Implement dladdr.

9 files changed, 381 insertions, 24 deletions

diff --git a/gnu/usr.bin/ld/rtld/rtld.c b/gnu/usr.bin/ld/rtld/rtld.c
index b331cde..342ed74 100644
--- a/gnu/usr.bin/ld/rtld/rtld.c
+++ b/gnu/usr.bin/ld/rtld/rtld.c
@@ -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: rtld.c,v 1.50 1997/11/29 03:32:47 jdp Exp $
+ *	$Id: rtld.c,v 1.51 1997/12/05 02:06:37 jdp Exp $
  */
 
 #include <sys/param.h>
@@ -174,6 +174,8 @@ struct somap_private {
 #define RELOC_PCREL_P(s) ((s)->r_pcrel)
 #endif
 
+#define END_SYM		"_end"
+
 static char		__main_progname[] = "main";
 static char		*main_progname = __main_progname;
 static char		us[] = "/usr/libexec/ld.so";
@@ -205,9 +207,10 @@ static void		*__dlsym __P((void *, const char *));
 static const char	*__dlerror __P((void));
 static void		__dlexit __P((void));
 static void		*__dlsym3 __P((void *, const char *, void *));
+static int		__dladdr __P((const void *, Dl_info *));
 
 static struct ld_entry	ld_entry = {
-	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit, __dlsym3
+	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit, __dlsym3, __dladdr
 };
 
        void		xprintf __P((char *, ...));
@@ -302,11 +305,13 @@ struct _dynamic		*dp;
 	struct so_map		*main_map;
 	struct so_map		*smp;
 	char			*add_paths;
+	char			*main_path;
 
 	/* Check version */
 	if (version != CRT_VERSION_BSD_2 &&
 	    version != CRT_VERSION_BSD_3 &&
 	    version != CRT_VERSION_BSD_4 &&
+	    version != CRT_VERSION_BSD_5 &&
 	    version != CRT_VERSION_SUN)
 		return -1;
 
@@ -335,6 +340,8 @@ struct _dynamic		*dp;
 		__progname = crtp->crt_ldso;
 	if (version >= CRT_VERSION_BSD_3)
 		main_progname = crtp->crt_prog;
+	main_path = version >= CRT_VERSION_BSD_5 ? crtp->crt_argv[0] :
+	    main_progname;
 
 	/* Some buggy versions of crt0.o have crt_ldso filled in as NULL. */
 	if (__progname == NULL)
@@ -363,7 +370,7 @@ struct _dynamic		*dp;
 	anon_open();
 
 	/* Make a link map entry for the main program */
-	main_map = alloc_link_map(main_progname,
+	main_map = alloc_link_map(main_path,
 			     (struct sod *) NULL, (struct so_map *) NULL,
 			     (caddr_t) 0, crtp->crt_dp);
 	LM_PRIVATE(main_map)->spd_refcount++;
@@ -453,7 +460,7 @@ struct _dynamic		*dp;
 	(void)close(crtp->crt_ldfd);
 	anon_close();
 
-	return LDSO_VERSION_HAS_DLSYM3;
+	return LDSO_VERSION_HAS_DLADDR;
 }
 
 void
@@ -2024,6 +2031,89 @@ resolvesym(fd, sym, retaddr)
 	return (void *)addr;
 }
 
+static int
+__dladdr(addr, dlip)
+	const void	*addr;
+	Dl_info		*dlip;
+{
+	struct _dynamic	*dp;
+	struct so_map	*smp;
+	char		*stringbase;
+	long		 numsyms;
+	int		 symsize;
+	int		 i;
+
+	/* Find the shared object that contains the address. */
+	for (smp = link_map_head;  smp != NULL;  smp = smp->som_next) {
+		struct so_map		*src_map;
+		struct somap_private	*smpp;
+		struct nzlist		*np;
+
+		smpp = LM_PRIVATE(smp);
+		if (smpp->spd_flags & RTLD_RTLD)
+			continue;
+
+		if ((void *)smp->som_addr > addr)
+			continue;
+
+		src_map = smp;
+		if ((np = lookup(END_SYM, &src_map, 1)) == NULL)
+			continue;	/* No "_end" symbol?! */
+		if (addr < (void *)(smp->som_addr + np->nz_value))
+			break;
+	}
+	if (smp == NULL) {
+		generror("No shared object contains address");
+		return 0;
+	}
+	dlip->dli_fname = smp->som_path;
+	dlip->dli_fbase = smp->som_addr;
+	dlip->dli_saddr = (void *) 0;
+	dlip->dli_sname = NULL;
+
+	dp = smp->som_dynamic;
+	symsize	= LD_VERSION_NZLIST_P(dp->d_version) ?
+	    sizeof(struct nzlist) : sizeof(struct nlist);
+	numsyms = LD_STABSZ(dp) / symsize;
+	stringbase = LM_STRINGS(smp);
+
+	for (i = 0;  i < numsyms;  i++) {
+		struct nzlist	*symp = LM_SYMBOL(smp, i);
+		unsigned long	 value;
+
+		/* Reject all except definitions. */
+		if (symp->nz_type != N_EXT + N_ABS &&
+		    symp->nz_type != N_EXT + N_TEXT &&
+		    symp->nz_type != N_EXT + N_DATA &&
+		    symp->nz_type != N_EXT + N_BSS)
+			continue;
+
+		/*
+		 * If the symbol is greater than the specified address, or
+		 * if it is further away from addr than the current nearest
+		 * symbol, then reject it.
+		 */
+		value = (unsigned long) (smp->som_addr + symp->nz_value);
+		if (value > (unsigned long) addr ||
+		    value < (unsigned long) dlip->dli_saddr)
+			continue;
+
+		/* Update our idea of the nearest symbol. */
+		dlip->dli_sname = stringbase + symp->nz_strx;
+		dlip->dli_saddr = (void *) value;
+
+		if (dlip->dli_saddr == addr)	/* Can't get any closer. */
+		    break;
+	}
+	/*
+	 * Remove any leading underscore from the symbol name, to hide
+	 * our a.out-ness.
+	 */
+	if (dlip->dli_sname != NULL && dlip->dli_sname[0] == '_')
+		dlip->dli_sname++;
+	return 1;
+}
+
 static void *
 __dlsym3(fd, sym, retaddr)
 	void		*fd;
diff --git a/include/link.h b/include/link.h
index 5ff1f78..9d80d45 100644
--- a/include/link.h
+++ b/include/link.h
@@ -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: link.h,v 1.16 1997/11/28 19:05:11 jdp Exp $
+ *	$Id: link.h,v 1.17 1997/12/06 17:59:52 jdp Exp $
  */
 
 /*
@@ -41,6 +41,8 @@
 #ifndef _LINK_H_
 #define _LINK_H_
 
+struct dl_info;
+
 /*
  * A `Shared Object Descriptor' describes a shared object that is needed
  * to complete the link edit process of the object containing it.
@@ -158,6 +160,7 @@ struct so_debug {
 #define LDSO_VERSION_NONE	0	/* FreeBSD2.0, 2.0.5 */
 #define LDSO_VERSION_HAS_DLEXIT	1	/* includes dlexit in ld_entry */
 #define LDSO_VERSION_HAS_DLSYM3	2	/* includes 3-argument dlsym */
+#define LDSO_VERSION_HAS_DLADDR	3	/* includes dladdr in ld_entry */
 
 /*
  * Entry points into ld.so - user interface to the run-time linker.
@@ -171,6 +174,8 @@ struct ld_entry {
 	const char *(*dlerror) __P((void));		/* NONE */
 	void	(*dlexit) __P((void));			/* HAS_DLEXIT */
 	void	*(*dlsym3) __P((void *, const char *, void *)); /* HAS_DLSYM3 */
+	int	 (*dladdr) __P((const void *,
+			        struct dl_info *));	/* HAS_DLADDR */
 };
 
 /*
@@ -229,6 +234,7 @@ struct crt_ldso {
 	char		*crt_prog;	/* Program name (v3) */
 	char		*crt_ldso;	/* Link editor name (v4) */
 	struct ld_entry	*crt_ldentry;	/* dl*() access (v4) */
+	char		**crt_argv;	/* argument strings (v5) */
 };
 
 /*
@@ -238,6 +244,7 @@ struct crt_ldso {
 #define CRT_VERSION_BSD_2	2
 #define CRT_VERSION_BSD_3	3
 #define CRT_VERSION_BSD_4	4
+#define CRT_VERSION_BSD_5	5
 
 /*
  * Maximum number of recognized shared object version numbers.
diff --git a/lib/csu/i386/Makefile b/lib/csu/i386/Makefile
index 15d1892..42907dc 100644
--- a/lib/csu/i386/Makefile
+++ b/lib/csu/i386/Makefile
@@ -1,10 +1,10 @@
 #	from: @(#)Makefile	5.6 (Berkeley) 5/22/91
-#	$Id: Makefile,v 1.32 1997/10/11 02:37:42 asami Exp $
+#	$Id: Makefile,v 1.33 1998/01/12 18:29:02 eivind Exp $
 
 CFLAGS+=        -DLIBC_SCCS -fno-omit-frame-pointer -I${.CURDIR}
 OBJS=		crt0.o c++rt0.o gcrt0.o scrt0.o sgcrt0.o
 CLEANFILES+=	a.out
-MAN3+=		dlopen.3
+MAN3+=		dladdr.3 dlopen.3
 MLINKS+=	dlopen.3 dlsym.3 \
 		dlopen.3 dlerror.3 \
 		dlopen.3 dlclose.3
diff --git a/lib/csu/i386/crt0.c b/lib/csu/i386/crt0.c
index b3884e4..80759cf 100644
--- a/lib/csu/i386/crt0.c
+++ b/lib/csu/i386/crt0.c
@@ -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: crt0.c,v 1.30 1997/08/02 04:56:33 jdp Exp $
+ *	$Id: crt0.c,v 1.31 1997/11/22 03:34:45 brian Exp $
  */
 
 #include <sys/param.h>
@@ -85,7 +85,7 @@ static int		_strncmp();
 
 extern struct _dynamic	_DYNAMIC;
 static struct ld_entry	*ld_entry;
-static void		__do_dynamic_link ();
+static void		__do_dynamic_link(char **argv);
 #endif /* DYNAMIC */
 
 int			_callmain();
@@ -174,7 +174,7 @@ start()
 	/* sometimes GCC is too smart/stupid for its own good */
 	x = (caddr_t)&_DYNAMIC;
 	if (x)
-		__do_dynamic_link();
+		__do_dynamic_link(argv);
 #endif /* DYNAMIC */
 
 asm("eprol:");
@@ -190,7 +190,8 @@ asm ("__callmain:");		/* Defined for the benefit of debuggers */
 
 #ifdef DYNAMIC
 static void
-__do_dynamic_link ()
+__do_dynamic_link(argv)
+	char	**argv;
 {
 	struct crt_ldso	crt;
 	struct exec	hdr;
@@ -253,14 +254,20 @@ __do_dynamic_link ()
 	crt.crt_prog = __progname;
 	crt.crt_ldso = ldso;
 	crt.crt_ldentry = NULL;
+	crt.crt_argv = argv;
 
 	entry = (int (*)())(crt.crt_ba + sizeof hdr);
-	ldso_version = (*entry)(CRT_VERSION_BSD_4, &crt);
+	ldso_version = (*entry)(CRT_VERSION_BSD_5, &crt);
 	ld_entry = crt.crt_ldentry;
 	if (ldso_version == -1 && ld_entry == NULL) {
-		/* if version 4 not recognised, try version 3 */
-		ldso_version = (*entry)(CRT_VERSION_BSD_3, &crt);
-		ld_entry = _DYNAMIC.d_entry;
+		/* If version 5 not recognised, try version 4 */
+		ldso_version = (*entry)(CRT_VERSION_BSD_4, &crt);
+		ld_entry = crt.crt_ldentry;
+		if (ldso_version == -1 && ld_entry == NULL) {
+			/* if version 4 not recognised, try version 3 */
+			ldso_version = (*entry)(CRT_VERSION_BSD_3, &crt);
+			ld_entry = _DYNAMIC.d_entry;
+		}
 	}
 	if (ldso_version == -1) {
 		_PUTMSG("ld.so failed");
@@ -334,6 +341,16 @@ dlerror()
 	return (ld_entry->dlerror)();
 }
 
+int
+dladdr(addr, dlip)
+	const void	*addr;
+	Dl_info		*dlip;
+{
+	if (ld_entry == NULL || ldso_version < LDSO_VERSION_HAS_DLADDR)
+		return 0;
+	return (ld_entry->dladdr)(addr, dlip);
+}
+
 
 /*
  * Support routines
@@ -419,12 +436,19 @@ const char *name;
 	return NULL;
 }
 
-
 const char *
 dlerror()
 {
 	return "Service unavailable";
 }
+
+int
+dladdr(addr, dlip)
+	const void	*addr;
+	Dl_info		*dlip;
+{
+	return 0;
+}
 #endif /* DYNAMIC */
 
 
diff --git a/lib/csu/i386/dladdr.3 b/lib/csu/i386/dladdr.3
new file mode 100644
index 0000000..97af8ce
--- /dev/null
+++ b/lib/csu/i386/dladdr.3
@@ -0,0 +1,121 @@
+.\"
+.\" 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.
+.\"
+.\"	$Id$
+.\"
+.Dd February 5, 1998
+.Os FreeBSD
+.Dt DLADDR 3
+.Sh NAME
+.Nm dladdr
+.Nd find the shared object containing a given address
+.Sh SYNOPSIS
+.Fd #include <dlfcn.h>
+.Ft int
+.Fn dladdr "const void *addr" "Dl_info *info"
+.Sh DESCRIPTION
+.Nm
+queries the dynamic linker for information about the shared object
+containing the address
+.Fa addr .
+The information is returned in the structure specified by
+.Fa info .
+The structure contains at least the following members:
+.Bl -tag -width "XXXconst char *dli_fname"
+.It Li "const char *dli_fname"
+The pathname of the shared object containing the address.
+.It Li "void *dli_fbase"
+The base address at which the shared object is mapped into the
+address space of the calling process.
+.It Li "const char *dli_sname"
+The name of the nearest run-time symbol with a value less than or
+equal to
+.Fa addr .
+When possible, the symbol name is returned as it would appear in C
+source code.
+.Pp
+If no symbol with a suitable value is found, both this field and
+.Va dli_saddr
+are set to
+.Dv NULL .
+.It Li "void *dli_saddr"
+The value of the symbol returned in
+.Li dli_sname .
+.El
+.Pp
+.Nm
+is available only in dynamically linked programs.
+.Sh ERRORS
+If a mapped shared object containing
+.Fa addr
+cannot be found,
+.Nm
+returns 0.
+In that case, a message detailing the failure can be retrieved by
+calling
+.Fn dlerror .
+.Pp
+On success, a non-zero value is returned.
+.Sh SEE ALSO
+.Xr dlopen 3 ,
+.Xr rtld 1
+.Sh HISTORY
+The
+.Nm
+function first appeared in the Solaris operating system.
+.Sh BUGS
+This implementation is bug-compatible with the Solaris
+implementation.  In particular, the following bugs are present:
+.Bl -bullet
+.It
+If
+.Fa addr
+lies in the main executable rather than in a shared library, the
+pathname returned in
+.Va dli_fname
+may not be correct.  The pathname is taken directly from
+.Va argv[0]
+of the calling process.  When executing a program specified by its
+full pathname, most shells set
+.Va argv[0]
+to the pathname.  But this is not required of shells or guaranteed
+by the operating system.
+.It
+If
+.Fa addr
+is of the form
+.Va &func ,
+where
+.Va func
+is a global function, its value may be an unpleasant surprise.  In
+dynamically linked programs, the address of a global function is
+considered to point to its program linkage table entry, rather than to
+the entry point of the function itself.  This causes most global
+functions to appear to be defined within the main executable, rather
+than in the shared libraries where the actual code resides.
+.It
+Returning 0 as an indication of failure goes against long-standing
+Unix tradition.
+.El
diff --git a/lib/csu/i386/dlfcn.h b/lib/csu/i386/dlfcn.h
index e167ef2..ba61ebf 100644
--- a/lib/csu/i386/dlfcn.h
+++ b/lib/csu/i386/dlfcn.h
@@ -50,11 +50,22 @@
  */
 #define RTLD_NEXT	((void *) -1)
 
+/*
+ * Structure filled in by dladdr().
+ */
+typedef struct dl_info {
+	const char	*dli_fname;	/* Pathname of shared object */
+	void		*dli_fbase;	/* Base address of shared object */
+	const char	*dli_sname;	/* Name of nearest symbol */
+	void		*dli_saddr;	/* Address of nearest symbol */
+} Dl_info;
+
 __BEGIN_DECLS
+int dladdr __P((const void *, Dl_info *));
+int dlclose __P((void *));
+const char *dlerror __P((void));
 void *dlopen __P((const char *, int));
 void *dlsym __P((void *, const char *));
-const char *dlerror __P((void));
-int dlclose __P((void *));
 __END_DECLS
 
 #endif /* !_DLFCN_H_ */
diff --git a/libexec/rtld-aout/rtld.c b/libexec/rtld-aout/rtld.c
index b331cde..342ed74 100644
--- a/libexec/rtld-aout/rtld.c
+++ b/libexec/rtld-aout/rtld.c
@@ -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: rtld.c,v 1.50 1997/11/29 03:32:47 jdp Exp $
+ *	$Id: rtld.c,v 1.51 1997/12/05 02:06:37 jdp Exp $
  */
 
 #include <sys/param.h>
@@ -174,6 +174,8 @@ struct somap_private {
 #define RELOC_PCREL_P(s) ((s)->r_pcrel)
 #endif
 
+#define END_SYM		"_end"
+
 static char		__main_progname[] = "main";
 static char		*main_progname = __main_progname;
 static char		us[] = "/usr/libexec/ld.so";
@@ -205,9 +207,10 @@ static void		*__dlsym __P((void *, const char *));
 static const char	*__dlerror __P((void));
 static void		__dlexit __P((void));
 static void		*__dlsym3 __P((void *, const char *, void *));
+static int		__dladdr __P((const void *, Dl_info *));
 
 static struct ld_entry	ld_entry = {
-	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit, __dlsym3
+	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit, __dlsym3, __dladdr
 };
 
        void		xprintf __P((char *, ...));
@@ -302,11 +305,13 @@ struct _dynamic		*dp;
 	struct so_map		*main_map;
 	struct so_map		*smp;
 	char			*add_paths;
+	char			*main_path;
 
 	/* Check version */
 	if (version != CRT_VERSION_BSD_2 &&
 	    version != CRT_VERSION_BSD_3 &&
 	    version != CRT_VERSION_BSD_4 &&
+	    version != CRT_VERSION_BSD_5 &&
 	    version != CRT_VERSION_SUN)
 		return -1;
 
@@ -335,6 +340,8 @@ struct _dynamic		*dp;
 		__progname = crtp->crt_ldso;
 	if (version >= CRT_VERSION_BSD_3)
 		main_progname = crtp->crt_prog;
+	main_path = version >= CRT_VERSION_BSD_5 ? crtp->crt_argv[0] :
+	    main_progname;
 
 	/* Some buggy versions of crt0.o have crt_ldso filled in as NULL. */
 	if (__progname == NULL)
@@ -363,7 +370,7 @@ struct _dynamic		*dp;
 	anon_open();
 
 	/* Make a link map entry for the main program */
-	main_map = alloc_link_map(main_progname,
+	main_map = alloc_link_map(main_path,
 			     (struct sod *) NULL, (struct so_map *) NULL,
 			     (caddr_t) 0, crtp->crt_dp);
 	LM_PRIVATE(main_map)->spd_refcount++;
@@ -453,7 +460,7 @@ struct _dynamic		*dp;
 	(void)close(crtp->crt_ldfd);
 	anon_close();
 
-	return LDSO_VERSION_HAS_DLSYM3;
+	return LDSO_VERSION_HAS_DLADDR;
 }
 
 void
@@ -2024,6 +2031,89 @@ resolvesym(fd, sym, retaddr)
 	return (void *)addr;
 }
 
+static int
+__dladdr(addr, dlip)
+	const void	*addr;
+	Dl_info		*dlip;
+{
+	struct _dynamic	*dp;
+	struct so_map	*smp;
+	char		*stringbase;
+	long		 numsyms;
+	int		 symsize;
+	int		 i;
+
+	/* Find the shared object that contains the address. */
+	for (smp = link_map_head;  smp != NULL;  smp = smp->som_next) {
+		struct so_map		*src_map;
+		struct somap_private	*smpp;
+		struct nzlist		*np;
+
+		smpp = LM_PRIVATE(smp);
+		if (smpp->spd_flags & RTLD_RTLD)
+			continue;
+
+		if ((void *)smp->som_addr > addr)
+			continue;
+
+		src_map = smp;
+		if ((np = lookup(END_SYM, &src_map, 1)) == NULL)
+			continue;	/* No "_end" symbol?! */
+		if (addr < (void *)(smp->som_addr + np->nz_value))
+			break;
+	}
+	if (smp == NULL) {
+		generror("No shared object contains address");
+		return 0;
+	}
+	dlip->dli_fname = smp->som_path;
+	dlip->dli_fbase = smp->som_addr;
+	dlip->dli_saddr = (void *) 0;
+	dlip->dli_sname = NULL;
+
+	dp = smp->som_dynamic;
+	symsize	= LD_VERSION_NZLIST_P(dp->d_version) ?
+	    sizeof(struct nzlist) : sizeof(struct nlist);
+	numsyms = LD_STABSZ(dp) / symsize;
+	stringbase = LM_STRINGS(smp);
+
+	for (i = 0;  i < numsyms;  i++) {
+		struct nzlist	*symp = LM_SYMBOL(smp, i);
+		unsigned long	 value;
+
+		/* Reject all except definitions. */
+		if (symp->nz_type != N_EXT + N_ABS &&
+		    symp->nz_type != N_EXT + N_TEXT &&
+		    symp->nz_type != N_EXT + N_DATA &&
+		    symp->nz_type != N_EXT + N_BSS)
+			continue;
+
+		/*
+		 * If the symbol is greater than the specified address, or
+		 * if it is further away from addr than the current nearest
+		 * symbol, then reject it.
+		 */
+		value = (unsigned long) (smp->som_addr + symp->nz_value);
+		if (value > (unsigned long) addr ||
+		    value < (unsigned long) dlip->dli_saddr)
+			continue;
+
+		/* Update our idea of the nearest symbol. */
+		dlip->dli_sname = stringbase + symp->nz_strx;
+		dlip->dli_saddr = (void *) value;
+
+		if (dlip->dli_saddr == addr)	/* Can't get any closer. */
+		    break;
+	}
+	/*
+	 * Remove any leading underscore from the symbol name, to hide
+	 * our a.out-ness.
+	 */
+	if (dlip->dli_sname != NULL && dlip->dli_sname[0] == '_')
+		dlip->dli_sname++;
+	return 1;
+}
+
 static void *
 __dlsym3(fd, sym, retaddr)
 	void		*fd;
diff --git a/sys/sys/link_aout.h b/sys/sys/link_aout.h
index 5ff1f78..9d80d45 100644
--- a/sys/sys/link_aout.h
+++ b/sys/sys/link_aout.h
@@ -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: link.h,v 1.16 1997/11/28 19:05:11 jdp Exp $
+ *	$Id: link.h,v 1.17 1997/12/06 17:59:52 jdp Exp $
  */
 
 /*
@@ -41,6 +41,8 @@
 #ifndef _LINK_H_
 #define _LINK_H_
 
+struct dl_info;
+
 /*
  * A `Shared Object Descriptor' describes a shared object that is needed
  * to complete the link edit process of the object containing it.
@@ -158,6 +160,7 @@ struct so_debug {
 #define LDSO_VERSION_NONE	0	/* FreeBSD2.0, 2.0.5 */
 #define LDSO_VERSION_HAS_DLEXIT	1	/* includes dlexit in ld_entry */
 #define LDSO_VERSION_HAS_DLSYM3	2	/* includes 3-argument dlsym */
+#define LDSO_VERSION_HAS_DLADDR	3	/* includes dladdr in ld_entry */
 
 /*
  * Entry points into ld.so - user interface to the run-time linker.
@@ -171,6 +174,8 @@ struct ld_entry {
 	const char *(*dlerror) __P((void));		/* NONE */
 	void	(*dlexit) __P((void));			/* HAS_DLEXIT */
 	void	*(*dlsym3) __P((void *, const char *, void *)); /* HAS_DLSYM3 */
+	int	 (*dladdr) __P((const void *,
+			        struct dl_info *));	/* HAS_DLADDR */
 };
 
 /*
@@ -229,6 +234,7 @@ struct crt_ldso {
 	char		*crt_prog;	/* Program name (v3) */
 	char		*crt_ldso;	/* Link editor name (v4) */
 	struct ld_entry	*crt_ldentry;	/* dl*() access (v4) */
+	char		**crt_argv;	/* argument strings (v5) */
 };
 
 /*
@@ -238,6 +244,7 @@ struct crt_ldso {
 #define CRT_VERSION_BSD_2	2
 #define CRT_VERSION_BSD_3	3
 #define CRT_VERSION_BSD_4	4
+#define CRT_VERSION_BSD_5	5
 
 /*
  * Maximum number of recognized shared object version numbers.
diff --git a/sys/sys/link_elf.h b/sys/sys/link_elf.h
index 5ff1f78..9d80d45 100644
--- a/sys/sys/link_elf.h
+++ b/sys/sys/link_elf.h
@@ -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: link.h,v 1.16 1997/11/28 19:05:11 jdp Exp $
+ *	$Id: link.h,v 1.17 1997/12/06 17:59:52 jdp Exp $
  */
 
 /*
@@ -41,6 +41,8 @@
 #ifndef _LINK_H_
 #define _LINK_H_
 
+struct dl_info;
+
 /*
  * A `Shared Object Descriptor' describes a shared object that is needed
  * to complete the link edit process of the object containing it.
@@ -158,6 +160,7 @@ struct so_debug {
 #define LDSO_VERSION_NONE	0	/* FreeBSD2.0, 2.0.5 */
 #define LDSO_VERSION_HAS_DLEXIT	1	/* includes dlexit in ld_entry */
 #define LDSO_VERSION_HAS_DLSYM3	2	/* includes 3-argument dlsym */
+#define LDSO_VERSION_HAS_DLADDR	3	/* includes dladdr in ld_entry */
 
 /*
  * Entry points into ld.so - user interface to the run-time linker.
@@ -171,6 +174,8 @@ struct ld_entry {
 	const char *(*dlerror) __P((void));		/* NONE */
 	void	(*dlexit) __P((void));			/* HAS_DLEXIT */
 	void	*(*dlsym3) __P((void *, const char *, void *)); /* HAS_DLSYM3 */
+	int	 (*dladdr) __P((const void *,
+			        struct dl_info *));	/* HAS_DLADDR */
 };
 
 /*
@@ -229,6 +234,7 @@ struct crt_ldso {
 	char		*crt_prog;	/* Program name (v3) */
 	char		*crt_ldso;	/* Link editor name (v4) */
 	struct ld_entry	*crt_ldentry;	/* dl*() access (v4) */
+	char		**crt_argv;	/* argument strings (v5) */
 };
 
 /*
@@ -238,6 +244,7 @@ struct crt_ldso {
 #define CRT_VERSION_BSD_2	2
 #define CRT_VERSION_BSD_3	3
 #define CRT_VERSION_BSD_4	4
+#define CRT_VERSION_BSD_5	5
 
 /*
  * Maximum number of recognized shared object version numbers.