point in
the future.

libexec/rtld-elf/rtld.c

@@ -22,7 +22,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- *      $Id: rtld.c,v 1.6 1998/09/02 02:51:12 jdp Exp $
+ *      $Id: rtld.c,v 1.7 1998/09/04 19:03:57 dfr Exp $
  */
 
 /*
@@ -75,6 +75,7 @@ static void digest_dynamic(Obj_Entry *);
 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t);
 static Obj_Entry *dlcheck(void *);
 static char *find_library(const char *, const Obj_Entry *);
+static const char *gethints(void);
 static void init_rtld(caddr_t);
 static bool is_exported(const Elf_Sym *);
 static void linkmap_add(Obj_Entry *);
@@ -626,6 +627,12 @@ elf_hash(const char *name)
  *
  * If the second argument is non-NULL, then it refers to an already-
  * loaded shared object, whose library search path will be searched.
+ *
+ * The search order is:
+ *   LD_LIBRARY_PATH
+ *   ldconfig hints
+ *   rpath in the referencing file
+ *   /usr/lib
  */
 static char *
 find_library(const char *name, const Obj_Entry *refobj)
@@ -643,9 +650,10 @@ find_library(const char *name, const Obj_Entry *refobj)
 
     dbg(" Searching for \"%s\"", name);
 
-    if ((refobj != NULL &&
+    if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
+      (pathname = search_library_path(name, gethints())) != NULL ||
+      (refobj != NULL &&
       (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
-      (pathname = search_library_path(name, ld_library_path)) != NULL ||
       (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
 	return pathname;
 
@@ -746,6 +754,45 @@ find_symdef(unsigned long symnum, const Obj_Entry *refobj,
     return NULL;
 }
 
+/*
+ * Return the search path from the ldconfig hints file, reading it if
+ * necessary.  Returns NULL if there are problems with the hints file,
+ * or if the search path there is empty.
+ */
+static const char *
+gethints(void)
+{
+    static char *hints;
+
+    if (hints == NULL) {
+	int fd;
+	struct elfhints_hdr hdr;
+	char *p;
+
+	/* Keep from trying again in case the hints file is bad. */
+	hints = "";
+
+	if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
+	    return NULL;
+	if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
+	  hdr.magic != ELFHINTS_MAGIC ||
+	  hdr.version != 1) {
+	    close(fd);
+	    return NULL;
+	}
+	p = xmalloc(hdr.dirlistlen + 1);
+	if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
+	  read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
+	    free(p);
+	    close(fd);
+	    return NULL;
+	}
+	hints = p;
+	close(fd);
+    }
+    return hints[0] != '\0' ? hints : NULL;
+}
+
 /*
  * Initialize the dynamic linker.  The argument is the address at which
  * the dynamic linker has been mapped into memory.  The primary task of

sbin/ldconfig/Makefile

@@ -1,7 +1,7 @@
-#	$Id: Makefile,v 1.12 1998/06/01 13:58:19 peter Exp $
+#	$Id: Makefile,v 1.13 1998/06/12 10:43:18 peter Exp $
 
 PROG=	ldconfig
-SRCS=	ldconfig.c shlib.c support.c
+SRCS=	elfhints.c ldconfig.c shlib.c support.c
 LDDIR?= ${.CURDIR}/../../libexec/rtld-aout
 CFLAGS+=-I${LDDIR} -DFREEBSD_AOUT
 MAN8=	ldconfig.8

sbin/ldconfig/elfhints.c

@@ -0,0 +1,280 @@
+/*-
+ * Copyright (c) 1998 John D. Polstra
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND 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 AUTHOR OR 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.
+ *
+ * $Id$
+ */
+
+#include <sys/param.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#include <ctype.h>
+#include <dirent.h>
+#include <elf.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "ldconfig.h"
+
+#define MAXDIRS		1024		/* Maximum directories in path */
+#define MAXFILESIZE	(16*1024)	/* Maximum hints file size */
+
+static void	add_dir(const char *, const char *);
+static void	read_dirs_from_file(const char *, const char *);
+static void	read_elf_hints(const char *, int);
+static void	write_elf_hints(const char *);
+
+static const char	*dirs[MAXDIRS];
+static int		 ndirs;
+
+static void
+add_dir(const char *hintsfile, const char *name)
+{
+	int	i;
+
+	for (i = 0;  i < ndirs;  i++)
+		if (strcmp(dirs[i], name) == 0)
+			return;
+	if (ndirs >= MAXDIRS)
+		errx(1, "\"%s\": Too many directories in path", hintsfile);
+	dirs[ndirs++] = name;
+}
+
+void
+list_elf_hints(const char *hintsfile)
+{
+	int	i;
+	int	nlibs;
+
+	read_elf_hints(hintsfile, 1);
+	printf("%s:\n", hintsfile);
+	printf("\tsearch directories:");
+	for (i = 0;  i < ndirs;  i++)
+		printf("%c%s", i == 0 ? ' ' : ':', dirs[i]);
+	printf("\n");
+
+	nlibs = 0;
+	for (i = 0;  i < ndirs;  i++) {
+		DIR		*dirp;
+		struct dirent	*dp;
+
+		if ((dirp = opendir(dirs[i])) == NULL)
+			continue;
+		while ((dp = readdir(dirp)) != NULL) {
+			int		 len;
+			int		 namelen;
+			const char	*name;
+			const char	*vers;
+
+			/* Name can't be shorter than "libx.so.0" */
+			if ((len = strlen(dp->d_name)) < 9 ||
+			    strncmp(dp->d_name, "lib", 3) != 0)
+				continue;
+			name = dp->d_name + 3;
+			vers = dp->d_name + len;
+			while (vers > dp->d_name && isdigit(*(vers-1)))
+				vers--;
+			if (vers == dp->d_name + len)
+				continue;
+			if (vers < dp->d_name + 4 ||
+			    strncmp(vers - 4, ".so.", 4) != 0)
+				continue;
+
+			/* We have a valid shared library name. */
+			namelen = (vers - 4) - name;
+			printf("\t%d:-l%.*s.%s => %s/%s\n", nlibs,
+			    namelen, name, vers, dirs[i], dp->d_name);
+			nlibs++;
+		}
+		closedir(dirp);
+	}
+}
+
+static void
+read_dirs_from_file(const char *hintsfile, const char *listfile)
+{
+	FILE	*fp;
+	char	 buf[MAXPATHLEN];
+	int	 linenum;
+
+	if ((fp = fopen(listfile, "r")) == NULL)
+		err(1, "%s", listfile);
+
+	linenum = 0;
+	while (fgets(buf, sizeof buf, fp) != NULL) {
+		char	*cp, *sp;
+
+		linenum++;
+		cp = buf;
+		/* Skip leading white space. */
+		while (isspace(*cp))
+			cp++;
+		if (*cp == '#' || *cp == '\0')
+			continue;
+		sp = cp;
+		/* Advance over the directory name. */
+		while (!isspace(*cp) && *cp != '\0')
+			cp++;
+		/* Terminate the string and skip trailing white space. */
+		if (*cp != '\0') {
+			*cp++ = '\0';
+			while (isspace(*cp))
+				cp++;
+		}
+		/* Now we had better be at the end of the line. */
+		if (*cp != '\0')
+			warnx("%s:%d: trailing characters ignored",
+			    listfile, linenum);
+
+		if ((sp = strdup(sp)) == NULL)
+			errx(1, "Out of memory");
+		add_dir(hintsfile, sp);
+	}
+
+	fclose(fp);
+}
+
+static void
+read_elf_hints(const char *hintsfile, int must_exist)
+{
+	int	 		 fd;
+	struct stat		 s;
+	void			*mapbase;
+	struct elfhints_hdr	*hdr;
+	char			*strtab;
+	char			*dirlist;
+	char			*p;
+
+	if ((fd = open(hintsfile, O_RDONLY)) == -1) {
+		if (errno == ENOENT && !must_exist)
+			return;
+		err(1, "Cannot open \"%s\"", hintsfile);
+	}
+	if (fstat(fd, &s) == -1)
+		err(1, "Cannot stat \"%s\"", hintsfile);
+	if (s.st_size > MAXFILESIZE)
+		errx(1, "\"%s\" is unreasonably large", hintsfile);
+	/*
+	 * We use a read-write, private mapping so that we can null-terminate
+	 * some strings in it without affecting the underlying file.
+	 */
+	mapbase = mmap(NULL, s.st_size, PROT_READ|PROT_WRITE,
+	    MAP_PRIVATE, fd, 0);
+	if (mapbase == MAP_FAILED)
+		err(1, "Cannot mmap \"%s\"", hintsfile);
+	close(fd);
+
+	hdr = (struct elfhints_hdr *)mapbase;
+	if (hdr->magic != ELFHINTS_MAGIC)
+		errx(1, "\"%s\": invalid file format", hintsfile);
+	if (hdr->version != 1)
+		errx(1, "\"%s\": unrecognized file version (%d)", hintsfile,
+		    hdr->version);
+
+	strtab = (char *)mapbase + hdr->strtab;
+	dirlist = strtab + hdr->dirlist;
+
+	if (*dirlist != '\0')
+		while ((p = strsep(&dirlist, ":")) != NULL)
+			add_dir(hintsfile, p);
+}
+
+void
+update_elf_hints(const char *hintsfile, int argc, char **argv, int merge)
+{
+	int	i;
+
+	if (merge)
+		read_elf_hints(hintsfile, 0);
+	for (i = 0;  i < argc;  i++) {
+		struct stat	s;
+
+		if (stat(argv[i], &s) == -1)
+			err(1, "%s", argv[i]);
+		if (S_ISREG(s.st_mode))
+			read_dirs_from_file(hintsfile, argv[i]);
+		else
+			add_dir(hintsfile, argv[i]);
+	}
+	write_elf_hints(hintsfile);
+}
+
+static void
+write_elf_hints(const char *hintsfile)
+{
+	struct elfhints_hdr	 hdr;
+	char			*tempname;
+	int			 fd;
+	FILE			*fp;
+	int			 i;
+
+	if (asprintf(&tempname, "%s.XXXXXX", hintsfile) == -1)
+		errx(1, "Out of memory");
+	if ((fd = mkstemp(tempname)) ==  -1)
+		err(1, "mkstemp(%s)", tempname);
+	if (fchmod(fd, 0444) == -1)
+		err(1, "fchmod(%s)", tempname);
+	if ((fp = fdopen(fd, "wb")) == NULL)
+		err(1, "fdopen(%s)", tempname);
+
+	hdr.magic = ELFHINTS_MAGIC;
+	hdr.version = 1;
+	hdr.strtab = sizeof hdr;
+	hdr.strsize = 0;
+	hdr.dirlist = 0;
+	memset(hdr.spare, 0, sizeof hdr.spare);
+
+	/* Count up the size of the string table. */
+	if (ndirs > 0) {
+		hdr.strsize += strlen(dirs[0]);
+		for (i = 1;  i < ndirs;  i++)
+			hdr.strsize += 1 + strlen(dirs[i]);
+	}
+	hdr.dirlistlen = hdr.strsize;
+	hdr.strsize++;	/* For the null terminator */
+
+	/* Write the header. */
+	if (fwrite(&hdr, 1, sizeof hdr, fp) != sizeof hdr)
+		err(1, "%s: write error", tempname);
+	/* Write the strings. */
+	if (ndirs > 0) {
+		if (fputs(dirs[0], fp) == EOF)
+			err(1, "%s: write error", tempname);
+		for (i = 1;  i < ndirs;  i++)
+			if (fprintf(fp, ":%s", dirs[i]) < 0)
+				err(1, "%s: write error", tempname);
+	}
+	if (putc('\0', fp) == EOF || fclose(fp) == EOF)
+		err(1, "%s: write error", tempname);
+
+	if (rename(tempname, hintsfile) == -1)
+		err(1, "rename %s to %s", tempname, hintsfile);
+	free(tempname);
+}

sbin/ldconfig/ldconfig.8

@@ -27,7 +27,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\"	$Id: ldconfig.8,v 1.14 1997/08/22 04:42:12 peter Exp $
+.\"	$Id: ldconfig.8,v 1.15 1998/01/01 02:31:47 alex Exp $
 .\"
 .Dd October 3, 1993
 .Dt LDCONFIG 8
@@ -37,6 +37,7 @@
 .Nd configure the shared library cache
 .Sh SYNOPSIS
 .Nm ldconfig
+.Op Fl aout | Fl elf
 .Op Fl Rmrsv
 .Op Fl f Ar hints_file
 .Op Ar directory | file Ar ...
@@ -44,25 +45,21 @@
 .Nm
 is used to prepare a set of
 .Dq hints
-for use by the run-time linker
-.Xr ld.so 1
+for use by the dynamic linker
 to facilitate quick lookup of shared libraries available in multiple
 directories.  It scans a set of built-in system directories and any
 .Ar directories
-specified on the command line (in the given order) looking for shared
-libraries and stores the results in the file
-.Pa /var/run/ld.so.hints
-to forestall the overhead that would otherwise result from the
-directory search operations
-.Xr ld.so 1
-would have to perform to load the required shared libraries.
+specified on the command line (in the given order) looking for
+shared libraries and stores the results in a system file to forestall
+the overhead that would otherwise result from the directory search
+operations the dynamic linker would have to perform to load the
+required shared libraries.
 .Pp
 Files named on the command line are expected to contain directories
 to scan for shared libraries.  Each directory's pathname must start on a new
 line.  Blank lines and lines starting with the comment character
 .Ql \&#
-are ignored.  A standard name for this file is
-.Xr /etc/ld.so.conf.
+are ignored.
 .Pp
 The shared libraries so found will be automatically available for loading
 if needed by the program being prepared for execution. This obviates the need
@@ -77,7 +74,7 @@ directories where shared libraries might be found.
 is a
 .Sq \:
 separated list of directory paths which are searched by
-.Xr ld.so 1
+the dynamic linker
 when it needs to load a shared library. It can be viewed as the run-time
 equivalent of the
 .Fl L
@@ -90,13 +87,16 @@ is typically run as part of the boot sequence.
 The following options recognized by
 .Nm ldconfig:
 .Bl -tag -width indent
+.It Fl aout
+Generate the hints for a.out format shared libraries.
+.It Fl elf
+Generate the hints for ELF format shared libraries.
 .It Fl R
 Rescan the previously configured directories.  This opens the previous hints
 file and fetches the directory list from the header.  Any additional pathnames
 on the command line are also processed.
 .It Fl f Ar hints_file
-Read and/or update the specified hints file, instead of
-.Pa /var/run/ld.so.hints .
+Read and/or update the specified hints file, instead of the standard file.
 This option is provided primarily for testing.
 .It Fl m
 Instead of replacing the contents of the hints file
@@ -121,7 +121,7 @@ Special care must be taken when loading shared libraries into the address
 space of
 .Ev set-user-Id
 programs. Whenever such a program is run,
-.Nm ld.so
+the dynamic linker
 will only load shared libraries from the hints
 file. In particular, the
 .Ev LD_LIBRARY_PATH
@@ -131,12 +131,44 @@ specify the trusted collection of directories from which shared objects can
 be safely loaded. It is presumed that the set of directories specified to
 .Nm ldconfig
 are under control of the system's administrator.
+.Sh ENVIRONMENT
+.Bl -tag -width OBJFORMATxxx -compact
+.It Ev OBJFORMAT
+Overrides
+.Pa /etc/objformat
+(see below) to determine whether
+.Fl aout
+or
+.Fl elf
+is the default.  If set, its value should be either
+.Ql aout
+or
+.Ql elf .
+.El
 .Sh FILES
-.Bl -tag -width /var/run/ld.so.hintsxxx -compact
+.Bl -tag -width /var/run/ld-elf.so.hintsxxx -compact
 .It Pa /var/run/ld.so.hints
-Default
-.Dq hints
-file.
+Standard hints file for the a.out dynamic linker.
+.It Pa /var/run/ld-elf.so.hints
+Standard hints file for the ELF dynamic linker.
+.It Pa /etc/ld.so.conf
+Conventional configuration file containing directory names for
+invocations with
+.Fl aout .
+.It Pa /etc/ld-elf.so.conf
+Conventional configuration file containing directory names for
+invocations with
+.Fl elf .
+.It Pa /etc/objformat
+Determines whether
+.Fl aout
+or
+.Fl elf
+is the default.  If present, it must consist of a single line
+containing either
+.Ql OBJFORMAT=aout
+or
+.Ql OBJFORMAT=elf .
 .Sh SEE ALSO
 .Xr ld 1 ,
 .Xr link 5

sbin/ldconfig/ldconfig.c

@@ -30,7 +30,7 @@
 
 #ifndef lint
 static const char rcsid[] =
-	"$Id: ldconfig.c,v 1.23 1998/07/06 07:02:26 charnier Exp $";
+	"$Id: ldconfig.c,v 1.24 1998/08/02 16:06:33 bde Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -40,6 +40,7 @@ static const char rcsid[] =
 #include <a.out.h>
 #include <ctype.h>
 #include <dirent.h>
+#include <elf.h>
 #include <err.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -49,6 +50,7 @@ static const char rcsid[] =
 #include <string.h>
 #include <unistd.h>
 
+#include "ldconfig.h"
 #include "shlib.h"
 #include "support.h"
 
@@ -56,17 +58,29 @@ static const char rcsid[] =
 /* test */
 #undef _PATH_LD_HINTS
 #define _PATH_LD_HINTS		"./ld.so.hints"
+#undef _PATH_ELF_HINTS
+#define _PATH_ELF_HINTS		"./ld-elf.so.hints"
 #endif
 
 #undef major
 #undef minor
 
+enum obj_format { Unknown, Aout, Elf };
+
+#ifndef DEFAULT_FORMAT
+#ifdef __ELF__
+#define DEFAULT_FORMAT	Elf
+#else
+#define DEFAULT_FORMAT	Aout
+#endif
+#endif
+
 static int			verbose;
 static int			nostd;
 static int			justread;
 static int			merge;
 static int			rescan;
-static char			*hints_file = _PATH_LD_HINTS;
+static char			*hints_file;
 
 struct shlib_list {
 	/* Internal list of shared libraries found */
@@ -82,13 +96,14 @@ struct shlib_list {
 static struct shlib_list	*shlib_head = NULL, **shlib_tail = &shlib_head;
 static char			*dir_list;
 
-static void	enter __P((char *, char *, char *, int *, int));
-static int	dodir __P((char *, int));
-int		dofile __P((char *, int));
-static int	buildhints __P((void));
-static int	readhints __P((void));
-static void	listhints __P((void));
-static void	usage __P((void));
+static int		buildhints __P((void));
+static int		dodir __P((char *, int));
+int			dofile __P((char *, int));
+static void		enter __P((char *, char *, char *, int *, int));
+static enum obj_format	getobjfmt __P((int *, char **));
+static void		listhints __P((void));
+static int		readhints __P((void));
+static void		usage __P((void));
 
 int
 main(argc, argv)
@@ -97,7 +112,10 @@ char	*argv[];
 {
 	int		i, c;
 	int		rval = 0;
+	enum obj_format	fmt;
 
+	fmt = getobjfmt(&argc, argv);
+	hints_file = fmt == Aout ? _PATH_LD_HINTS : _PATH_ELF_HINTS;
 	while ((c = getopt(argc, argv, "Rf:mrsv")) != -1) {
 		switch (c) {
 		case 'R':
@@ -124,6 +142,15 @@ char	*argv[];
 		}
 	}
 
+	if (fmt == Elf) {
+		if (justread)
+			list_elf_hints(hints_file);
+		else
+			update_elf_hints(hints_file, argc - optind,
+			    argv + optind, merge || rescan);
+		return 0;
+	}
+
 	dir_list = strdup("");
 
 	if (justread || merge || rescan) {
@@ -179,6 +206,62 @@ char	*argv[];
 	return rval;
 }
 
+static enum obj_format
+getobjfmt(argcp, argv)
+	int *argcp;
+	char **argv;
+{
+	enum obj_format	  fmt;
+	char		**src, **dst;
+	const char	 *env;
+	FILE		 *fp;
+
+	fmt = Unknown;
+
+	/* Scan for "-aout" or "-elf" arguments, deleting them as we go. */
+	for (dst = src = argv + 1;  *src != NULL;  src++) {
+		if (strcmp(*src, "-aout") == 0)
+			fmt = Aout;
+		else if (strcmp(*src, "-elf") == 0)
+			fmt = Elf;
+		else
+			*dst++ = *src;
+	}
+	*dst = NULL;
+	*argcp -= src - dst;
+	if (fmt != Unknown)
+		return fmt;
+
+	/* Check the OBJFORMAT environment variable. */
+	if ((env = getenv("OBJFORMAT")) != NULL) {
+		if (strcmp(env, "aout") == 0)
+			return Aout;
+		else if (strcmp(env, "elf") == 0)
+			return Elf;
+	}
+
+	/* Take a look at "/etc/objformat". */
+	if ((fp = fopen("/etc/objformat", "r")) != NULL) {
+		char buf[1024];
+
+		while (fgets(buf, sizeof buf, fp) != NULL) {
+			if (strcmp(buf, "OBJFORMAT=aout\n") == 0)
+				fmt = Aout;
+			else if (strcmp(buf, "OBJFORMAT=elf\n") == 0)
+				fmt = Elf;
+			else
+				warnx("Unrecognized line in /etc/objformat: %s",
+				    buf);
+		}
+		fclose(fp);
+	}
+	if (fmt != Unknown)
+		return fmt;
+
+	/* As a last resort, use the compiled in default. */
+	return DEFAULT_FORMAT;
+}
+
 static void
 usage()
 {

sbin/ldconfig/ldconfig.h

@@ -0,0 +1,39 @@
+/*-
+ * Copyright (c) 1998 John D. Polstra
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND 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 AUTHOR OR 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.
+ *
+ * $Id$
+ */
+
+#ifndef LDCONFIG_H
+#define LDCONFIG_H 1
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+void	list_elf_hints __P((const char *));
+void	update_elf_hints __P((const char *, int, char **, int));
+__END_DECLS
+
+#endif